Lecture (2/13) Week 5 Tuesday

Question 1

Air molecules do not linearly move to transmit the sound energy, they….

Answer 1

pass energy on from one molecule onto another

Question 2

Dampening definition

Answer 2

gradual decrease in amplitude due to friction

Question 3

describe a lossless system

Answer 3

sound goes on forever

Question 4

describe a low-dampened system

Answer 4

sound echos, takes longer to dampen

Question 5

describe a high-dampened system

Answer 5

sound is absorbed, quicker to dampen

Question 6

definition of impedance

Answer 6

opposition that energy encounters when it is transferred from its source to a load

Question 7

because sound waves constantly encounter barriers in their travel, this results in a change in

Answer 7

impedance

Question 8

T/F impedance is a vector

Answer 8

true

Question 9

The two components of impedance are

Answer 9

reactance and resistance

Question 10

reactance=

Answer 10

mass and elasticity

Question 11

resistance=

Answer 11

friction

Question 12

What four things can happen when a change of impedance occurs?

Answer 12

-transmission
-reflection
-absorption
-diffraction

Question 13

Transmission definition

Answer 13

amount of energy that successfully travels from the source to the load

Question 14

For energy to be transferred, the impedance of the source must be _________ to the impedance of the load

Answer 14

similiar

Question 15

What is the equation for transmission?

Answer 15

H=4ZbZa/(Zb+Za)2
H= proportion of energy transmitted
Za=impedance of medium a (source)
Zb= impedance of medium b (load)

Question 16

What is reflection?

Answer 16

The amount of energy not transferred from the source to the load (or medium to medium)

Question 17

What is the equation for reflection?

Answer 17

1.0-H= amount of sound reflected

Question 18

What are the two waves of reflection?

Answer 18

-incident wave (original wave)
-reflective wave (energy that bounces back)

Question 19

The reflective wave is always at the same _____ as the incident wave

Answer 19

angle

Question 20

The reflected waves travels at the ____ ____ as the original wave

Answer 20

same speed

Question 21

The angles of reflected ray to the perpendicular…

Answer 21

equal the angles of the incident rays to the perpendicular

Question 22

Definition of echo

Answer 22

time delay between the reflective waves and the incident wave

Question 23

Definition of reverberation

Answer 23

-delay between incident wave and reflective wave that is not detected by ear
-time it takes for a sound to decay to .001 of its original amplitude
-time it takes, in seconds, for a sound to decrease 60dB

Question 24

Long reverberation time

Answer 24

higher number of seconds
-space with reflected surfaces (live room)

Question 25

short reverberation time

Answer 25

fewer seconds
-space with absorptive surfaces (dead room)

Question 26

anechoic chambers

Answer 26

soundproof rooms
(no reverberation)

Question 27

an object will vibrate with the ____ _____ at its natural frequency

Answer 27

greatest amplitude

Question 28

as you move away from the natural frequency, the _____ lessens

Answer 28

amplitude

Question 29

the increased amplitude at the natural frequency can actually be ____ _____ than the sound that was introduced

Answer 29

more intense

Question 30

Definition or resonators and filters

Answer 30

change or shape sound
-filters that alter the output of the sound

Question 31

what are the 4 types of filters?

Answer 31

low pass
high pass
band with
band reject

Question 32

Definition of a low pass filter

Answer 32

low frequencies get through and high frequencies get cut off
-gradual decrease of high frequencies

Question 33

Cut off frequency of a low-pass filter or high pass filter

Answer 33

frequency at -3dB

Question 34

How do you find the attenuation rate?

Answer 34

how many dB are attenuated per octave (doubling of frequency)

Question 35

What does a low-pass frequency slope look like

Answer 35

negative slope

Question 36

Definition of high pass filter

Answer 36

high frequencies get through and low frequencies get cut off
-gradual decrease of low frequencies

Question 37

What does the slope of a high pass filter look like?

Answer 37

positive slope

Question 38

Definition of band pass filter

Answer 38

band of frequencies get through
-both high frequencies and low frequencies get rejected

Question 39

bandpass filter and band reject filter have ____ cut off frequencies

Answer 39

2
-one at the low end and one at the high end

Question 40

bandwidth of a bandpass filter or band reject filter is

Answer 40

F1-F2 or F high- F low

Question 41

definition of a band reject/ notch filter

Answer 41

all frequencies get through except a band