auditory perception - exam 2 Flashcards
sound transformation up the auditory pathway
sound waves begin as vibrations in the air
enter ear canal
move through various stages
converted to neural signals in the brain
air bone fluid
air = sound waves
bone = ossicular vibrations
fluid = basilar membrane waves
outer ear
filters the sound
air
ear canal resonance
the resonance of the ear canal = the resonance of the vocal tract
amplifies the resonant frequencies of speech
middle ear
converts air vibrations into mechanical vibrations using eardrum & ossicles
inner ear (cochlea)
translates mechanical vibrations into electrical signals through hair cells
auditory nerve
carries electrical signals to the brain
interpreted as sound
limits of the auditory system
upper & lower bounds of hearing freqs (20-20,000 Hz)
neural saturation
temporal resolution - VOT
neural saturation
where high sound intensities cause neurons to max out
restricting dynamic range & clarity in hearing
sounds that follow other sounds don’t get as big of a neural response - neurons need time to rest
threshold of audibility
softest sound that can be heard
varies w/ freq
“0 loudness”
equal loudness curve
different freqs need varying sound pressures to be perceived as equally loud
low & high freq sounds need greater amp to be heard at same loudness as mid freq sounds
effects of inner ear on audition
cochlea converts sound to electrical impulses
responds to diff freqs along length of basilar membrane
linear scale of auditory representation
measure freqs uniformly
Hz
nonlinear scale of auditory representation
reflect human perception
smaller changes in lower freqs are more noticable than in higher freqs (stretch it out @ lower freqs, condense @ higher freqs)
Bark
cochlea
frequency masking
each neuron responds to multiple freqs
if already firing to 1 freq (1000Hz)
can’t increase firing much to another (1100Hz)
temporal masking
sounds that come in very close sequence (10-25ms) may obscure each other
upward spread of masking
sounds are more easily masked when they are higher in freq than the masker
low freqs travel farther along the BM, therefore moving more of the BM
high freqs don’t vibrate as much of the BM so are not able to mask lower freqs
the traveling waves loses it’s energy after it hits the characteristic place - doesn’t vibrate beyond that
as sound waves enter the ear, they are transformed from waves in _____ to waves in _____ to waves in ______ before before being transduced into electrical signals by the hair cells
air
bone
fluid
what part of the ear conducts a kind of Fourier analysis on the incoming acoustic signal
basilar membrane
auditory nerve innervates the…
cochlea
what accounts for the “bump” between 2700-5000Hz
filtering of the pinna
resonant freqs of the ear canal
which the bigger diff in auditory freq
1kHz to 2kHz
7kHz to 8kHz
the same
1kHz to 2kHz
the neural response to a tone 2 seconds in duration will be ____ at the onset of the tone & ______ after it has been playing for 1 second
large
smaller
stages up the auditory pathway
sound waves enters outer ear
travels through ear canal & strikes the eardrum
vibrations transferred to ossicles in the middle ear
vibrations enter cochlea, where hair cells convert them to electrical signals
signals travel through the auditory nerve to the brain
where along a freq scale are changes in pitch more audible
lower freqs (100-500Hz)
due to Bark scale’s nonlinear structure – reflecting our sensitivity to pitch vibrations in that range
Explain how engineers take advantage of our knowledge of hearing and our knowledge of speech production to enable good-sounding speech to be encoded and sent over networks with limited bandwidth.
Engineers apply frequency masking and equal loudness curves to reduce data, keeping only parts of the sound most perceptible to human hearing. They discard redundant data, creating clear audio with smaller file sizes, as seen in formats like MP3.
