Primer
Crestron
Surround Sound
response of 2 dB within the range of 50 Hz to 18 kHz. This means that
the speaker is within 2 dB (at the limit of perception) of a flat response
within the given frequency range. All speakers will fluctuate above and
below an ideal flat response. Speakers that remain within two or three
dB of a flat response are very linear and nearly flat. Most speakers have
a drop off in response in the very low and very high frequency ranges.
These frequency areas are outside of the critical midrange frequencies
to which human hearing is most attuned.
Equalization
Equalization is a change in the frequency response of an audio signal.
This is accomplished by adjusting the amplitude of the signal within a
range of frequencies. The aim of equalization is to achieve a flatter
frequency response (more closely matching the original signal), by
compensating for the room acoustics and speaker deficiencies.
The following diagram illustrates the use of equalization on an audio
signal. The listening area is first tested with a pink noise generator and
a sound level meter to determine the flatness of the room. Equalizers
are then used to increase or decrease those portions of the audio
spectrum that fall above or below the ideal response of 0 dB. The result
of this compensation is a flatter response, more closely resembling the
original audio recording as intended. The equalizer settings mirror the
actual room readings. In practice, sound engineers would not increase
the amplitude of frequencies that fall below the flat response line.
Generally, an artificial increase of those frequencies can introduce
undesirable distortion.
NOTE:
Equalizer adjustments should only be performed when the
actual room response is known.
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Surround Sound
Primer – DOC. 6122