Quiz 1 Review (Part 2) Flashcards
3 parameters allowing the brain to recognize sound?
pitch intensity and time
what is pitch
subjective or perceptual attribute that corresponds closely to the physical attribute of frequency
A change in frequency is heard as a change in
pitch
can we measure pitch
not diretly
measured by matching the pitch in question
what is pitch related to
the physical repetition rate of the waveform of sound
Increasing repetition rate = sensation of increasing pitch
How do we know if something is high or low pitch
More vibrations in a given time = high pitch
Less vibrations in a given time = low pitch
what the audiometer is testing
frequency
perception we hear
pitch
what is frequency discrimination
ability to detect changes in frequency
Normal hearing in humans can differentiate as low as 3 Hz difference
Discriminate between 2 sinusoids that are simultaneous with a brief interval between them
Ex → 1000 Hz sinusoid can just be differentiated (just noticeable difference-jnd) from a 1003 Hz sinusoid with a silent interval between them
what is frequency selectivity
ability to resolve complex sounds into its component frequencies
Not the same as discrimination
Complex sounds: speech, music etc.
The cochlea achieves frequency selectivity through its structure, where different parts respond to different frequencies (higher frequencies at the base, lower frequencies at the apex).
“tuning” of the cochlea.
Example → When listening to a conversation in a noisy environment, frequency selectivity helps us focus on the frequencies of the speaker’s voice while ignoring background noise
ability to separate or filter out specific frequencies from complex sounds.
selectivity
ability to notice small differences between two sound frequencies.
discrimination
what are the pitch perception theories
place theory
temporal/volley theory
what is the place theory
explains how we perceive different pitches (the highness or lowness of a sound) based on where sound waves stimulate the cochlea
Both discrimination and selectivity are closely connected here
what is frequency place mapping
explains how specific sound frequencies are linked to precise locations along the cochlea → helps us understand how our brain decodes different pitches based on where the cochlea is activated
A high-pitched sound causes maximum vibration at the _____ of the cochlea
base
A low-pitched sound causes maximum vibration at the
apex
suggests that our perception of pitch is linked to where in the cochlea the sound waves create the most activity and that specific places correspond to specific pitches.
place theory
how does the place theory work
Specific Regions of the Cochlea → The cochlea is “tonotopically organized,” (different parts of it are sensitive to different frequencies (pitches)). The base of the cochlea (closest to the outer ear) responds to high-frequency sounds, while the apex (the inner tip) responds to low-frequency sounds.
Pitch Perception → the pitch we hear is determined by the specific location (or “place”) along the cochlea where the sound waves cause the strongest vibrations, the point of maximum displacement in the traveling wave
Place Theory suggests that our perception of pitch is linked to where in the cochlea the sound waves create the most activity and that specific places correspond to specific pitches.
true
what is the temporal/volley theory
explains how we perceive pitch, especially at lower frequencies, based on the timing of neural firing rather than the specific location of activation along the cochlea
Auditory neurons phase lock to vibrations of the BM
Pitch assigned to a signal is determined by the timing pattern of neural impulses evoked by a stimulus
When LFs are heard, neurons fire at a particular phase of the waveform so that the neural spikes are at or close to the integer multiples of the period of the pure-tone
Different frequencies produce different patterns of neural spikes across time
how to determine timing of a tone
T = 1/f x 1000
500 Hz pure tone
t= 1/500 = .002 x 1000 = 2 ms
550 Hz pure tone
t= 1/550 x 1000 = 1.8 ms
Information from timing cues breaks down at around
5 kHz
how is pitch
determined in complex signals
There are many different frequencies but only one dominant pitch
The pitch above is matched ot a 100 Hz tone = fundamental (f0)
Pitch perception of harmonic complexes are explained by either ____ or ______
place or timing
how is pitch perception explained by place
max energy at 100 Hz causing excitation at the place corresponding to 100 Hz
how is pitch perception explained by timing
time-domain waveform could be periodic with a period equal to 1/f0 (t = 1/f)
to find period 1/f
to find frequency 1/t
other terms for missing fundamental
virtual pitch or residue pitch
what is the phenomenon of the missing fundamental
First tone that is heard has all of the frequencies, second tone has the fundamental removed but keeps all of the higher harmonics, each one after removes the lowest harmonic but although each note changes the pitch remains the same
this happens because they are harmonics and complex signals so they have the timing consistent with the fundamental even without it being present in the signal
Even though the fundamental frequency was removed from the signal the pitch perception stayed the same due to the brain interpreting the repetition patterns (harmonics-periodicity) that is present
what could or could not explain the missing fundamental
Cannot be explained by place theory because excites BM at that fundamental but now that the fundamental is gone it doesn’t explain how we still pick up the pitch so volley explains this
Could be explained through temporal theory because even though the fundamental is absent the temporal pattern of neurological activity is related to the period that is still being detected
what is cochlear HL associated with
reduced frequency selectivity (broad auditory filters)
When a sound contains multiple tones it is harder to tell them apart when there are a moderate number of them, making it more challenging to understand speech clearly or appreciate music
true
why do people with HL for a while think they are fine and can understand?
they have memory, context, etc.
but out of context they will have a hard time
what do PTs with cochlear HL rely on
depend on temporal cues and less on spectral information due to reduced frequency selectivity from the broad auditory filters
Those with cochlear loss have variable results even with similar audio results due to
individual differences in auditory filter size
neural synchrony
when do cochlear loss PTs have good pitch disrimination
Well preserved neural synchrony
when do cochlear loss PTs have poor pitch disrimination
Poor preserved neural synchrony Regardless of degree of the cochlear loss (broadening of the auditory filters)
Pitch is important in order to understand
language
Pitch perception is important to
Distinguish most important utterances in speech
This is why those with HL have issues understanding unless there is context
Indicate structure of sentences of phrases, especially for tonal languages (e.g. Mandarin, Chinese, Thai)
Convey nonlinguistic information
Gender, age and emotional status
Supplement speech reading
Voicing information is helpful (seeing your mouth etc.)
what is temporal resolution/acuity
how the as processes time-varying information changes
what is gap detection
Ability to detect changes over time between two brief stimuli
two main processes of temporal resolution
Within-channel gap detection threshold
Across-channels gap detection threshold
what is within channel GDT
minimum time needed to detect a gap between sounds that have the SAME spectrum
Within each frequency filter you can detect the timing changes (close frequencies)
what are channels
filters in the cochlea
if there is a larger gap
harder time understanding speech
if you have two sounds in the same spectrum and they are separated, how far apart in time do they need to be for the brain to recognize they are different?
3 ms
what is across-channel GDT
minimum time needed to detect gap between sounds presented to two ears
sounds that are spectrally dissimilar (e.g., tone and noise)
able to detect that sounds are two different ones
what are the differences between within and across
w/in: relies on detecting a temporal gap in a single frequency channel
Across: requires integrating information from multiple channels making it more complex and usually yielding higher thresholds
what is temporal integration/summation
Ability of the as to add information over time
if the sound is heard for a short time it will be harder to hear than one heard for a longer time
auditory system appears to integrate pure tone signal over
200-300 ms period
Auditory thresholds do NOT improve if the signal duration >300ms
true