Sound (Audition)

Question 1

Pressurized Sound Wave

Answer 1

when you clap, the air molecules between your hands become pressurized (as there is less space in between)
-this pressure forces the air molecules to escape creating areas of high and low pressure = sound waves (can be far apart or close together)

Question 2

Auditory Pathway

Answer 2

1. Sound waves hit pinna, outer part of the ear
2. Sound gets funneled from the pinna to the external auditory meatus (auditory canal)
3. It then heats the tympanic membrane (eardrum), which vibrates back and forth; end of external ear
4. This vibration causes 3 ossicles to vibrate in the order of Malleus, Incus, Stapes; middle ear
5. The vibration of the stapes in turn leads to the vibration of the oval window
6. The vibration of the oval window pushes the fluid inside the cochlea around and when it reaches the round window gets pushed the other way back to beginning
7. The process of fluid moving around the cochlea occurs until energy of the sound wave dissipates and stops moving.

Question 3

Organ of Corti

Answer 3

composed of the tectatorial and basilar membranes and is located in the center of the cochlea; located between these two membranes

• as fluid flows around the organ, the hair cells move back and forth
• each hair cell has filaments known as kinocilium which are connected to one another by tip links, which are connected to the gate of K+ channels
• endolymph movement pushes the tip links back and forth, allowing for the opening of the K+ channels and for the flow of K+ in
• Ca2+ cells get activated by K+ allowing for Ca2+ to flow in, triggering an AP which activates a spiral ganglion cell, which then activates the auditory nerve

Question 4

Place Theory

Answer 4

theory of hearing which states that our perception of sound depends on where each component frequency provides vibrations along the basilar membrane
-able to hear different pitches because different sound waves trigger activity at different places along the cochlea’s basilar membrane

Question 5

Basilar Tuning

Answer 5

hair cells at the base or the start of the cochlea are activated by high frequency sounds (1600 Hz) whereas hair cells at the apex or the end of the cochlea are activated by low frequency sounds (25 Hz)

Question 6

Primary Auditory Cortex

Answer 6

in the brain and receives all the information from hair cells of cochlea; separated into regions which detect different frequencies

Question 7

Tonotopical Mapping

Answer 7

you can listen to different frequencies at the same time; the ear is able to break up this mixture of different frequencies as different frequencies travel different lengths along the cochlea

Question 8

Cochlear Implants

Answer 8

surgical procedure that attempts to restore some degree of hearing to individuals with sensorineural narrow hearing loss (nerve deafness) = individuals with problem of conducting sound waves from cochlea to the brain

Question 9

Pathway of Implant

Answer 9

Sound –> Microphone –> Speech Processor –> Transmitter (outside skull) –> Receiver (inside skull) –> Stimulator –> Cochlea (electrical impulse to neural impulse) –> Brain