Chapter 2

Question 1

Acoustics

Answer 1

the study of the production, transmission and reception of sound

Question 2

sound

Answer 2

the propagation of energy into a medium, usually the air, transmitted as a pressure wave

Question 3

when the tuning fork moves outward

Answer 3

air molecules directly adjacent to it compress

Question 4

when the tuning fork moves inward

Answer 4

the air molecules expand

Question 5

longitudinal wave

Answer 5

the movement of the oscillation is parallel to the direction of movement overall

Question 6

frequency

Answer 6

• measured in Hz

- the rate at which the troughs of a wave pass a point in a given measure of time

Question 7

Pitch

Answer 7

the frequency of vibration of the source of sound

Question 8

Amplitude

Answer 8

maximum displacement compared to the resting state

Question 9

two things needed for coupled acoustics

Answer 9

1. something which generates the sound wave

2. something which is coupled to the first thing and amplifies it

Question 10

the initial vibration is activated by the _________ and is often ___________ to be able to hear the whole sound

Answer 10

performer

insufficient

Question 11

Bowed Strings

Answer 11

such as violins and double basses

- string is continuously supplied with energy from a moving bow

Question 12

Harpsichords etc

Answer 12

a string is set in vibration after brief contact with something that plucks the string

Question 13

third group of strings

Answer 13

struck by a hammer, the hammer rebounds almost immediately off the string

Question 14

sitar

Answer 14

not plucked but vibrates in sympathy with the vibrations of the melody and drone strings

Question 15

edge tones

Answer 15

created by an action such as blowing across a hole and onto a sharp edge

Question 16

how do edge tones work

Answer 16

• upper and lower planes of the edge produce asymmetrical vortices as the air stream passes over the edge
• asymmetry creates oscillations which are picked up and amplified

Question 17

what instrument do edge tones occur in

Answer 17

woodwind

Question 18

reed tones

Answer 18

produced by the player setting one or two reeds vibrating

Question 19

how do reed tones work

Answer 19

reeds vibrate which produce sound waves in adjacent air columns

Question 20

what instruments do reed tones occur in

Answer 20

clarinets, saxophones, oboes etc

single reed and double reed instruments

Question 21

Direct sound

Answer 21

travels directly from source to listener

Question 22

reflected sound

Answer 22

reaches the listener by bouncing off one or more surfaces

Question 23

initial time delay gap (ITDG)

Answer 23

the time at which the first reflection is heard after the direct sound

Question 24

most optimal ITDG

Answer 24

15s

Question 25

unoptimal ITDG

Answer 25

greater than 35s it will sound like an arena

Question 26

clarity index

Answer 26

a measure of the ratio of early sound energy to late sound energy

Question 27

early reflections

Answer 27

arrive within first 80ms of direct sound

Question 28

late reflections

Answer 28

arriving after 80ms

Question 29

shoebox shaped

Answer 29

most highly rated concert hall

• narrow width of the halls allow for stronger side to side reflections
• creates the sensation of being bathed in sound

Question 30

fan shaped

Answer 30

• most problematic
• widening walls directs lateral reflections away from the listener
• weakens sense of acoustic intimacy, listener envelopment, and warmth

Question 31

horseshoe shaped

Answer 31

• not acoustically ideal yet still preferred by listeners

- increases visual clarity and acoustical clarity

Question 32

Porous Absorbers

Answer 32

absorb high frequency sounds more efficiently than bass sounds
- curtains

Question 33

Resonant Absorbers

Answer 33

are set into vibration by the energy released by the sound source

• respond to low frequency sounds
• wood panels

Question 34

reverberation time

Answer 34

the time for a sound to decay by 60db

Question 35

ease of ensemble

Answer 35

the degree to which performers can hear and play together

- early sound reflections are critical

Question 36

support

Answer 36

the degree to which the room facilitates musicians effors to create tones and fill the space
- both early and late reflections are important

Question 37

dry space

Answer 37

sound disappears quickly making it hard for performers to feel like they are filling up the space

Question 38

horizontal clarity

Answer 38

the distinctiveness of tones played successively

Question 39

vertical clarity

Answer 39

tones played simultaneously

Question 40

highest rated concert halls have reverberation time of __________

Answer 40

1.8-2.0 seconds

Question 41

venues designed for speech require shorter Ts of _________

Answer 41

0.7 - <1.0 s