the ear and sound Flashcards
what is the stimulus for hearing?
pressure waves / sound waves
what do pressure waves represent a form of?
mechanical energy
ears translate pressure energy ino?
neural code
regardless of the barrier pressure waves are being transmitted through, we hear these waves that are created through
expansion and compression of the molecules
what does frequency refer to?
the number of cycles per second
what is frequency usually measured in?
hertz
what is frequency related to?
the perceptual experience of pitch
if there is a higher frequency, what length is the wavelength?
short
what is amplitude?
the amount of compression and expansion of molecules in conducting medium
what is amplitude related to?
perceptual experience of perceived loudness
if something has a lower amplitude, the sound is?
quiet!
what is amplitude measured in?
decibels (dB)
what is the auditory system designed to do?
funnel in pressure (sound) waves and translate them into neural impulses for transduction
what does the outer ear funnel sound towards?
the eardrum (tympanic membrane)
what does the tympanic membrane do in response to incoming soundwaves?
the eardrum vibrates
what does the middle ear consist of? what do they do?
three tiny bones that amplify the pressure waves relayed by the eardrum
what are the three small bones in the middle ear?
the hammer (malleus), the anvil (incus) and the stirrup (stapes)
what is the malleus connected to? what does it form?
connected to the eardrum, which forms the boundary between the outer/middle ear
what is the incus connected to?
the other two bones (malleus and stapes)
what is the stapes connected to? what does it form?
connected to the oval window, which forms the boundary between the middle/inner ear
what happens in the inner ear?
pressure waves actually become sound
what are the three main parts of the inner ear?
cochlea, organ of corti, and basilar membrane
what is the cochlea?
a fluid filled tube that moves when vibrations hit it
what is the organ of corti?
within the cochlea that rests on the basilar membrane and contains hair cells that act as sound receptors
vibrations from the oval window cause the fluid in the cochlea to move, which creates?
waves in the basilar membrane
what do the sound waves do when they come into contacts with the hair cells?
these waves bend the hair cells, causing them to fire action potentials
what does the hair cells form a synapse with?
the auditory nerve
what are the steps of sound transduction as they go through each part of the ear?
- outer ear: sound enters outer auditory canal and strikes the eardrum, causing eardrum to vibrate
- middle ear: these vibrations cause the hammer, anvil and stirrup to vibrate and amplify the sound wave, which in turn vibrates the oval window
- inner ear: these vibrations from the oval window cause the fluid inside the cochlea to move, movement of fluid bends the hair cells, causes neurotransmitter release in the auditory nerves they synapse with
how is a high amplitude sound wave coded for?
higher amplitude sound waves bend hair cells more, resulting in a neurotransmitter release, resulting in a higher rate of firing
how is loudness coded for?
as a function of both firing rate and identity of which neurons are firing
what is frequency theory?
nerve impulses match the frequency of sound waves being coded
what is a problem with frequency theory?
cannot explain the coding of higher frequencies that we can perceive
what is place theory?
the specific place in the cochlea where a particular frequency of sound waves bends a hair cell most strongly will contribute to the coding of pitch
what is our coding of pitch theory now?
low pitches are coded in accordance with frequency theory while high pitches are coded in accordance with place theory
in the localization of sound, what is binaural hearing?
hearing with two ears
how is the difference in arrival time between both ears informative?
sound arrives at the closer ear first which allows us to know where sound is coming from
how is the difference in intensity between both ears informative?
the sound arriving at the closest ear is most intense
how does conduction of deafness result?
from problems relating to the mechanical conduction of sound to the cochlea (middle ear is not working properly)
would hearing aids be effective for conduction damage?
yes!
