Audition Flashcards
What is the simplest sound?
A pure tone
What makes a complex sound like speech different from a pure tone?
Many sound components with separate frequencies and amplitudes
Name for ear canal
External auditory meatus
How does the outer ear amplify sound?
Resonance in the concha and the external auditory meatus produces an increase in pressure between 2-7 kHz.
Leads to an amplification of sound
Localisation of an auditory target in the vertical plate or front/back dimension requires…
Spectral cues
Spectral cues are produced by…
The outer ear
What is the principle behind spectral cues?
Amplitude of different frequencies is modified in different ways by the outer ear shape depending on the location of the sound source.
Where does the eustacian tube connect?
Nasopharynx with middle ear
What is the role of the eustacian tube?
Maintains atmospheric pressure in middle ear
What connects the tympanic membrane to oval window of the cochlea?
Ossicles
Three ossicles
Malleus, incus, stapes
What does the malleus attach?
Tympanic membrane to incus
What does incus attach?
Malleus to stapes
What does the stapes attach?
Incus to the oval window
What muscle is attached to the malleus?
Tensor tympani
What muscle is attached to the stapes?
Stapedius
What do middle ear bones prevent?
Prevent loss in sound pressure that would occur due to the increased density of cochlea fluids (than air)
How is pressure increased by the middle ear for impedance matching?
Eardrum has greater surface area than the stapes
What is the role of the middle ear muscles?
Contract, reduce movement of the ossicles, reduce sound transmission (middle ear reflex) when one using their own voice or sustained loud noise
Ascending limbs of the middle ear reflex?
Auditory nerve fibres
What bone does the inner ear lie in?
Petrous part of temporal bone
What fluid fills the membranous labyrinth?
Endolymph
What fluid fills the area between membranous labyrinth and bony margin?
Perilymph
Endolymph is similar to?
ICF (high potassium)
Perilymph is similar to?
ECF (low potassium)
Scala vestibuli
Oval window (above media)
Scala tympani
Round window (below media)
What membrane separates the scala media and scala vestibuli?
Reissner’s
What membrane separates the scala media and scala tympani?
Basilar
Endocochlea potential
Potential difference between the endolymph in the scala media and the perilymph of the other two chambers of about 80 millivolts - scala media is positively charged relative to the other two chambers.
Hair cells have
Stereocilia
Tallest stereocilia called?
Kinocilium
What contacts the stereocilia on the basilar membrane?
Tectorial membrane
Which HC contact the tectorial membrane?
Just OHC, IHC free
Do hair cells generate APs?
No, just GP, which leads to NT release which activates an AP in second order neuron
What is generated across scala media?
Pressure gradient
What makes a tuning curve look the way it does?
Hair cells and fibres are tonotopically organised – at any position, hair cells are sensitive to a particular frequency, namely their characteristic frequency .
What causes hair cell depolarisation?
Bundle is pushed toward the tallest, cilium it will increase the tension the tip links, open mechanosensitive gated ion channels and lead to hair cell depolarization.
What causes hair cell hyperpolarisation?
Bundle goes in the opposite direction it will reduce the tension in the tip link, close the mechanosensitive channels and lead to hair cell hyperpolarization.