auditory Flashcards
humans are stuck within the ___ to ____ range
20 Hz-20 kHz
Middle ear cavity is ___-filled
Inner ear is ___-filled.
If sound waves were to impinge directly on the oval window, the membrane would barely move. Most of the sound would be reflected back because the fluid in the inner ear is denser than air and resists being moved much more than air does.
Consequently, in order to drive the movement of the oval window and vibrate the fluid, greater ___ is needed.
Middle ear cavity is air-filled
Inner ear is fluid-filled.
If sound waves were to impinge directly on the oval window, the membrane would barely move. Most of the sound would be reflected back because the fluid in the inner ear is denser than air and resists being moved much more than air does.
Consequently, in order to drive the movement of the oval window and vibrate the fluid, greater pressure is needed.
conductive hearing loss
Diminished sense of hearing due to the reduced ability of sounds to be mechanically transmitted to the inner ear. Common causes include occlusion of the ear canal, perforation of the tympanic membrane, and arthritic degeneration of the middle ear ossicles. Contrast with sensorineural hearing loss.
endolymph
-what is found there?
The potassium-rich fluid filling both the cochlear duct and the membranous labyrinth; bathes the apical end of the hair cells.
fluid of the labyrinth and the cochlear duct
what is sound? ***
• In physical terms:
• In casual terms:
- In physical terms: pressure waves generated by vibrating air molecules
- In casual terms: sounds refers to an auditory percept
• Two physical components of sound
- Displacement component- movement of molecules
- Pressure component- More about the density of molecules
• Sound is created by pressure waves in air. These waves are often induced by vibrating membranes such as vocal cords.
***What part of sound can we hear?
• what component of sound are humans sensitive to?
-between what Hz?
• Human ears are sensitive only to the pressure component, and only between 20 Hz and 20 kHz alternating compression and rarefaction (reduction in density)
Two characteristics we attend to most:
frequency and intensity
Humans cannot actually detect the movement of sound molecules but are sensitive to the pressure compnent of sound between 20 Hz and 20 kHz alternating compression and rarefaction
define rarefaction and compression
Compression- get more dense
• Rarefaction- get less dense
frequnecy def
A. The spacing between waves or period. This can also be thought of in terms of how many wave cycles pass by in one second- that is, the sound’s frequency in Hz=cycles/second
intensity def (measured in..)
The intensity of amplitude of the sound measured in decibels.
Tasks of the auditory system
**
Tasks of the auditory system
- Resolve intensity (loudness) and frequency (pitch, timbre) components of sound stimuli
- Encode temporal features
- Localize sound sources in space
compression
- air molecules gets more dense
- Peak
do animal vocalizations, speech, and music or environmental sounds such as wind contain highly periodic elements?
Note that animal vocalizations, speech, and music can contain highly periodic (tonal and harmonic) elements, whereas environmental sounds such as wind lack such periodic structure. (Courtesy of Timothy Warren.)
audible spectrum
-does it differ among species?
Species-specific
May have to shift want saying depending species
This, in turn, has an effect on the types of vocalizations each animal makes
Stick to ones within the realms of perception
Humans try to keep speaking within the spectrum
Same with the other species
Mice are always chatting – we just cant hear it (goes outside our range of hearing)
We are blocked within our rhelm of hearing
***How does the outer ear contribute to hearing?
- The outer ear and canal guide, amplify, and filter sound.
- Collects the sound energy and concentrates it on the TYMPANIC MEMBRANE (ear drum)
- The tympanic membrane and ossicles transmit the vibrations to the cochlea
- Especially effective at amplifying sounds in 2-5kHz range… super important for speech perception
- -Helps determine elevation of sound
• All sound is still air-based at this point
tympanic membrane
eardrum
-this is where the outer ear collects the sound energy and concentrates it
what air sound runs into
for what range is the outer ear effective at amplifying?
this helps to determine?
- Especially effective at amplifying sounds in 2-5kHz range… super important for speech perception
- -Helps determine elevation of sound
How does the middle ear contribute to hearing? ***
The vibrations from the eardrum set the ossicles into motion. The ossicles are actually tiny bones — the smallest in the human body. The three bones are named after their shapes: the malleus (hammer), incus (anvil) and stapes (stirrup). The ossicles further amplify the sound. The ossicles connect the tympanic membrane to the oval window
• At this point, we need to start converting sound in air to sound in liquid (Remember- sound consists of pressure waves). The tympanic membrane and auditory ossicles are a mechanism for transferring sound energy from the air medium to the liquid medium of the cochlea
• Air: low impedance; Liquid: high impedance
Each sound pressure wave moves the tympanic membrane back and forth, ultimately moving the oval window back and forth.
