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The threshold property of the DynamicCompressorNode interface is a k-rate AudioParam representing the decibel value above which the compression will start taking effect.

The threshold property's default value is -24 and it can be set between -100 and 0.

The threshold attribute has no effect on signals lowers than its value, but induce volume reduction on signal stronger than its value.


var audioCtx = new AudioContext();
var compressor = audioCtx.createDynamicsCompressor();
compressor.threshold.value = -50;


An AudioParam.

Note: Though the AudioParam returned is read-only, the value it represents is not.


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.setValueAtTime(-50, audioCtx.currentTime);
compressor.knee.setValueAtTime(40, audioCtx.currentTime);
compressor.ratio.setValueAtTime(12, audioCtx.currentTime);
compressor.attack.setValueAtTime(0, audioCtx.currentTime);
compressor.release.setValueAtTime(0.25, audioCtx.currentTime);

// connect the AudioBufferSourceNode to the destination

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

  } else if(active == 'true') {
    button.setAttribute('data-active', 'false');
    button.innerHTML = 'Add compression';



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

Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support14 Yes25 No156
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidOpera AndroidiOS SafariSamsung Internet
Basic support Yes14 Yes2615 ? ?

See also

Document Tags and Contributors

 Contributors to this page: SphinxKnight, fscholz, erikadoyle, chrisdavidmills
 Last updated by: SphinxKnight,