Real World Digital Audio

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Many different kinds of microphones are available, but fundamentally, they

all work on the same principle: sound waves move a plate or membrane

(diaphragm) inside the mic, and this movement is translated into electrical

voltage. The exact details of how this is implemented impact the way

recordings sound.

While trying to figure out whether a given mic is the right choice for a par-

ticular recording chore, we need to look at several qualities:

• Amplitude response: Sensitivity to sounds of different loudness

• Directionality: Sensitivity to sounds coming from different angles

• Frequency response: Sensitivity to different parts of the frequency

spectrum as well as specific low-frequency characteristics (Figure 6.1)

Figure 6.1 Frequency

response curves vary by mic.

A smooth response (top; a

Shure KSM-32) responds

relatively consistently across

the frequency spectrum.

(The dotted line shows the

proximity effect: bass frequen-

cies are boosted when the

source is 15 centimeters from

the mic as opposed to 60.)

A less consistent curve (bot-

tom; a Shure SM-58) might

reduce low frequencies and

accentuate mid frequencies.

Smooth is not necessarily

better: the response on the

bottom can be perceived as

a “warmer” sound and is

intended for use with vocals.

(Images courtesy Shure, Inc.)

A mic capsule is the

construction that houses

the diaphragm and

other microphone com-

ponents.

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6: R

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