Kinds of Hearing Losses
© April 2006 by Neil Bauman, Ph.D.
Question: Karen asked: What is a reverse-slope loss?
I have something called a cookie bite loss. I have no idea what it is, but that
is what my audiologist called it.
Answer: These terms refer to the shape your
hearing loss makes on your audiogram. Each of these shapes have been given
strange colloquial names such as ski-slope loss, cookie-bite loss, flat loss,
reverse cookie-bite loss and reverse-slope (reverse curve) loss. Here is a quick
run down on them.
Before you can appreciate what the various hearing losses
look like on an audiogram, you first need to know what normal hearing looks
like. "Perfect" hearing theoretically would be a straight line at the 0 dB level
(Fig. 1). In actual fact, audiologists typically consider “normal” hearing to
range anywhere from -10 dB (negative numbers lie above the 0 dB line) to 25 dB.
Fig. 2 shows an example of “normal” hearing.
A hearing loss that is approximately the same at all
frequencies is more or less a straight horizontal line and is called
appropriately enough a “flat loss.” or a “flat curve” (which is a bit of an
oxymoron). This kind of loss is more common in people with conductive losses.
Fig. 3 gives an example of a flat loss.
Ski-slope losses are by far the most common kind of hearing
losses. These losses get their name from the “ski-slope” shape of the hearing
loss on the
audiogram. With ski-slope hearing losses, there is little or no
hearing loss in the low frequencies but considerable loss in the higher
frequencies. Often the mid frequency range is severe to profound. The audiogram
looks much like a ski slope—the top of the hill is on the left and the slope
drops to the right. There is an almost infinite variety of ski-slope curves—some
slope down gently (Fig. 4), while others are much steeper. In extreme cases the
curve is almost flat in the low frequencies and then, as Fig. 5 illustrates,
just about drops straight down (really more like a ski-jump loss)!
A reverse-slope loss is the reverse of the ski-slope loss
(hence its name). In reverse-slope losses, the curve is low at the low
frequencies and slopes up to the right. Thus, the ski-hill is on the right and
drops to the left. A person with a reverse-slope loss hears better in the high
frequencies than in the low frequencies. This is a very rare kind of hearing
loss. Fig 6. depicts a mild reverse-slope loss, Fig. 7 illustrates an
and Fig. 8 shows an extreme reverse slope loss such as I have. Notice that the high frequency
hearing extends to and incredible -30 dB. Also note that this audiogram shows
the hearing curve up to 20,000 Hz, whereas the other audiograms all stop at
8,000 Hz, the highest frequency audiologists normally test.
A cookie-bite loss looks like someone took a bite out of
the top of the audiogram (Fig. 9). Thus, the curve is higher at both the
lower and higher frequencies and lower in the middle. People with cookie-bite
losses hear low and high frequency sounds well, but have a loss in the
mid-frequencies. This kind of loss is less common than the ski-slope loss.
A notch loss is a variation of the cookie-bit loss. It
looks like a narrow, steep-sided valley (Fig. 10). Notch losses typically occur
around 4,000 Hz and are caused by the initial stages of noise-induced hearing
Reverse Cookie-Bite Loss
The reverse cookie-bite loss looks like someone took a bite
out of the bottom of the audiogram (Fig. 11). This curve is lower at both
ends and higher in the middle. A person with this kind of loss hears well in the
mid-frequencies but has considerable loss in both the low and the high
frequencies. This is also a rare kind of loss.