Web Audio: Reverb with ConvolverNode

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The ConvolverNode in the Web Audio API applies a linear convolution effect to audio. This is often used to simulate reverberation based on an impulse response (IR), which captures the acoustic signature of a physical space.

What is Linear Convolution?

Linear convolution is a process that combines two signals—typically an input signal and an impulse response—to produce a new signal. In audio, this means shaping an input sound based on how it would behave in a real-world environment (like a concert hall or chapel).

Loading an Impulse Response

To use a ConvolverNode, you need to load an audio file that contains the impulse response and decode it into an AudioBuffer. This buffer is then assigned to the buffer property of the convolver. Here's how that works:

Reverb with a Convolver Node

const createReverb = async function() {
    // Load impulse response
    let response = await fetch("ir/TPAC-chapel.wav");
    let arraybuffer = await response.arrayBuffer();
    let ir = await audioContext.decodeAudioData(arraybuffer)

    //create and return AudioNode for reverb effect.
    return new ConvolverNode(audioContext, {buffer: ir});
}

// Usage
reverb = await createReverb();
reverb.connect(outputGain);

This example loads an impulse response from TPAC-chapel.wav and sets it as the buffer for a ConvolverNode. Once created, the reverb is connected to the audio graph through outputGain.