Chp 5.4: Audition

Question 1

sound

Answer 1

pressure waves in air, water, or some other conducting medium

Question 2

frequency

Answer 2

in audition, the number of cycles per second in a sound wave, responsible for the pitch of the sound; the measure of frequency is the hertz (Hz), which equals one cycle per second

Question 3

amplitude

Answer 3

the vertical size of the sound wave, which gives rise to the perception of loudness and is measured in terms of decibels

Question 4

Outer Ear (3)

Answer 4

• Pinnae (part you use for earrings & sunglasses)
• Sound enters auditory canal
• Causes tympanic membrane to vibrate

Question 5

Middle ear (3)

Answer 5

•Vibration cause malleus (hammer),
incus (anvil), stapes (stirrup) to vibrate
•Amplify sound more than 30X
•Oval window moves in and out

Question 6

Cochlea (Inner ear)

Answer 6

•A coiled, snail-shaped tube about 3.5 centimetres in length that is filled with fluid

Question 7

Basilar Membrane

Answer 7

Sheet of tissue running the length of the cochlea

Question 8

Organ of Corti

Answer 8

Rests on top of the basilar membrane

Contains ~16,000 “hair cells” that are responsible for sensory transduction

Question 9

How does sensory transduction work in the Organ of Corti by the hair cells? (3)

Answer 9

• Hairs touch the tectorial membrane
• Vibration along the basilar membrane displaces these hairs relative to the tectorial membrane, generating neural impulses

-Hair cells synapse with the auditory nerve, which makes its way to the thalamus and eventually the auditory cortex

Question 10

Frequency Theory

Answer 10

• Nerve impulses ‘match’ frequency of wave (440 Hz = 440 impulses/second)
• Does not work for higher frequencies (>1000 Hz)

Question 11

Place Theory

Answer 11

•Specific frequencies peak at certain places on basilar membrane

Question 12

How accurate are the frequency and place theories?

Answer 12

Frequency theory (Hz = # of neural impulses) more dominant for lower frequencies
Place theory (location along basilar membrane) needed for higher frequencies

Question 13

Sound Localization (2)

Answer 13

When you have two ears, you can rely on subtle differences of how a sound arrives to both ears

• Slight differences in timing (interaural time differences)
• Slight differences in loudness (interaural level differences)

Question 14

Conduction deafness (3)

Answer 14

= mechanical system of hearing
•e.g., punctured eardrum, loss of function of bones of middle ear
•Hearing aids (which amplify the sound wave) can help

Question 15

Nerve deafness (3)

Answer 15

= damaged receptors
•Exposure to loud sounds can damage hair cells
•Hearing aids cannot help