mtof/index.js

convert MIDI note number to corresponding frequency

module.exports = function mtof(midiNote, concertPitch) {
  if (concertPitch === undefined) concertPitch = 440;

  if (typeof midiNote !== 'number') {
    throw new TypeError("'mtof' expects its first argument to be a number.")
  }

  if (typeof concertPitch !== 'number') {
    throw new TypeError("'mtof' expects its second argument to be a number.")
  }

  return Math.pow(2, (midiNote - 69) / 12) * concertPitch;
}