Auditory system Flashcards
A sinusoidal sound wave could be characterized as biphasic. What are its two phases?
Condensation and rarefaction.
What are representing condensations and rarefactions?
Changes in air pressure.
What are the 4 sound features?
- Intensity (amplitude)
- Pitch (frequency)
- Waveform (texture)
- Phase (location)
How can a complex sound be modeled?
As the sum of different sinusoidal sound waves varying in their properties.
What is lost first in the human ear between the perception of high and low frequencies?
High frequencies lost more rapidly.
What is the principle function of the external and middle ear?
Amplify sound for the inner ear.
What is the principal role of the external ear? What are the two main structures of the external ear and their substructures? What is the role of each structure?
Principal role: serves as a parabolic antenna to boost sound pressure of frequencies.
Auricle: composed of pinna and concha, which filter different frequencies and provide cues about elevation of sound source = VERTICAL PLANE SOUND LOCALIZATION.
Canal: auditory meatus boosts sound pressure of frequencies.
What is the principal role of the middle ear? What are its two pressure-boosting mechanisms?
Principle role: amplification of sound for the impedance shift between air transmission and aqueous transmission.
Pressure-boosting mechanisms:
-Tympanic membrane is much larger than base of stapes in oval window →vibrations (sound) are amplified
- Lever action of ossicles
What are the three ossicles?
Malleus, incus and stapes.
What are the two structures regulating transmission in the middle ear?
- Tensor tympani
- Stapedius
How can damage to external and middle ears be tested?
By the Weber fork test.
How is named the structural organization found in the basilar membrane of the cochlea for the processing of sound frequencies?
Tonotopy.
What are the perilymph chambers?
- Scala vestibuli
- Scala tympani
- Scala media
With what liquid are filled the perilymph chambers?
Scala vestibuli and tympani -> perilymph
Scala media -> endolymph
How is the endolymph of the scala media moved?
Liquid in scala vestibuli is pushed by vibrations coming from oval window of stapes ->induces vibrations to the reissner membrane -> vibrations transmitted to scala media.
In the tonotopy of the basilar membrane of the cochlea, ____ pitch sounds move the ____ of the membrane, ____ oval window, whereas ____ pitch sounds move the ____ of the membrane, ____ oval window.
Words to place:
apex high base low away from close to
In the tonotopy of the basilar membrane of the cochlea, high pitch sounds move the base of the membrane, close to oval window, whereas low pitch sounds move the apex of the membrane, away from oval window.
Hair cells are found between what membranes?
Tectorial and basilar membranes.
What are the two types of hair cells? What are they responsible for?
Inner hair cells: innervated by afferents from CN VIII → transmit impusles toward CNS (mechano-electric conduction).
Outer hair cells: innervated by efferents →modulate the “stiffness” of the basilar membrane to adjust the “volume” and produce otoacoustic emissions.
What is the ion channel responsible for depolarization in the hair cells?
Mechanically-gated potassium channel.
What are cells the “hairs” of the hair cell? What is the name of the tallest one?
- Stereocilia
- Kinocilium