chapter 11 pt 1 Flashcards

1
Q

physical definition of sound

A

pressure changes in the air or other medium

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2
Q

perceptual definition

A

the experience we have when we hear

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3
Q

how do loud speakers produce sound

A

by cycling through the processes of condensation and rarefication to increase and decrease hair pressure in a pattern

the pattern of air pressure changes is called a sound wave

remember: air pressure changes but the air molecules dont change place, they just move back and forth

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4
Q

condensation

A

first part of a loud speaker making sound - the diaphragm of the speaker moves out, pushing air molecules together - increase in density = local increase in air pressure above atmospheric pressure

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5
Q

rarefaction

A

second part of a loud speaker making sound
- the diaphragm moves in, pulling the air apart - air molecules spread out to fill in the increased space - decreased density = decrease in air pressure

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6
Q

amplitude

A

difference in pressure between high and low peaks of a wave

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7
Q

perception of amplitude

A

loudness

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8
Q

pure tone

A

a simple sound that occurs when changes in air pressure occur in a since wave pattern

fundamental building blocks of sound - but rare in the environment

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9
Q

what is the measure of loudness

A

decibel dB - the decibel scale relates the amplitude of the stimulus with the psychological experience of loudness

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10
Q

frequency

A

number of cycles within a given time period

oscilliations/second

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11
Q

how is frequency measured

A

in Hertz (Hz) - 1 Hz is one cycle per second

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12
Q

is perception of pitch related to frequency or loudness

A

frequency

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13
Q

tone height

A

the increase in pitch that happens when frequency is increased

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14
Q

fundamental frequency

A

the repetition rate and is called the first harmonic

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15
Q

periodic complex tones

A

consist of several pure tones called harmonics

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16
Q

additional harmonics

A

multiples of the fundamental frequency

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17
Q

additive synthesis

A

process of adding harmonics to create complex sounds

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18
Q

frequency spectrum

A

display of harmonics of a complex sound

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19
Q

missing fundamental

A

can still hear a tone without the fundamental frequency

because even when wave form changes, periodicity remains the same

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20
Q

what is the perceptual quality most closely related to the level or amplitude of an auditory stimulus

A

loudness

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21
Q

human hearing range

A

20 to 20 000 Hz

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22
Q

audibility curve

A

different frequencies take different amounts of sound in order for us to be able to hear them. The audibility curve shows the threshold of hearing in relation to frequency

changes on this curve show that humans are most sensitive to 2000 to 4000 Hz

23
Q

periodic waveform

A

a pattern of repeating pressure changes

the repetition rate of a periodic waveform is the fundamental frequency

24
Q

first harmonic

A

pure tone with a frequency equal to the fundamental frequency, also called the fundamental of the tone

the fundamental of a complex tone has a frequency which matches the repetition rate of the complex tone

25
Q

higher harmonics

A

pure tones with frequencies that are whole number multiples of the fundamental frequency

adding higher harmonics to the fundamental results in the waveform of a complex tone

26
Q

frequency spectra

A

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

27
Q

why do tones remain the same, even when we remove the first harmonic/fundamental?

A

because removing a harmonic changes a tone’s waveform, but the rate of repetition remains the same

remember the spacing between harmonics equals the repetition rate - and removing the fundamental doesn’t change the spacing

28
Q

what are the perceptual aspects of sound

A

loudness: differences in the perceived magnitude of a sound

pitch: involves differences in the low to high quality of sounds

29
Q

auditory response area

A

the portion of the audibility curve that contains tones we can hear

tones below the audibility response area are too low to hear and tones above are too painful/damage our auditory system

30
Q

threshold of feeling

A

the upper boundary of the auditory response curve that contains high amplitude tones that are painful/can cause damage to the auditory system

31
Q

equal loudness curves

A

a part of the audibility curve that indicates the sound levels that create the same perception of loudness at different frequencies

determined by presenting a pure tone of one frequency and having ps adjust the level of pure tones with frequencies across the range to match its loudness

32
Q

pitch

A

property of auditory sensation in terms of which sounds may be ordered on a musical scale extending from low to high

its variation is associated with musical melodies

33
Q

tone chroma

A

the perceptual similarity of notes separated by one or more octaves (tones that have frequencies that are binary multiples of each other)- notes with the same letter (A,B,C D, E, F, G)

notes with the same chroma have fundamental frequencies that are separated by a multiple of two

