Sensation And Perception Ch.11

Front 1

Additive synthesis

Back 1

In hearing, the process of building a complex tone by starting with the fundamental frequency and adding pure tone harmonics.

Front 2

Amplitude

Back 2

In the case of a repeating sound wave, such as the sine wave of a pure tone, amplitude represents the pressure difference between atmospheric pressure and the maximum pressure of the wave.

Front 3

Apex of the cochlea

Back 3

The end of the basilar membrane farthest from the middle ear.

Front 4

Audibility curve

Back 4

A curve that indicates the sound pressure level (SPL) at threshold for frequencies across the audible spectrum.

Front 5

Auditory canal

Back 5

The canal through which air vibrations travel from the environment to the tympanic membrane.

Front 6

Auditory receiving area (A1)

Back 6

The area of the cortex, located in the temporal lobe, that is the primary receiving area for hearing.

Front 7

Auditory response area

Back 7

The psychophysically measured area that defines the frequencies and sound pressure levels over which hearing functions. This area extends between the audibility curve and the curve for the threshold of feeling.

Front 8

Base of the cochlea

Back 8

The part of the basilar membrane nearest the middle ear.

Front 9

Basilar membrane

Back 9

A membrane that stretches the length of the cochlea and controls the vibration of the cochlear partition.

Front 10

Belt area

Back 10

Auditory area in the temporal lobe that receives signals from the core area and sends signals to the parabelt area.

Front 11

Central pitch processor

Back 11

A hypothetical central mechanism that analyzes the pattern of a tone’s harmonics and selects the fundamental frequency that is most likely to have been part of that pattern. It has been proposed that this mechanism is involved in our perception of periodicity pitch.

Front 12

Characteristic frequency

Back 12

The frequency at which a neuron in the auditory system has its lowest threshold.

Front 13

Cilia

Back 13

Fine hairs that protrude from the inner and outer hair cells of the auditory system. Bending the cilia of the inner hair cells leads to transduction.

Front 14

Cochlea

Back 14

The snail-shaped, liquid-filled structure that contains the structures of the inner ear, the most important of which are the basilar membrane, the tectorial membrane, and the hair cells.

Front 15

Cochlear implant

Back 15

A device in which electrodes are inserted into the cochlea to create hearing by electrically stimulating the auditory nerve fibers. This device is used to restore hearing in people who have lost their hearing because of damaged hair cells.

Front 16

Cochlear nucleus

Back 16

The nucleus where nerve fibers from the cochlea first synapse.

Front 17

Cochlear partition

Back 17

A partition in the cochlea, extending almost its full length, that separates the scala tympani and the scala vestibuli. The organ of Corti, which contains the hair cells, is part of the cochlear partition.

Front 18

Core area

Back 18

The area in the temporal lobe that includes the primary auditory cortex (A1) and some nearby areas. Signals from the core area are transmitted to the belt area of auditory cortex.

Front 19

Decay

Back 19

The decrease in the sound signal that occurs at the end of a tone.

Front 20

Decibel (dB)

Back 20

A unit that indicates the presence of a tone relative to a reference pressure: dB = 20 log (p/po) where p is the pressure of the tone and po is the reference pressure.

Front 21

Eardrum

Back 21

Another term for the tympanic membrane, the membrane located at the end of the auditory canal that vibrates in response to sound.

Front 22

Effect of the missing fundamental

Back 22

Removing the fundamental frequency and other lower harmonies from a musical tone does not change the tone’s pitch. See also Periodicity pitch.

Front 23

Envelope of the traveling wave

Back 23

A curve that indicates the maximum displacement at each point along the basilar membrane caused by a traveling wave.

Front 24

Equal loudness curve

Back 24

A curve that indicates the sound pressure levels that result in a perception of the same loudness at frequencies across the audible spectrum.

Front 25

Fourier analysis

Back 25

A mathematical technique that analyzes complex periodic waveforms into a number of sine-wave components.

Front 26

Frequency

Back 26

In the case of a sound wave that repeats itself, such as the sine wave of a pure tone, frequency is the number of times per second that the wave repeats itself.

