Anatomy, Physiology and Psychophysics of Hearing, Auditory scales Flashcards
does perception always match the articulatory or acoustic domain
perception doesn’t always match articulatory or acoustic domain
the hearing organ
ear
the external ear is made up of what 3 things
auricle (pinna)
meatus (ear canal)
tympanic membrane (ear drum)
auricle
- pinna
- localize sound
- important to evolution
meatus
- ear canal
- about 2.5cm long
- 0.9mm
- 1/4 wavelength resonator
- amplifies frequencies between 2,000 Hz and 5,000 Hz
tympanic membrane
- ear drum
- works like a loud speaker or microphone membrane
The middle ear is made up of what 3 things
- malleus
- incus
- stapes
what ossicle connect directly to outer ear
malleus
which ossicle connects directly to inner ear
stapes
what is fluid in the inner ear called
lymphatic fluid inside the inner ear
pressure increase in middle ear
Ossicles function like a cone: from large surface (tympanic membrane) to smallest surface (stapes)
how do we avoid reflection form occurring in ear
pressure increase is necessary to generate the necessary activation of the liquid (otherwise reflection would occur)
how does the middle ear performs a kind of “volume control”
the muscles of malleus can be tensed, resulting in a low frequency damping
how are middle ear muscles activated
neural impulses
when are middle ear mucscles activated
- loud noise
- before you speak to protect against own voice
is the middle ear completely airtight
no
what allows pressure equalization in middle ear
eustachian tube
prevents feeling of pressure in the ear
cochlea
part of the inner ear relevant for hearing -> sound waves are transformed into neural impulses
parts of basilar membrane
- Upper: Scala vestibuli
- Lower: Scala tympani
- These two passages meet at the apex in the helicotrema
physiology of hearing
- The pressure waves from the middle ear (stapes) reach the cochlea through the oval window -> longitudinal pressure waves are generated in internal ear fluid through scala vestibuli to the apex
- These pressure waves return via scala tympani to the round window
Round window serves as
pressure release, since the fluids are incompressible
Organ of Corti consists of
the tectorial membrane, the hair cells and a number of additional supporting cells
Unlike the basilar membrane, the tectorial membrane
does not cover the whole width of the cochlea, but only partly overlaps the basilar membrane
are the basilar and tectoral membrane
One edge of the tectorial membrane is attached to the basilar membrane
the outer hair cells are coded in ______
3 rows tallest to shortest along basilar membrane
how many outer hair cells are there
about 20 000
the outer hair cells rest upon the __________
basilar membrane
inner hair cells transmit _____-____
sound info to the brain
outer hair cells go tallest to shortest in which direction
apex -> base
tall -> short
brain sends signals to outer hair cells that _____
move basilar membrane
actual transmission of information to the brain is done by ________
the inner hair cells
Outer hair cells can be controlled by …
the brain via a feedback loop
how many inner cells are there
Around 3500 inner hair cells
what do inner hair cells do
he conversion of the mechanical movement of the basilar membrane into neural impulses
how are inner hair cells organized
a single row inside the organ of corti
each inner hair cell is linked to how many nerve cells
1 inner hair cell links to about 1o nerve cells
what is located on the top of the inner hair cells main cell body
stereocilia
Frequency information is encoded in what manner
tonotopic (each area of reach their maximum displacement for different frequencies -> causing the nerve cells to fire at different frequencies)
the basilar membrane acts as a mechanical …
fourier transformation
oto-acoustic emissions
the change of shape of the outer hair cells results in a specific movement of the basilar membrane
oto-acoustics were discovered by who
Discovered by Kemp (1978) who projected short signal impulses into the ear -> with some delay the ear produced an echo of the impulses
Kemp experiment results
echo occurred much later and much stronger (higher amplitude) than expected by the reflective loop of the ear (external ear -> internal ear -> external ear) -> OAE’s are a reaction of the ear itself (including the brain)
what is application of oto-acoustics
babies and coma patients who cannot give verbal response
