The Bizarre World of Extreme
(or Low Frequency) Hearing Loss
(complete and unabridged)
(Click here to read the short, abridged version)
© April 2007 (latest revision June, 2014), by Neil Bauman, Ph.D.
Imagine a person with a hearing loss so severe he can’t
hear thunder rumbling overhead, yet, at the same time, has hearing so acute he
can hear a pin drop; or imagine a person that can’t hear you talking just 4 feet
away, yet clearly hears a whisper from across a large room; or imagine a person
that can’t hear a car motor running right beside him, yet can hear a single dry
leaf skittering along in the gutter 50 feet away.
“Impossible,” you say, “a person could never have such good
and bad hearing at the same time!”
Surprise! It’s true. Welcome to my world—the bizarre world
of people with extreme reverse-slope hearing losses.
What Is a Reverse-Slope (or Low Frequency) Hearing Loss?
Hearing losses are sometimes classified according to the
shape they form on an audiogram. They commonly go by strange names such as
ski-slope loss, cookie-bite loss, flat loss, reverse cookie-bite loss and
reverse-slope (or reverse curve) hearing loss. (My article
Kinds of Hearing
explains these different hearing losses and illustrates the various shapes they
form on audiograms.)
By far the most common kind of hearing loss is the typical
ski-slope loss where the line on the audiogram slopes down to the right.
In contrast, a reverse-slope loss (as its name implies) does the reverse and
slopes up to the right.
As a result this kind of hearing loss is sometimes referred
to as an up-sloping loss, a rising loss, or even a low frequency hearing loss,
but by far the most common name is the reverse-slope (or reverse curve) hearing
Don’t make the mistake of thinking that all reverse-slope
losses are the same. Nothing could be further from the truth. There is an
enormous difference in hearing between a mild gently-sloping reverse-slope
hearing loss, and a severe or profound steeply-sloping reverse-slope loss.
For practical purposes, we can group reverse-slope hearing
losses into three basic classes.
|Fig. 1. Ella's mild reverse-
Class 1. Perhaps the most common form of this
relatively-rare loss is a gently up-sloping line in the standard audiometric
frequencies between 250 and 8,000 Hz (Fig. 1). In this class, the worst
low-frequency hearing loss typically lies somewhere between mild and
Ella’s hearing fits this class. Her audiogram shows a 40 dB
loss at 250 Hz sloping up to around 25 dB at 1,000 Hz and reaching 10 dB by
4,000 Hz (Fig. 1).
|Fig. 2. Diane's mild reverse-
Diane has a bit worse reverse-slope loss. Her hearing loss
ranges from 50 dB at 500 Hz to 20 dB at 4,000 Hz (Fig. 2).
|Fig. 3. Severe reverse-slope
Class 2. Rarer, is a fairly-steep up-sloping
line in the standard audiometric frequencies. In this class, there is a moderate
to severe hearing loss in the frequencies below 1,000 Hz, but at the same time,
hearing becomes virtually normal somewhere in the range of 2,000 to 6,000 Hz
Lorene’s hearing loss falls into this category. She
explains, “The audiogram for my right ear starts at 90 dB at 250 Hz and rises to
30 dB at 8000 Hz.”
Class 3. The rarest form of the reverse-slope
loss reveals a steep up-sloping line ranging from 70 to 110 dB in the low
frequencies to incredible “dog-ears” hearing in the very high frequencies (those
frequencies above 8,000 Hz) (Fig. 4).
|Fig. 4. Neil's extreme reverse-slope loss
Years ago when I was around 20, my hearing ranged from 75
dB at 1,000 Hz to -30 dB above 16,000 Hz (Fig. 4). (Note: numbers above
the 0 dB line represent super-acute hearing, and are expressed as negative
numbers.) Hearing at -30 dB means you can hear sounds so faint that people with
normal (perfect) hearing can’t hear them at all. In fact, my very high frequency
hearing (well above 10,000 Hz) was at one time so sensitive that the energy
needed to produce the faintest sound I could hear needed to be multiplied 1,000
times before a person with “perfect” hearing could even begin to hear it!
That’s some incredible hearing. Since I could easily hear “silent” dog whistles,
some said I had “dog ears” hearing.
Reverse-slope hearing losses give rise to various degrees
of “weird” hearing. This is caused by two main factors. The first factor is the
amount (degree) of hearing loss we have in the low frequencies. This indicates
what sounds we will not hear. For example, if we have severe or worse
low-frequency hearing losses, we will not hear common loud sounds such as
thunder, car and truck motors running, fans whirring, and the speech sounds that
give speech most of its volume and fullness.
The second factor is the difference in volume (measured in
decibels) between the softest low-frequency sound we can hear and the softest
high-frequency sound we can hear. The greater this range, the weirder our
hearing losses become.
Notice that the total range of the reverse-slope loss in
Class 1 is not all that much—somewhere in the range of 30 dB. In the previous
examples, both Ella’s and Diane’s hearing losses only range 30 dB between their
worst and best frequencies. At this point, hearing loss is not all that strange,
but people with these losses begin to exhibit some of the characteristics of
those with more severe reverse-slope losses.
In Class 2 the range increases dramatically to somewhere
between 60 and perhaps 90 dB, and with this increased range, there is a marked
increase in the degree of hearing loss “weirdness.” Notice that Lorene’s hearing
loss has a range of 60 dB.
However, it is in Class 3, with its incredible range of
over 100 dB between the faintest low-frequency sound heard and the faintest
high-frequency sound heard that truly bizarre hearing is the most pronounced. My
hearing loss spanned an incredible range of 105 dB. No wonder people were always
confused about what I could, and could not, hear!
Incidentally, since hearing is normally only tested to
8,000 Hz (because the typical audiometers in use today are only calibrated to
8,000 Hz), an audiogram of people with incredible high-frequency hearing gives a
false impression of what that person really hears. In fact, people with my kind
of hearing loss have been sent to “shrinks” because the medical professionals
were so sure they were lying about what they could hear!
Therefore, if a person has a Class 2 or 3 reverse-slope
loss, it is imperative that their hearing be tested to at least 16,000
Hz. (and preferably to the highest frequency they can hear), and to the
softest sound they can hear, in order to properly diagnose their reverse-slope
loss. (Back to Table of Contents)
How Common Are Reverse-Slope (or Low Frequency) Hearing Losses?
Reverse-slope hearing losses are not common. Most
people with reverse-slope losses tend towards the milder form, but I have run
across a few people with severe to extreme forms like mine.
In fact, significant reverse-slope hearing losses like mine
are very rare. Out of roughly 38 million hard of hearing people in the USA and
Canada, only about 3,000 of us have this unusual hearing loss according to Dr.
Charles Berlin, formerly the head of the Kresge Institute in Louisiana, one
researcher that has studied this kind of hearing loss fairly extensively.
This means that only one person out of every 12,000 hard of
hearing people has a significant reverse-slope loss. No wonder hearing health
care professionals seldom see such cases. Consequently, there is little
authoritative information written on this subject. (Back to
Table of Contents)
Causes of Reverse-Slope (or Low Frequency) Hearing Losses
There are a number of causes of reverse-slope losses, but
the two most common causes seem to be certain genetic (hereditary) abnormalities
and Meniere’s Disease. (Back to Table of Contents)
When people think of causes of reverse-slope losses,
typically they think about Meniere’s disease. Classic Meniere’s disease does
indeed often, but not always, result in a reverse-slope hearing loss, at least
in the beginning stages. From what I have seen, reverse-slope losses due to
Meniere’s Disease tend to be more of the Class 1 kind of curve. (Back
to Table of Contents)
Probably the most common cause of reverse-slope hearing
losses, particularly in Classes 2 and 3, is of genetic origin. Hereditary losses
seem to run in our families more often than not. For example, Dolores explained,
“I think my reverse-slope hearing loss is genetic. My mother and sister have it
Reverse-slope hearing loss runs in my family—at least it
has for the past four generations. Those that I know of include my maternal
grandfather, my mother, myself, my brother, my younger daughter and my brother’s
older son. My hearing loss is the worst in the tribe, with my daughter’s poor
hearing coming in a close second. In addition, I know of other people who also
have reverse-slope hearing losses running in their families—at least for the
past 4 or 5 generations.
From the above, it appears that extreme reverse-slope
hearing losses are a dominant genetic trait. It certainly is in my
family. Each person born in my family has a 50% chance of having this kind of
In contrast, most other cases of genetic hearing loss seem
to stem from recessive genes. In such cases, there is only a 25% chance of each
child having a hearing loss (although there is a 50% chance of any child being a
carrier, but not having a hearing loss). Furthermore, if the hearing loss is
caused by a recessive gene, it may appear to skip several generations. This is
because in order for it to show up, both parents have to be carriers of
the same recessive gene.
