Sensation and Perception - Chapter 10

Acoustic reflex

a reflex that tightens the tensor tympani and the stapedius in response to chronic loud noise

Amplitude

the difference between maximum and minimum sound pressures

Basilar membrane

the membrane that separates the tympanic canal from the middle canal; the organ of Corti lies on the basilar membrane

Characteristic frequency

the frequency to which any particular location along the basilar membrane responds best

Cochlea

the snail

Complex sounds

sounds consisting of a mix of frequencies

Cycle

in a sound wave, the amount of time between one peak of high pressure and the next

Decibel (dB)

a physical unit that measures sound amplitude

Eustachian tube

a thin tube that connects the middle ear with the pharynx and serves to equalize air pressure on either side of the eardrum

External auditory canal (external auditory meatus)

the channel that conducts sound from the pinna to the tympanic membrane

Fourier analysis

a mathematical procedure for taking any complex waveform and determining the simpler waveforms that make up that complex pattern; the simpler waves used are sine waves

Frequency (sound stimulus)

the number of cycles that occur in a second

Fundamental frequency

the lowest frequency in a complex sound, which determines the perceived pitch of that sound

Hair cells

cells that have stereocilia for transducing the movement of the basilar membrane into a neural signal

Harmonics

higher frequencies present in a complex sound that are integer multiples of the fundamental frequency (main frequency)

Hertz (Hz)

a unit of measure indicating the number of cycles per second

Incus

an ossicle in the middle ear; receives vibrations from the malleus and transmits them to the stapes

Inner hair cells

cells that are responsible for transducing the neural signal

Loudness

the perceptual experience of the amplitude or intensity of a sound stimulus

Malleus

the first ossicle in the middle ear; receives vibrations from the tympanic membrane and transmits them to the incus

Middle canal (cochlear duct)

one of the three chambers in the cochlea; separated from the tympanic canal by the basilar membrane; contains the organ of Corti

Organ of Corti

a structure on the basilar membrane that houses the hair cells that transduce sound into a neural signal

Ossicles

three small bones in the middle ear

Outer hair cells

cells that sharpen and amplify the responses of the inner hair cells

Perilymph

the fluid that fills the tympanic canal and the vestibular canal

Phase

the position in one cycle of a wave; there are 360 degrees in a single cycle of a wave

Pinna

the structure that collects sound and funnels it into the auditory canal

Pitch

the subjective experience of sound that is most closely associated with the frequency of a sound stimulus; related to the experience of whether the sound is high or low, such as the two ends of the keyboard of a piano

Place code theory

the view that different locations along the basilar membrane respond to different frequencies

Pure tones

sound waves in which changes in air pressure follow a sine wave pattern

Reissner’s membrane

the membrane that separates the vestibular and middle canals

Round window

a soft tissue substance at the base of the tympanic canal whose function is as an “escape” valve for excess pressure from loud sounds that arrive in the cochlea

Sound stimulus

the periodic variations in air pressure traveling out from the source of the variations

Sound waves

the waves of pressure changes that occur in the air as a function of the vibration of a source

Stapedius

the muscle that is attached to the stapes

Stapes

an ossicle in the middle ear; receives vibrations from the incus and transmits them to the oval window of the inner ear

Stereocilia

the hairlike parts of the hair cells on the top of the inner and outer hair cells

Tectorial membrane

a membrane that rests above the hair cells within the organ of Corti

Temporal code theory

the view that frequency representation occurs because of a match between sound frequency and the firing rates of the auditory nerve

Tensor tympani

the muscle that is attached to the malleus

Timbre

the perceived sound differences between sounds with the same pitch but possessing different higher harmonics

Tympanic canal

one of the three chambers in the cochlea; separated from the middle canal by the basilar membrane

Tympanic membrane

a thin elastic sheet that vibrates in response to sounds coming through the external auditory canal; commonly known as the eardrum

Vestibular canal

one of the three chambers in the cochlea; separated from the middle canal by Reissner’s membrane