Exam 1

Question 1

What is physics?

Answer 1

The science that deals with matter, energy, motion, and force.

Question 2

Define acoustics.

Answer 2

A branch of physics that deals with sound and the study of sound.

Question 3

What does psychoacoustics study?

Answer 3

The study of how the brain perceives sound; the psychological response to sound.

Question 4

What is physical sound?

Answer 4

An audible disturbance in a medium caused by a vibrating source.

Question 5

What is psychological sound?

Answer 5

Our perception of the audible disturbance.

Question 6

Define intensity in the context of sound.

Answer 6

The power of sound.

Question 7

What does frequency refer to?

Answer 7

How quickly the air molecules move back and forth.

Question 8

What is loudness?

Answer 8

Our perception of the intensity of sound.

Question 9

Define pitch.

Answer 9

How we perceive that vibration.

Question 10

What does timbre describe?

Answer 10

The quality of sound; purely perceptual, e.g., smooth, rough, breathy, flat.

Question 11

What is Newton’s First Law?

Answer 11

All bodies remain at rest or in a state of motion unless another force acts in opposition.

Question 12

How is mass related to inertia?

Answer 12

The amount of inertia is directly proportional to the mass of an object.

Question 13

What does Newton’s Third Law state?

Answer 13

With every force, there must be an equal reaction force in the opposite direction.

Question 14

Define elasticity.

Answer 14

The reaction force to inertia.

Question 15

Air compression results in?

Answer 15

Increased density.

Question 16

Air rarefaction results in?

Answer 16

Decreased density.

Question 17

What is the unit of measurement for length?

Answer 17

Meters.

Question 18

What is mass measured in?

Answer 18

Grams.

Question 19

How is time measured?

Answer 19

In seconds.

Question 20

What is displacement (x)?

Answer 20

A change in position that involves both distance and direction; meter (m).

Question 21

Define velocity (c).

Answer 21

The amount of displacement per unit of time; meters per second (m/s).

Question 22

What does pressure (p) measure?

Answer 22

The amount of force per unit; newton per square meter (N/m2), dyne per square centimeter (dyne/cm2), or Pascal (Pa).

Question 23

What does amplitude measure?

Answer 23

The amount of energy transferred by a wave.

Question 24

What is frequency measured in?

Answer 24

Cycles per second (cps) or hertz (Hz).

Question 25

What does the period of a wave represent?

Answer 25

The amount of time to complete one cycle.

Question 26

Fill in the blank: T = 1/f, also, f = _______.

Answer 26

1/T

Question 27

What is direct proportionality in the context of frequency?

Answer 27

As elasticity increases, freqeuncy increases

Question 28

What exhibits inverse proportionality with frequency?

Answer 28

As mass increases, the frequency decreases

Question 29

What is the speed of sound?

Answer 29

34,000 cm/s

Question 30

What determines the speed of sound?

Answer 30

The medium, not the source.

Question 31

Define Hooke's Law.

Answer 31

The restoring force is equal to the initial displacement.

Question 32

What is equilibrium in a waveform?

Answer 32

0, 180 & 360 degrees.

Question 33

What does compression refer to in sound waves?

Answer 33

Peak

Question 34

What does rarefaction refer to in sound waves?

Answer 34

Trough

Question 35

What does a sine wave represent?

Answer 35

The value of each point on the waveform based on the SIN ⍬ function.

Question 36

What are the dimensions of a sound wave?

Answer 36

Amplitude, Frequency, Phase & Wavelength.

Question 37

Define phase in the context of sound waves.

Answer 37

The angle or degree of a sine wave when it starts or interacts with another wave.

Question 38

What is wavelength?

Answer 38

The distance traveled by a sine wave during one period of vibration; λ=speed of sound/frequency.

Question 39

What determines frequency?

Answer 39

Mass (inversely proportional) and Stiffness (directly proportional).

Question 40

What is damping?

Answer 40

Amplitude will diminish over time, therefore, the vibrations or sound are dampened.

Question 41

What causes friction in sound systems?

Answer 41

Air medium and internal friction within the oscillating system.

Question 42

What is the effect of friction on sound vibrations?

Answer 42

Friction acts as a damping force, causing a decrease in the amplitude of vibrations over time.

Question 43

What characterizes low damped systems?

Answer 43

Little damping, vibrations last longer, amplitude increases gradually.

Question 44

What characterizes high damped systems?

Answer 44

Significant damping, vibrations are brief, amplitude has a steep increase.

Question 45

Define acoustic impedance.

Answer 45

The total opposition to motion.

Question 46

What is resistance in acoustics?

Answer 46

All motion is opposed by resistance (R); an energy-dissipating component measured in ohms.

Question 47

Is resistance frequency dependent?

Answer 47

No, resistance is independent of frequency.

Question 48

What is reactance?

Answer 48

The component of a system responsible for storage of energy; an energy-storage component measured in ohms.

Question 49

Is reactance frequency dependent?

Answer 49

Yes, reactance is frequency dependent.

Question 50

What is mass reactance (Xm)?

Answer 50

Greater effect on high frequencies.

Question 51

What is compliant reactance (Xc)?

Answer 51

Greater effect on low frequencies.