- 5 -
A Word about Audio Processing
Loudness and coverage are increased by reducing the peak-to-average ratio of the audio. If
peaks are reduced, the average level can be increased within the permitted modulation limits.
The effectiveness with which this can be accomplished without introducing objectionable side
effects (like clipping distortion) is the single best measure of audio processing effectiveness.
Density is the extent to which the short-term RMS amplitude of audio envelope peaks is made
uniform (at the expense of dynamic range). Programs with large amounts of short-term
dynamic range have low density; highly compressed programs have high density. Reducing the
peak-to-average ratio of the audio increases loudness. If peaks are reduced, the average level
can be increased within the permitted modulation limits. The effectiveness with which this can
be accomplished without introducing objectionable side effects (such as pumping or
intermodulation distortion) is the single best measure of audio processing effectiveness.
Compression reduces the difference in level between the soft and loud sounds to make more
efficient use of permitted peak level limits, resulting in a subjective increase in the loudness of
soft sounds. It cannot make loud sounds seem louder. Compression reduces dynamic range
relatively slowly in a manner similar to riding the gain: Limiting and clipping, on the other hand,
reduce the short-term peak-to average ratio of the audio.
Limiting increases audio density. Increasing density can make loud sounds seem louder, but can
also result in an unattractive busier, flatter, or denser sound. It is important to be aware of the
many negative subjective side effects of excessive density when setting controls that affect the
density of the processed sound.
Clipping sharp peaks does not produce any audible side effects when done moderately.
Excessive clipping will be perceived as audible distortion.
Look-ahead limiting is limiting that prevents overshoots by examining a few milliseconds of the
unprocessed sound before it is limited. This way the limiter can anticipate peaks that are
coming up.
Summary of Contents for BT-HPSA V2
Page 1: ......
