IIRFilterNode

The IIRFilterNode interface of the Web Audio API is a AudioNode processor which implements a general infinite impulse response (IIR)  filter; this type of filter can be used to implement tone control devices and graphic equalizers as well. It lets the parameters of the filter response be specified, so that it can be tuned as needed.

Number of inputs 1
Number of outputs 1
Channel count mode "max"
Channel count Same as on the input
Channel interpretation "speakers"

Typically, it's best to use the BiquadFilterNode interface to implement higher-order filters. There are several reasons why:

  • Biquad filters are typically less sensitive to numeric quirks.
  • The filter parameters of biquad filters can be automated.
  • All even-ordered IIR filters can be created using BiquadFilterNode.

However, if you need to create an odd-ordered IIR filter, you'll need to use IIRFilterNode. You may also find this interface useful if you don't need automation, or for other reasons.

Once the node has been created, you can't change its coefficients.

IIRFilterNodes have a tail-time reference; they continue to output non-silent audio with zero input. As an IIR filter, the non-zero input continues forever, but this can be limited after some finite time in practice, when the output has approached zero closely enough. The actual time that takes depends on the filter coefficients provided.

Constructor

IIRFilterNode()
Creates a new instance of an IIRFilterNode object.

Properties

This interface has no properties of its own; however, it inherits properties from its parent, AudioNode.

Methods

Inherits methods from its parent, AudioNode. It also has the following additional methods:

getFrequencyResponse()
Uses the filter's current parameter settings to calculate the response for frequencies specified in the provided array of frequencies.

Examples

You can find a simple IIR filter demo live on Codepen. Also see the source code on GitHub. It includes some different coefficient values for different lowpass frequencies — you can change the value of the filterNumber constant to a value between 0 and 3 to check out the different available effects.

Also see our Using IIR filters guide for a full explanation.

Specifications

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

Browser compatibility

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidEdge MobileFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
Basic supportChrome Full support 49Edge Full support YesFirefox Full support 50IE No support NoOpera Full support 36Safari ? WebView Android Full support 49Chrome Android Full support 49Edge Mobile Full support YesFirefox Android Full support 50Opera Android Full support 36Safari iOS ? Samsung Internet Android Full support 5.0
IIRFilterNode() constructorChrome Full support 55
Notes
Full support 55
Notes
Notes Before version 59, the default values were not supported.
Edge ? Firefox Full support 53IE No support NoOpera Full support 42Safari ? WebView Android Full support 55
Notes
Full support 55
Notes
Notes Before version 59, the default values were not supported.
Chrome Android Full support 55
Notes
Full support 55
Notes
Notes Before version 59, the default values were not supported.
Edge Mobile ? Firefox Android Full support 53Opera Android Full support 42Safari iOS ? Samsung Internet Android Full support 6.0
getFrequencyResponseChrome Full support 49Edge Full support YesFirefox Full support 50IE No support NoOpera Full support 36Safari ? WebView Android Full support 49Chrome Android Full support 49Edge Mobile Full support YesFirefox Android Full support 50Opera Android Full support 36Safari iOS ? Samsung Internet Android Full support 5.0

Legend

Full support  
Full support
No support  
No support
Compatibility unknown  
Compatibility unknown
See implementation notes.
See implementation notes.

See also

Document Tags and Contributors

Last updated by: chrisdavidmills,