Chapter 9: Hearing: Physiology and Psychoacoustics Flashcards Preview

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Flashcards in Chapter 9: Hearing: Physiology and Psychoacoustics Deck (75):
1

amplitude or intensity

The magnitude of displacement (increase or decrease) of a sound pressure wave. Amplitude is perceived as loudness.

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frequency

For sound, the number of times per second that a pattern of pressure change repeats. Frequency is perceived as pitch.

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hertz (Hz)

A unit of measure for frequency. One hertz equals one cycle per second.

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loudness

The physiological aspect of sound related to perceived intensity (amplitude).

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pitch

The psychological aspect of sound related mainly to perceived frequency.

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decibel (dB)

A unit of measure for the physical intensity of sound. Decibels define the difference between two sound as the ratio between two sound pressures. Each 10:1 sound pressure ratio equals 20 dB, and a 100:1 ratio equals 40 dB.

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sine wave or pure tone

A waveform for which variation as a function of time is a sine function.

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Spectrum

A representation of the relative energy (intensity) present at each frequency.

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harmonic spectrum

The spectrum of a complex sound in which energy is at integer multiples of the fundamental frequency.

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fundamental frequency

The lowest frequency component of a complex periodic sound.

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timbre

The psychological sensation by which a listener can judge that two sounds with the same loudness and pitch are dissimilar. timbre quality is conveyed by harmonics and other high frequencies.

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pinna

The outer, funnel like part of ear.

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ear canal

The canal that conducts sound vibrations from the pinna to the tympanic membrane and prevents damage tot he tympanic membrane.

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Tympanic membrane (eardrum)

The eardrum; a thin shit of skin at the end of the outer ear canal. The tympanic membrane vibrates in responds to sound.

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outer ear

The external sound-gathering portion of the ear, consisting of the pinna and the ear canal.

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middle

An air-filled chamber containing the middle bones, or ossicles. The middle ear conveys and amplifies vibration from the tympanic membrane to the oval window.

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ossicle

Any of three tiny bones of the middle ear: malleus, incus, and stapes.

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malleus

One of the three ossicles, receives vibration from the tympanic membrane and is attached to the incus.

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incus

The middle of the three ossicles connecting malleus to stapes.

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Stapes

Third ossicle. Connects to incus and presses against oval window of cochlea.

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oval window

The flexible opening to the cochlea through which the stapes transmits vibration to the fluid inside.

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inner ear

A hollow cavity in the temporal bone of the skull, and the structures within the cavity: the cochlea and the semicircular canals of the vestibular system.

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tensor tympani

The muscle attached to the malleus; tensing the tensor tympani decreases vibration.

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stapedius

The muscle attached to the stapes. Tensing the steapedius decreasese vibration,

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acoustic reflex

A reflex that protects the ear from intense sounds, via contraction of the stapedius and tensor tympani muscles.

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cochlea

A spiral structure of the inner ear containing the organ or Corti.

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tympanic canal

One of three fluid filled passages in the cochlea. The tympanic canal extends from the round window at the base of the cochlea to the helicotrema at the apex. Also called scala tympani.

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vestibular canal

One of three fluid filled passages in the cochlea. The vestibular canal extends from the oval window at the base of the cochlea to the helicotrema at the apex. Also called scala vestibuli.

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middlew canal

One of three fluid filled passages in the cochlea. The middle canal is in between vestibular/tympanic canals at apex of cochlea.

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helicotrema

The opening that connects the tympanic and vestibular canals at the apex of the cochlea

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Reisnner's membrane

A thin sheath of tissue separating vestibular and middle canals in cochlea.

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basilar membrane

A plate of fibers that forms the base of the cochlear partition and separates the middle and tympanic canals in the cochlea.

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cochlear partition

The combined basilar membrane, tectorial membrane, and organ of Corti, which are together responsible for the transduction of sound waves into neural signals.

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round window

A soft area of tissue at the base of the tympanic canal that releases excess pressure remaining from extremely intense sounds.

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organs of Corti

A structure on the basilar membrane of the cochlea that is compose of hair cells and dendrite pf auditory nerve fibers. Translates movements of cochlear partition into neural signals.

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hair cell

Any cell that has stereocilia for transducing mechanical movements in inner ear into neural activity sent to the brain; some hair cells also receive inputs from the brain.

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auditory nerve fiber

A collection of neurons convey info from hair cells in cochlea to and from brain stem.

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stereocilium

Any of the hairlike extensions on the tips of the hair cells in the cochlea that, when flexed, initiate the release of neurotransmitters.

