static double normalizedAutocorrelationOfAudioSamples(short[] samples, int start, int end) {
  double factor = absShortMax(samples, start, end);
  ret doubleRatio(autocorrelationOfAudioSamples(samples, start, end), sqr(absShortMax));
}

static double normalizedAutocorrelationOfAudioSamples(short[] samples, IntRange r) {
  ret normalizedAutocorrelationOfAudioSamples(samples, r.start, r.end);
}