Hearing continued Flashcards
stereocilia cause changes in ____ ________ as they are flexed
graded potentials
______ in response to sound results in neurotransmitter release to auditory nerve
depolarization
depolarization is the opposite of photoreceptors that __________ when exposed to light
hyperpolarize
responses of individual AN fibers to different frequencies are related to their place along the cochlear partition is called
place coding
clearest when sounds are very faint is called
frequency selectivity
what is the name for a graph plotting thresholds of a neuron or fiber in response to sine waves with varying frequencies at the lowest intensity that will give rise to a response
threshold tuning curve
what happens to specificity of AN fibers at high amplitudes?
they get washed out/muddied
all AN fibers synapse to the _____ _____ for the ___ ___ ___
cochlear nuclei; same side ear
cells in the cochlear nuclei can code for … and use _____ _______
sound onset for particular frequencies or sets of frequencies; lateral inhibition
where are two places that we have learned about that use lateral inhibition?
horizontal cells in the eyes
cochlear nuclei
superior olives
first place auditory information from both ears meets
which system receives information first from both eyes/ears: auditory or visual?
auditory
inferior colliculus
receives input from both ears, but stronger signal from contralateral ear
order of places information received in sound
- cochlear nucleus
- superior olive
- inferior colliculus
- MGN
- Auditory cortex
MGN
part of thalamus
frequency-based, tonotopic organization maintained at all levels even into cortex
primary auditory cortex (A1)
first part of cortex to respond to sound, relatively basic processing of any sound
much like V1
Secondary and associational auditory areas (belt and parabelt)
respond to more complex sounds
parabelt communicates w/ other senses
tonotopic description of auditory cortex
sorted on frequency
the more anterior = lower
the more posterior = higher
psychoacoustics
psychophysical study of how auditory information impacts perception of sound (and thus the auditory system)
audibility threshold
the lowest sound pressure level that can be reliably detected at a given frequency
remember: 50% threshold
equal-loudness curve
a graph plotting sound pressure level vs. the frequency for which a listener perceives constant loudness (JND)
2 sounds that sound almost identical in loudness @ different frequencies/amplitudes
_______ and _______ have an impact on loudness, proven by equal loudness curve
frequency; amplitude
temporal integration
longer sounds of the same amplitude will seem louder than shorter ones (in the range of 100-200 ms)
can we detect a pitch change from 1000 to 1001 Hz?
yes!
masking
where a 2nd sound is played on top of another
2nd sound usually white noise
mask needs to be higher in amplitude than tone to drown it out
white noise
all wavelengths of sound at once
bandwidth of 20-20,000 Hz
critical bandwidth
increasing the bandwidth further no longer affects the tone
role of the ear canal
transmit sound
blocking the ear canal will …
impact how sound can be transmitted
conductive hearing loss
found in middle ear
caused by issue with ossicles (can grow too large for example in otosclerosis)
sensorineural hearing loss
caused by deficits in cochlea and/or auditory nerve, usually due to hair cell damage
most common form of hearing loss, caused by excessive loud noise, infections, and drugs
presbycusis
age-related hearing loss
which gender sees more hearing loss with age?
men
interaural time differences (ITD)
tiny differences in timing between when the sound hits each ear
measured in microseconds
negative degrees of hearing means …
coming from the left
azimuth
angle of sound on horizontal plane relative to head
best detection of smallest just noticeable difference is @ _____ Hz
1000
positive degrees of hearing means ….
coming from the right
ITD detection is ______ dependent
frequency
where are the cells that are in our brain that process these timing differences from each ear?
medial superior olive (MSO)
for the medial superior olive, think medial –> _______
microseconds/time
2 theories on medial superior olive and ITDS
there are differences in the length of their axons to various cells, meaning their signals exacerbate timing differences
or
signal travels slightly further in one ear than the other down the cochlea, making slight difference in frequency
interaural level difference (ILD)
intensity of sound to each ear
heavily impacted by your head
an increase of frequency = ________ in the interaural level difference
increase
lateral superior olive (LSO)
gets excitatory inputs from ipsilateral (same) ear and inhibitory from contralateral (opposite) ear
think lateral = level/loudness
“cone of confusion”
a lot of locations will have similar ILDs/ITDs
directional transfer function
your pinna, ear canal, etc. change the intensity of sounds with different frequencies when they arrive at each ear from different locations in space
your brain knows your pinna and uses its reflection of sound to …
understand location and elevation
inverse-square law for distance perception
as distance increases, intensity decreases faster
spectral composition of sound
higher frequencies decrease in energy more than lower frequencies as sound travels over distance
why can people who are blind hear better?
visual cortex can “remap” to process auditory information in the absence of visual inputs
in vision, the first part of the brain with cells that receive information from both eyes is in _____, while in hearing the first part is in _____.
a. LGN; MGN
b. V1, A1
c. V1, Superior Olive
d. LGN, superior olive
c
An 1800 Hz tone is masked on Trial 1 with noise that has a bandwidth of 1750-1850 Hz. The tone is just barely audible at this point. What would happen if the bandwidth of noise was widened to 1500-2100 Hz? Assume amplitude is never adjusted for either sound.
a) The tone would become clearer against the irrelevant bandwidths
b) The tone would not be affected by the increasing bandwidth, as 100 Hz is generally the critical bandwidth
c) The tone would become inaudible, as increasing bandwidth in this range generally mask overlapping tones
d) The tone would be audible, but it would sound like it was at a different frequency
c
A sound produces a maximal Interaural Timing Difference but almost no Interaural Level Difference. Which of the following most likely would produce that?
a) A sound at 90 degrees at 6000Hz
b) A sound at 180 degrees at 6000Hz
c) A sound at 180 degrees at 200 Hz
d) A sound at 90 degrees at 200 Hz
d
