Well,
When making a recording keeping levels where there is not gross distortion is important. With digital going into the red is a no, no because gross distortion happens immediately and sounds like dragging a wire brush across a blackboard. With audio tape going into the red may not even be auditable for the most part. The writers at HI Fi Stereo Review once did tests to see how much distortion was needed before you could detect it. On a fundimental frequency it took 6 percent before they could detect it.

For a better look at how loudness affects the human ear you need to look at the Fletcher-Munson Curves that did tests to see how sensitive the ear was at different frequencies.

Last edited by Ray E. Strode; 02/11/17 02:09 PM.
Ray E. Strode