Figure 15.13. Human skull, from the 1918 edition of Henry Gray’s Anatomy of
the Human Body.Did you guess? The answer is the sound of hearing one’s own voice
as one speaks or sings or hums. The vibration of the vocal cords and
other structures involved in the generation of these sounds produces
variations in air density that propagate away from the body. This is
what others hear. These air pressure variations also enter one’s own
external ear canal, and some of what we hear when we hear the sound
of our own voice enters the auditory system in the way we have de-
scribed. But plug your ears as tightly as you can and you can still hear
yourself speak perfectly well, even when very quietly whispering.
Much of the vibrational energy sensed when we hear ourselves speak
enters the auditory system via internal vibration of the skull (Fig.
15.13).
The character of the transmitted frequencies is somewhat different
for the vibrations that propagate through the air space external to our
body compared with the vibrations that propagate through our bones
and other body parts. Thus, the frequency composition will differ for
one’s voice as heard by oneself compared with what is heard by an-
other person. This is why people are generally surprised the first time
they hear a recording of their own voice, often maintaining that it
does not sound like them. This is true: one’s voice heard by the speaker
while speaking does sound different than that same voice heard by
another listener. The rhythm and tempo are the same, but the Fourier
frequency composition is different.
In auditory signaling, neurotransmitter is released from the hair
cell, and a signal is generated in the postsynaptic dendrite of cranial
nerve 8. The cell bodies for these nerves are located nearby in a cluster