GoldWave Manual

The Compressor/Expander effect dynamically alters the audio volume level. It is commonly used as a compressor, limiter, expander, or gate.

This effect does not change the size of the file. For file compression, use Save As on the File menu and change the type and attributes.

Compressors and limiters are used to decrease or limit the dynamic range of audio. In simple terms, they reduce the volume of loud sounds while leaving the rest of the sound unchanged. Expanders and gates are used to increase the dynamic range of audio. They reduce or eliminate quiet sections while leaving louder sections unchanged, which can help to reduce background noise.

Compressors always work on loud sections and expanders always work on quiet sections. Normally, both compressors and expanders only reduce the volume. However, GoldWave also allows you to boost the volume.

Compressor/Expander Settings
Setting	Description
Multiplier (dB)	Sets the amount of volume change. It is the scale factor applied to the sound when the threshold is met. For compressors, it is the amount to scale the loud sections. For expanders, it is the amount to scale the quiet sections. Normally a value less than 0dB should be used to reduce the volume.
Threshold (dB)	Sets the audio level to activate the expander or compressor. Compressors scale the volume level of all sounds above that level. Expanders scale the volume level of all sounds below that level.
Attack (s) Release (s)	Set the amount of time required to fully activate the effect. An `Attack` value of 0.100 means that the audio level will have to cross the threshold for at least one tenth of a second before the multiplier is used at full strength. A `Release` value of 0.100 means the multiplier will continue to be used for one tenth of a second after the audio level no longer crosses the threshold.
Expander Compressor	Sets the type of processing required. Use `Expander` to change volumes of quiet sounds. Use `Compressor` to change volumes of loud sounds.
Anticipate attack	Scans ahead for audio that crosses the threshold and activates the effect. If the `Attack` time is set to 0.100, then the effect scans ahead by 0.100 seconds. This means that the multiplier will be at full force the instant the threshold is crossed rather than building to full 0.100 seconds later.
Use smoother	Smoothes out any sudden volume changes which may occur during processing with small attack/release times.
Process channels independently	Controls how each channel is processed. When checked, each channel is processed separately and different gains may be applied to each channel. When unchecked, one gain is applied to all channels, usually the lowest to avoid clipping.

Setting

Description

Multiplier (dB)

Sets the amount of volume change. It is the scale factor applied to the sound when the threshold is met. For compressors, it is the amount to scale the loud sections. For expanders, it is the amount to scale the quiet sections. Normally a value less than 0dB should be used to reduce the volume.

Threshold (dB)

Sets the audio level to activate the expander or compressor. Compressors scale the volume level of all sounds above that level. Expanders scale the volume level of all sounds below that level.

Attack (s)
Release (s)

Set the amount of time required to fully activate the effect. An Attack value of 0.100 means that the audio level will have to cross the threshold for at least one tenth of a second before the multiplier is used at full strength. A Release value of 0.100 means the multiplier will continue to be used for one tenth of a second after the audio level no longer crosses the threshold.

Expander
Compressor

Sets the type of processing required. Use Expander to change volumes of quiet sounds. Use Compressor to change volumes of loud sounds.

Anticipate attack

Scans ahead for audio that crosses the threshold and activates the effect. If the Attack time is set to 0.100, then the effect scans ahead by 0.100 seconds. This means that the multiplier will be at full force the instant the threshold is crossed rather than building to full 0.100 seconds later.

Use smoother

Smoothes out any sudden volume changes which may occur during processing with small attack/release times.

Process channels independently

Controls how each channel is processed. When checked, each channel is processed separately and different gains may be applied to each channel. When unchecked, one gain is applied to all channels, usually the lowest to avoid clipping.

Compressor Example
You have recorded some music that has a few loud moments, but you want to raise the overall volume without distorting the loud parts. Select the "Reduce loud parts" preset. After compression, use the Maximize Volume effect to stretch the volume to the full dynamic range. Alternatively you could use the "Boost quiet parts" preset.

Expander Example
You have recorded someone talking and notice background noise during the quiet parts. To reduce the noise, select the "Noise gate" preset or the "Reduce quite parts" preset.