Final Exam Study Guide Flashcards
what happens when stiffness is increased
rate of vibration increases
what happens when mass is increased
rate of vibration decreases
What are the phases of a wave?
90 - peak (compression)
180 - on the line
270 - trough (rarefaction)
360 or 0
What happens when two sound waves are added together, when the sound waves have the same amplitude
both sound waves have the same frequency the two sound waves are 180o out of phase
the resulting wave will equal zero and this is called a cancellation interference.
what is represented on the x axis of a waveform
time
describe simple harmonic motion, starting and ending with equilibrium, and the forces and physical properties involved.
Object is at rest (equilibrium)
Object is set in motion by a force
It is displaced to a max displacement
It then returns back to equilibrium due to restoring force of elasticity
It is displaced again to a max displacement in the opposite direction (due to inertial forces)
The object returns back to equilibrium because of restoring forces of elasticity
This motion continues indefinitely until damping (friction) causes it to stop
Once a sound source has been generated, describe how sound energy travels from the source through air. Include what happens to sound over time in a natural sound environment.
Sound source is at rest (equilibrium)
Sound source is set into motion
this motion causes the air molecules next to it to begin vibrating
Those first set of air molecules then cause the next set of molecules beside them to begin to vibrate
This area where there is an increase in air pressure is called condensation
Each individual air molecule is moving in SHM in their own axis
The first set of air molecules then return back to their equilibrium and this area of low pressure is called rarefaction
Damping, due to friction, occurs over time in a natural sound environment causing this motion to stop.
has a tonal quality
periodic
comprised of freq that have no particular math relationship to each other
aperiodic
comprised of harmonics
periodic
single pure tone
periodic
If a sound has a sound pressure level of 0 dB SPL, what is the pressure of that sound in micropascals?
20
Imagine someone tells you that a sound is “35 dB”. Why is this incomplete information?
This is incomplete because we don’t know the full reference. For example, it could mean it is 35 dB SPL or it could be 35 dB IL.
What does the term rms amplitude refer to?
average amplitude
If a waveform has a period of .004 seconds, what is the frequency in Herz?
250
What are harmonics? What does it mean to say that sounds within a harmonic complex are harmonically related?
Harmonics are the individual components of a complex sound. They are whole number multiples of the fundamental frequency, meaning that they are harmonically related.
Imagine that you are reading a research paper with your clinical preceptor and the sound descriptions are all in dB IL (dB intensity level). Your clinic preceptor asks you which type of dB is greater, dB IL or dB SPL. How you do answer?
dB IL and dB SPL are equal to each other
What is the log of 100?
2
amount of change from equilibrium position
amplitude
refers to a point within the cycle of SHM
phase
number of full cycles of SHM within a period of time
frequency
accurately describe sound transmission through air
sound can be described as a disturbance or vibrations of the molecules of an elastic medium
air molecules that are in a sound wave’s path move in SHM
Sound propagation causes regions of high and low pressure that alternate over time
Combine two tones of the same frequency, that have the same amplitude and starting phase
resulting wave has double the amplitude with same phase
Combine two tones of the same frequency, that have the same amplitude, and are 180 degrees out of phase
two tones cancel each other out
Combine two tones of the same frequency, that differ in starting phase by something other than 0 degrees or 180 degrees
will have areas of increased and decreased amplitude throughout the cycle, period stays the same
Calculate dB IL for a sound intensity of 10-10 watt/m2
20
Going from 0 dB SPL to 20 dB SPL represents what amount of increase in pressure?
Ten times the pressure (ten-fold increase)
A constant-percentage bandwidth filter is what type of filter?
band pass filter
The attenuation rate or the rejection rate refers to what?
amount of change in dB per octave
something that changes the frequency composition of a sound or how sound changes when it passes through a system
filters/transfer function
high pass filter has
lower cutoff
low pass filter has
upper cutoff
band pass has
upper and lower cutoff = BW
allows all sound frequencies to pass except for a very brief frequency range.
band reject filter
Calculate dB SPL for a sound pressure of 200 micropascals.
20
what is clinical definition of threshold
50% or .5
Each point along the basilar membrane has a best or characteristic frequency, where the response is optimal to sounds of a specific frequency.