Another interesting characteristic of severe or extreme
reverse-slope hearing losses such as mine is that they are non-syndromic—that
is, they don’t have any other conditions or syndromes associated with them. This
is also in contrast to many cases of hearing loss from recessive genes where
various syndromes are associated with these hearing losses.
I think many people, including doctors, stretch to find
obvious causes for these hearing losses—and fail to realize that they really may
be hereditary. For example, my mom was knocked down and run over by a street car
when she was 5 or 6. When they noticed that she had poor hearing after that,
they attributed it to the head trauma she sustained in that accident—yet it is
now obvious that she really had an hereditary reverse-slope loss that she passed
on to me and my brother. (Back to Table of Contents)
Various childhood diseases are also thought to sometimes
result in reverse-slope hearing losses. For example, Debbie wrote, “I acquired
my loss from a rare illness when I was four years old. My daughter also shares
my type of loss, although it has never been concluded that it is genetic in
nature. Like me, she was not born with a hearing loss but acquired it from
complications of chicken pox at age 2. The complications led to the same serious
disease that I had when I was four.”
Judith explained, “My hearing loss apparently was the
result of measles at the age of 2. My audiologist says I have reverse-slope
hearing loss.” (Back to Table of Contents)
How Reverse-Slope Hearing (or Low Frequency) Losses Progress
Whether reverse-slope losses get worse with time depends on
what caused the loss in the first place. In general, it doesn’t seem that
reverse-slope losses progress much differently from other kinds of hearing
losses with two notable exceptions. (Back to Table of
One of the characteristics of Meniere’s Disease is that it
results in a progressive, fluctuating step-wise hearing loss. Thus if you have
Meniere’s Disease, initially you may have a Class 1 type of reverse-slope loss.
Over time, as your Meniere’s Disease progresses, you will likely find that this
reverse-slope loss slowly evolves into a reverse cookie-bite or flat loss and
ultimately into some degree of a severe or profound ski-slope loss. (Back
to Table of Contents)
With hereditary reverse-slope losses, we seem to go through
three distinct stages.
Stage 1: The first stage occurs from birth to around
5 years of age. It appears that although there is some degree of hearing loss at
birth, hearing in the lower frequencies rapidly decreases until around age 5 or
When my daughters were born, we were expecting one of them
to be hard of hearing. Thus, we carefully observed them from birth in order to
watch for any developing hearing loss. As a result, my hard of hearing daughter
had several audiograms in her early childhood years which documented her
increasing hearing loss from birth to age 5.
Furthermore, it seems that because of our excellent
high-frequency hearing and because of our good speechreading skills at a very
early age (of which our parents are typically totally unaware), our hearing
losses do not become apparent until something traumatic happens as was the case
with my mother (mentioned above), or something happens to drive home the fact
that we cannot hear well.
For example, my parents didn’t discover I had a hearing
loss until I was about 4 or 5. One day my dad, who was standing behind me where
I couldn’t speechread him, asked, “Do you want to come for a ride in the car
with me?” I totally ignored him, and continued playing on the floor. He knew
something was wrong because I loved riding in the car! (It was a ‘29 Buick in
those days.) Another time he asked me if I wanted some ice cream—which I still
love—and again I ignored him. It was at this point that my parents had my
hearing tested and discovered I had a severe hearing loss!
Stage 2: The second stage goes from about age 5 to
around age 50 (if there are no other factors involved such as hearing loss from
noise damage or from taking ototoxic drugs, for example).
The good news is that in stage 2, hearing loss doesn’t
change much if at all. It remains stable through childhood, and early and middle
adulthood. Debbie explained, “My hearing has for the most part, remained stable
for as long as I can remember.” This has been my experience too, and my mother’s
and daughter’s experience as well.
Thus, once we learn to adapt to our strange hearing losses,
our coping strategies can remain the same for most of our lives.
Stage 3: The third stage kicks in about age 50 and
continues for the rest of our lives. This is not really our reverse-slope
hearing loss progressing, but rather, the effects of aging dramatically
impinging on our precious high-frequency hearing. Here’s what happens.
|Fig. 5. Average hearing loss with increasing
As people age, they typically begin to lose their
high-frequency hearing. This happens slowly and insidiously over many years.
Fig. 5 plots “average” curves showing increasing high-frequency hearing loss
from ages 40 (top line) to age 80 (bottom line).
The fact that people normally lose much of their
high-frequency hearing as they age has some important ramifications for those of
us with reverse-slope losses.
Notice that people with the typical ski-slope losses have
already lost their high-frequency hearing (but retain their low-frequency
hearing). Thus as they age, they don’t have much high-frequency hearing left to
In contrast, those of us with extreme reverse-slope losses
have most of our residual hearing in the high (and very high)
frequencies, yet it is these very frequencies that people typically lose as they
get older. As a result, somewhere around age 50 or so we begin to notice a
significant drop in our hearing. Our reverse-curve loss rapidly begins to
flatten and in time becomes more or less a flat curve.
|Fig. 6. Neil's reverse-slope loss at age 59
For example, between age 50 and age 60, I lost a lot of my
excellent high-frequency hearing. As a result, I don’t hear much at all any
more—but this is the result of aging, rather than from a progressive
reverse-slope hearing loss.
To verify this, compare my audiogram taken at around age 21
(Fig. 4) with my current audiogram (Fig. 6) taken at age 59. As you can see, I
have lost much of my high-frequency hearing. I no longer hear many of the
familiar high-frequency sounds I used to depend on. Now I am having to learn
other coping skills to make up for this loss. My world is rapidly becoming more
and more silent. Eventually, if I follow my mother's pattern, I’ll probably have
a flat “curve” at around 80 dB or so.) (Back to Table of
Characteristics of Reverse-Slope (or Low
Frequency) Hearing Losses
What It’s Like to Live with a Reverse-Slope Hearing Loss
Having a Class 2 or 3 reverse-slope loss makes for some
interesting experiences. Here are some of the things that we hear, or don’t
hear, and how we cope with it.
- We don’t hear normal sounds that tell us that certain appliances
are running. For example, I have to put my hand on some of my household
appliances and feel the vibrations in order to know if they are running, or
watch them for movement. Furthermore, I can’t hear the low-frequency hum of the
furnace, fridge, washer, drier, dishwasher, etc. so, likewise, in order to know
if they are running, I have to put my hand on them (or look at the dials).
However, the interesting thing is that we can easily hear the faint clicks of
the relays kicking in/out to start/stop all these appliances. Thus, we can tell
when they start or stop—we just don’t know whether they just started or just
stopped. Lorene echoes my experiences when she explains, “I can hear the fridge
kicking in, but can’t hear it when it is running.”
- When hard of hearing people get together in a room, those with
ski-slope hearing losses complain how the noisy heating and air conditioning
systems drown out speech, yet, without our hearing aids, we don’t even know
these devices are making sounds at all!” These sounds certainly don’t bother us!
- In noisy conditions such as in mills and manufacturing plants,
hearing people have to shout over all the low-frequency noise around them. Since
we don’t hear low-frequency sounds well, we clearly hear the people shouting.
That’s the one situation where I tell people (tongue in cheek), “You don’t have
to yell at me. I’m not deaf!”
- Since loud low-frequency sounds mask softer high-frequency sounds,
and since we don’t hear low-frequency sounds well, the softer high-frequency
sounds stand out clearly to us. When we hear such soft high-frequency sounds,
people think we must have incredible hearing, not that we are almost deaf. No
wonder hearing people sometimes don’t think we are hard of hearing at all!
- Our hearing is exactly backwards to that of the typical hard of
hearing person. As Debbie explains, “I have near normal hearing in the high
frequencies, but my hearing drops off in the low and speech frequencies.” This
is just the opposite of what people with ski-slope losses have. Thus most things
they hear, we don’t, and most things we hear, they don’t.
- We generally can’t hear car motors running. This can make for some
interesting experiences in parking lots. As a result, we need to use our eyes
and watch for back-up lights and/or brake lights coming on if we are walking
behind cars, or watch for their driving lights coming on if we are in front of
- Since I can’t hear my car’s motor running, sometimes when I am
parked I may try to start my car a second time thinking it hadn’t started. The
suddenly-swiveled heads of the people nearby tell me that I just ground the
gears on the starter—again! Now, since modern cars have tachometers, I always
look at the tachometer first. If it’s not reading 0, I leave the starter alone!
- I hear squeaking fan belts and squealing brakes very well. Often
that is all I hear of motor vehicles approaching me, or running nearby.
- The screech of the wheels of trains on the tracks is so loud to me
that it hurts my ears—yet to most people this is not even a loud sound. Imagine
not being able to hear the loud roar of a train bearing down on you, yet getting
headaches from the painfully-loud screech (to me) of the train wheels against
the tracks as the train goes around a curve. This includes modern light rail
systems in most big cities.
