Audition Flashcards
What creates sound waves?
the compression or rarefication of air molecules
What frequencies can the human ear perceive?
between 20 and 20 000 times per second
What are the three physical dimensions of sound?
- Loundness (amplitude)
- Pitch (frequency of the molecular vibrations)
- Timbre (complexity)
What determines the loudness?
- the difference of air pressure between the compressed and rarefied air
Anatomically, what is the impact of loundness?
- bigger or smaller deformation of the eac drum
What is pitch?
the frequency of the molecular vibrations (number of cycles per second)
What is timbre?
The complexity of the sound. It can be used to identify the source of the sound wave.
What are the four subdivisions of the ear?
1) outer ear
2) middle ear
3) inner ear
What is the pinna?
The outer ear
how does the sound that is funneles through the pinna reach the middle ear?
- the sound travels through the ear canal
- it makes the tympanic membrane vibrate
- the vibrations are then transferred to the middle ear
What composes the middle ear?
the ossicles
What are the three ossicles?
malleus, incus, stapes
What separates the outer and middle ear?
oval window
what composes the outer ear?
- pinna
- tympanic membrane
What is detected by the outer ear?
Variations in air pressure
What creates the movement of the ossicles?
the vibrations of the tympanic membrane
Why does the tympanic membrane vibrate instead of just keeping its new/deformed shape?
the middle ear has an air pressur almost identical to that of the outer air
What happens when the ossicles vibrate?
- Creates waves in the water that is contained in the cochlea
- the waves in the water create bends in the basilar membrane at different spots depending on the pitch
What separates the middle ear from the inner ear?
the oval window
What are the components of the inner ear?
cochlea
What is the structure of the cochlea?
Long coiled tube-like structure that contains sensory neurons. it is filled with fluid
How does the structure of the basilar membrane allow the human ear to encode the different notes?
- the tension of the membrane varies
- the membrane bends in different places depending on the frequency of the sound
Where are high-piched noises perceived in the basilar membrane?
in the end that is closest to the oval window
What occurs when the basilar membrane has to perceive low-frequency sounds?
the tip of the basilar membrane flexes in synchrony with the virbations
What are the three divisions of the cochlea?
- scala vestibuli
- scala media
- scala tympani
What is the receptive organ of the ear?
- organ of corti
where is situated the organ of corti?
inside the scala media
what composes the organ of corti?
basilar membrane, tectorial membrane and auditory hair cells sandwiched in the middle
What are auditory hair cells?
cells that transduce sound
How do the auditory hair cells perceive the vibrations caused by sound?
through their cilia
What are the different types of hair cells?
- outer hair cells
- inner hair cells
What happens when an auditory hair cell perceives vibrations?
1) pulls open ion channels
2) depolarization of the auditory hair cells
3) sends an action potential down the axon of the auditory neurons
What is the cilia of outer hair cells attached to?
tectorial membrane
where is the cell body (soma) of the outer hair
on the basilar membrane
What is the difference between inner and outer hair cells?
the cilia of the outer hair cells are physically attached to the rigid tectorial membrane, the inner hair cell’s cilia is free in the fluid of the cochlea
Which type of hair cell transmits auditory information to the brain?
inner hair cells