Audio demo

audio.html

<audio src="./Maple_Leaf_RagQ.ogg" controls></audio>
<script type="text/javascript">
    const audioCtx = new AudioContext();
    const myAudio = document.querySelector('audio');

    const source = audioCtx.createMediaElementSource(myAudio);
    const gainNode = audioCtx.createGain();
    gainNode.gain.value = 0.5;

    const gainNode2 = audioCtx.createGain();
    gainNode2.gain.value = 0.2;

    const lowFilter = audioCtx.createBiquadFilter();
    lowFilter.type = 'lowpass';
    lowFilter.frequency = 2000;

    const highFilter = audioCtx.createBiquadFilter();
    highFilter.type = 'highpass';
    highFilter.frequency = 1000;

    const noiseNode = audioCtx.createScriptProcessor(4096, 1, 1);

    noiseNode.onaudioprocess = (e) => {
        var outputBuffer = e.outputBuffer;
        var inputBuffer = e.inputBuffer;

        for (var channel = 0; channel < outputBuffer.numberOfChannels; channel++) {
            var inputData = inputBuffer.getChannelData(channel);
            var outputData = outputBuffer.getChannelData(channel);

            for (var sample = 0; sample < inputBuffer.length; sample++) {
                outputData[sample] = inputData[sample];
                outputData[sample] += ((Math.random() * 2) - 1) * 0.1;
            }
        }
    };

    source.connect(highFilter);
    highFilter.connect(lowFilter);
    lowFilter.connect(gainNode);
    lowFilter.connect(noiseNode);
    noiseNode.connect(gainNode2);
    gainNode2.connect(gainNode);
    gainNode.connect(audioCtx.destination)

    myAudio.play();
</script>