- We don’t hear the low-frequency sounds of things like big
18-wheelers rumbling beside us, but when their air compressors bleed off with a
“pshhhhhh,” that sound is so loud that it is one of the few outside sounds I can
hear from inside a building.
- We can hear whispers from considerable distances. For example, in
school, I used to hear kids whispering from across the classroom, yet couldn't
hear the teacher talking only a few feet away. (I always had to speechread my
teachers to know what they were saying.) It always puzzled me that the teachers
never heard all the whispering that to me was so loud.
- We can hear phones ringing—especially if they have the old style
bells for ringers—but can’t hear people talking on them. For example, I could
clearly hear the phone ringing in my mom’s house while I was standing on the far
side of the highway across from her house, even though her house was set back
from the road a ways, the phone was mounted on an inside wall and the doors and
windows were shut. Debbie has similar hearing to mine and relates, “I hear the
alarm and phone ringing even when my hearing husband doesn't!” With such
incredible hearing, people can’t understand why pressing the receiver tight
against our ears still doesn’t let us hear and understand the person on the
other end unless we have special amplified phones.
- When it comes to using phones, we are at a decided disadvantage.
You see, the high frequencies upon which we depend are deliberately chopped off
to save “bandwidth.” Standard commercial phones are designed to have a flat
frequency response from about 300 Hz to 3,400 Hz. After that, the frequency
response drops off sharply. As a result, even when we use special amplified
phones to give us the overall volume we need, we still find speech difficult to
understand because the sound signal lacks the high-frequency component we so
much rely on to give speech its intelligence.
- We can easily hear sounds most people don’t hear. For example,
when I was younger, I could easily hear the inaudible (to most people) 15,734 Hz
whine produced by the fly-back transformer of a TV from anywhere in the house,
and even from outside the house, yet I had to put my ear about 6 inches
from the TV’s speaker in order to understand any speech from it (if the volume
was set to normal hearing levels).
- We hear insects that other people don’t seem to hear well, if at
all. To me, certain insects chirping from a block away (even just one insect)
produce a racket loud enough to drown out the voice of a person standing almost
nose-to-nose speaking to me. The “funny” thing (to me) is that people with
normal hearing either can’t hear that insect at all, or only hear it very
- We hear some birds singing and chirping away, but not others. For
example, I have never heard the low-frequency sounds of an owl hooting or a
Mourning Dove cooing (although I have a flock of Mourning Doves right outside my
back door). I cannot hear a large flock of geese honking overhead, unless they
are flying almost at ground level, yet I can easily hear a male hummingbird’s
high-pitched angry squeaks as it chases off a competitor, or the wonderful
trilling sounds it makes as it power dives to impress its prospective mate.
- Water running in the sink typically drowns out any speech for us.
We have to turn the water off in order to converse.
- We cannot understand what is said via public address systems. As
Lorene explains, “I cannot understand any announcements in stores or malls.”
This is my experience too.
- We hear women’s higher-pitched voices better than men’s
lower-pitched voices—exactly the opposite of those with the more-common kinds of
- When inside, we do not hear traffic going by outside the house.
Traffic noise definitely does not disturb our sleep!
- Road noise does not bother us much, even when the windows are
- We can hear sirens if we are outside and they are close by.
However, if we are in our cars or houses, we don’t hear a thing. For example,
for 10 years I lived right beside the fire hall and the fire trucks could roar
out with their sirens blaring and I’d not hear a thing if I was inside the
house. (Since I was a fireman, it would have been a bit embarrassing if they had
left without me!)
- We hear/don’t hear the strangest things. For example, I can hear a
dry leaf skittering down the street from 50 feet away, but can’t hear a car
motor running right beside me.
- We do not hear somebody coming up behind us on a bicycle, and, as
Lorene relates, “scaring the life out of me as they whiz past.”
- We cannot hear jets flying overhead when we are outside.
- We only hear thunder when it is very loud and almost
overhead. We seldom hear the rain beating on the windows—unless it is a violent
storm driving the rain into the glass, or there is hail or ice in the rain. Even
then, we only hear the high-frequency component of the sound hail makes when
hitting the windows.
- Although we have severe hearing losses in the speech frequencies,
we can easily hear faint high-frequency sounds such as a pin dropping on a table
or hard floor. Sarah explains, “I have a 60-80 dB reverse-slope hearing loss. I
can hear a pin drop, but normally can’t hear thunder! I’m the same. I can easily
hear pins dropping, but not thunder unless it is very loud.
- We don’t hear strange noises outside. (What? You mean there are
strange noises outside!) That's like the hearing person who asked a group of us
(hard of hearing people) if it bothered us when people talked about us behind
our backs and we replied, “They do?”
- Sound deadening tiles deaden the higher-frequency sounds we
normally hear. Thus, we find it more difficult to hear in rooms with acoustical
tile since the purpose of the tile is to absorb the high-frequency noises most
people find annoying, but to us are critical to understanding what we are
- Adjusting the treble on a radio or stereo changes the volume for
us. As strange as it my seem, for years I couldn't tell much difference between
the treble control and the volume control on a radio or stereo. Turning up the
treble made the sound louder, just like turning up the volume control did. I can
remember when my wife would turn on the radio, and if it was bothering me I’d
just turn down the tone until I couldn’t hear it—and both of us were happy. (I
could also precisely tune (zero-beat) a radio to an FM station I couldn’t even
hear. I would just tune it for no “hiss” or “whistle” and when it was in perfect
tune, I couldn’t hear a thing! My wife could never do that with her normal
hearing. (Back to Table of Contents)
Reverse-Slope Losses vs. Ski-Slope Losses
There are some very real differences between how we
perceive speech as compared to how people with ski-slope losses hear speech.
Naturally, the worse our hearing is, the more pronounced these differences
These differences are largely the result of the following 6
basic facts concerning speech and hearing. I think you will find this very
- Speech is composed of vowels and consonants. Vowels
are loud sounds while consonants generally are softer sounds. In
fact, roughly 95% of speech energy goes into producing the 5 vowel sounds. This
means that only 5% of speech energy is left to produce the 21 remaining
- Vowels basically produce lower-frequency
sounds, while many consonants produce higher-frequency sounds.
- Most of the volume of speech comes from the
- Most of the intelligence of speech is
contained in the (higher-frequency) consonants. Thus, to a large extent, vowels
give speech its volume, while consonants give speech its intelligence. You can
easily prove this. Write out a sentence, then take out all the vowels leaving
blanks—and show it to someone, and they, with a bit of reflection, will be able
to fill in the blanks and read the sentence correctly. Now try the same
sentence, but with all the consonants removed. The sentence is impossible to
decipher. If you tried pronouncing it, all you would hear is something akin to
an Indian chant or war-cry.
- Low-frequency sounds travel considerable distances
- High-frequency sounds are quickly attenuated in air
so they don’t travel very far.
Now let’s put all these facts together and see exactly what
it means to those of us with reverse-slope losses as opposed to those with the
common ski-slope losses. Many of the coping skills you read about are for people
with ski-slope losses, not for those of us with reverse-slope losses.
1. If you have a ski-slope loss you hear the loud
vowel sounds, but not the soft consonants. Thus you hear people talking with no
problem, but because most of the intelligence of speech is in the consonants,
you don’t understand what people are saying. To you, speech sounds muffled
because you don’t hear the high-frequency sounds. Thus you want more clarity.
In contrast, those of us with reverse-slope losses hear the
soft high-frequency consonant sounds. Thus speech is thin, almost inaudible and
often sounds like whispers. For example, as I approach someone talking, the
first sounds I hear are the high-frequency voiceless “s” sounds. This is how I
know someone is talking. We do not really hear a person talking until we get
very close so we can hear the “voiced sounds.” Fortunately, we generally
understand speech when it is finally loud enough for us to hear it. Thus we
typically need more volume.
One of the “rules” when speaking to a hard of hearing
person (really meaning those with ski-slope losses) is that you do not “yell” at
them, but speak in a normal volume. Since they need clarity, not more volume,
they want you to speak at a normal level, but speak slowly and clearly to enable
them to catch the high-frequency consonantal sounds as best they can.
This approach is totally wrong for those of us with
reverse-slope losses. We need people to speak louder in order to
hear speech in the first place because we do not hear the low-frequency sounds
that give speech much of its volume.
2. If you have a ski-slope loss, you can hear people
talking from a considerable distance because low-frequency vowel sounds travel
well in air. As a result, you can hear a person calling to you from a distance.
Thus, you would turn around at a shouted warning (to see what the racket was
However, those of us with reverse-slope losses cannot hear
people until we are almost nose-to-nose with them because we don’t hear the
vowel sounds that give speech its volume and ability to travel far in air. As a
result, we don’t hear people calling to us from any distance at all, so we often
do not respond to shouted warnings.