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tectorial membrane

A gelatinous structure, attached on one end, that extends into middle canal, floating above inner hair cells and touching outer hair cells.

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tip link

A tiny filament that stretches from the tip of a stereocilium to the side of its neighbor.

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place code

Tuning of different parts of the cochlea to different frequencies, in which information about the particular frequency of an incoming sound wave is coded by the place along the cochlear partition that has the greatest mechanical displacement.

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afferent fiber

A neuron that carries sensory information to the CNS.

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efferent fiber

A neuron that carries info from CNS to periphery.

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threshold tuning curve

A graph plotting the thresholds of a neuron or fiber in response to sine waves with varying frequencies at the lowest intensity that will give rise to a response.

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characteristic frequency (CF)

The frequency to which a particular auditory nerve fiber is most sensitive.

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two tone suppression

A decrease in the firing rate of one auditory nerve fiber due to one tone, when a second tone is presented at the same time.

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isointensity curve

A map plotting the firing rate of an auditory nerve fiber against varying frequencies at a steady intensity.

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rate saturation

The point at which a nerve fiber is firing as rapidly as possible and further stimulation is incapable of increasing the firing rate.

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rate intensity function

A graph plotting the firing rate of an auditory nerve fiber in response to a sound of constant frequency to at increasing intensities.

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low-spontaneous fiber

An auditory nerve fiber that has a low rate (less than 10 spikes per second) of spontaneous firing; low-spontaneous fibers require relatively intense sound before they will fire at higher rates.

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high-spontaneous fiber

An auditory nerve fiber that has a high rate (more than 30 spikes per second) of spontaneous firing; high-spontaneous fibers increase their firing rate in response to relatively low levels of sound.

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mid-spontaneous fiber

An auditory nerve fiber that has a medium rate (10-30 spikes per second) of spontaneous firing. The characteristics of mid-spontaneous fibers are intermediate between love and high spontaneous fibers.

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phase locking

Firing a single neuron at one distinct point in the period (cycle) of a sound wave at a given frequency. (The neuron need not fire on every cycle, but each firing will occur at the same point in the cycle.)

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temporal code

Turing of different parts of the cochlea to different frequencies, in which info about the particular frequency of an incoming sound wave is coded by the timing of neural firing as it related to the period of the sound.

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volley principle

The idea that multiple neurons can provide a temporal code for frequency if each neuron fires at a distinct point in the period of a sound wave but done not fire on every period.

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cochlear nucleus

The first brain stem nucleus at which afferent auditory nerve fibers synapse

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superior olive

An early brain stem region in the auditory pathway where inputs from both ears converge.

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inferior colliculus

A midbrain nucleus in the auditory pathway

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medial geniculate nucleus

The part of the thalamus that relays auditory signals to the temporal cortex and receives input from the auditory cortex.

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tonotopic organization

An arrangement in which neurons that respond to different frequencies are organized anatomically in order of frequency.

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primary auditory cortex (A1)

The first area within the temporal lobes of the brain responsible for processing acoustic info.

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belt area

A region of cortex, directly adjacent to the primary auditory cortex (A1), with inputs from A1, where neurons respond to more complex characteristics of sounds.

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parabelt area

A regions of cortex, lateral and adjacent to the belt area, where the neurons respond to more complex characteristics of sound, as well as to input from other senses.

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psychoacoustics

The study of the psychological correlates of the physical dimensions of acoustics; branch of psychophysics.

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audibility threshold

The lowest sound pressure level that can be reliable detected at a given frequency.

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equal-loudness curves

A graph plotting sound pressure level (dB SPL) against the frequency for which a listener perceives constant loudness.

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temporal integration

The process by which a sound at a constant level is perceived as being louder when it is of greater duration.

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masking

using a second sound, frequently noise, to make the detection of another sound more difficult.

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white noise

Noise consisting of all audible frequencies in equal amounts. White noise in hearing is analogous to white light in vision, for which all wavelengths are present.

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critical bandwidth

The range of frequencies conveyed within a channel in the auditory system.

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conductive hearing loss

Hearing loss caused by problems with the bones of the middle ear.

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otitis media

inflammation of the middle ear, commonly in children as a result of infection.

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otosclerosis

Abnormal growth of the middle-ear bones that causes hearing loss.

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sensorineural hearing loss

Hearing loss due to defects in the cochlea or auditory nerve.

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ototoxic

Producing adverse effects on cochlear or vestibular organs or nerves.