Specific loudness generalizes beyond loudness to describe sharpness

Evidence

In previous chapters, it was shown that excitation level is a useful and interesting value for describing hearing effects. Specific loudness is an even more hearing equivalent value of similar importance that is very useful for describing other effects in hearing such as sharpness. — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1278

Categorization

• XREF: Links specific loudness to sharpness and other psychoacoustic metrics in the wider hearing-modeling literature; the reader’s own model-building on psychoacoustics would reuse N’ as the common derived quantity.
• SEED: Angle: specific loudness as the primitive currency of audition - a single derived quantity that predicts loudness, sharpness, and roughness alike could anchor a piece on how hearing models unify.
• corroborated: 2 independent passages support this claim — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1278