3. Another bit of “common wisdom” is that hard of
hearing people hear men better than women and children. This is true for people
with the typical ski-slope losses because they hear the louder, lower-pitched
voices of men better since they hear low-frequency sounds best. Women and
children with their higher-pitched (and often softer) voices are much more
difficult for them to hear and understand.
This “wisdom” is also totally wrong for those of us with
reverse-slope losses. Since we hear the higher-frequency sounds best, we
typically hear women’s voices better than men’s voices. As Rusty says, “Men’s
voices have been difficult for me to hear.” I, too, much prefer talking to women
as their voices are higher pitched and more in tune with my ears. Their high
soprano voices are so lovely for me to hear and understand. Debbie explains, “I
do not use the phone unless it is someone I can understand, namely a
high-pitched female voice.”
Unfortunately for us, women don't put as much sound energy
into their voices as men do. Thus, we can’t hear them from any distance, but
close up they are so easy to hear and understand. As a result, I normally stand
almost nose-to-nose when I am talking to someone. I remember talking to my hard
of hearing friend Elizabeth. We were out in the middle of a big, almost-empty
arena—yet we were standing there nose-to-nose enjoying our chat.
4. People with ski-slope losses can’t hear whispers.
Surprisingly enough, those of us with reverse-slope losses
hear whispers very clearly—even from across a room. My former mother-in-law
wouldn’t believe my hearing was as bad as it was because she would whisper when
she didn’t want me to hear something, and I would hear her. (She never got it
through her head that if she just spoke in a normal voice, I wouldn’t have
understood a thing!)
To me, whispering seemed quite loud, so when I used to
“whisper,” I’d actually use “low voice” (which to me sounded very faint as
compared to whispering). To my chagrin, everyone around me heard me
“whispering.” My wife kept telling me to “whisper.” It eventually dawned on me
that others couldn’t hear the whispers I so easily heard.
5. If you have a ski-slope loss, you can’t hear in the
presence of low-frequency noise.
In contrast, we typically hear better in “noisy”
situations (if the noise is all low-frequency sounds) because we don’t hear
these louder low-frequency sounds much, and people in noise tend to speak
up (or shout) in such situations. Since we need more speech volume anyway, this
is exactly what we need in order to hear.
Because people with normal hearing lower their voices in
quiet situations so much that they are inaudible to me, I use a sneaky trick to
“force” them speak up. For example, if I am outside mowing the grass or
rototilling the garden and someone wants to talk to me, I generally leave the
motor on—just idling—so they have to speak up (over the noise). That way I can
then hear them much better. I discovered that if I turned the motor off, they
would lower their voices and I couldn’t hear them at all. This is just one of
the tricks I use to cope with my weird hearing loss.
6. A person with a ski-slope loss can hear a car or
truck approaching from a distance because they hear the low-frequency sounds of
the motor. For example, I was once talking with a hard of hearing farmer with
the typical high-frequency hearing loss. He heard a truck approaching while it
was still half a mile down the road and turned to see who was coming. In
contrast, I never heard a sound even when the truck turned into the farm yard
and stopped right in front of me!
Since we don’t hear low-frequency sounds, being around
moving vehicles can be dangerous to us. Thus, we have to rely on our eyes.
Furthermore, we can’t rely on our ears alone when crossing roads. Crossing
streets is particularly dangerous for us when it is foggy and we neither can see
nor hear vehicles approaching.
7. People with ski-slope losses don’t hear
high-frequency sounds, and thus aren’t bothered by them.
In contrast, high-pitched sounds may hurt our ears but not
bother people with normal hearing. Thus, they discount the pain we feel from
such sounds. This is particularly true for those of us who have Class 2 or 3
reverse-slope losses. Debbie explains, “Sometimes high-pitched sounds seem so
loud they hurt my ears.” I have the same problem. Another lady explained, “The
things that bring me out of my seat are the screaming crowds at sports games on
TV and small children’s shrill voices.” (Back to Table of
Supersensitivity to High-Frequency Sounds
Those of us with Class 3 reverse-slope losses have
super-acute hearing in the very high frequencies. For example, Kathi wrote, “I
used to be able to hear dog whistles, bats, and all kinds of crazy things that
other people couldn’t hear. It never occurred to me that I should tell my ENT
doctor about it.” Rusty related, “I hear high-pitched sounds that drive me
bats—like the Celtic flute and bagpipes.” Personally, I love listening to
bagpipes! (I guess it is the Scot in me.)
Paul revealed, “I could hear a watch
alarm go off 100 yards away but couldn’t understand speech at all. I was
supersensitive to high frequency sounds.” Grant explained, “I recall as a cub
scout having someone come in with some sound equipment. One of the things he did
was to try to get people to hear some really high-pitched noise. I could still
hear it when all the others couldn’t. Shirley confessed, “Chirping birds drive
me nuts! I also respond well to dog whistles!”
I also used to hear “silent” dog whistles and other
high-frequency sounds that no one around me could hear. In fact, I had a silent
dog whistle years ago—my idea was to give it to my partner when I was timber
cruising—and we could communicate like that without disturbing other people
around us. However, it didn't work out in practice. First, it was so shrill to
me that it gave me an instant headache. Second, since high-frequency sounds
attenuate very fast in air, I couldn’t hear it from any distance at all.
Because we hear sounds that people with normal hearing
can’t, it is hard for anyone to believe that we are as deaf as we are. At the
same time, these high-frequency sounds may be very loud to us and hurt, and no
one can understand why we are cringing, when these sounds seem normal, or faint,
to them. (Back to Table of Contents)
Music Appreciation and Reverse-Slope Losses
Another aspect of Class 2 and 3 reverse-slope hearing
losses is that we experience music much differently than do people with normal
hearing. For example, when listening to acoustical guitars, all I heard was the
pick, pick, pick sound of the pick on the strings, not the tones the strings
themselves produced. For many years, I wondered why anyone would make and play
such a “stupid” musical instrument—one that didn’t even produce musical sounds!
At the other end of the music spectrum, piccolos and flutes are so shrill and
thin and “hissy” that the sounds they produce sound more like fingernails
screeching on a blackboard than beautiful music. This was Marge’s experience
also. She explains, “I have never really enjoyed, or been able to hear, music
that was pleasant to me. I hear only high tones, so ‘real music’ is all
irritating and ‘screechy’.”
Since I was born with a severe reverse-slope loss, I don't
know what music really should sound like either. However, I love music and enjoy
what little music I can hear.
However, to be really enjoyable, music has to be transposed
to the octaves that make it come alive for us. For example, one lady with
reverse-slope hearing loss tried a special hearing aid designed specifically to
transpose low-frequency sounds to higher-frequency sounds. She reported, “So
stirring was the music that suddenly I began to cry. The beauty of the sounds I
was hearing was almost torture—I simply couldn’t get enough of it.”2
That is my experience too. In one church I used to attend,
I once told the organist how my strange hearing only let me really enjoy music
played in a certain narrow range, and with no harmony accompanying the melody.
From then on, each Sunday, Ruth would transpose and play a piece at the specific
pitch my ears hear best—so I too, could really enjoy the music (at least part of
the time). Everyone else in the congregation thought she is just utilizing all
the different voices the electric piano had—but she really did it for me. That
music was so beautiful, tears would well up in my eyes, and my soul really
soared listening to it. (Back to Table of Contents)
Speech Quality and Reverse-Slope Losses
One of the things that surprises many people is that all of
us with severe reverse-slope losses have perfectly-normal or near-normal speech.
Imagine a person that is essentially deaf, yet has flawless enunciation,
perfectly-formed and well-modulated speech, all without having had any speech
therapy. This is one of the blessings of having a severe reverse-slope hearing
Debbie relates, “Both my daughter Heather and I have
perfect speech, which is one of the bonuses of having this strange hearing
loss.” Shirley explains, “Because I have high-frequency hearing, my voice has
never been affected by my hearing loss, although my hearing loss is profound.”
By perfectly-normal speech, I mean speech that is
indistinguishable from the speech produced by people with normal hearing.
Given the degree of our hearing losses in the speech range, you would expect us
to produce the “flat” or “deaf” speech so prevalent in those with severe and
profound hearing losses, but we don’t.
In a three-way study comparing the speech of people with
normal hearing to people with reverse-slope losses, and to people with ski-slope
losses, every person that received an “A” (excellent) for speech (meaning their
speech sounded virtually as if the person had no hearing loss at all) either had
normal hearing, or had considerable high-frequency hearing (hearing above 8 kHz,
i.e. a reverse-slope hearing loss). In contrast, every person that received an
“F” (failure) for speech had measurable hearing only in the frequencies below 3
kHz (i.e. had a ski-slope hearing loss).3
Because my speech is also indistinguishable from the speech
of people with normal hearing, I’ve had many people refuse to believe how bad my
hearing really is. I am talking about hearing health care professionals, not
just the man on the street. It is impossible to tell that I have a hearing loss
from my speech (unless, on the rare occasion, you hear me mispronounce a word
that I’ve never heard spoken aloud before).
