BaseAudioContext: createGain() method

{{ APIRef("Web Audio API") }}

The createGain() method of the {{ domxref("BaseAudioContext") }} interface creates a {{ domxref("GainNode") }} , which can be used to control the overall gain (or volume) of the audio graph.

[!NOTE] The {{domxref("GainNode.GainNode", "GainNode()")}} constructor is the recommended way to create a {{domxref("GainNode")}} ; see Creating an AudioNode.

Syntax

createGain()

Parameters

None.

Return value

A {{domxref("GainNode")}} which takes as input one or more audio sources and outputs audio whose volume has been adjusted in gain (volume) to a level specified by the node’s {{domxref("GainNode.gain")}} a-rate parameter.

Examples

The following example shows basic usage of an {{domxref("AudioContext")}} to create a GainNode, which is then used to mute and unmute the audio when a Mute button is clicked by changing the gain property value.

The below snippet wouldn’t work as is — for a complete working example, check out our Voice-change-O-matic demo (view source.)

<div>
  <button class="mute">Mute button</button>
</div>

const audioCtx = new AudioContext();
const gainNode = audioCtx.createGain();
const mute = document.querySelector(".mute");
let source;

if (navigator.mediaDevices.getUserMedia) {
  navigator.mediaDevices.getUserMedia(
    // constraints - only audio needed for this app
    {
      audio: true,
    },

    // Success callback
    (stream) => {
      source = audioCtx.createMediaStreamSource(stream);
    },

    // Error callback
    (err) => {
      console.error(`The following gUM error occurred: ${err}`);
    },
  );
} else {
  console.error("getUserMedia not supported on your browser!");
}

source.connect(gainNode);
gainNode.connect(audioCtx.destination);

// …

mute.onclick = () => {
  if (mute.id === "") {
    // 0 means mute. If you still hear something, make sure you haven't
    // connected your source into the output in addition to using the GainNode.
    gainNode.gain.setValueAtTime(0, audioCtx.currentTime);
    mute.id = "activated";
    mute.textContent = "Unmute";
  } else {
    gainNode.gain.setValueAtTime(1, audioCtx.currentTime);
    mute.id = "";
    mute.textContent = "Mute";
  }
};

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}

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