Chapter 5

Question 1

Specs help us understand how ____

Specs provide insight into the quality of ____.

Answer 1

How an item works and design and construction.

Question 2

Frequency response is the ability of a device to ___.
For microphones, it is the acoustic level at the ___ vs. ___ signal at the connector.
With signal processors it describes the change in a wave form from ___ to ____.

Answer 2

accurately reproduce something.
diaphragm vs electrical
input to output

Question 3

What are the two important aspects of frequency response specifications?

Answer 3

The range of frequencies over which the device is reliable.

The degree of deviations (tolerance) within that range.

Question 4

The term frequency range is appropriate if we are examining the ___ and ___ frequencies that might be generated such as 16Hz to 22kHz.

Answer 4

highest and lowest

Question 5

What is a good frequency response spec?

Answer 5

1. With any spec “good” must be judged in the context of the application.
2. The flatter and wider the frequency response spec, the more accurately the system reproduced the sound.
3. It is often desirable to restrict low frequency response to block mic rumble.

Question 6

1. Noise is the sound you did/didn’t intentionally create.
2. Noise has the overall affect of inducing/reducing the available dynamic range.
3. High/low noise levels are very annoying and fatiguing.
4. Noise also wastes ___ power, increases effective ___, and hastens ___ failure.

Answer 6

1. didn’t
2. reducing
3. High
4. amplifier, distortion, and loud speaker

Question 7

Name some of the many kinds of sounds that qualify as noise. Which two are intentionally created?

Answer 7

white noise, pink noise, hum, buzz, static, popcorn noise, etc.

white and pink noises are intentional (used as test signals)

Question 8

1. White noise is filtered/unfiltered, altered/unaltered thermal noise.
2. White noise is used to ___ electronic equipment, has a ___ dB per octave rise in energy.

Answer 8

1. unfiltered and unaltered

2. calibrate / 3

Question 9

1. Pink noise is ___ that has been modified with a pinking filter. Such a filter is nothing more than a ___ dB per octave roll-off that reduced the level as the frequency goes higher/lower.
2. Since pink noise has equal/unequal energy per octave, it is more useful as a loudspeaker test and calibration signal.

Answer 9

1. white noise / 3 / higher

2, equal

Question 10

1. Hum is generally the result of leakage of ac/dc power line energy into the ___ circuit.
2. What causes hum?

Answer 10

1. AC / audio

2. Poorly isolated power transformer, a power supply problem, by electromagnetic coupling.

Question 11

1. The result of leakage of AC power line energy into the audio circuit.
2. Caused by distant lighting by problematic AC, or by radio frequency energy.
3. Sporadic, crackling sound that can be caused by internal breakdown by transmitters or by dirty patch points or other connections.

a. popcorn noise c. static
b. hum

Answer 11

1 = hum
2 = static
3 = popcorn

Question 12

Proper ___ and ___ goes a long way towards minimizing most noise.

Answer 12

grounding and shielding

Question 13

There is a number of different standard operating levels in audio circuitry. Most audio engineers think of operating levels in three general categories. What are they?

Answer 13

Mic level / low level
Line level / medium level
Speaker level / high level

Question 14

Mic level / low level range extends ___ to ___. This level is prior to any form of amplification (before pre-amps). Name them.

Answer 14

0dBm to -20dBm.

outputs of microphones, guitar pickups, phono cartridges, and tape heads.

Question 15

Line level / medium level range extends from ___ to ___. It covers the output levels of nearly all equipment except power amplifiers. Name them.

Answer 15

-20dBm - 30dBm

Synthesizer outputs, preamp and counsole outputs, and most of the inputs and outputs of any single processing equipment.

Question 16

1. Signal leakage from one circuit to another is called ____.
2. The best way to avoid this is to use ___.
3. If __ level cables must run to the same place as __ level cables, separate them from the greatest distance practical. Where they cross, have them cross as close to a right angle as possible..

Answer 16

1. cross talk
2. separate, not multi-core cable; and to bundle it loosely, not tightly.
3. line / mic

Question 17

Filters are generally specified by the rate at which they attenuate signal below or above a specified ____ (slope rate / turn-over frequency)

Answer 17

turn-over frequency

Question 18

Match:
Turnover frequency / Slope rate
1. The ___ is the frequency at which the level has dropped 3dB relative to the pass band.
2. The ___, expressed in dB octave, is the rate at which the level drops beyond the turn-over frequency.

Answer 18

1. Turn-over frequency

2. Slope rate

Question 19

When ___ measurements are made, a calibrated microphone is used.

Answer 19

accoustic