Lecture 18

Question 1

What is the physical definition of sound?

Answer 1

pressure changes in the air or other medium

Question 2

What is the perceptual definition of sound

Answer 2

the experience we have when we hear

Question 3

What is condensation?

Answer 3

The diaphragm of the speaker
moves out, pushing air molecules
together

• aka compression

Question 4

What is rarefaction?

Answer 4

The diaphragm also moves in, pulling the air molecules apart called rarefaction (expansion)

Question 5

What are pure tones?

Answer 5

tones which create
changes in air pressure that can be
described by a single sine wave (a
mathematical concept)

Question 6

What is frequency?

Answer 6

number of
cycles within a given time
period
* Measured in Hertz (Hz): 1 Hz
is one cycle/second
* Perception of pitch is
related to frequency

Question 7

What is tone height?

Answer 7

the increase
in pitch that happens when
frequency is increased

Question 8

What is amplitude?

Answer 8

Difference in pressure between high and low peaks of a wave

Question 9

What does the decibel scale measure?

Answer 9

Loudness

Question 10

What are periodic tones?

Answer 10

tones in which the
waveform repeats

• includes pure and some complex tones

Question 11

Describe periodic complex tones

Answer 11

Periodic complex tones consist of a number of pure tones called harmonics

Question 12

What is fundamental frequency?

Answer 12

the repetition rate and is also referred to as the
first harmonic

Question 13

What is higher harmonics?

Answer 13

multiples of the fundamental frequency

Question 14

What are frequency spectras?

Answer 14

They plot the
harmonics of a complex sound

e.g. Complex periodic sound w/ ff of 200 Hz

1st harmonic (fundamental) = 200 Hz

2nd = 400 Hz

and so on

Question 15

Describe the audibility curve

Answer 15

The audibility curve shows the threshold of hearing in relation to frequency

Question 16

Describe the auditory response area

Answer 16

The auditory response
area falls between the
audibility curve and
the threshold for
feeling (point at which
sounds we can ‘feel’
sounds, where they
can cause pain)

• It shows the range of
  response for human
  audition

Question 17

Describe equal loudness curves

Answer 17

They can
be determined by using a
standard 1,000 Hz tone
(using two dB levels: 40 and
80)

Question 18

What is pitch?

Answer 18

perceptual quality we describe as high and low

Question 19

What is timbre?

Answer 19

: all other perceptual aspects of a sound besides loudness, pitch, and
duration

Question 20

What is the effect of missing fundamental frequency

Answer 20

removal of the first harmonic
results in a sound with the same perceived pitch, but with a different timbre

Question 21

What is the attack of tones?

Answer 21

buildup of sound at the beginning of a tone

Question 22

What is the decay of tones

Answer 22

decrease in sound at end of tone

Question 23

What is the pinna?

Answer 23

• sticks out of side of head
• Helps with sound location

Question 24

What is the auditory canal?

Answer 24

tube-like 3 cm long structure
* Protects the tympanic membrane (the eardrum) at the end
of the canal

Question 25

What is resonance?

Answer 25

Resonance occurs when sound waves that are reflected back from the tympanic membrane interact with sound waves entering the canal, which can reinforce (increase the intensity of) certain frequencies

Question 26

What is resonant frequency?

Answer 26

The frequency that is most reinforced between 1000 and 5000 Hz

Question 27

Wha is the middle ear?

Answer 27

a two cubic centimetre cavity separating the inner from outer ear - contains three ossicles (smallest bones in the body)

Question 28

Describe the malleus

Answer 28

moves due to the vibration of the tympanic membrane (ear drum)

Question 29

Describe the incus

Answer 29

transmits vibrations of the malleus

Question 30

Describe the stapes

Answer 30

transmits vibrations of the incus to the inner ear (via the oval window of the cochlea)

Question 31

Describe the cochlea

Answer 31

the main structure of the inner ear, and the location at which transduction of pressure waves occurs

Question 32

What is the cochlear partition?

Answer 32

Divides the cochlea into the Scala vestibula (upper half) and Scala tympani (lower half)

Question 33

Describe the organ of corti

Answer 33

The organ of Corti is located within the cochlear partition and contains inner and outer hair cells, which are the receptors for hearing

Question 34

What does the basilar membrane do?

Answer 34

vibrates in response to sound and supports the organ of Corti

Question 35

What is the tectorial membrane's function?

Answer 35

extends over the hair cells

Question 36

Describe transduction in the inner ear?

Answer 36

The ‘back and forth’ motion of the oval window transmits vibrations to the liquid inside the cochlea: * Puts the basilar membrane into an ‘up-and-down’ motion (see the blue arrow in the diagram above) * Puts the tectorial membrane into a ‘back and forth’ motion (see the red arrow in the diagram above)