Peggy, herself hard of hearing, after hearing me speak,
exclaimed, “Do you realize that your speech is absolutely perfect? You must have
worked very hard to perfect your tone like that what with growing up hard of
The surprising truth is that those of us with severe
reverse-slope losses don’t need speech therapy. My perfectly-normal
speech just came naturally. I’ve never had, or needed, speech therapy.
In contrast, it is a rare person that has a severe or worse
ski-slope hearing loss that speaks normally. Some deaf, or profoundly hard of
hearing, people do have excellent speech. In fact, I am amazed how well they
speak considering they haven’t heard anything for years. For example,
Hilda—totally deaf for years—has excellent speech, but it is not perfect. Her
good speech comes from excellent speech memory, plus extensive speech therapy
and regular “touch-up” speech therapy sessions from time to time.
All this speech therapy is not necessary for those of us
with reverse-slope hearing losses. Back in 1978, Dr. Chuck Berlin realized that
“one of the interesting characteristics of people with significant reverse-slope
hearing losses in the severe to profound range is that they have unusually good
speech. This capability has usually been attributed to post-lingual hearing loss
or to unique methods of oral speech training.” However, it seems that the secret
to our excellent speech is that we have good hearing in those frequencies above
the traditional frequencies tested (i.e. above 8,000 Hz).4
In fact, the real secret to perfectly-normal speech is
hearing all speech frequencies, especially the high-frequency consonants
such as “s,” “f,” “sh,” “ch,” “t,” and “th.” These high-frequency consonants do
not have any “voice.” They are simply produced by air hissing between the teeth,
and around the tongue, in various ways.
When you can’t hear these sounds, it is very difficult to
produce them properly. In fact, I can tell if a person is hard of hearing just
by the way they move their lips when they try to produce these sounds. Think how
difficult or impossible it would be to learn to whistle if you couldn’t hear any
of the sounds you were trying to produce. In like manner, these voiceless sounds
depend so much on aural feedback—meaning you listen to the sound you make, and
if it isn’t “right on” you immediately correct it. If you cannot hear it, you
don’t get this feedback so you don’t correct these sounds, and your poor speech
Since those of us with severe reverse-slope losses hear
these “voiceless” sounds the best, we use them correctly in our speech and thus
avoid the flat “deaf speech” patterns of those with the typical ski-slope
Let me illustrate the contrast between reverse-slope and
ski-slope losses by examining the word “stop.” It is composed of 3 voiceless
consonants. These consonants—“s,” “t” and “p”—are actually just air forced out
of the mouth without any sound produced by the vocal cords. It contains one
vowel “o” that produces vocal sound.
Breaking it down into the sounds of the individual letters,
here is what actually happens.
s - air hissing between the teeth—a very high frequency
t - a burst of air released from behind the teeth—another
high frequency sound.
o - a loud lower-frequency vowel sound produced by the
p - a puff of air from the cheeks forced between the lips.
Now, if you have the typical ski-slope loss where you hear
low-frequency sounds quite well, and do not hear high frequency sounds much, if
at all, when someone says the word “stop” all you hear is the loud “short oh”
sound “awe” and thus, that is what you repeat.
However, those of us with severe reverse-slope losses hear
the voiceless sounds of the “s,” “t” and “p” and, because the “o” is a loud
sound, we likely hear a bit of it too. Thus, we hear the whole word
correctly—assuming it is loud enough for us to hear in the first place,
otherwise we’d hear nothing. Because we hear all the sounds in the word, we also
naturally produce them correctly when we speak.
Another interesting characteristic of those of us with
severe reverse-slope hearing losses is that while our speech is perfectly
normal, we may pitch our voices somewhat higher than normal. Thus, for example,
you might think I was a baritone rather than a bass. However, when we wear
properly-fitted hearing aids a surprising thing happens. Instantly our voices
pitch themselves to normal.
The reason we pitch our voices higher is so we can better
hear our own voices when we speak. This is a totally subconscious reflex. I have
never been aware of it myself. However, people tell me that when I put my
hearing aids on, the pitch of my voice drops instantly.
Dr. Berlin found the same thing in his research. Some years
ago, he helped develop a special hearing aid designed specifically for those of
us with severe reverse-slope losses. In one case, he noted that whenever a
certain young lady wore her special hearing aid, “the fundamental frequency of
her voice dropped sharply and the vowel formant frequencies became normal.” He
added, “The most remarkable and consistent observation in successful users is
the sudden drop in fundamental frequency of the voice, even within the first few
seconds of use.”5 (Back to Table of Contents)
Hearing Testing and Reverse-Slope (or Low Frequency) Hearing Losses
Reverse-Slope Losses Often Misdiagnosed
One of the tragic characteristics of having a severe
reverse-slope loss is that in the past, hearing health care professionals have
often misdiagnosed us. Since ski-slope losses are so common, few hearing health
care professionals realize just how differently those of us with severe
reverse-slope losses perceive speech. Thus, they treat us as though we had
ski-slope losses, and that is wrong!
Dr. Berlin wrote, “Virtually all of these people [with
severe reverse-slope losses] have normal or nearly-normal speech, and in good
listening conditions act as if they have no hearing impairment; yet with no
visual cues, they sometimes appear to be quite deaf. Depending on the slope and
the nature of their losses, they are among the most misdiagnosed and
mismanaged hearing loss patients.”6
Such wrong diagnoses include malingering (pretending to
have a hearing loss when you don’t), central hearing loss (in the brain rather
than in the ears), or even normal hearing.7
Sarah wrote, “I’m fed up with having to deal with so many ignorant people
who are convinced I'm faking it.”
One audiologist accused a man of lying about his hearing loss because she had
not run across a reverse slope loss before. He explained, "The first audiologist
I went to told me I was lying about not being able to hear. She had me take the
test 3 times and was clearly frustrated with my 'horrible lies'. To her
credit, she apologized after consulting with her colleagues. It was the first
time she had seen that type of loss."
Rusty related, “I could hear the dog’s toenails on the
cement walk and would tell my parents that Rex was coming. As a result, they
thought my hearing was fine, and it was many years before I got my first hearing
test and hearing aids.” I can relate to similar experiences with hearing the
dog’s toenails clearly clicking on the floor.
Of course when you can hear a pin drop, or a whisper from
across a room, and have perfectly-normal speech, it’s hard for people to believe
that you have a severe hearing loss and can’t hear much at all!
Thus, sometimes, instead of believing their own
audiological tests, some hearing health care professionals assume we are
pretending to have a hearing loss, and thus need a “shrink.” This really
happens. In fact, one lady was treated by psychiatrists and psychologists for
ten years because they just assumed she had “functional hearing
loss”—i.e. was faking it, before finally being diagnosed correctly as having a
severe reverse-slope hearing loss.8
This was because she:
- Had a pure-tone average of 80 dB, yet had a speech
detection (or reception) threshold (SRT) of only 25 dB. (Obviously if you can
detect speech at 25 dB, you can’t have a loss of 80 dB—so they thought.)
- Had virtually perfect articulation of
high-frequency consonants such as “s”, “sh”, “f”, “th” and so on. (She acted as
if she heard sibilants so well that no one could believe she was hearing
- Had superb lip reading ability.
- Would respond to a very faint and deliberate hiss
and could be called from the opposite end of her home if someone simply hissed
- Refused standard hearing aids, and seemed to do
much better without them than with them.10
Dr. Berlin continues, “These errors in classification stem
from the almost normal sensitivity to environmental sounds that contain
broad-band transients or sibilant-like hisses. Their extraordinary hearing
outside the standard range also allows them to develop unusually fine speech in
both the sibilant articulation areas and even speech timing, provided they are
not forced to wear powerful binaural aids, which occlude their ears and
mask their good high-frequency hearing. When they take pure-tone audiograms,
they appear to have substantial losses though the speech range (300 to 3000 Hz),
which is grossly incompatible with their communication abilities.”11
Dr. Berlin then cautions, “These people are difficult to
diagnose unless one is vigilant for their salient characteristics: unusually
good speech and sensitivity to environmental sounds in the presence of poor
speech perception (without visual cues) and severe pure-tone hearing losses in
the presence of unusually good speech-detection thresholds. Their audiograms
suggest they are hearing impaired or deaf, while their behaviors suggest that
they have good hearing sensitivity and speech production, but poor speech
perception. Many of these people reject standard hearing aids and often function
well without them.”12
A simple way to test for the presence of a reverse-slope
hearing loss is to use the Ling 5 sound test (ah, oo, ee, ss, sh). The tester
should stand behind the person being tested and using his own natural voice,
pronounce “ah, oo, ee, s, sh” with even intonation, asking the person to raise a
hand each time anything is heard.