34
Q

timbre

A

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

35
Q

attack and decay of a tone

A

attack: buildup of sound at the beginning of a tone

decay: decrease in sound at the end of a tone

36
Q

periodic sounds

A

a sound stimulus in which the pattern of pressure changes repeats

37
Q

aperiodic sounds

A

sound waves that do not repeat

no perception of pitch
- door slamming shut, bunch of people talking at the same times, static on a radio

38
Q

outer ear

A

pinnae - ‘ear’ part - structures that stick out of the head

auditory canal - tube that protects the tympanic membrane/eardrum and keeps everything at a constant temperature

also enhances the intensities of some sounds by means of resonance

sound first enters here

39
Q

resonance

A

occurs in the auditory canal when sound waves that are reflected back from the closed end of the auditory canal interact with sound waves that are entering the canal

the interaction reinforces some of the sound’s frequencies, with the frequency that is reinforced the most being determined by the length of the canal

40
Q

resonant frequency

A

the frequency that is most strongly enhanced by resonance

the resonance frequency of a closed tube is determined by the length of the tube

41
Q

middle ear

A

small cavity that separates the outer and inner ears

contains the ossicles:
malleus - set into vibration by the tympanic membrane
incus - receives vibrations from the malleus
stapes - receives vibrations from the incus and transmits its vibrations to the inner ear by pushing on the membrane covering the oval window

42
Q

why are the ossicles necessary

A

they concentrate the vibration of the large tympanic membrane onto the much smaller stapes, increasing the pressure - important because the inner ear is filled with fluid, so it takes more pressure to vibrate it

they also create a lever action - ex. pushing on the long end of the board makes it possible to lift a heavy weight on the short end
- basically amplifying a small force - the lever action of the ossicles amplifies the sound vibrations reaching the tympanic inner ear

43
Q

middle ear muscles

A

the smallest skeletal muscles in the body found in the middle ear

attached to the ossicles, and at very high sound levels they contract to dampen the ossicle’s vibration
- reduces the transmission of low frequency sounds and helps to prevent intense low frequency components from interfering with our perception of high frequencies

44
Q

inner ear

A

innermost division of the ear containing the cochlea and receptors for hearing

45
Q

cochlea

A

snaillike structure in the inner ear that contains the basilar membrane and the organ of corti

its upper half and lower half is separated by the cochlear partition, which extends almost the entire length of the cochlea, from the base near the stapes to its apex at the far end

46
Q

organ of corti

A

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

47
Q

basilar membrane

A

a membrane that stretches the length of the cochlea and controls the vibration of the cochlear paritition

48
Q

tectorial membrane

A

a membrane that stretches the length of the cochlea and is located directly over hair cells - vibrations of the cochlear partition cause the tectorial membrane the bend the hair cells by rubbing against them

49
Q

tectorial membrane

A

a membrane that stretches the length of the cochlea and is located directly over hair cells - vibrations of the cochlear partition cause the tectorial membrane the bend the hair cells by rubbing against them

50
Q

stereocilia

A

small processes at the tips of hair cells which bend in response to pressure changes

the stereocilia in the the tallest row of outer hair cells are embedded in the tectorial membrane, and the stereocilia in the rest of the outer hair cells and all of the inner hair cells are not

51
Q

what does the motion of the basilar membrane do and how is it started

A

it sets the organ of corti into an up and down vibration and it causes the tectorial membrane to move back and forth

the movement causes the stereocilia that are connected to the tectorial membrane to bend (and the other stereocilia)

it is set into motion by vibrations that cause the oval window to move, transmitting those vibrations to the liquid inside the cochlea

52
Q

transduction in the ear

A

bending of the stereocilia one way causes tip inks to stretch, which opens tiny ion channels in the membrane of the stereocilia

when the stereocilia bend the other way, the links slacken, the ion channels close and ion flow stops

the back and forth bending causes alternating bursts of electrical signals

the electrical signal result in the release of neurotransmitters at the synapse separating the inner hair cells from the auditory nerve fibers, causing the fibers to fire

potassium ions flow into the cell and an electrical signal results

53
Q

what is the pattern of auditory nerve firing

A

fibers fire in synchrony with the pressure changes of a pure tone

stereocilia bend one way to pressure increases and fall back the other way in response to pressure decreases

this is called phase locking because firing occurs in the place as the sound stimulus