Sound Propagation

Question 1

If the intensity of a sound 10 meters from the sound source is 100, what is the intensity
20 meters from the sound source?
30 meters from the source?
40 meters from the source?

Answer 1

100
25
11
6.25

Question 2

If the intensity of a sound 8 meters from the sound source is 50, what is the intensity
16 meters from the sound source?
24 meters from the sound source?
32 meters from the sound source?
40 meters from the sound source?

Answer 2

50
12.5
5.56
3.13
2

Question 3

If the dB SPL of a sound 20 meters from the sound source is 60 dB SPL, what is the dB SPL
40 meters from the sound source?
80 meters from the sound source?
160 meters from the sound source?

Answer 3

60 dB SPL
54 dB SPL
48 dB SPL
42 dB SPL

Question 4

If the dB SPL of a sound 15 meters from the sound source is 80 dB SPL, what is the dB SPL
60 meters from the sound source?
120 meters from the sound source?

Answer 4

80 dB SPL
68 dB SPL
62 dB SPL

Question 5

What are the 4 things that happen when a sound wave encounters an object?

Answer 5

DART
Transmission
Reflection
Diffraction
Absorption

Question 6

What is sound transmission

Answer 6

occurs when the characteristics of each medium are similar

Question 7

What influence sound flow or lack of sound flow

Answer 7

mass/elasticy - impedance

Question 8

Only ____ of sound energy is transmitted from air to water

Answer 8

0.1%

Question 9

What kinds of objects does sound travel through?

Answer 9

wall
curtain
paper
mask

Question 10

What kind of objects, besides water, does sound NOT travel through?

Answer 10

water, sound treated rooms,

Question 11

Review transmission and how it relates to impedance. (Impedance is a term that has to do with sound energy flow or lack of sound energy flow.) Why do we say that the middle ear is an impedance matcher?

Answer 11

It is when one sound goes from one medium to another and will transmit if the impedance characteristics are similar and if they are different they will not
IMM because without it sound would be reflected off of the TM

Question 12

Explain what happens when sounds are reflected from a plane surface (a wall, for example).

Question 13

Explain what happens when sounds are reflected off of convex surfaces and concave surfaces.

Answer 13

convex = curved opposite direction and causes sound to scatter
concave = curved in the same direction and causes the waves to gather together and become concentrated

Question 14

what is diffraction

Answer 14

bending or scattering of a wave

Question 15

High frequency sound (short wavelength) encounters a relatively large opening?

Answer 15

sound go straight through

Question 16

Low frequency sound (long wavelength) encounters a relatively small opening?

Answer 16

go through and scatter

Question 17

High frequency sound (short wavelength) encounters a relatively large obstacle?

Answer 17

acoustic shadow

Question 18

Low frequency sound (long wavelength) encounters a relatively small obstacle?

Answer 18

go around it

Question 19

Is there a relationship b/w wavelength and obstacle size

Answer 19

yes

Question 20

do small children have same head shadow as adults?

Answer 20

no, higher frequency acoustic shadows

Question 21

What is absorption and how does it differ from transmission?

Answer 21

when sound is absorbed by material where it doesn’t continue to go through like in transmission

Question 22

What is an absorption coefficient?

Answer 22

absorption coefficient is an index of how much power the material will absorb.

Question 23

What types of materials have low absorption coefficients? What types of materials have high absorption coefficients?

Answer 23

Low would be glass and high would be acoustic paneling.