Unit 1

Question 1

Sound

Answer 1

perception of pressure changes as it moves through a medium such as air

Question 2

Degree of pressure related to

Answer 2

driving force of vibration.

Greater driving force= greater the pressure= farther the particles move= louder the sound will be

Question 3

Sound Pressure level of hearing: decibels

Answer 3

.0002 dynes/cm2

dyne: measurement of force or pressure
decibel: gives sound intensity

Question 4

Formula for dB

Answer 4

20 X (log P1/Pr)
P1: measured from meter
Pr: reference for pressure for threshold of human hearing

Question 5

Period

Answer 5

time it takes to complete one cycle

fewer cycles per second, lower the pitch

Question 6

compression

Answer 6

air particles compress together at higher pressure

Question 7

rarefaction

Answer 7

air particles moving away from each other at lower pressures

Question 8

dampening

Answer 8

wave gets smaller and smaller until the point you don’t hear it anymore and it dies away

Question 9

Two velocity for sound

Answer 9

speed of vibration of a mass

speed of how fast the power wave moves through medium

Question 10

Velocity of a sound in air

velocity of a sound ins ayer

Answer 10

how fast an object is traveling through a medium
1130ft/sec
4 x 1130 ft/sec
Velocity: distance/ time

Question 11

Wavelength calculation

Answer 11

V/F= wavelength  (1130/ X Hz) 
Frequency= V/wL

Question 12

Impedance

Answer 12

resistance to a current

Question 13

Incident wave

Answer 13

original wave that is sent out

Question 14

reflective wave

Answer 14

wave that is sent back

Question 15

constructive interference

Answer 15

When the wave comes back and based on their phase relationship, if they combine to make the resulting wave louder it is called constructive interference
If they combine that makes their wave smaller because they are out of phase, it is destructive interference

Question 16

destructive interference

Answer 16

if they combine that makes their wave smaller because they are out of phase, it is destructive

Question 17

standing wave

Answer 17

when two waves of the same frequency collide into each other a big wave will result that isn’t moving

Question 18

A complex combined wave

Answer 18

takes the lowest frequency components and it is the fundamental frequency

Question 19

Fourier

Answer 19

found that you can take any complex waves no matter how complex or frequency, and that complex wave can be broken down into a series of sine waves

Question 20

Period of the fundamental frequency

Answer 20

from the first peak to the second peak, longest period (first harmonic

Question 21

lower harmonics have ___ than higher harmonics

Answer 21

power

Question 22

hamronics

Answer 22

1st harmonic: 1 x fundamental frequency

4th harmonic: 4 x fundamental frequency

Question 23

spacing and tonality

Answer 23

as you get lower in frequency, the harmonics get closer together (fuller sound)

as harmonics spread out you won’t hear as much tonality and has a brighter sound

Question 24

Attack time (onset) 
decay (offset)

Answer 24

attack: time it takes to build up to maximum amplitude is the attack time
time it takes from going to 0 amplitude to the peak of the signal, delay is reversed

decay: 90 to 10 and attack is 10 to 90