From the chirping of crickets to the roar of a rocket engine, sound waves are collected by the external ear and funneled to the eardrum to make it vibrate. Attached to the eardrum, the hammer transmits the vibration to the anvil, which passes the vibration on to the stirrup. The stirrup pushes on the oval window which separates the air-filled middle ear from the fluid-filled inner ear to produce pressure waves in the inner ear’s snail-shaped cochlea.
The separation of frequencies occurs in the cochlea, which is tuned along its length to different frequencies, so that a high note causes one region of the cochlea’s membrane to vibrate, while a lower note has the same effect on a different region. Riding on the vibrating membrane are hair cells which convert the mechanical vibration to electrical signals, which in turn excite the 30,000 fibers of the auditory nerve. Because each hair cell rides on a different part of the membrane, each responds to a different frequency, and so each nerve fiber carries information about a different frequency. Auditory information is analyzed by multiple brain centers as it flows to the auditory cortex, the part of the brain involved in perceiving sound.
In the auditory cortex, adjacent neurons tend to respond to tones of similar frequency. However, they specialize in different combinations of tones. Some respond to pure tones, such as those produced by a flute, and some to complex sounds like those made by a violin. Some respond to long sounds and some to short, and some to sounds that rise or fall in frequency. Other neurons might combine information from these specialist neurons to recognize a word or an instrument.
Like the visual system, our hearing system picks up several qualities in the signals it detects (for example, a sound’s location, its loudness, and its pitch). But our hearing system does not blend the frequencies of different sounds, as the visual system does when different wavelengths of light are mixed to produce color. Instead, it separates complex sounds into their component tones or frequencies so that we can follow different voices or instruments as we listen to conversations or to music.
Write Sexercise: Write a sex scene that can’t you see. Separate out the strands of sound. Describe the sounds. Write the sounds. Take 50 minutes.
Nicholson Baker’s Vox is a novel made up entirely of the exchanges between a man and a woman having phone sex.
This was 1990, when it felt like there was a mini-sexual revolution going on after the real sexual revolution. And I felt that by starting the book with that phrase, ‘What are you wearing,’ it just tilted everything forward. It seemed like literary novels then had a very set sexual pattern: four or five sex scenes among some literary-sounding writing. So I said to myself: ‘Just do it. Stay with the sex. Accept that you’re reading and writing this with mixed motives.’
The novel ends with the woman on the one end of the line crying out: “Oh! Nnnnnnnn! Nnn! Nnn! Nnn! Nnn! Nnn! Nnn!”