When a person has a fairly-severe reverse-slope loss, you
will notice that they hear the “s” and “sh” sounds at much softer sound levels
than the “ah, oo, and ee” sounds.13
Here are 8 characteristics that those of us with severe
reverse-slope losses generally have. If we exhibit most of these
characteristics, we very likely have a severe reverse-slope loss. These
- Hearing loss of 70 to 110 dB at 1,000 Hz.
- Better than expected Speech Recognition Threshold
(SRT) scores for this degree of hearing loss, i.e. excellent speech detection.
- Do not like wearing conventional hearing aids.
- Remarkably precise articulation (i.e. great speech)
without any amplification.14
- Poor pitch control when singing.15
(e.g. I can’t tell when my voice is pitched to a given note when I am singing.
In fact, I don’t even have a clue in which “key” I am singing!)
- Higher-pitched voices when not wearing hearing
aids, yet virtually perfect articulation, especially of fricative sounds such as
“f” “v” “s” and “z”.
- Excellent language expression and comprehension.
- Readily hear selected higher-frequency
environmental sounds.16 (Back to Table of
High-Frequency Testing Is the Answer
Most of the above problems with misdiagnoses could be
instantly eliminated if audiometers were designed with our hearing losses in
mind—i.e. were sensitive down to at least -30 dB and were calibrated to test
hearing up to 20,000 Hz, and if audiologists would consistently test people to
the highest frequency, and softest sound, they can hear.
Unfortunately, modern audiometers generally only test to
8,000 Hz, rather than up to 20,000 Hz. Back in the mid 1960s, I was tested with
an old audiometer (old in those days too) that was calibrated to cover the
frequencies well above 8,000 Hz.
At 1,000 Hz I couldn't hear anything until the volume was
set quite high (probably about 7 or 8 out of a range of 0 to 9). However at the
highest frequency tested (16,000 or 20,000 Hz), I could hear all the way down to
0 and it was still loud to me. I bet the tester that I could take the
earphones off and hold them at arm’s length, and since the volume was as low as
it would go, if she would turn the power switch off and on, I could tell her
when it was on or off—and I did. This illustrates the incredible sensitivity of
our high-frequency hearing. It’s about time the audiometers we need are readily
available to test our hearing! (Back to Table of Contents)
Amplification for Reverse-Slope (or Low
People with reverse-slope hearing losses have completely
different amplification needs than people with the much more common ski-slope
losses. Thus, effectively fitting hearing aids, cochlear implants and assistive
devices to people with reverse-slope losses requires a somewhat different
approach than is usually taken. (Back to Table of Contents)
Hearing Aids and Reverse-Slope Losses
People with reverse-slope losses often ask, “Which is the
best hearing aid for my kind of hearing loss?” In the past there were no “best”
hearing aids. In fact, there weren’t even any “good” hearing aids for us. No
wonder Terry lamented, “Is there any kind of hearing aid for my kind of
hearing loss? It seems everything out there is for high frequency loss.”
Hearing aid manufacturers have not concerned themselves
with the unique needs of people with reverse-slope hearing losses. They just
make hearing aids for the most common kind of hearing loss (the ski-slope loss).
From their point of view, there are not enough of us for them to have the
financial motive to develop a hearing aid to fit us.
Think about it. Since reverse-slope losses like mine only
occur in 1 person in 12,000 hard of hearing people, assuming that all of us with
reasonably-severe reverse-slope losses bought such hearing aids, the
manufacturers would be able to sell a total of maybe 3,000 or so in North
America! Not much of an incentive, is it?
Some people with reverse-slope losses have wondered why
hearing aids such as the AVR ImpaCt, a high to low frequency-transposing hearing
aid designed specifically for those with severe ski-slope losses, couldn’t be
reverse designed to transpose the low frequencies to higher ones.
For example, Patti wrote, “It seems that they should be
able to develop a hearing aid that could take low frequencies and compress them
into the high frequencies so that we could hear more.”
You may be surprised to learn that some years ago (back in
the 1980s), Drs. Berlin, Halperin and Killon did exactly that. They designed
some experimental hearing aids that transposed the lower frequencies to the
higher frequencies that those of us with reverse-slope losses can hear well. Dr.
Halperin ultimately made 50 prototypes of these special translating aids.17
However, not everyone who tried one of these aids liked
them because all sounds were higher pitched, making people sound more like
Mickey Mouse than human. They took a bit of getting used to.
When one lady began wearing this special translating
hearing aid, she wrote, “It sounded very strange and for the first hour or so I
fooled around with the translator and direct aid controls. Voices sounded like
jabberwocky because they were so different. I opened a door and let it slam. I
expected the slam would be harsh but it wasn’t—a surprise! My cousin spent the
evening with us and I tried the aid while conversing with him. He has a low
voice and I often needed to strain to follow his conversation. Well, the hearing
aid unquestionably made his voice clearer and easier to follow. I found myself
relaxing while listening to him, and I was able to understand him despite the
fact that he has a mustache. Later in the evening I listened to the sounds of a
lively New Orleans jazz band; it was loud but not glaring.”18
Fortunately, with new digital hearing aid technology,
having frequency-transposing hearing aids is much less of a concern. This is
largely because of two innovations. The first is that new digital hearing aids
have multiple channels in them (typically between 7 and 16). (Note: channels are
basically just a way of dividing up the audio frequency spectrum so that each
channel can be programmed independently from each other.) Thus you can have your
hearing aids set to exactly match your hearing loss—frequency by frequency.
Therefore, theoretically, you can properly program digital hearing aids to match
any reverse-slope loss.
The second innovation is the development of wide-band
hearing aids. Typical hearing aids cover the frequencies up to 6,000 or 8,000
Hz. The new wide-band hearing aids work up to 16,000 Hz where those of us with
reverse-slope losses typically have much of our hearing.
Because we hear relatively well between 4 kHz and 16kHz, we
need hearing aids that don’t amplify these high frequencies much—but, at the
same time, allow these sounds to come through without obstruction, and yet
amplify lower-frequency sounds.19
It is critical that our hearing aids don’t block or mask the high-frequency
sounds that are so important to us. We use the very high-frequency sounds to
understand speech, and to recognize environmental and warning sounds.
My current hearing aids are the very first wide-band
(16,000 Hz) hearing aids America Hears produced. They work well for me. In
contrast, Rusty tried the Widex Inteo (Widex IN-19) and is having excellent
results with them. (Back to Table of Contents)
Fitting Hearing Aids to People with Reverse-Slope Losses
Since reverse-slope hearing losses are quite rare, few
audiologists have much experience programming hearing aids to meet our needs.
The truth is, fitting hearing aids to people with reverse-slope hearing losses
is not as straightforward as it first seems. There is no cut and dried method
that works for everyone.
Many audiologists rely on the manufacturer’s fitting
software. However, programming our hearing aids according to the manufacturer’s
theoretical programming protocols seldom (if ever) works for us, especially if
we have the more severe reverse-slope hearing losses. Audiologists that do this
end up with unhappy patients like Terry, Judith and Dolores.
Terry wrote, “I have a couple of Siemens in-the-ear,
programmable aids that have been mostly useless because I can’t get them
Judith explained, “The audiologist I now rely on says I
have a “reverse-slope loss”. The hearing aid I now have is less than
satisfactory. The audiologists I have been going to have told me it is a very
difficult loss to correct, and each would rather the other assist me. It is not
fun to spend $2,650.00 for unsatisfactory equipment!”
Dolores was totally upset with her fitting experience. She
related, “My audiologist adjusted my hearing aids according to the
manufacturer’s fitting protocol. When I walked out, the door squeaked loudly and
my footsteps rang in my ears. I started the engine and the roar overpowered the
radio. My nerves were shot by then, and I began to cry.”
It is obvious that the programming software just doesn’t
make proper provision for people like us. In fact, the audiologist my wife goes
to told me she wouldn’t be able to program digital aids to fit me because of the
The reason for this is that we perceive sounds somewhat
differently than normal—especially if we have had reverse-slope hearing losses
from birth. Doreen explained, “My audiologist said reverse-slope losses are
harder to fit because each person's perception of normal sound is so different.”
Audiologist Brad Ingrao, Au.D. definitely agrees. He wrote, “The real trick, in
my experience, is in unraveling the pattern of loudness and pitch perception in
a reverse-curve loss. I haven’t ever found a reliable pattern, so ended up
taking each one individually.”
Since this is the case, audiologists need to follow Brad’s
example—really listen to us, then specifically set the volume by frequency to
what we like—and largely forget about the theoretical fitting curves and
suchlike if they want to successfully fit reverse-slope hearing losses. As
Doreen discovered, “The computer program tells the audiologist what settings to
use based on my audiogram. They set my aid as specified by the computer and it
was awful. I ended up with my aids set almost opposite to what the
computer said it should be.”
