Auto Gain

Menu Command: Effect | Volume | Auto Gain

Auto Gain evens out the volume to a consistent level across the selection. When recording a speech, interview, or telephone conversation, for example, the volume tends to vary depending on the position of the microphone relative to the person speaking. If the person or microphone moves around, the volume fluctuates. With telephone recordings, one person often sounds louder than the other.

Auto Gain automatically varies the volume level to increase it when it is low and decrease it when it is high (but it cannot correct overloaded or clipped audio).

The primary setting is the Target volume. It controls the final volume of the audio. The other settings control how often the volume changes (Update interval), how quickly it changes from one value to another (Attack/release), the maximum increase allowed (Maximum gain), and the level at which no gain should be applied to avoid amplifying background noise (Silence level).

Update interval
Controls how often the volume is adjusted to match changes in the audio. Values under one second give the best results. Use a smaller value if the audio level varies quickly. Use a larger value if the audio level is mostly even already, but needs occasional adjustments.

Attack/release
Controls how quickly the volume is changed from one interval to the next. Larger values smooth out volume changes so that they are more gradual. Setting this value to zero applies the new volume instantly every update interval. Usually values less than the Update interval value work best.

Note that when using a non-zero setting, peaks may exceed the target volume briefly as the volume gradually changes from a higher level to a lower one.

Target volume
Controls the final peak level of the audio. The volume is increased or decreased so that the peak level always hovers around this value. A value close to or slightly below 0dB (100%) is recommend for maximum volume. Values less than 0dB can be used to limit or clamp the peak level to a certain volume. The "Peak reducer" preset shows how peaks can be reduced to 90% without affecting the average volume.

Maximum gain
Controls the maximum amount the volume can be increased. Audio containing many noisy silences can result in sudden bursts of noise if the Silence level setting is not set high enough. By limiting the maximum gain, explosive volume increases for quiet sections are reduced.

Silence level
Controls the level of noise to be considered as silence. Any audio below this level is ignored and not adjusted. In other words, Auto Gain is turned off while the audio level is below this threshold. Care must be taken when setting this value. Setting it too low greatly amplifies background noise. Set it as high as possible while still getting good gain results.

Notes
One drawback of the Auto Gain effect is that background noise is amplified along with the foreground audio. In recordings where the background noise is consistent, but the foreground audio varies, the end result will be consistent foreground audio with varying background noise. Use the or other effects in GoldWave before using Auto Gain to reduce or eliminate that problem.

For stereo files, the left and right channels are processed independently. While this ensures that the channels are balanced, it may cause some unbalanced audio for short update intervals. In such cases where stereo audio is not needed, it is best to convert the file to mono or use the stereo effect in GoldWave to mix the channels into mono before using Auto Gain.

See Also