signaltohertz

calculate Hertz frequency from audio buffer. Nothing more nothing less.

// include library
var sig2hz = require('signaltohertz');

// input an array with frequencies.
var hertz = sig2hz(frequencyArray);

// input an array with frequencies and add a rate that
// if yours is different to the defaults.
var hertz = sig2hz(frequencyArray, {
    rate: 0.5
    });

You can use it with the WebAudioContext like so:

var audio, volume, frequencies, frequency, audioContext, analyser, 
    microphone, waveform, amplitude;
    
navigator.getUserMedia(
    {
    audio: true, 
    video: false
    }, function (stream) {
        audioContext = new AudioContext();
        analyser = audioContext.createAnalyser();
        frequencies = new Float32Array(analyser.frequencyBinCount);
        console.log(analyser)
        amplitude = new Uint8Array(analyser.frequencyBinCount);
        
        volume = audioContext.createGain();
        
        microphone = audioContext.createMediaStreamSource(stream);
        microphone.connect(volume);
        microphone.connect(analyser);
        
        renderFrame();
    }, function (error) { console.log(error) };

  function renderFrame () {
      setTimeout(requestAnimationFrame(renderFrame), 100);
      analyser.getFloatFrequencyData(frequencies);
      analyser.getByteTimeDomainData(amplitude);

      frequency = signaltohertz(frequencies);
      console.log(frequency);
    };