package extractfreq

import "math"

// A-weight filter is supposed to correspond to how a human would perceive
// loudness.
func AWeight(f float64) float64 {
	return (148693636.0 * f * f * f * f) /
		((424.36 + f*f) *
			math.Sqrt((f*f+11599.29)*(f*f+544496.41)) *
			(f*f + 148693636.0))
}