The response (output) of a healthy basilar membrane at the characteristic frequency to varying levels of sound input is (select one)
nonlinear/compressive
With regards to human hearing, the term dynamic range refers to:
The range between the least audible sound and the highest tolerable sound (90-120dB)
the least amount of amplitude of a stimulus detected
absolute threshold
least amount of noticeable change along a single dimension
difference threshold
Explain why cochlear nonlinearities are responsible for the low auditory thresholds seen in the typical and unimpaired human auditory system
It is because the outer hair cells amplify low level inputs that is how we get our very low auditory thresholds.
the range of input equals the range output
linear
NOT equal or the same
compressive/nonlinear/logarithmic
what is sensation leve
threshold minus presentation
If a patient’s hearing threshold is 45 dB HL and you present a tone at 60 dB HL, what is the dB SL of the tone?
15 dB SL
Your patient has a hearing threshold at 2000 Hz of 40 dB HL. You want to present a tone to them at the same frequency at 40 dB SL. At what presentation level are you presenting the tone for it to be 40 dB SL?
80 dB
Minimum detectable signal strength with a 50% response rate.
threshold
physical process the sensory receptors are detecting sensory stimuli (ABR)
sensation
psychological process, organization, interpretation and requires conscious experience of those sensations. (Hearing screening, behavioral threshold) you need a response
perception
the amount of change divided by the original stimulus.
weber’s fraction
Presented at 10 they noticed the difference at 20
10-20 =10 (you subtract the difference) 10/10=1
Presented at 1,000 and you notice a difference at 1,005
1,000-1,005= 5 5/1,000= 0.005
what is weber’s law
1st is that as your initial quantity gets larger you need a bigger difference to tell them apart. (so the Just noticeable difference differential sensitivity gets bigger/larger) 2nd is that the fraction should be the same throughout. Webers fraction should be a constant. Weber’s fraction is the amount of change divided by the original stimulus.
Test assesses the smallest detectable difference between two stimuli that vary in sound pressure.
difference sensitivity
Test assesses the least amount of sound pressure level at which a subject responds 50% of the time.
absolute sensitivity
What makes a psychoacoustic procedure adaptive?
Each successive presentation level is determined based on the patient/subject response
stimuli presented at random order, multiple trials per level
method of constant stimuli
patient controls the stimulus
method of adjustment
threshold estimated using descending and ascending runs with pre determined starting levels
method of limits
If we wanted to understand how much to increase a sound level for it to be perceived as double the original sound, what method would we chose?
direct scaling procedure
convert 60 dB HL to SPL at 2000 Hz using TDH 49/50 headphones
71
Your patient’s threshold is 25 dB HL. You present a tone at 65 dB HL at the same frequency. At what level in dB SL did you present the tone? Enter the number only.
40
According to our current understanding of measuring perceptual sensitivity, a subject or patient would never respond to a stimulus presented below their measured threshold of sensitivity for that sound.
false
What is dB level of a 2000 Hz tone perceived as having a loudness of 100 phons? (see chart)
95 dB
Using thephon curves what is the loudness in phons of a 70 dB SPL tone at 300 Hz?
74 phons
With regards to Signal Detection Theory, someone with a liberal criterion will present with thresholds that are relatively better or relatively poorer? (which one?)
They would have relatively better thresholds because someone with liberal criterion is more likely to press the button and say yes they heard the sound, making it seem that they perceive the low frequencies rather than someone with a conservative criterion.
describe the effects of signal duration on absolute threshold. What is the minimum presentation length of a pure tone to ensure valid testing?
Absolute threshold is the least amount of something that can be detected. If signal duration is presented for less than the minimum presentation length, the test subject may have a worse threshold because it needed to be louder for them to hear it for less than the 200 msec. If we present it at that minimum length required, their absolute threshold will be more accurate.
The minimum length of a pure tone to ensure valid testing is about 200 msec.
For listeners with typical hearing, a doubling of loudness is approximately equivalent to an increase of how many dB?
10
jnd for intensity
1 dB or better depending on presentation level
jnd for frequency
approx .5%
jnd for duration
as short as 2-3 msec
Why would the jnd for frequency be different at 2,000 Hz than it is at 1,000 Hz?
The JND is the smallest detectible change between two stimuli. For typical human hearing thresholds, the loudness perception is not the same or equal at all of the frequencies and our most sensitive frequency range is 1,000-5,000 Hz. Our JND would therefore be different at 2,000 Hz compared to 1,000 Hz because it is in the most sensitive frequency range and we would notice a larger difference at the larger frequency being 2,000 Hz.
List four factors that affect threshold estimation.
Attention level
Motivation
Understanding of the directions
Effects of habituation
What are the five parameters for measuring thresholds behaviorally? In other words, what are the five things that you need to decide on ahead of time when measuring a threshold of some kind?