Front 27

Frequency spectrum

Back 27

A plot that indicates the amplitudes of the various harmonics that make up a complex tone. Each harmonic is indicated by a line that is positioned along the frequency axis, with the height of the line indicating the amplitude of the harmonic.

Front 28

Frequency tuning curve

Back 28

Curve relating frequency and the threshold intensity for activating an auditory neuron.

Front 29

Fundamental frequency

Back 29

Usually the lowest frequency in the Fourier spectrum of a complex tone. The fundamental frequency is also called the first harmonic. The tone’s other components, called higher harmonics, have frequencies that are multiples of the fundamental frequency.

Front 30

Hair cell

Back 30

Neuron in the cochlea that contains small hairs, or cilia, that are displaced by vibration of the basilar membrane and fluids inside the inner ear. There are two kinds of hair cells: inner and outer.

Front 31

Hair cell, inner

Back 31

Auditory receptor cell in the inner ear that is primarily responsible for auditory transduction and the perception of pitch.

Front 32

Hair cells, outer

Back 32

Auditory receptor cells in the inner ear that amplify the response of the inner hair cells. See also Motile response.

Front 33

Harmonics

Back 33

Fourier components of a complex tone with frequencies that are multiples of the fundamental frequency.

Front 34

Hearing

Back 34

The experience of perceiving sound.

Front 35

Hertz (Hz)

Back 35

The unit for designating the frequency of a tone. One Hertz equals one cycle per second.

Front 36

Hierarchical processing

Back 36

Processing signals through a sequence of areas. This occurs in the visual system as signals are transmitted from the LGN to primary visual receiving area, and then to higher areas. It occurs in the auditory system as signals are transmitted from the core to the belt to the parabelt regions of the cortex.

Front 37

Incus

Back 37

The second of the three ossicles of the middle ear. It transmits vibrations from the malleus to the stapes.

Front 38

Inferior colliculus

Back 38

A nucleus in the hearing system along the pathway from the cochlea to the auditory cortex. The inferior colliculus receives inputs from the superior olivary nucleus.

Front 39

Inner ear

Back 39

The innermost division of the ear, containing the cochlea and the receptors for hearing.

Front 40

Level

Back 40

Short for sound level. Indicates the decibels or sound pressure of a sound stimulus.

Front 41

Loudness

Back 41

The quality of sound that ranges from soft to loud. For a tone of a particular frequency, loudness usually increases with increasing decibels.

Front 42

Malleus

Back 42

The first of the ossicles of the middle ear. Receives vibrations from the tympanic membrane and transmits these vibrations to the incus.

Front 43

Masking (auditory)

Back 43

Occurs when presentation of one sound decreases a listener’s ability to hear another sound.

Front 44

Medial geniculate nucleus

Back 44

An auditory nucleus in the thalamus that is part of the pathway from the cochlea to the auditory cortex. The medial geniculate nucleus receives inputs from the inferior colliculus and transmits signals to the auditory cortex.

Front 45

Middle ear

Back 45

The small air-filled space between the auditory canal and the cochlea that contains the ossicles.

Front 46

Middle-ear muscles

Back 46

Muscles attached to the ossicles in the middle ear. The smallest skeletal muscles in the body, they contract in response to very intense sounds and dampen the vibration of the ossicles.

Front 47

Motile response

Back 47

A response to sound of the outer hair cells in which these cells move. The cells tilt and get slightly longer, which increases basilar membrane vibration and therefore amplifies the response of the inner hair cells.

Front 48

Octave

Back 48

Tones that have frequencies that are binary multiples of each other (2, 4, etc.). For example, an 800-Hz tone is 1 octave above a 400-Hz tone.

Front 49

Organ of Corti

Back 49

The major structure of the cochlear partition, containing the basilar membrane, the tectorial membrane, and the receptors for hearing.

Front 50

Ossicles

Back 50

Three small bones in the middle ear that transmit vibrations from the outer to the inner ear.

Front 51

Outer ear

Back 51

The pinna and the external auditory meatus.

Front 52

Oval window

Back 52

A small, membrane-covered hole in the cochlea that receives vibrations from the stapes.

