https://en.wikipedia.org/wiki/Equal-loudness_contours https://en.wikipedia.org/wiki/Equal-loudness_contours The problem is, a lot of modern music has this same

https://en.wikipedia.org/wiki/Equal-loudness_contours https://en.wikipedia.org/wiki/Equal-loudness_contours The problem is, a lot of modern music has this same curve (the "smile") heavily applied to it already, so it can disintegrate into a mess quite quickly.