Nancy explained, "Fitting a reverse slope loss is somewhat counter intuitive.
My audiologist had to turn off the 'learning' programming in my new hearing
aids. It would try to adapt my hearing aids to my environment. Unfortunately,
the algorithms were developed with the usual high-frequency hearing loss in
mind. As a result, it completely messes things up for those of us with reverse
Audiologists can’t follow their fitting algorithms when
fitting me either. I don’t understand speech well when my audiologist sets my
hearing aids the way they are theoretically supposed to be set. To me it sounds
like a person talking with several whole plums in his mouth (if that is
possible)! It is bassy, boomy and largely unintelligible.
I need my hearing aids programmed according to how my brain
perceives speech, not slavishly following my audiogram. This means programming
my hearing aids so everyone sounds more like Mickey Mouse. Since my brain has
never heard low-frequency sounds well, it thinks that sounding like Mickey Mouse
is normal, so that is where I understand speech the best.
I think the reason my hearing is like it is results from
two key factors. First, I had a severe reverse-slope hearing loss from birth. As
a result, my brain didn’t know that speech contained a lot of lower-frequency
sounds. Second, I did not get hearing aids until well after my brain had “wired”
itself to think that normal speech was largely devoid of low-frequency sounds.
(Your brain finishes wiring itself around age 6 or 7.)
In my case, I didn’t wear a hearing aid until I was 15
years old (although I had tried one for a few months when I was 8). By that
time, I understood speech only when the high-frequency sounds were predominant.
Thus, I needed my hearing aids set to the way my brain understood speech—not to
the way the audiogram indicated my hearing aids should be programmed.
In contrast, my younger daughter, who has a similar
reverse-slope loss to mine, began wearing two hearing aids when she was 3 or
4—while the auditory circuits in her brain were still plastic. Thus her hearing
aids allowed her brain to wire itself more normally.
Apart from getting fitted with hearing aids at a very young
age while the brain is still plastic, there are two other secrets to
successfully fitting hearing aids to people with reverse-slope losses. These
both address the same problem, but they do it in two different ways.
The problem is that we need to hear the very high-frequency
sounds we rely on to understand speech. If this is not done, we end up as
frustrated as Dolores. She explained, “I’ve tried hearing aids twice before and
have once again begun trying another. I’m having an awful time with it. I don’t
understand what people are saying, and even with the hearing aid it’s not
helping—everything is muffled and the phone is a nightmare.”
Dolores is experiencing problems because her hearing aids
and/or earmolds are blocking the very high-frequency sounds she needs for
understanding speech. Without these high-frequency sounds, to us speech sounds
Therefore, when you fit hearing aids to people with
reverse-slope losses, you need to be aware of the serious deleterious effects
that occluding our ear canals has on us. Whenever, or if ever, our ear canals
must be occluded by hearing aids or earmolds, you need to provide some other way
for us to hear very high-frequency sounds.
There are two ways to do this. The first way is to use
non-occluding earmolds. These can be either open-fitted earmolds, or earmolds
with vents of sufficient size to allow us to hear the high-frequency sounds we
The second way, especially if open-fitted earmolds or
vented earmolds will cause feedback, is to fit us with special wide-band hearing
aids that amplify sounds up to 16 kHz or higher, rather than topping out at 6 or
8 kHz as regular hearing aids do.
The secret here is to program the aids to “pass through”
these very high-frequency sounds, even though we have normal hearing in this
range, because the earmolds are blocking us from otherwise hearing them.
If this is not done, we will complain that you are giving
us too much low-frequency amplification, and not enough high-frequency
Traditional hearing aids both mask and occlude the
high-frequency portion of the hearing spectrum. This forces us to use the less
effective, low-frequency hearing we have at our disposal,20
rather than our good high-frequency hearing on which we generally rely, and that
This was Missy’s problem. She wrote, “The trouble I have
experienced is when they give me what I need to boost my lows, it overpowers my
Liz has a similar problem. She writes, “Part of my problem
is that my aids have been programmed with too much lows and not enough highs.”
Liz further states, “My audiologist doesn’t want to fix
that because she feels that I need the lows, and that my highs are essentially
normal, but I told her I’m not getting the consonants to help me differentiate
Liz is absolutely right. Her audiologist is programming in
too much low-frequency amplification.
This stems from two different fitting philosophies. The
better NAL fitting philosophy is to equalize, rather than normalize
loudness relationships across speech frequencies. If all the speech frequencies
are amplified so that they are heard equally loud, speech intelligibility is
However, when other fitting methods try to preserve this
normal relationship of loudness among the speech frequencies, they tend to
prescribe too much gain for the low frequencies.22
Therefore, the key is to amplify less at frequencies
where there is severe to profound hearing losses, which in the case of
reverse-slope losses means the low frequencies, and amplify more at the
frequencies of better hearing.23
This is because the frequency regions of poorest hearing will contribute the
least towards speech intelligibility.24
In fact, this is the principle of effective audibility.
As Ted Venema, Ph.D. explains, “Effective audibility refers
to how much information can be extracted from speech sounds once they are
audible. As hearing loss increases, for people with severe or greater hearing
loss, a small sensation level might give some amount of information, while a
high sensation level will not necessarily add much more information for
understanding speech. Thus for those with profound hearing loss, audibility
might be accompanied with virtually no added effective audibility.25
This seems to be the problem with the fitting philosophy in
Missy’s and Liz’ cases.
In fact, for properly fitting reverse-slope losses, the
NAL-NL1 fitting protocol does not target any gain below 500 Hz, and
reduced gain at 500 Hz itself, because these frequencies will not contribute to
Thus for effectively fitting reverse-slope losses, we need
reduced low-frequency amplification so it does not overpower the high-frequency
and very high-frequency amplification on which we so much depend.
Finally, never forget about the effects of recruitment
(where certain sounds are perceived as much too loud). Recruitment can be a real
problem for those of us with reverse-slope losses. At some frequencies, my
recruitment is quite severe. Unfortunately, these are the very frequencies I
need to understand speech. Thus by setting the compression levels for comfort,
it means I no longer have as good as discrimination as otherwise—but at least I
can stand the recruiting sounds, so this is a mixed blessing.
To be effective, at least in my experience, compression
needs to be programmed into our hearing aids frequency by frequency.
Unfortunately, few audiologists program compression this way.
Francis Kuk, Ph.D. in his study of people with reverse-slope hearing loss
- A digital multi-channel nonlinear hearing aid has more features than a
linear hearing aid to match the gain requirement of people who have a
low-frequency hearing loss.
- Use of wide dynamic range compression (WDRC) with a low compression
threshold (CT) and high level compression may be more effective (than linear
or WDRC with high CT) in preserving audibility and maintaining comfort
across listening environments.
- People with a reverse-slope audiogram do prefer amplification in the low
frequencies. However, their gain preference, compared to the recommendations
of some proprietary fitting targets, may vary depending on input levels.
- A broad bandwidth, including amplification in the normal or near-normal
frequency region, is desirable. However, the specific amount needs
One word of caution in relation to Dr. Kuk's conclusions: from what I can
determine, the people he studied generally fell into the Class 1
reverse-slope category. Therefore, his conclusions need to be modified to
include such things as wideband hearing aids and allowing pass-through very high
frequency sounds, as I have explained above, in order to apply more particularly
to people with Class 2 and Class 3 reverse slope losses.
Oticon has a 15-minute podcast that explains the principles of effectively
fitting hearing aids to people with reverse slope hearing losses. In it,
Oticon's Don Schum explains much of what I have explained above with graphs and
charts/audiograms. You would do well to
watch/listen to it now.
Note: just because a person has a reverse-slope hearing
loss doesn’t guarantee that a hearing aid will help him. For example, people
with Auditory Neuropathy/Auditory Dys-synchrony (AN/AD) often have reverse-slope
hearing losses, yet such people generally do not benefit from wearing hearing
aids (with some notable exceptions, although they often benefit from cochlear
implants). Therefore, it is important to test middle ear muscle reflexes,
otoacoustic emissions and auditory brainstem response to ensure a proper
diagnosis of the problem.28
|Fig. 7. Reverse-slope loss
of a person with
The salient features of people with AN/AD include:
- Otoacoustic emissions are, or at one time were, present.
- Auditory Brainstem Response (ABR) is absent or grossly abnormal.
- Middle ear reflexes are absent.29
People that have AN/AD fit the above conditions, yet they
may have a very pronounced reverse-slope audiogram (Fig. 7). According to Dr.
