Competence vs. Performance

Equal steps on the mel scale do not sound musically equal:

• a composition played using the mel scale may sound reasonable in the central range but increasingly incorrect toward higher and lower ranges;
• Listen to wider spacing at the lower-end range of a mel descending chromatic scale

Distinction can be seen in linguistics where Noam Chomsky distinguished between competence and performance:

• grammar people know to be correct is different from what they actually use in speaking;
• rules are known, but limited memory and processing power inhibit their use.

Similarly, rules that govern musical interval relationships may be known, but limitations inhibit perception/production at extremes of the frequency range.

The mel scale is not an appropriate musical scale, but can (and has likely) inform(ed) musicians:

• musical compositions have statistically higher number of close intervals in the central frequency range.