Mid-Term

Question 1

What is sound?

Answer 1

The passage of a disturbance through a medium

Question 2

What is vibration?

Answer 2

Displacement of air molecules caused by air pressure

Question 3

Three components necessary for sound production?

Answer 3

1) energy source (human body)
2) vibratory source (vocal folds)
3) transmitting medium (air)

Question 4

What are longitudinal waves?

Answer 4

• Particles are displaced in a parallel direction
• to provide energy transport to air molecules
• that consist of “compressions” and “rarefactions”
• that travel up & down to the sound energy.

Question 5

What is propagation?

Answer 5

Transportation of energy.

Question 6

What is elasticity?

Answer 6

Tendency to return to the original state

Question 7

What is inertia?

Answer 7

A body in motion will remain in motion - molecules overshoot the origin

Question 8

What is resistance?

Answer 8

Dissipation of energy, oftentimes in the form of heat

Question 9

What is damping?

Answer 9

Resistance to vibration energy

Question 10

What is characteristics of SHM (simple harmonic motion)?

Answer 10

periodic, repeating vibration

Question 11

What is amplitude?

Answer 11

1. Displacement/Intensity

2. how much the molecules have been displaced from neutral

Question 12

What does a sinuoid wave describe?

Answer 12

The relationship between displacement & time

Question 13

A sine wave has what two terms to describe it?

Answer 13

Amplitude (aka displacement or wavelength) & time

Question 14

What is a period?

Answer 14

Time it takes to complete one cycle.

Question 15

What is frequency?

Answer 15

The number of complete cycles that occur in 1 second (how fast it vibrates)

Question 16

What is amplitude?

Answer 16

displacement of particles (how much its vibrating-distance/height)

Question 17

What is Phase?

Answer 17

The point in the cycle that the vibrator is located at a given instant in time (its placement)

Question 18

The number of cycles per second is measured in ___?

Answer 18

Hertz (Hz)

Question 19

Inversely proportional to period (T) is the time it takes to complete one cycle? So, if f = 1000 Hz, what is T?

Answer 19

.001 sec

Question 20

If T=.25ms, and F= 1000/T, what is the frequency?

Answer 20

onvert ms to s first

.25/1000 = .00025; 1/.00025 = [4000 Hz]

Question 21

What is the frequency?

T=0.04s

Answer 21

F = 1/T = 1/.004 = [250Hz]

Question 22

What is the frequency?

T = 100 ms

Answer 22

F = 1/T, so convert if it's in ms
100/1000 = .1; 1/.1 = [10Hz]

Question 23

What is the period in seconds?

f = 100Hz

Answer 23

T = 1/f
1/100 = [.01s]

Question 24

What is the period in seconds?

f = 8000Hz

Answer 24

T = 1/f
1/8000 = [.000125 sec]

Question 25

What is the period in milliseconds?

f = 2000Hz

Answer 25

T = 1/f so 1/2000 = .0005 sec; .0005 x 1000 = [0.5 ms]

Question 26

What is the period in milliseconds?

f = 150Hz

Answer 26

1/f = 1/150 = .0067 sec.; .0067 x 1000 = [6.7 msecs]

Question 27

High vs. Low Frequency

Long, slow waves are ______ frequency.

Answer 27

Low

Question 28

High vs. Low Frequency

The longer the period, the ____ cycles per second and the lower the frequency.

Answer 28

fewer

Question 29

High vs. Low Frequency

The shorter the period, the more cycles per second the _____ the frequency.

Answer 29

higher

Question 30

Which unit of time has a higher frequency - T = 3.3 ms or T = 0.25 ms

Answer 30

T = 0.25 ms

Question 31

Which Hz indicates a higher frequency - 1000Hz or 50Hz

Answer 31

1000Hz

Question 32

What is Amplitude?

Answer 32

Amt. of vibratory displacement, changes constantly causing inconsistent measurements.

Question 33

What are four ways of measuring amplitude?

Answer 33

1) Instantaneous
2) Peak Amplitude
3) Peak-to-Peak
4) RMSquare

Question 34

Instantaneous

Answer 34

amplitude at a specific point in time

Question 35

Peak amplitude

Answer 35

displacement in one direction (positive or negative)

Question 36

Peak-to-Peak amplitude

Answer 36

amplitude from the maximum positive peak to the maximum negative peak

Question 37

Root mean square amplitude

Answer 37

the square root of the average of all amplitude squared - or 0.707 times the peak amplitude

Question 38

Root Mean Square (RMS) Amplitude - How does it help the ear hear?

Answer 38

by averaging the amplitude of the entire signal and interpreting its overall loudness - similar to how we calculate RMS

Question 39

Amplitude Measurement is:

Answer 39

pressure (y) and time (x)

Question 40

When we talk about amplitude, we usually refer to the ____. It is also called _____, as it measured in _____

Answer 40

• RMS value
• intensity
• Dbs

Question 41

Phase of sinusoid corresponds to the point in the _____ of an air molecule at a specific moment in time.

Answer 41

cycle

Question 42

Phase is defined in

Answer 42

angles

Question 43

Phys. Description (acoustics - sound vibration in air) vs. Human Perception (psychoacoustics) - What is frequency?

Answer 43

Physical descriptor that has pitch as a perceptual correlate

Question 44

Phys. Description (acoustics - sound vibration in air) vs. Human Perception (psychoacoustics)
What is Amplitude?

Answer 44

A physical dimension that has loudness as a perceptual correlate

Question 45

Phys. Description (acoustics - sound vibration in air) vs. Human Perception (PSYCHOACOUSTICS)
What is Phase?

Answer 45

a physical measure that helps in sound localization in terms of perception