Front 53

Parabelt area

Back 53

Auditory area in the temporal lobe that receives signals from the belt area.

Front 54

Periodicity pitch

Back 54

The constancy of a complex tone’s pitch when the fundamental frequency and other lower harmonics are eliminated. See also Effect of the missing fundamental.

Front 55

Phase locking

Back 55

Firing of auditory neurons in synchrony with the phase of an auditory stimulus.

Front 56

Pinna

Back 56

The part of the ear that is visible on the outside of the head.

Front 57

Pitch

Back 57

The quality of sound, ranging from low to high, that is most closely associated with the frequency of a tone.

Front 58

Place theory of hearing

Back 58

The proposal that the frequency of a sound is indicated by the place along the organ of Corti at which nerve firing is highest. Modern place theory is based on Békésy’s traveling wave theory of hearing.

Front 59

Psychophysical tuning curve (hearing)

Back 59

A function that indicates the intensity of masking tones of different frequencies that cause a low-intensity pure tone to become just barely detectable.

Front 60

Pure tone

Back 60

A tone with pressure changes that can be described by a single sine wave.

Front 61

Resonance

Back 61

A mechanism that enhances the intensity of certain frequencies because of the reflection of sound waves in a closed tube. Resonance in the auditory canal enhances frequencies between about 2,000 and 5,000 Hz.

Front 62

Resonant frequency

Back 62

The frequency that is most strongly enhanced by resonance. The resonance frequency of a closed tube is determined by the length of the tube.

Front 63

Sound (perceptual)

Back 63

The perceptual experience of hearing. The statement “I hear a sound” is using “sound” in that sense.

Front 64

Sound (physical)

Back 64

The physical stimulus for hearing. The statement, “The sound’s level was 10 dB” is using “sound” in that sense.

Front 65

Sound level

Back 65

The pressure of a sound stimulus, expressed in decibels. See also Sound pressure level.

Front 66

Sound pressure level (SPL)

Back 66

A designation used to indicate that the reference pressure used for calculating a tone’s decibel rating is set at 20 micropascals, near the threshold in the most sensitive frequency range for hearing.

Front 67

Sound wave

Back 67

Pattern of pressure changes in a medium. Most of the sounds we hear are due to pressure changes in the air, although sound can be transmitted through water and solids as well.

Front 68

Stapes

Back 68

The last of the three ossicles in the middle ear. It receives vibrations from the incus and transmits these vibrations to the oval window of the inner ear.

Front 69

Subcortical structure

Back 69

Structure below the cerebral cortex. For example, the superior colliculus is a subcortical structure in the visual system. The cochlear nucleus and superior olivary nucleus are among the subcortical structures in the auditory system.

Front 70

Superior olivary nucleus

Back 70

A nucleus along the auditory pathway from the cochlea to the auditory cortex. The superior olivary nucleus receives inputs from the cochlear nucleus.

Front 71

Tectorial membrane

Back 71

A membrane that stretches the length of the cochlea and is located directly over the hair cells. Vibrations of the cochlear partition cause the tectorial membrane to bend the hair cells by rubbing against them.

Front 72

Timbre

Back 72

The quality that distinguishes between two tones that sound different even though they have the same loudness, pitch, and duration. Differences in timbre are illustrated by the sounds made by different musical instruments.

Front 73

Tone chroma

Back 73

The perceptual similarity of notes separated by one or more octaves.

Front 74

Tone height

Back 74

The increase in pitch that occurs as frequency is increased.

Front 75

Tonotopic map

Back 75

An ordered map of frequencies created by the responding of neurons within structures in the auditory system. There is a tonotopic map of neurons along the length of the cochlea, with neurons at the apex responding best to low frequencies and neurons at the base responding best to high frequencies.

Front 76

Traveling wave

Back 76

inn the auditory system, vibration of the basilar membrane in which the peak of the vibration travels from the base of the membrane to its apex.

Front 77

Tympanic membrane (eardrum)

Back 77

A membrane at the end of the auditory canal that vibrates in response to vibrations of the air and transmits these vibrations to the ossicles in the middle ear.