One asper of roughness is standardized by a 70-Hz fully modulated 60-dB tone

Evidence

To define the roughness of 1 asper, we have chosen the 60-dB, I-kHz tone that is 100% modulated in amplitude at a modulation frequency of 70 Hz. — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1436

Categorization

• DEFINE: Standardizes the asper unit, anchoring it to a specific reference stimulus the way sones anchor loudness.
• XREF: Analogous to how ‘sone’ and ‘phon’ anchor loudness scales — the reader has been building a mental catalog of psychoacoustic units.