Sone

The sone is a unit of perceived loudness N after a proposal of S. Smith Stevens in 1936. In acoustics, loudness is a subjective measure of the sound pressure. One sone is equivalent to 40 phons, which is defined as the loudness level NL of a 1 kHz tone at 40 dB SPL. The number of sones to a phon was chosen so that a doubling of the number of sones sounds to the human ear like a doubling of the loudness, which also corresponds to increasing the sound pressure level by approximately 10 dB, or increasing the mean square sound pressure by a factor 10. At frequencies other than 1 kHz, the measurement in sones must be calibrated according to the frequency response of human hearing, which is a subjective process. The study of apparent loudness is included in the topic of psychoacoustics.

To be fully precise, a measurement in sones must be qualified by the optional suffix G, which means that the loudness value is calculated from frequency groups, and by one of the two suffixes D (for direct field or free field) or R (for room field or diffuse field). We have a R/D ratio.

Examples of sound pressure, sound pressure levels, and loudness in sone

 * {| class="wikitable"

! Source of sound !! sound pressure !! sound pressure level !! loudness ! &#160; !! align="center" | pascal !! align="center" | dB re 20 µPa !! align="center" | sone
 * threshold of pain || align="right" | 100 || align="right" | 134 ||align="right" | ~ 676
 * hearing damage during short-term effect || align="right" | 20 || align="right" | approx. 120 || align="right" | ~ 250
 * jet, 100 m distant || align="right" | 6 - 200 || align="right" | 110 - 140 || align="right" | ~ 125 - 1024
 * jack hammer, 1 m distant / discotheque || align="right" | 2 || align="right" | approx. 100 || align="right" | ~ 60
 * hearing damage during long-term effect || align="right" | 6×10−1 || align="right" | approx. 90 || align="right" | ~ 32
 * major road, 10 m distant || align="right" | 2×10−1 - 6×10−1 || align="right" | 80 - 90 || align="right" | ~ 16 - 32
 * passenger car, 10 m distant || align="right" | 2×10−2 - 2×10−1 || align="right" | 60 - 80 || align="right" | ~ 4 - 16
 * TV set at home level, 1 m distant || align="right" | 2×10−2 || align="right" | ca. 60 || align="right" | ~ 4
 * normal talking, 1 m distant || align="right" | 2×10−3 - 2×10−2 || align="right" | 40 - 60 || align="right" | ~ 1 - 4
 * very calm room || align="right" | 2×10−4 - 6×10−4 || align="right" | 20 - 30 || align="right" | ~ 0.15 - 0.4
 * leaves' noise, calm breathing || align="right" | 6×10−5 || align="right" | 10 ||align="right" | ~ 0.02
 * auditory threshold at 2 kHz || align="right" | 2×10−5 || align="right" | 0 ||align="right" | 0
 * }
 * passenger car, 10 m distant || align="right" | 2×10−2 - 2×10−1 || align="right" | 60 - 80 || align="right" | ~ 4 - 16
 * TV set at home level, 1 m distant || align="right" | 2×10−2 || align="right" | ca. 60 || align="right" | ~ 4
 * normal talking, 1 m distant || align="right" | 2×10−3 - 2×10−2 || align="right" | 40 - 60 || align="right" | ~ 1 - 4
 * very calm room || align="right" | 2×10−4 - 6×10−4 || align="right" | 20 - 30 || align="right" | ~ 0.15 - 0.4
 * leaves' noise, calm breathing || align="right" | 6×10−5 || align="right" | 10 ||align="right" | ~ 0.02
 * auditory threshold at 2 kHz || align="right" | 2×10−5 || align="right" | 0 ||align="right" | 0
 * }
 * leaves' noise, calm breathing || align="right" | 6×10−5 || align="right" | 10 ||align="right" | ~ 0.02
 * auditory threshold at 2 kHz || align="right" | 2×10−5 || align="right" | 0 ||align="right" | 0
 * }
 * auditory threshold at 2 kHz || align="right" | 2×10−5 || align="right" | 0 ||align="right" | 0
 * }


 * {| class="wikitable"

! sone ! phon
 * 1 || 2 || 4 || 8 || 16 || 32 || 64
 * 40 || 50 || 60 || 70 || 80 || 90 || 100
 * }