Lecture (2/13) Week 5 Tuesday Flashcards

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1
Q

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

A

pass energy on from one molecule onto another

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2
Q

Dampening definition

A

gradual decrease in amplitude due to friction

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3
Q

describe a lossless system

A

sound goes on forever

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4
Q

describe a low-dampened system

A

sound echos, takes longer to dampen

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5
Q

describe a high-dampened system

A

sound is absorbed, quicker to dampen

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6
Q

definition of impedance

A

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

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7
Q

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

A

impedance

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8
Q

T/F impedance is a vector

A

true

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9
Q

The two components of impedance are

A

reactance and resistance

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10
Q

reactance=

A

mass and elasticity

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11
Q

resistance=

A

friction

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12
Q

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

A

-transmission
-reflection
-absorption
-diffraction

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13
Q

Transmission definition

A

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

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14
Q

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

A

similiar

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15
Q

What is the equation for transmission?

A

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

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16
Q

What is reflection?

A

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

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17
Q

What is the equation for reflection?

A

1.0-H= amount of sound reflected

18
Q

What are the two waves of reflection?

A

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

19
Q

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

A

angle

20
Q

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

A

same speed

21
Q

The angles of reflected ray to the perpendicular…

A

equal the angles of the incident rays to the perpendicular

22
Q

Definition of echo

A

time delay between the reflective waves and the incident wave

23
Q

Definition of reverberation

A

-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

24
Q

Long reverberation time

A

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

25
Q

short reverberation time

A

fewer seconds
-space with absorptive surfaces (dead room)

26
Q

anechoic chambers

A

soundproof rooms
(no reverberation)

27
Q

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

A

greatest amplitude

28
Q

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

A

amplitude

29
Q

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

A

more intense

30
Q

Definition or resonators and filters

A

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

31
Q

what are the 4 types of filters?

A

low pass
high pass
band with
band reject

32
Q

Definition of a low pass filter

A

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

33
Q

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

A

frequency at -3dB

34
Q

How do you find the attenuation rate?

A

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

35
Q

What does a low-pass frequency slope look like

A

negative slope

36
Q

Definition of high pass filter

A

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

37
Q

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

A

positive slope

38
Q

Definition of band pass filter

A

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

39
Q

bandpass filter and band reject filter have ____ cut off frequencies

A

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

40
Q

bandwidth of a bandpass filter or band reject filter is

A

F1-F2 or F high- F low

41
Q

definition of a band reject/ notch filter

A

all frequencies get through except a band