DynamicsCompressorNode.reduction

The reduction property of the DynamicsCompressorNode interface is a float representing the amount of gain reduction currently applied by the compressor to the signal.

Intended for metering purposes, it returns a value in dB, or 0 (no gain reduction) if no signal is fed into the DynamicsCompressorNode. The range of this value is between -20 and 0 (in dB).

Syntax

var audioCtx = new AudioContext();
var compressor = audioCtx.createDynamicsCompressor();

Value

An AudioParam.

Example

The below code demonstrates a simple usage of createDynamicsCompressor() to add compression to an audio track. For a more complete example, have a look at our basic Compressor example (view the source code).

// Create a MediaElementAudioSourceNode
// Feed the HTMLMediaElement into it
var source = audioCtx.createMediaElementSource(myAudio);

// Create a compressor node
var compressor = audioCtx.createDynamicsCompressor();
compressor.threshold.value = -50;
compressor.knee.value = 40;
compressor.ratio.value = 12;
compressor.reduction.value = -20;
compressor.attack.value = 0;
compressor.release.value = 0.25;

// connect the AudioBufferSourceNode to the destination
source.connect(audioCtx.destination);

button.onclick = function() {
  var active = button.getAttribute('data-active');
  if(active == 'false') {
    button.setAttribute('data-active', 'true');
    button.innerHTML = 'Remove compression';

    source.disconnect(audioCtx.destination);
    source.connect(compressor);
    compressor.connect(audioCtx.destination);
  } else if(active == 'true') {
    button.setAttribute('data-active', 'false');
    button.innerHTML = 'Add compression';

    source.disconnect(compressor);
    compressor.disconnect(audioCtx.destination);
    source.connect(audioCtx.destination);
  }
}

Specifications

Specification	Status	Comment
Web Audio API The definition of 'reduction' in that specification.	Working Draft

Browser compatibility

[1] Before Chrome 52 and Opera 39, this was an AudioParam

See also

• Using the Web Audio API