Chapter 1 Sound Reinforcement

Question 1

Sound is technically called _______.

Answer 1

acoustical energy

Question 2

Acoustical energy is the pushing and pulling of a _____.

Answer 2

physical / medium (usually air)

Question 3

A complete wave cycle is 1/2 cycle of ____, followed by 1/2 cycle of ____.

Answer 3

compression / rarefraction

Question 4

A rate of ___ is called the frequency.

Answer 4

fluctuations

Question 5

To be called sound, the frequency must be between ____ cycles per second (cps)

Answer 5

20 and 20,000

Question 6

The unit of frequency is ___.

Answer 6

Hertz (Hz) 20 Hz = 20cps

Question 7

Sound waves travel through air at ___.

Answer 7

1130 ft/second (at sea level and temp of 59 degree F

Question 8

___ is independent of frequency.

Answer 8

Speed of sound

Question 9

Physical measurement of a wave is the ___. Wavelength = ____

Answer 9

wavelength / speed/frequency

Question 10

An ___ is an electrical version of sound; audio equipment, the ___ or ___ fluctuates at the same rate as the accoustical energy.

Answer 10

audio signal
voltagee
current

Question 11

The amplitude or strength of an audio signal is called the ____.

Answer 11

signal level

Question 12

Relationship between a wave and known time reference is called the ____.

Answer 12

phase

Question 13

___ is expressed in degrees. One complete cycle of a ___ equals 360 degrees.

Answer 13

phase / sine wave

Question 14

___ is very important in sound systems. Phase must be controlled because it effects how sounds add together.

Answer 14

Phase

Question 15

When ___ are mixed in a console or in the air, they add algebraically.

Answer 15

audio signals

Question 16

A sound system is a system of electronic components that’s designed to amplify sound. Name the three most common reasons.

Answer 16

Help people hear better.
Make sound louder for artistic reasons.
Enable people to hear sounds in remote locations.

Question 17

Sound systems convert ___ energy into ___ energy, modifying the ___ energy and then converting it to ___ energy.

Answer 17

acoustic / electrical / acoustic

Question 18

In audio electronics, devices that convert energy from one form into another are called ___. Devices that change one or more aspects of an audio signal are called ___.

Answer 18

transducers

signal processors

Question 19

Input transducers convert ___ energy into ___ energy; then signal processors alter one or more characteristics of the ___. Output transducers convert the ___ energy (amplified for otherwise processed) back into acoustic energy.

Answer 19

acoustic / electrical / audio signal / electrical

Question 20

Examples of input transducers

Answer 20

Air pressure or velocity microphones, contact pickups, magnet pickups, tape heads, phonograph pickups (cartridges), lazer pickups, optical pickups.

Question 21

Examples of output transducers

Answer 21

woofer, midrange, tweeter, full range, subwoofer, supertweeter, monitor, and headphones

Question 22

Name the three devices that make up a basic model of sound system.

Answer 22

Input transducers (microphones), signal processing (mixing console -> power amplifiers) output transducers (loudspeakers)

Question 23

___ describes the relationship between a device’s input and output with regard signal frequency and amplitude, gives the usable range of signal frequencies for a device.

Answer 23

frequency response

Question 24

What’s the range and tolerance of 30Hz to 18Hz, +3dB?

Answer 24

Range for 30Hz to 18Hz, tolerance 3dB (maximum expected deviation between output and input over the range).

Question 25

The ___ is an interval between two tones - ratio frequency of the tones 2:1

Answer 25

octive

Question 26

Response of dynamic microphones used in sound work falls off rapidly above ___

Answer 26

10kHz

Question 27

Loudspeakers usually have the ___ variations in frequency response.

Answer 27

greatest

Question 28

Differences in dividing sound reinforcement and loudspeakers (full/limited).

Answer 28

Full do most frequencies pretty well.

Limited - narrower frequency bands, but do it better than full range. Typically they are used together in some way.

Question 29

Describe differences in full-range reinforcement, subwoofers and tweeters.

Answer 29

Full-range reinforcement have a frequency response from 100Hz to 15Hz. Subwoofers typically designed below 200Hz and usually perform down to 30Hz. Tweeters above about 8kHz

Question 30

Speaking voice range is typically ____ and has very little high frequency content, a loss of frequencies above ___ can affect intelligibility.

Answer 30

100Hz - 6Hz 1 kHZ

Question 31

When a complex waveform has a distinct pitch, that waveform can be created by combining a set of precisely related sine waves called ___.

Answer 31

harmonics

Question 32

Effects of acoustical factors (indoor and outdoor)

Answer 32

Indoor - reflections from the wall, ceiling and floor surfaces, room resonances.
Outdoor - wind - modulate the sound
Temp - reflects or retracts sound.
Humidity - effects high frequencies

Question 33

When sound travels through air, ___ frequency signals are absorbed faster than ___ frequency signals.

Answer 33

high / low