One acum is defined by a 1 kHz narrow-band noise at 60 dB.
Evidence
The most important parameters influencing sharpness are the spectral content and the centre frequency of narrow-band sounds. In order to give quantitative values, a reference point and a nnit have to be defined. In Latin, the expression “acum” is used for sharp. The reference sound producing 1 acum is a narrow-band noise one critical-band wide at a centre frequency of 1 kHz having a level of 60 dB. — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1342
Categorization
Category: Definitional Content
- DEFINE: Defines the acum unit for sharpness with its reference sound and etymology.
- CANDY: “Acum” from Latin for sharp is a fun trivia fact for introducing the sharpness metric.
Related
- Sharpness is modeled as a weighted first moment of specific loudness (similarity 0.83)
- Sharpness depends on the spectral envelope, not fine structure (similarity 0.80)
- Sound level has only a weak effect on perceived sharpness (similarity 0.80)
- Sharpness depends primarily on spectral content, not on level or bandwidth. (similarity 0.79)
- Doubling sound level from 30 to 90 dB only doubles perceived sharpness (similarity 0.79)
- Narrow-band noise sharpness grows proportionally with critical-band rate up to about 3 kHz (similarity 0.78)
- One asper of roughness is standardized by a 70-Hz fully modulated 60-dB tone (similarity 0.78)
Broader Connections
- One dura is defined by a 1 kHz, 60 dB tone of one second
#corroborates(0.95) — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1476 - Narrow-band noise behaves like a randomly amplitude-modulated pure tone.
#expands(0.80) — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 88 - One vacil equals a 60 dB 1 kHz tone fully amplitude-modulated at 4 Hz
#responds-to(0.75) — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1382