Method Presentation
Starting level
Step size
Stopping rule
How we define or calculate threshold
Loudness is the perceptual correlate of intensity.
True or false: loudness perception is dependent upon the frequency of the stimulus
true
10 of this unit would be double the loudness of the 5 unit
sone scale
there is no relationship implied
phon scale
Using the RETSPL table below, convert 60 dB HL to dB SPL, at 2000 Hz, using TDH 49-50 headphones.
71
Your patient has a hearing threshold at 2000 Hz of 40 dB HL. You want to present a tone to them at the same frequency at 40 dB SL. At what presentation level are you presenting the tone for it to be 40 dB SL?
80
The cochlea is nonlinear, meaning that the amount of gain differs based on input level. Is more gain applied at low-level inputs, mid-level inputs, or high-level inputs?
low-level inputs
True or false: 30 dB SPL is a doubling of the pressure from 15 dB SPL.
false
For listeners with normal hearing, a doubling of loudness is approximately equivalent to an increase of how many dB
10
The human auditory system is equally sensitive at all frequencies between 20 Hz and 20,000 Hz.
false
The frequency range where the auditory system is the most sensitive is
1,000-5,000 Hz
When we test hearing, we test at a selection of discrete frequencies. When we plot the test results, we make assumptions about the hearing thresholds for the frequencies that we do not test.
For example, if the hearing threshold at 1,000 Hz is 10 dB HL and the hearing threshold at 2,000 Hz is also 10 dB HL, we assume the hearing thresholds for the frequencies between 1,000 - 2,000 Hz (1,200 Hz, for example, which we do not test) is also 10 dB HL.
Is this a correct assumption? (In other words, are we correct to assume this for each of the frequencies?)
false
A phon is a measure of
loudness
The reference for a phon is
1,000 Hz
Pitch is perceived based on maximum excitation along the basilar membrane.
place model
Bundles of auditory nerve fibers fire at the compression phase of a signal, giving the brain a cue for the period of the signal.
temporal model
Based on spectral representation of the stimulus (information contained in the spectrum).
place model
Based on the waveform of the stimulus.
temporal model
We see that a 250 Hz tone can mask a 1,000 Hz tone above certain presentation levels. What is the amount of masking when the 250 Hz tone is presented at 60 dB? (see masking curves (quiz 6)
28 dB of masking
The duration of a signal can (but may not always) affect what in terms of perception?
perception of tonality
absolute threshold
loudness perception
loudness
perception
intensity or SPL
physical
frequency
physical
pitch
perceptual
phase
physical
duration
both physical and perceptual
The jnd for frequency (also referred to as dlf) at 1,000 Hz is approximately 5 Hz. The jnd for frequency at 10,000 Hz is approximately 50 Hz. This is an example of (select the correct answer):
weber’s law
Frequency selectivity refers to the auditory system’s ability to
detect one sound in the presence of another, different sound
Pitch perception is affected by the presentation level.
true
How does presentation duration affect absolute threshold?
If the presentation time is less than 200 msec, threshold will be too high
Perception of loudness (how a person perceives the loudness of a sound) can depend on which of the following?
duration, frequency and bandwidth of a signal
With this type of psychoacoustic procedure, each subsequent presentation level depends on the subject’s or patient’s response
adaptive procedure
Which definition best describes frequency selectivity?
ask (quiz 7)
low frequency cue
ITD
high frequency cue
ILD
arises due to head shadow effect
ILD
sound arrives at each ear at a different point in the cycle (phase)
ITD
How is the spectrum of a sound affected with transient distortion
spectral splatter
How is the spectrum of a sound affected with harmonic distortion
distortion products are added, which are harmonics of the original signal
How is the spectrum of a sound affected with frequency distortion
amplitude is reduced at certain frequencies based on characteristics fo a filter
What is the “cocktail party effect?” (Cherry, 1953)
ability to attend to a target in the presence of competing noise
better ear effect
as takes advantage of the fact that one ear has a more favorable SNR
binaural squelch
the as takes adv of information received from both ears with different SNRs
signal threshold improved when tones to each ear are out of phase
masking level difference
copies of sound in reverberant room don’t interfere because of this
echo suppression
guitar string after being plucked
free vibration
tuning fork after being hit
free vibration
ossicles vibrating because of music
forced vibration
table vibrates when stem of a tuning fork is placed on it
forced vibration
measure to avoid spectral splatter
5 ms ramped rise time/fall time??
