code: func NominalScale(buf *audio.PCMBuffer) error {
  	if buf == nil || buf.Format == nil {
  		return audio.ErrInvalidBuffer
  	}
  	buf.SwitchPrimaryType(audio.Float)
  	min, max := analysis.MinMaxFloat(buf)
  	// check if already in the right scale
  	if min >= -1 && max <= 1 {
  		return nil
  	}
  
  	max = float64(audio.IntMaxSignedValue(buf.Format.BitDepth))
  	for i := 0; i < buf.Len(); i++ {
  		buf.Floats[i] /= max
  	}
  
  	return nil
  }
docs: // NominalScale converts the input to a -1.0 / +1.0 scale