Module 20: Hearing Flashcards
Audition
The sense or act of hearing
Frequency
The number of complete wavelengths that pass a point in a given time (per second)
*the higher the frequency the higher the pitch and vice versa
Pitch
A tone’s experienced highness or lowness; depends on frequency.
Middle Ear
The chamber between the eardrum and cochlea containing three tiny bones (hammer, anvil, & stirrup; malleus, incus, & stapes) that concentrate the vibrations of the eardrum on the cochlea’s oval window
Cochlea
A coiled bony, fluid-filled tube in the inner ear; sound waves traveling through the cochlear fluid trigger nerve impulses
Inner ear
The innermost part of the ear, containing the cochlea, semicircular canals, and vestibular sacs.
Sensorineural Hearing Loss
Hearing loss caused by damage to the cochlea’s receptor cells or to the auditory nerves; also called nerve deafness.
Conduction Hearing Loss
Hearing loss caused by damage to the mechanical system - eardrum and middle bones - that conducts sound waves to the cochlea.
Cochlear Implant
A device for converting sounds into electrical signals and stimulating the auditory nerve through electrodes threaded into the cochlea.
Place Theory
In hearing, the theory that links the pitch we hear with the place where the cochlea’s membrane is stimulated
*how we register high frequencies mostly
The brain determines a sound’s pitch by recognizing the specific area on the basilar membrane that is generating the neural signal
Frequency Theory
In hearing, the theory that the rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone, thus enabling us to sense its pitch.
*how we register low frequency
Volley Principle
Neural cells can alternate firing - by firing in rapid succession, they can achieve a combined frequency above 1000 waves per second
- part of Frequency theory which explains how we sense low pitches
Amplitude
The maximum amount of vibration indicates a sound’s loudness. The stronger the vibration is the greater the amplitude and thus a louder sound.
Describe the steps of hearing/ the journey of vibrating air pressure through the different parts of the ears.
- Pinna funnels soundwave into the middle portion of the ear through the Auditory Canal
- Soundwaves are channeled towards the tympanic membrane (eardrum) causing the membrane to vibrate
- Eardrum vibrate the Incus, Malleus, & Stapes amplifying the soundwaves and sending them to the inner ear via the cochlea
- Cochlea contains fluid which ripples, rippling tiny hair bundles (Stereocilias).
- Stereocilias convert the soundwaves into electrical signals (potassium ions run to the top of brain cells releasing chemicals at the bottom of the hair cells binding to the auditory nerve creating the electrical signal)
- Auditory Nerve sends the electrical signal to the brain
How do we perceive loudness?
The ear perceives loudness based on the amount of activated hair cells
*NOT the strength of the hair cells response
Note
Even when hair cell loses sensitivity to soft sounds it could still respond to loud sounds
Where does low and high pitch sound register on the basilar membrane?
High frequencies create large vibrations near the start of the cochlea’s membrane
Low Frequencies vibrate closer to the end of the membrane
How do our ears locate sounds?
- Lag Time: The difference in time from sound hitting one ear before reaching the other ear
- Reflection: How sound bounces off the objects in a room
- Inaudible High-Frequency Sound we can’t physically hear but our brain regestures
Pinna
Outer Ear
- gathers soundwaves from our environment and funnels them into the ear canal