2, 2011, at about 6:55 AM I was involved in a serious auto accident. My car and another vehicle collided almost
head-on. The air-bag in my vehicle
deployed. The windows of my vehicle were
closed. The result was a terrific
acoustic shock to my ears. At the same
time my body lunged forward on to the steering wheel and I suffered a broken sternum. I was hospitalized until Saturday, November
5. I came home and recuperated from the
accident with the help of a hired care-giver during the day. The pain in my chest, especially when I tried
to lift myself from a lying position in bed was severe enough that I had to
sleep in a Laz-e-boy reclining chair for more than a week.
week after the accident I endeavored to play a recorder or longitudinal
flute. I was able to play correctly the
notes from F (349 Hz) to B-flat (932 Hz).
The next note, C (1047 Hz) sounded like D-sharp (1245 Hz), a minor third
higher in pitch. Notes above that were
similarly displaced upward in pitch by a minor third. My first reaction was that I had forgotten
how to finger the instrument correctly.
I went to the piano and played notes of the same range of pitch as those
I had just played on the recorder. The
effect was the same. Above 950 Hz all
musical notes seemed to me to be a minor third too sharp or high in pitch.
not hearing loss but pitch distortion.
It has persisted to this day (October 31, 2012). It is no longer possible for me to enjoy
music with notes that cross this strange discontinuity in my pitch
perception. I hear some favorite music
by Bach, such as “Sheep may safely graze” or “Jesu joy of man’s desiring” and
the high notes on a flute or recorder don’t sound right to me. I am confined to enjoying music without the
high notes above high B-flat.
given this problem a lot of thought. I
haven’t found any account of another person who suffered this type of hearing
change. I have read that an air bag
deployment can cause temporary deafness.
I haven’t found any literature on pitch perception change. To be honest, I haven’t conducted a thorough
literature search of the subject.
worked out a model to explain what happened to my sense of hearing. I start by imagining the little cilia in the
cochlea, the little coiled tube in the inner ear. Imagine the cochlea straightened out as
illustrated in the left hand part of the following diagram. On the left are the cilia or little bristles
immersed in the fluid. Any musical note
that is transmitted to the inner ear causes the little bristles whose resonant
frequencies are near the frequency of the note to vibrate.
think of a frequency meter for an electric generator with vanes or stiff metal
reeds that vibrate. When the generator is running at the correct speed, the
vane corresponding to 60 Hz vibrates with a large amplitude. Vanes for adjacent frequencies, 60.1, 60.2,
..., 59.9, 59.8, etc, vibrate at amplitudes that are lower the farther the
resonant frequency of the vane is from 60 Hz.
In the same way a single frequency excites several of the little
bristles in the cochlea.
Next, I come
to the question of how does the nerve bundle convey this information to the
brain? Is each bristle part of a nerve
that communicates its frequency directly?
That sounds highly unlikely. One
would have to have nerves that in a normal youthful human could conduct
electrical impulses at a rate of up to 15,000 Hz and above. Nerves don’t work that way. In my model, each bristle is part of a nerve that
transmits a regular signal in the range of 10 to 100 Hz whenever the bristle is
caused to vibrate. The frequency of the
signal indicates the amplitude of the vibration. In the brain, each nerve fiber is connected
to an individual nerve cell. That nerve
cell interprets the incoming signal as a musical note.
diagram above, G denotes the frequency at which the pitch displacement
occurs. The other notes in the diagram
are self-explanatory. The brain cells on
the right enclosed in the heavy dashed line are those that the connections from
the bristle nerve were originally attached to.
As a result of the concussion those connections were all shifted to
nerve cells that interpret impulses as higher frequencies.
one feature of my present hearing that the model doesn’t explain. It is true that there is a gap or difference
between my pitch perception below and above a frequency of about 950 Hz, at
least in my right ear. However, the
pitch does not jump immediately by about a minor third (approximately 20
percent in frequency). The perceived
pitch changes rapidly but, as far as I can tell, smoothly from b-flat through
b-natural to c. The model can not be an
accurate diagram of the mechanism of pitch perception in my head.