Equalization Filters
An audio equalizer allows you to increase or decrease the strength of an audio signal
within selected frequency ranges, or bands. For example, a three-band equalizer may
have a gain control for the lows, midrange, and highs, so you can change the sonic
“shape” of a sound by turning up some frequencies or reducing others. In general, it is
much better to subtract frequencies than to amplify them, as this eliminates the
possibility of distortion.
If you find that a sound is lacking “brilliance,” or high-end frequencies, try filtering out
some of the bass or midrange frequencies. The overall effect is that the high-end
frequencies are stronger than the lower-range frequencies. It’s easy to go too far when
amplifying some frequencies, so get in the habit of reducing frequencies first. Particular
kinds of sound—men’s voices, women’s voices, tape hiss, and traffic noise—all appear
at different frequencies of the audio spectrum. Equalization (EQ) filters can be used for
many things, from minimizing background noise in a recording to accentuating a
narrator’s voice over background music. EQ filters can also create effects like making a
voice sound as though it were coming through a telephone or loudspeaker (this is
because telephones and loudspeakers generally don’t reproduce the high and low
frequencies, only the midrange).
Chapter 8
Using Audio Filters
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