Stevens defined one sone as a 40 dB SPL 1000-Hz tone

Evidence

Using magnitude estimation, Stevens (1956) and later investigators measured the growth of loudness in healthy human listeners for 1000- Hz pure tones. In this type of experiment, listeners hear two tones: a reference tone (a 40 dB SPL tone) followed by a test tone. In different experimental conditions, test tones are presented at a range of levels. Listeners are told that the reference tone (a 1000-Hz tone presented at 40 dB SPL) should be assigned a rating of 1. Stevens defined this reference sound as one sone, the unit of loudness. — Jennifer Lentz, Psychoacoustics- Perception of Normal…, 710

Categorization

• DEFINE: Defines the sone, the fundamental unit of loudness.