harmonic distortion
input level exceeds max output level
intermodulation distortion
input level exceeds max output level
linear system
proportionate change in input and output
nonlinear system
disproportionate change in input and output
one sound causes the threshold of another sound to be increased
masking
signal and masker are presented to opposite ears; the masker in the opposite ear increases the threshold of the signal
central masking
monaural masking; target signal and masker are presented simultaneously
psychoacoustic masking
the masker is presented either before or after the signal or target
temporal masking (forward and backward masking)
this masking takes place in the cochlea
psychoacoustic masking
this masking takes place in the binaural auditory neural pathway
central masking
the precise mechanism of this type of masking is unknown but it is presumed to be neural and not cochlear
temporal masking
You are carrying on a conversation with a friend next to a noisy piece of equipment. Your friend’s voice (RMS amplitude) is 65 dB SPL as it reaches your ears. The level of the noise coming from the equipment is 60 dB SPL as it reaches your ears. What is the SNR?
5 dB
what provides better hearing in noise
spatial separation of target signal and noise
binaural squelch
better ear advantage
What would happen to the resonant frequency of a tube if the length of the tube were increased
resonant frequency would decrease
The barrier is small relative to the wavelength? The barrier is large relative to the wavelength
sound will scatter around and fill in behind the barrier
there will be an acoustic shadow behind the barrier
The opening is small relative to the wavelength?
The opening is large relative to the wavelength
sound will pass through the opening and scatter as if it is a new sound source
sound will pass through the opening unchanged
small opening and large wavelength =
sound scatters and becomes new sound source
large opening and small wavelength =
sound passes through unchanged
small barrier and large wavelength =
sound will scatter around it and fill in behind it
large barrier and small wavelength =
acoustic shadow behind barrier
If the intensity of a sound 10 meters from the source is 36 watts/m2, what is the intensity 20 meters from the sound source in watts/m2?
9
If the level of a sound 25 meters from a sound source is 40 dB SPL, what is the level 50 meters from the sound source?
34 dB SPL
describes the flow of sound energy
acoustic immittance
component of impedance, opposes high frequency vibration
mass reactance
ease of sound flow
admittance
component of impedance, frequency independent
resistance
what components of impedance are frequency dependent? independent
mass and stiffness reactance
resistance
opposition to sound flow
impedance
component of impedance, opposes low frequency vibration
stiffness reactance
begins one wavelength from the sound source
far field
sound is circulating around the source and inverse square law doesn’t apply
near field
part of far field, inverse square law doesn’t apply, contains reverberations
diffuse field
inverse square law applies here
free field
explain equal loudness contours
Its is the phons scale, Everything on the scale is perceived the same. Frequency affects loudness and loudness depends on frequency. All sounds on multiple frequencies at the same dB are not equally loud.
What is dB level of a 2000 Hz tone perceived as having a loudness of 100 phons?
approx. 95 dB
How is the sone scale different from the phon scale? What do we know about a sound, for example, if it is 20 sones?
The sone scale is different from phons because the sone scale is comparing loudness on One/ same frequency and phons is comparing loudness on/across multiple, different frequencies.
1 sone = 40 db but every plus 10 db from there is double the sone amount.
Ex: 1sone = 40db
2 sone = 50 db
4 sone = 60db
8 sone= 70 db
The sones scale will tell us the relationships between sounds. If you double the amount of sones you double the loudness. What do we know about a sound if it is 20 sones. So….
20 sones is twice as loud as 10 sones. And 20 sones is ½ as loud as 40 sones.
(this is at the same frequency)
( you use the sones scale because it tell us the relationships since its only at one frequency at a time.)
doubling of intensity
3 dB
doubling of pressure
6 dB
doubling of loudness
10 dB
loudness recruitment
defined as an abnormally rapid increase in loudness with an increase in intensity of stimulus, and it is characteristic of disorders affecting the hair cells of the cochlea
explain loudness growth function for typical hearing, conductive hearing loss, and cochlear hearing l
see image
sudden changes in sound, sound that fluctuates in amplitude at a regular rate
amp modulated
What is temporal ordering? How is it assessed? Why is it important?
being able to process information in order that it comes in, important because of speech
assessed by syllable or words and repeat them back in correct order
At what modulation rates (low frequency or high frequency?) is the auditory system able to detect changes in an amplitude modulated signal.
at low frequency rates
faster rate sounds like a steady noise to listener
How does presentation duration affect the perception of tonality?
it is perceived as a click
Minimum presentation length
200 msec
temporal integration
adding together everything it receives in a time window
How does presentation duration affect loudness perception?
