a-weighting

Perform A-weighting (and others) for a frequency. Useful for creating believable spectrum images and audio measurements.

Usage

var aWeight = require('a-weighting/a');
var ft = require('fourier-transform');

//get a-weighted frequencies
var frequencies = ft(waveform).map(function (magnitude, i, data) {
	var frequency = 22050 * i / data;

	return aWeight(frequency) * magnitude;
});

Note that weight function returns normalized 0..1 weight values, it does not do decibels calculation. If you need to convert weight to decibels, do 20 * Math.log(weight) / Math.log(10).

Implemented weights:

• A-weighting
• B-weighting
• C-weighting
• D-weighting
• Z-weighting (zero weighting)
• M-weighting

Credits

Thanks to all the specialists who researched and described these curves (years of work I guess) and wikipedia for detailed articles on this.

Related

• fourier-transform — fft fast implementation.
• gl-spectrum — spectrum rendering component.
• Equal-loudness-contours.