chapter 11: hearing Flashcards
what is the difference between the physical and the perceptual definition of sound
physical: pressure change
perceptual: experience
when does a sound stimulus occur
mov or vibrations of an object causes pressure change in air/water or other elastic medium
explain the compression and the rarefaction process
compression: push surrounding air molecules together, density ↑
rarefaction: air molecules spread out to fill increased space, density ↓
what is a sound wave
pattern of alternating high and low pressure regions
- speed of 340meters/sec
true or false? when sound causes air to move, the air molecules travel further and further away from the sound stimulus
false, they move back and forth but stay in the same place
what is a pure tone
changes in air pressure that occur in a pattern called sine wave
differentiate frequency and amplitude
frequency: number of cycles per second
amplitude: size of pressure change
sound frequency are measured in … and higher frequencies are associated with higher …
Hertz (Hz)
pitch
sound amplitude are measured in … and the amplitude of a sound is associated with the …
decibel (dB)
loudness
what is a periodic waveform
waveform that repeats
what is called the repetition rate of a waveform
fundamental frequency
the first harmonic is the frequency equal to the fundamental frequency. how are higher harmonics calculated?
multiples of the fundamental frequency
- 2nd harmonic is frequency x 2
describe the frequency spectra
line position indicates frequency (horizontal axis)
line height indicates harmonic’s amplitude
In a complex tone, removing a harmonic doesn’t change the rate of repetition, only the waveform. Why is that
when the fundamental is removed, the spacing remains so there is still info in the waveform indicating the frequency of the fundamental
what is the equation used to transform sound pressure level into decibels
dB = 20 x log10 (p/po)
where p = pressure of sound
po = reference pressure
what procedure was used to determine the relationship between level in decibels and loudness
magnitude estimation
in the audibility graph, indicate what the audibility curve, the auditory response area, the threshold of feeling, and the equal loudness curve represent
audibility curve: threshold for hearing
aud resp area: tones we can hear
threshold of feeling: when tones become painful and can cause damage
equal loud curve: diff frequencies, same loudness
the lowest and the highest note on the piano is represented by how many hertz
low: 27.5Hz
high: 4186Hz
define tone height
perceptual experience of increasing pitch that accompanies increases in a tone’s fundamental frequency
define tone chroma
different octaves of the same note
- fundamental frequencies that are multiple of two
what is the effect of the missing fundamental
when pitch remains the same, even when the fundamental or other harmonics are removed
what is a sound’s timber
quality that distinguished between two tones that have the same loudness, pitch and duration, but still sound different
what are the two things a sound’s timber depends on
- steady-state harmonic structure
- attack and decay of the tone’s harmonic
define what are a tone’s attack and a tone’s decay
attack: buildup of sound at the beg of the tone
decay: decrease in sound at the end of tone
what are aperiodic sounds
waveforms that do not repeat
name the three tasks the auditory system accomplishes as sound enters the ear and culminates inside the ear
- delivers sound stimulus to receptors
- transduces stimulus from pressure change to electrical signal
- process electrical signal
what are the structures in the outer ear
- pinnae
- auditory canal
- tympanic membrane (eardrum)
what are the two functions of the auditory canal
- protects middle ear structures
- enhance intensities of sound: resonance
explain the physical principle of resonance
sound waves that are reflected back from the closed end of the auditory canal interact with sound waves that are entering the canal
what do we call the frequency that is reinforced the most
resonant frequency
name the structures in the middle ear
ossicles: malleus, incus, stapes
oval window
why is it necessary to enhance sound intensities from the middle ear to the inner ear
pressure changes in the air are transmitter poorly to the liquid in the inner ear
how do ossicles help transmit the vibrations from the middle ear to the inner ear
- concentrates vibration of the large tympanic membrane onto the much smaller stapes
- creates lever action
name the structures in the inner ear
cochlea
- scala vestibuli
- scala tympani
- cochlear partition
describe the organ of Corti in the cochlear partition
- rests on basilar membrane
- 1 row of inner hair cells and 3 rows of outer hair cells
- stereocilia of tallest row of outer hair cells embedded in tectorial membrane
how does vibration cause bending of the stereocilia
- back and forth mov of oval window transmits vibration to liquid in cochlea
- basilar membrane moves
- organ of Corti vibrates up and down
- tectorial membrane move back and forth
- stereocilia of outer hair cells embedded bend
- other hair cells bend to pressure waves
where does electrical signals occur
in inner hair cells
how does bending of the stereocilia cause electrical signals (transduction)
when stereocilia bend
- tip links stretch
- open tiny open ion channels in membrane of stereocilia
- K+ ions flow in cell, electrical signal created
when stereocilia bends in other direction, inverse happens
release of NT in synapse = auditory nerve fibers fire
when the pressure increase, towards which direction does the stereocilia bend
to the right
define phase locking
property of firing at the same place in the sound stimulus
for high-frequency tones, why don’t nerve fiber fire every time
needs to rest after it fires
as the frequency increases, the place on the membrane that vibrates the most moves from the … to the …
apex; base of the oval window
what is called the map of frequencies
tonotopic map
how do outer hair cells function as cochlear amplifiers
- ion flow causes mechanical changes in cell that causes it to expand and contract
- pulls stereocilia in one direction and the other
- pulls on basilar membrane and increases its motion
- sharpens its response to specific frequencies
what is the place theory that explains the physiology of pitch
brain identifies which neurons on the basilar membrane responds the most to determine pitch
what is the pathway from auditory nerve fiber to auditory cortex
cochlear nucleus
superior olivary nucleus
inferior colliculus
medial geniculate nucleus
primary auditory cortex
in which region do signals from the left and right ear first meet
superior olivary nucleus
what is the frequency-matched noise
noise stimulus covers the same range as pitch stimulus
which area in the cortex is most responsive to pitch
anterior auditory cortex
- mainly to resolved harmonics, not unresolved
what is the difference between resolved and unresolved harmonics
resolved: lower harmonics can be distinguished by a peak
unresolved: higher harmonics doesn’t indicate individual harmonic
between resolved and unresolved harmonics, which result in a stronger perception of pitch
resolved
what are amplitude-modulated noise
sound stimulus that weren’t associated with vibration of a particular place on basilar membrane, but still created perception of pitch
define amplitude modulation
level of noise was changed = loudness of noise fluctuated rapidly up and down
pitch perception and phase locking only occurs up to how many hertz
5 000
what is one of the main cause of hearing loss
noise in the environment
damage to outer hair cells results in …
loss of sensitivity and loss of sharp frequency tuning
what is presbycusis
hair cell damage resulting from the cumulative effects over time of noise exposure, ingestion of drugs that damage hair cells and age-related degeneration
what is hidden hearing loss
people with “normal” hearing who have trouble hearing in noisy environment
what test is used to determine if someone has “normal” hearing
detect faint noise in quiet room
- threshold
- “normal” is 0dB on audiogram
true or false? hair cells damage are permanent after noise exposure
false, auditory nerve damage is permanent. hair cells recover after 8 weeks