Berlin, “In AN/AD the audiogram is virtually meaningless, so before you try to
treat a reverse-slope loss, you have to rule out AN/AD because no hearing aid
easily helps it.”30 (Back to Table of Contents)
Cochlear Implants and Reverse-Slope Losses
Since not many hard of hearing people have reverse-slope
losses, it follows that not many have received cochlear implants (CI) either.
Thus, for those with extreme reverse-slope losses, there is little history of
how well cochlear implants will perform.
This has led to concern on the part of people with reverse
slope losses that they won’t get good results with a cochlear implant. For
example, Lorene wrote, “I am scared that if the CI didn’t work, I would not be
able to use what is left of my residual hearing in my right ear.”
Part of this concern stems from the fact that ski-slope
losses and reverse-slope losses have residual hearing at opposite ends of the
cochlea. The cochlea is shaped like a snail, and consists of 2½ turns. High
frequency hearing occurs at the base and low frequency hearing at the tip
With the normal ski-slope loss you basically have no
high-frequency hearing left, so when the doctor inserts the cochlear implant
electrodes into the base of the cochlea where they would normally destroy any
residual high-frequency hearing, there is none there left to lose. Also, since
the electrodes don’t quite reach the tip where the low frequencies reside, some
residual low-frequency hearing may remain.
However, with a reverse-slope loss, the residual
(high-frequency) hearing is at the base of the cochlea where it is destroyed
when the electrodes are inserted. Thus, people with reverse-slope losses have
more to risk in that sense if the cochlear implant should fail to work well for
However, if you wait until your hearing is so poor and
garbled that you can’t understand much anyway, you really don’t have much to
lose, so why worry about keeping any residual hearing?
As noted in the previous section, in Dr. Berlin’s
experience, people with AN/AD often do well with a cochlear implant, in spite of
having reverse-slope losses. For example, the person whose audiogram is shown in
Fig. 7 “benefited remarkably from a cochlear implant” according to Dr. Berlin.
Programming a cochlear implant for a person with a
long-standing extreme reverse-slope hearing loss likely will be quite a
challenge since cochlear implant fitting protocols are set up for those that
have the typical ski-slope loss. When people with a ski-slope loss get a CI,
they typically tell how all voices then sound high-pitched and Mickey-Mousey.
This is because they haven’t heard high-frequency sounds for years. Now, all of
a sudden, the CI gives them those sounds.
In contrast, a person with a reverse-slope loss, when
turned on, not having heard low-frequency sounds for years or a lifetime, will
likely find the low-frequency sounds overpowering. In fact, this is exactly the
case with one who reported that voices now sounded very low-pitched and growly
and were mostly incomprehensible.
I can well believe this for when my hearing aids are
programmed for “normal” I also feel like I am being drowned in a sea of loud,
low-frequency incomprehensible noise. A partial solution seems to be in turning
off a number of the low frequency electrodes. Only time will tell what the real
solution will ultimately prove to be. (Back to Table of
Assistive Devices and Reverse-Slope Losses
If you have a more severe reverse-slope loss, you will soon
find that a number of the wonderful assistive devices to help hard of hearing
people hear better are not so wonderful after all. This is because they have
been engineered in such a way that we cannot hear and understand speech well
when using them.
This is especially true when we try to find an amplified
phone we can hear on. For example, Karen wrote: "We were at a seminar where a Clarity (new name for the old
Ameriphone/Walker company) representative was heavily pitching their “Clarity
Power” telephones as hot new items that are to replace the old Ameriphone line.
When asked from the audience “why was there no tone control with Clarity Power”
the engineer said that tone controls are obsolete, and that it is much better to
have the tone embedded in the volume control so that as the volume increases, so
does the frequency emphasis. He was pretty strong in his having “engineer
expertise” so no one challenged him."
Karen then asked: "Am I missing something in my understanding of what the
combined tone/volume control does? How would someone get the right amplification
in their frequency range? I'm pretty sure I'm right, but I'm not an engineer."
This is a classic example of engineers doing shoddy
research into the needs of hard of hearing people.
If he had said that the Clarity products were
designed only for hard of hearing people with ski-slope losses, I
would have agreed with him that having an integrated volume and tone control
might be a smart idea.
However, such a design is stupid for people with flat
losses and cookie-bite losses, and is totally asinine for those of us with
severe reverse-slope losses. If he had ears like mine, he would never
have made such a ridiculous statement.
This is much the same kind of thinking that went into the
design of a wonderful phone for hard of hearing people—the Williams Sound
Teletalker™ phone. To their credit, the designers included both a volume
and a tone (they call it an enhance) control.
Unfortunately, they bought into the above misconception
about what all hard of hearing people need. Although this phone is billed
as having 55 dB of gain (which would be wonderful for my hearing loss), instead
of putting all the power into the volume control, they assumed that hard of
hearing people would never need more than 25 dB of overall gain, so they put 25
dB gain into the volume control, and then put the other 30 dB of gain into their
tone (enhance) control.
Since I need much more than 25 dB of basic gain, I
need to crank the tone control way up to get the required volume, but, by the
time I have enough volume, all that extra high-frequency gain so distorts
people’s voices that I can’t understand them.
Thus I have a wonderful phone designed specifically for
hard of hearing people, yet I can’t use it. I’ve suggested to Williams Sound
that they put all the gain on the volume control, but so far, they have ignored
As an effective workaround for both the TeleTalker and the
Clarity phone I now use, I have added the Ameriphone HA-40 in-line amplifier.
This neat little gizmo has separate volume and tone controls. Thus, I can add in
the extra volume I need without distorting the higher frequencies.
To be sure, there are a number of other assistive devices
that have straight volume or have both volume and tone controls that work pretty
well for us. For example, the Williams PockeTalker personal amplifier has both
volume and tone controls and works great for me.
Since our perception of speech is so different from other
hearing losses, it is imperative that we try out any assistive devices before we
buy them to be sure they will work for us (or be allowed to return them if they
prove unsatisfactory). (Back to Table of Contents)
If you (or a family member) have a reverse-slope loss
and would like to join an information and support email list for people (and
parents of children) with reverse-slope hearing losses, type your E-mail address in the box and click on the Yahoo Groups button. You can unsubscribe at any time.)
Subscribe to the Reverse Slope
Hearing Loss (RSHL) list
(Back to Table of Contents)
Berlin, Charles I., et. al. 1978. Superior
Ultra-Audiometric Hearing: A New Type of Hearing Loss Which Correlates Highly
with Unusually Good Speech in the Profoundly Deaf. ORL.
Berlin, Charles I. 1980. Ultra-Audiometric Hearing in the
Hearing Impaired and the Use of Upward-Shifting Translating Hearing Aids. Kresge
Hearing Research Laboratory of the South. Louisiana State University Medical
Center. New Orleans, Louisiana.
Berlin, Charles I. 1985. Unusual Forms of Residual
High-Frequency Hearing. In: Seminars in Hearing—Volume 6, Number 4. Kresge
Research Laboratory, New Orleans, Louisiana.
Berlin, Charles I., et. al. 2002. Chapter 8, The
Physiological Bases of Audiological Management. In: Hair Cell Micromechanics
and Otoacoustic Emissions. Singular.
Berlin, Charles I., et. al. 2003. Auditory
Neuropathy/Dyssynchrony, Its Diagnosis and Management. Pediatr. Clin. N. Am. 50
(2003) pp. 331-340.
Kuk, Francis, et. al. 2003. Changing with the Times: Managing Low-Frequency
Hearing Loss. Hearing Review, November 2003.
Venema, Theodore. 2001. The NAL-NL1 Fitting Method.
(Back to Table of Contents)
1 Berlin, 1985. p. 389.
2 Berlin, 1980. p. 50.
3 Berlin, 1980. p. 48.
4 Berlin, 1978. p. 111.
5 Berlin, 1985. p. 392.
6 Berlin, 1985. p. 393.
7 Berlin, 1980. p. 53.
8 Berlin, 1978. p. 112.
9 Berlin, 1985. p. 391.
10 Berlin, 1985. p. 389.
11 Berlin, 1980. pp. 53-54.
12 Berlin, 1980. p. 54.
13 Berlin, 1985. pp. 393-394.
14 Berlin, 1980. p. 50.
15 Berlin, 1978. pp. 111-112.
16 Berlin, 1980. pp. 44-45.
17 Berlin, 1985. p. 392.
18 Berlin, 1980. p. 50.
19 Berlin, 1980. p. 46.
20 Berlin, 1980. p. 49.
21 Venema, 2001. p. 2.
22 Venema, 2001. p. 3.
23 Venema, 2001. p. 4.
24 Venema, 2001. p. 7.
25 Venema, 2001. p. 4.
26 Venema, 2001. p. 5.
27 Kuk, 2003. p. 6.
28 Berlin, 2002. p. 139.
29 Berlin, 2003. p. 333.
30 Berlin, 2006. Personal communication
(Back to Table of Contents)