Design and acoustics considerations

Question 1

What are the sounds levels in Decibels (dBA) of:
Boom car, jet takeoff, shotgun, rock concert, thunder clap, lead blower, motorcycle, lawn mower, traffic noise, conversation, whisper and breathing?

Answer 1

boom car- 140
jet takeoff- 140
shotgun- 130
rock concert- 125
thunder clap- 120
leaf blower- 100
motorcycle- 95 
lawn mower- 90
traffic noise- 80 
conversation- 50 
whisper- 30
breathing- 10

Question 2

What are the levels of human sound sensitivity in Decibels?

Pain threshold, hearing loss risk, very annoying, intrusive, comfortable, very quiet, just audible

Answer 2

Pain threshold-125
Hearing loss risk-100
Very annoying-90
Intrusive-70
Comfortable-60
Very quiet-30
Just audible-20

Question 3

What are the two major aspects of acoustics principles?

Answer 3

1. sound conditions within a space

2. sound transfer between spaces

Question 4

How do we hear sound?

Answer 4

We hear sound as a response to pressure on the ear drum

Question 5

What are the levels of pressure on the ear drum for a human from inaudible to threshold of pain?

Answer 5

20-100,000,000 micro pascals

-response is not linear

Question 6

What is silence to threshold of pain in decibels?

Answer 6

0-130 dB

Question 7

Approximately how many decibels does a sound need to increase by to double the perceived noise?

Answer 7

10 dB

Question 8

What two things respond differently to different frequencies?

Answer 8

the ear and materials

Question 9

What are dB and dBA used for?

Answer 9

dB- pure sounds

dBA- weighted average

Question 10

What causes a sound to decay?

Answer 10

distance

Question 11

What happens when you double the distance away from a sound?

Answer 11

The sound reduces by a factor of 4- a reduction of 6 dB

Question 12

What is the sound we hear made up of?

Answer 12

a range of frequencies

Question 13

What is the range of frequencies we hear normally divided into?

Answer 13

octave bands

Question 14

What are the frequencies a sinusoidal wave goes through to experience the entire human audio spectrum?

Answer 14

20Hz to 20kHz

Question 15

What 4 things do good acoustics within a space depend on?

Answer 15

1. direct and reflected sound transmission from the source to the listener
2. volume and shape of space- if the sound path is too long, sound may be inaudible
3. absorption of the sound but surface materials
4. conditions are expressed by “reverberation time” the time it takes for sound to fall in level by 60dB

Question 16

Name 4 sound absorption materials?

Answer 16

people
furniture
finishes
acoustic panels