Timbral "Dimensions" According to Gregory Roy Giese (1984):

1. Spectral envelope

2. Harmonic content

3. Brightness

4. Phase

5. Inharmonicity

6. Aperiodicity

7. Temporal transitions

From the forward of the 1984 Ph. D. thesis:

http://roger.ucsd.edu/search/a?
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Bill Flavell