Chapter 2: sound

Question 1

what kind of wave is sound?

Answer 1

mechanical

Question 2

what does compressed mean? rarefied?

Answer 2

squeezed together; stretched apart

Question 3

how does sound travel?

Answer 3

in a straight line

Question 4

sound waves are ____________ waves

Answer 4

longitudinal

Question 5

what are acoustic propagation properties?

Answer 5

Effects of the medium upon the sound wave

Question 6

what are biologic effects?

Answer 6

the effects of the sound wave upon the biologic tissue through which it passes

Question 7

sound waves are aka what? how are these identified?

Answer 7

acoustic waves; identified by oscillations in acoustic variables

Question 8

what are the 3 acoustic variables?

Answer 8

pressure, density, distance

Question 9

what is pressure? units?

Answer 9

conc of force in an area; pascals (Pa)

Question 10

what is density? units?

Answer 10

conc of mass in a volume; kg/cm^3

Question 11

what is distance? units?

Answer 11

measure of particle motion; cm, feet, mile

Question 12

what is used to describe the characteristics of a sound wave?

Answer 12

acoustic parameters

Question 13

what are the 7 acoustic parameters?

Answer 13

period, frequency, amplitude, power, intensity, wavelength, propagation speed

Question 14

how do the particles move in a transverse wave?

Answer 14

perpendicular (right angles) to the direction that the wave propagates. (ex: wave moves left to right particles in the wave move up and down)

Question 15

how do particles move within a longitudinal wave?

Answer 15

in the same direction that the wave propagates (ex: wave moving left to right, particles in the wave move left to right)

Question 16

are sound waves transverse or longitudinal?

Answer 16

longitudinal

Question 17

when would a pair of waves be considered in-phase?

Answer 17

when their peaks (max value) and troughs (min value) occur at the same time and location

Question 18

when would a pair of waves be considered out-of-phase?

Answer 18

their peaks/troughs occur at different times (out of step)

Question 19

what is interference?

Answer 19

when multiple sound beams arrive at an identical location at exactly the same time. The waves lose individual characteristics and combine to form a single wave.

Question 20

do in-phase or out-of-phase waves combine to create interference?

Answer 20

both

Question 21

what is constructive interference? what waves make this up?

Answer 21

interference of in-phase waves creating a single wave of greater amplitude than either of its components

Question 22

what is destructive interference? Which waves make this up?

Answer 22

interference of a pair of out-of-phase waves resulting in the formation of a single wave of lesser amplitude than at least one of its components

Question 23

what happens when two out-of-phase waves are of equal amplitude?

Answer 23

complete destructive interference; they cancel each other out

Question 24

what happens when waves of different frequencies interfere?

Answer 24

at some point the waves are in phase and the interference is constructive at another point the waves are out of phase and interference is destructive; both constructive and destructive interference occur

Question 26

what do waves transfer from one location to another?

Answer 26

energy

Question 27

what best describes a sound wave?

Answer 27

series of compressions and rarefactions