Audition Part 1

Question 1

what are the two steps of sound & what do they mean

Answer 1

compression = pushing air molecules together
rarefraction = then stretches them apart & repeat..

Question 2

what is a pure tone?

Answer 2

a tone with one frequency

Question 3

what is a wave of a pure tone called

Answer 3

sine wave

Question 4

a graph of pressure changes over time is called a…

Answer 4

waveform

Question 5

what are the three critical features or parameters of waves

Answer 5

• frequency: how many full waves in a second (in Hz), corresponds to pitch of the sound - pitch
• amplitude: how high is the wave? (deciBels, or dB), corresponds to loudness of the sound - loudness
• phase: how far through the wave are we (degrees) - timbre

Question 6

what are sound waves?

Answer 6

linear e.g. they add together logically (sum the values at each point in time)

Question 7

what are natural sounds a collection of?

Answer 7

simple sine waves added together

Question 8

the waveform of any sound can be expressed as what?

Answer 8

a sum of sine waves with different freqs, amps & phases

Question 9

what is fourier analysis

Answer 9

when you decompose a complex sound into its component frequencies, amplitude & phase

Question 10

what happens when you add two soundwaves

Answer 10

the frequency stays the same but the amplitude gets higher

Question 11

what happens when you add sounds of different frequencies

Answer 11

they form a complex wave

Question 12

discuss a complex wave form

Answer 12

• made up of sounds of different frequencies

- wave forms are periodic (they repeat) the x-axis (time) gives little info

Question 13

what is a spectrum

Answer 13

when you re-plot the wave-form graph as amplitude vs frequency rather than amplitude v time

Question 14

what is a fundamental

Answer 14

the component with the lowest frequency

Question 15

what does the fundamental frequency give

Answer 15

the pitch

Question 16

what gives the characteristic sound in instruments that have the same frequency/pitch

Answer 16

the characteristic overtones

Question 17

what are the three parts to the ear

Answer 17

• outer ear
• middle ear
• inner ear

Question 18

what composes the outer ear

Answer 18

• pinna

- meatus

Question 19

what composes the middle ear

Answer 19

• ossicles

- tympanic membrane (ear drum)

Question 20

what composes the inner ear

Answer 20

• cochlea

- baslar membrane

Question 21

what does the outer ear do

Answer 21

pinna: the flexible flap on outside of the ear
focuses sound waves into the ear canal (meatus)
shape and size of outer ear have the effect of amplifying medium sound frequencies

Question 22

what does the middle ear do

Answer 22

the small bones (ossicles) in the middle ear transmit sound energy from the eardrum to the oval window in the ear

Question 23

discuss the inner ear

Answer 23

containes a small coiled tube (cochlea) filled with fluid

• oval window & other window help to make the fluid vibrate
• has three parts
• transfers sound energy into chemical energy that is used by the nerves

Question 24

how do the middle ear & the inner ear work together

Answer 24

the middle ear vibrates the inner ear’s fluid & transmits this vibrating energy into the inner ear

Question 25

what is the organ of Corti (inner hair cells)

Answer 25

receptor organ located in the cohlea has epithelial cells and allows for the transduction of auditorty signals into nerve impulses action potential

Question 26

how many inner hairs do we have & where do they protrude from

Answer 26

3500, basilar membrane

Question 27

how many nerve fibres do we have

Answer 27

50,000

Question 28

the base of the baslar membrane is

Answer 28

thin & stiff & hears high frequency

Question 29

the apex of the baslar membrane is

Answer 29

wide & floppy & hears low frequency