AudioListener.forwardY

The forwardY read-only property of the AudioListener interface is an AudioParam representing the y value of the direction vector defining the forward direction the listener is pointing in.

Note: The parameter is a-rate when used with a PannerNode whose panningModel is set to equalpower, or k-rate otherwise.

Syntax

var audioCtx = new AudioContext();
var myListener = audioCtx.listener;
myListener.forwardY.value = 0;

Value

An AudioParam. Its default value is 0, and it can range between positive and negative infinity.

Example

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!

Note how we have used some feature detection to either give the browser the newer property values (like AudioListener.forwardX) for setting position, etc. if it supports those, or older methods (like AudioListener.setOrientation()) if it still supports those but not the new properties.

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

var xPos = Math.floor(WIDTH/2);
var yPos = Math.floor(HEIGHT/2);
var zPos = 295;

// define other variables

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;

if(panner.orientationX) {
  panner.orientationX.value = 1;
  panner.orientationY.value = 0;
  panner.orientationZ.value = 0;
} else {
  panner.setOrientation(1,0,0);
}

var listener = audioCtx.listener;

if(listener.forwardX) {
  listener.forwardX.value = 0;
  listener.forwardY.value = 0;
  listener.forwardZ.value = -1;
  listener.upX.value = 0;
  listener.upY.value = 1;
  listener.upZ.value = 0;
} else {
  listener.setOrientation(0,0,-1,0,1,0);
}

var source;

var play = document.querySelector('.play');
var stop = document.querySelector('.stop');

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

var listenerData = document.querySelector('.listener-data');
var pannerData = document.querySelector('.panner-data');

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

xIterator = WIDTH/150;

// listener will always be in the same place for this demo

if(listener.positionX) {
  listener.positionX.value = xPos;
  listener.positionY.value = yPos;
  listener.positionZ.value = 300;
} else {
  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() {
  if(panner.positionX) {
    panner.positionX.value = xPos;
    panner.positionY.value = yPos;
    panner.positionZ.value = zPos;
  } else {
    panner.setPosition(xPos,yPos,zPos);
  }
  pannerData.innerHTML = 'Panner data: X ' + xPos + ' Y ' + yPos + ' Z ' + zPos;
}

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 math involved, but you will soon get used to it with a bit of experimentation.

Specifications

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

Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support No1 Yes No1 No No1 No
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidIE mobileOpera AndroidiOS Safari
Basic support No1 No1 Yes No1 No No1 ?

1. Supports a deprecated way of setting orientation — the setOrientation() method.

See also

Document Tags and Contributors

 Contributors to this page: sebbert, fscholz, chrisdavidmills
 Last updated by: sebbert,