PannerNode

This article is in need of a technical review.

The PannerNode interface represents the position and behavior of an audio source signal in space. It is an AudioNode audio-processing module describing its position with right-hand Cartesian coordinates, its movement using a velocity vector and its directionality using a directionality cone.

A PannerNode always has exactly one input and one output: the input can be mono or stereo but the output is always stereo (2 channels) — you need stereo sound for panning effects!

The PannerNode brings a spatial position and velocity and a directionality for a given signal.

  • Number of inputs 1
  • Number of outputs 1
  • Channel count mode "clamped-max"
  • Channel count 2
  • Channel interpretation "speakers"

Properties

Inherits properties from its parent, AudioNode.

PannerNode.panningModel
Is an enumerated value determining which spatialisation algorithm to use to position the audio in 3D space.
PannerNode.distanceModel
Is an enumerated value determining which algorithm to use to reduce the volume of the audio source as it moves away from the listener.
PannerNode.refDistance
Is a double value representing the reference distance for reducing volume as the audio source moves further from the listener.
PannerNode.maxDistance
Is a double value representing the maximum distance between the audio source and the listener, after which the volume is not reduced any further.
PannerNode.rolloffFactor
Is a double value describing how quickly the volume is reduced as the source moves away from the listener. This value is used by all distance models.
PannerNode.coneInnerAngle
Is a double value describing the angle, in degrees, of a cone inside of which there will be no volume reduction.
PannerNode.coneOuterAngle
Is a double value describing the angle, in degrees, of a cone outside of which the volume will be reduced by a constant value, defined by the coneOuterGain attribute.
PannerNode.coneOuterGain
Is a double value describing the amount of volume reduction outside the cone defined by the coneOuterAngle attribute. Its default value is 0, meaning that no sound can be heard.

Methods

Inherits methods from its parent, AudioNode.

PannerNode.setPosition()
Defines the position of the audio source relative to the listener (represented by an AudioListener object stored in the AudioContext.listener attribute.)
PannerNode.setOrientation()
Defines the direction the audio source is playing in.

Deprecated features

PannerNode.setVelocity()
Defines the velocity vector of the audio source — how fast it is moving and in what direction. In a previous version of the specification, the PannerNode had a velocity that could pitch up or down AudioBufferSourceNodes connected downstream. This feature was not clearly specified and had a number of issues, so it has been removed.

Examples

In the following example, you can see an example of how the createPanner() method, AudioListener  and PannerNode would be used to control audio spatialisation. Generally you will define the position in 3D space that your audio listener and panner (source) occupy initially, and then update the position of one or both of these as the application is used. You might be moving a character around inside a game world for example, and wanting delivery of audio to change realistically as your character moves closer to or further away from a music player such as a stereo. In the example you can see this being controlled by the functions moveRight(), moveLeft(), etc., which set new values for the panner position via the PositionPanner() function.

To see a complete implementation, check out our panner-node example (view the source code) — this demo transports you to the 2.5D "Room of metal", where you can play a track on a boom box and then walk around the boom box to see how the sound changes!

// define Web Audio API objects

var AudioContext = window.AudioContext || window.webkitAudioContext;
var audioCtx = new AudioContext();

var panner = audioCtx.createPanner();
panner.panningModel = 'HRTF';
panner.distanceModel = 'inverse';
panner.refDistance = 1;
panner.maxDistance = 10000;
panner.rolloffFactor = 1;
panner.coneInnerAngle = 360;
panner.coneOuterAngle = 0;
panner.coneOuterGain = 0;
panner.setOrientation(1,0,0);

var listener = audioCtx.listener;
listener.setOrientation(0,0,-1,0,1,0);

var source;

var boomBox = document.querySelector('.boom-box');

// set up listener and panner position information
var WIDTH = window.innerWidth;
var HEIGHT = window.innerHeight;

var xPos = WIDTH/2;
var yPos = HEIGHT/2;
var zPos = 295;

leftBound = (-xPos) + 50;
rightBound = xPos - 50;

xIterator = WIDTH/150;

// listener will always be in the same place for this demo
listener.setPosition(xPos,yPos,300);
listenerData.innerHTML = 'Listener data: X ' + xPos + ' Y ' + yPos + ' Z ' + 300;

// panner will move as the boombox graphic moves around on the screen
function positionPanner() {
  panner.setPosition(xPos,yPos,zPos);
  pannerData.innerHTML = 'Panner data: X ' + xPos + ' Y ' + yPos + ' Z ' + zPos;
}

// controls to move left and right past the boom box
// and zoom in and out
// only right movement code shown in this listing to save space
// look at the source code for full listing

var leftButton = document.querySelector('.left');
var rightButton = document.querySelector('.right');
var zoomInButton = document.querySelector('.zoom-in');
var zoomOutButton = document.querySelector('.zoom-out');

var boomX = 0;
var boomY = 0;
var boomZoom = 0.25;

var zoomInLoop;
var zoomOutLoop

function moveRight() {
  boomX += -xIterator;
  xPos += -0.066;

  if(boomX <= leftBound) {
    boomX = leftBound;
    xPos = (WIDTH/2) - 5;
  }

  boomBox.style.transform = "translate(" + boomX + "px , " + boomY + "px) scale(" + boomZoom + ")";
  positionPanner();
  rightLoop = requestAnimationFrame(moveRight);
  return rightLoop;
}

rightButton.onmousedown = moveRight;
rightButton.onmouseup = function () {
  window.cancelAnimationFrame(rightLoop);
}

Note: In terms of working out what position values to apply to the listener and panner, to make the sound appropriate to what the visuals are doing on screen, there is quite a bit of fiddly maths involved, but you will soon get used to it with a bit of experimentation.

Specifications

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

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support 10.0webkit 25.0 (25.0)  Not supported 15.0webkit
22 (unprefixed)
6.0webkit
Feature Android Firefox Mobile (Gecko) Firefox OS IE Mobile Opera Mobile Safari Mobile Chrome for Android
Basic support ? 26.0 1.2 ? ? ? 33.0

See also

Document Tags and Contributors

Contributors to this page: chrisdavidmills, padenotmoz, fscholz, kscarfone, teoli, Sheppy
Last updated by: chrisdavidmills,