• Since liquid in the cochlea is incompressible, movements of the oval window are compensated for by movements of the round window.
• Oval window-
membrane where the bones of the middle ear meet the inner ear
• Ossicles
- little bones (malleus, incus, and stapes) that connect the tympanic membrane to the oval window. Move in response to sound/movement of tympanic membrane. Their movement causes movement of the oval window
• Oval window-
• Oval window- membrane where the bones of the middle ear meet the inner ear
• Stapedius
- smallest muscle in body; helps stabilize the stapes
• Innervated by cranial nerve VII (facial nerve)
Tensor tympani
Tensor tympani- connected to the malleus
• Innervated by cranial nerve V (trigeminal)
why is chewing not that loud
- Together, the muscles help dampen loud sounds (thunder, chewing) by counteracting the movement of the ossicles to the sound
- Reducing the amount of sound going from one side…
- This is why chewing is not that loud
- Super loud noises: dampening it down
mechanism for transferring sound energy from the air medium to the liquid medium of the cochlea
The tympanic membrane and auditory ossicles are a mechanism for transferring sound energy from the air medium to the liquid medium of the cochlea
• Air: low impedance; Liquid: high impedance
the cochlea tansduces action potentials in the?
sound is transduced into depolarizations and then action potentials in the vestibular-cochlear nerve (cranial nerve 8) **
the cochlea can only perceive sound, not amplify it T/F
FALSE - can also amplify it
• Vibrations enter the cochlea via the ____ and exit via the ____
• Vibrations enter the cochlea via the round window and exit via the round window.
• Chambers of the chochlea (probs label these too)
•
- the scala tympani: The lowermost of the three chambers. It too has a basal aperture, the round window, which is closed by an elastic membrane.
- The scala vestibuli: forms the upper chamber
- The scala media (cochlear duct): separates the other two chambers along most of their length.
what type of coding is found in the cochlea? explain it
tonotopic map- a location code- formed on the cochlea. due to the basilar membrane
higher frequencies cause movement in the _____ of the cochlea, and deeper frequencies work at the _____.
higher frequencies cause movement in the base of the cochlea, and deeper frequencies work at the apex.
Reissner’s membrane
divides the scala vestibulli and the scala media
How is vestibular information collected? What types of movements are detected? Where does that information go? ***
- Utricle and Saccule- respond to translational movements (linear motion) of the head and static head position in relation to gravity
- Semicircular canals- respond to rotations of the head
• information gets relayed to the cerebellum, thalamus, and the cortex
What types of movements are detected by the vestibular information?
- translational movements (linear motion) of the head and static head position in relation to gravity : Uticle and Saccule
- rotations of the head: Semicircular canals
Air vs liquid in regards to impedance
Air: low impedance; Liquid: high impedance
impedance is = resistance i think
Labyrinth is composed of
Composed of two otolith organs- the utricle and saccule- and three semicircular canals
-vestibular information
Semicircular canals
the semicircular canal has hair cells in its ampullae (swellings at base)
- each canal has the hair cells oriented in one direction, giving a pretty good representation of X, Y, and Z axes
*rotations of the head
THE SEMICIRCULAR CANALS: HORIZONTAL, POSTERIOR, AND ANTERIOR.
These three semicircular canals lie perpendicular to one another and detect rotational acceleration
otolith organs*
collective term used to refer to the utricle and the saccule, two components of the vestibular system that are designed to detect gravitational forces and linear acceleration of the head.
do pressure waves usually have fixed spacing? why or why not?
• Because the membranes usually vibrate in a regular manner, the pressure waves have a fixed spacing.
the first membrane sound hits in the outer ear is
the tympanic membrane
cochlear duct
The scala media (cochlear duct): separates the other two chambers along most of their length.
order of the three bones
malleus, incus, stapes
the stapes strikes the oval window.
The Basilar membrane
The Basilar membrane separates the cochlear and tympanic ducts.
-on which the cohlear hair cells are located
The basilar membrane is thinnest at its ___ and widest at its ___.
The basilar membrane is thinnest at its base and widest at its apex.