Presentation duration affects loudness. Is that after a long duration, over a minute the sound begins to diminish. This is called adaptation. Loudness perception diminishes after a minute.
This is more prevalent (noticeable) at lower presentation levels because over time you will notice it less because there’s not as much going on. (the longer the duration the more itll drop off in loudness perception,)
(we are having on presentation and we are not changing the physical level. However, over time you auditory system will begin what is called adaptation. And the sound will begging to dimmish over time even though its not actually changing. Adaptation is more at lower levels because over time you will even eventually stop hearing it)
What is it called when the loudness perception diminishes?
adaptation
Is this effect more prevalent at lower or higher presentation levels?
lower levels
explain the temporal model of pitch perception for pure tones and for complex harmonic sounds
phase locking to a period of the stimulus and a bundle of fires fire as a whole to the same period as the stimulus
phase-locking applies up to ______ in the mammalian auditory system
3-5,000 Hz
A doubling of frequency results in a doubling of pitch perception
false
pitch perception is affected by intensity
true
What role does pitch perception play in understanding speech in noise?
helps us separate one sound from another (auditory scene analysis)
ability to hear more than one component of a sound
two tones
tones in noise
frequency selectivity
shifted threshold
masking
sounds softer but can still hear it
partial masking
probe signal
test signal
causing the masking
masker
how much has it shifted by the threshold
amount of masking
what is the f0 of a harmonic series with frequencies 500, 1000, 1500, 2000, and 2500
500
what is the f0 of a harmonic series with frequencies 2000, 3000, 4000
1,000
what is the f0 of a harmonic series with frequencies 200 and 250
50
sound A is 30 dB SPL Sound C measures 100 times
the pressure. What is the dB SPL of sound C?
70
Sound A is 50 dB SPL. Sound C measures 1000 times
the pressure. What is the dB SPL of sound C?
110
Filter has:
amp - 0dB
center freq - 2,000 Hz
BW - 400 Hz
what are the upper and lower cutoffs? what type of filter is this?
band pass
upper - 2200
lower - 1800
filter has:
amp 0dB
upper - 1,000
what type of filter is this
low pass filter
filter has:
amp 0dB
lower - 1,000
what type of filter is this
high pass filter
calculate the total SPL with pressure level of 46 dB SPL and BW of 100 Hz
SPL = L + 10LogBW
66
Why do we use dB HL clinically?
Typical hearing thresholds vary by frequency. dB hearing
takes the typical hearing thresholds as measured in dB
SPL and makes them all 0 dB HL.
convert 5 dB HL at 500 Hz to dB SPL
18.5
If a patient’s hearing threshold is 15 dB and you present a
tone at 40 dB SL, at what dB HL are you presenting the
tone?
55
If a patient’s hearing threshold is 45 dB HL and you
present a tone at 60 dB HL, what is the dB SL of the tone?
15
Explain why threshold is a probability of a response rather
than a discrete point on a continuum.
this is because of our understanding of the
psychometric function. The probability of a
response changes as the stimulus increases but
below the established threshold, there is still
some probability of a response and above the
established threshold, there is a probability of a
no response. There is no single point below which
there is always no response and above which
there is always a yes response
what is weber’s law and fraction
Weber’s fraction: absolute difference divided by
the value of the starting level
Weber’s law: the value of the Weber’s fraction
remains a constant, regardless of stimulus level
other terms for differential sensitivity
differential threshold, jnd, difference limen
What are direct scaling procedures? When might
we use this type of procedure?
A direct scaling procedure has a person establish
a relationship between a standard stimulus and a
comparison stimulus. We might use this to
understand HOW changes in stimuli are
perceived
Describe how magnitude estimation and
magnitude production would be administered
Magnitude estimation: Person is given a reference stimulus and told that it has a particular value. The person assigns values to the other stimuli presented to them, based on the
reference.
