The vacil unit anchors fluctuation strength to a 4 Hz modulated tone
Evidence
Because fluctuation strength is a sensation which one considers separately from other sensations, both absolute and relative values are useful. A fixed point is therefore defined for a 60-dB, I-kHz tone 100% amplitudemodulated at 4Hz, as producing 1 vacil (from vacilare in Latin, or vacillate in English). — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1382
Categorization
- DEFINE: Defines the unit ‘vacil’ with its calibration reference tone, the standard anchor for fluctuation strength.
- corroborated: 2 independent passages support this claim — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1382
- XREF: connects to: One vacil equals a 60 dB 1 kHz tone fully amplitude-modulated at 4 Hz; Frequency-modulated tones lose fluctuation strength above 1 kHz centre frequency