func comb(b audio.Buffer, delay int) (avg, n float64) {
length := b.Len()
var (
i int
done int
)
for i = length; (i - delay) > 0; i-- {
delayed := i - delay
if delayed < 0 {
break
}
done++
avg += (float64(b.At(delayed)) + 1.0) / 2.0
}
if done == 0 {
//fmt.Println(avg, done, avg / float64(done))
return 0, 0
}
return avg, float64(done)
}