Magnitude production: Same as magnitude estimation, except the person adjusts the stimulus
Describe how ratio estimation and ratio production would be administered
Same as magnitude estimation and production,
except with ratios instead of a reference number
Describe how a test using cross-modality would be administered
uses more than one sense. The person is asked to express the perceived magnitude for one sense in
terms of another sense. For example, express perceived magnitude for loudness in terms of a
line length
How is a simple up-down (staircase) method administered?
increase stimulus following “no response”
Decrease stimulus following “response”
How can an internal criterion be shifted? (In general.)
punish false positives and false negatives
Reward true positives and correct rejections
Describe and illustrate with a sketch how a gap detection experiment or test would be administered.
noises presented with gaps of silence between them. Trying to find the smallest detectable gap of silence
why does pitch of a harmonic sound stay the same even when f0 is removed
The fundamental frequency of a complex harmonic does not change when the physical component corresponding to the fundamental
frequency is removed because the fundamental frequency of the harmonic complex is not
changed. Phase-locking would still occur at the same rate (temporal model) and the distance
between peaks would be the same if the fundamental frequency were removed (place
model)
process of separating sounds from a background noise
auditory scene analysis
What is loudness summation and why is it evidence for auditory filters?
Loudness summation means that different sounds are perceived as louder, even if the level is the same, based on the nature of the sounds.
–With bands of noise, wider band signals are
perceived as louder than narrower band, even if
presented at the same level.
–With 2-tone complexes, the sounds are perceived as louder when the tones are further apart in terms of frequency.
This is evidence for auditory filters because it implies there is a critical bandwidth and sounds are perceived differently if the components of
the sounds fall within the critical bandwidth or not
what are 3 perceptual consequences of change in auditory filter shape
elevated hearing thresholds (HL)
increased susceptibility to masking
pitch perception ability decreases
why does a broader auditory filter have increased susceptibility to masking
With a broader auditory filter, the auditory system can not resolve the individual components of the signal and the noise. This could lead to masking occurring
when one sound raises threshold of another
maksing
occurs when one sound makes another sound more difficult to detect but doesn’t raise threshold
partial masking
what factors influence amount of masking
Intensity of the masker
spectral characteristics of the masker relative to the maskee or tone being masked
temporal characteristics of the masker (steady state vs. fluctuating)
Describe Fletcher’s critical bandwidth experiment. What were his findings?
Fletcher asked the question, “does increasing the bandwidth of the maker further raise the threshold of the maskee?” He found that increasing the bandwidth of the masker does further raise the threshold of the maskee, up to a point. Beyond that point, there is no further increase of threshold of the maskee. This lead to the model of the basilar membrane as a bank of overlapping filters. Filter bandwidth is approximately 19% of the center frequency.
on frequency listening
peak is at region on bm that is best frequency and that part of the bm is responding
off frequency listening
another part was responding
Why is a broader filter more susceptible to masking?
if sounds dont fall in same filter they are less likely to mask and if they are in the same one they are more likely to mask
binaural fusion
separate signals from each ear are perceived as a single fused auditory image
ability to improve perceptual performance on psychoacoustic tsak
binaural summation
f you had a patient with symmetrical
hearing thresholds and you fit them
with hearing aids providing the exact
same amount of amplification, would
there be a difference in loudness
perception if the patient wore only
one or wore both of the hearing aids?
Yes, it would be almost twice as loud
with both of the hearing aids in, due tobinaural loudness summation
azimuth
horizontal plane
elevation
vertical plane
directly in front
0 azimuth
directly to right
90 azimuth
directly to left
270 azimuth
directly behind
180 azimuth
How do interaural level differences
(ILD) arise? Is this a low frequency or a high frequency cue for sound source localization
LD’s arise because of the head
shadow. Sound is reflected off of the
head and casts an acoustic “shadow”
on the opposite side. The sound level is greater on the side where the sound
originated. This is a high frequency cue for sound source localization.
How do interaural timing differences
(ITD) arise? Is this a low frequency or a high frequency cue for sound source localization?
ITD’s arise because a sound arrives to
one ear sooner than it arrives to the
other. This is a low frequency
phenomenon.
same stimulus
diotic
differs in one dimension
dichotic
describe the precedence effect
says that the sound source localization is based on first copy of the sound to arrive to the as
two sounds with slightly different frequency co occur, compressions
and rarefactions overlap a portion of the time; perception is of a single
tone with fluctuating amplitude
beats
describe the doppler effect
Sound waves change when sound source is a moving object.
Perceptually, this results in a change in pitch. Sound moving away
from listener, wavelengths elongate, pitch lowers. Sound moving
towards listener, wavelengths are compressed, higher perception of
pitch
what causes standing waves
two waves moving in exact opposite directions, having same amp and freq
Name 3 instances where
standing waves are of
importance to an
audiologist.
Calibration issues when the ear canal is involved
Hearing aid measurements
Sound field testing
Explain why smaller animals have
better high frequency hearing,
based on ossicle size
They have smaller ossicles so their middle ear system can vibrate at high frequencies but not so much at low frequencies
