The Bark scale is a psychoacoustical scale proposed by Eberhard Zwicker in 1961. It is named after Heinrich Barkhausen, who proposed the first subjective measurements of loudness.Zwicker, E. (1961), "", The Journal of the Acoustical Society of America, Volume 33, Issue 2, p. 248 (1961). One definition of the term is "a frequency scale on which equal distances correspond with perceptually equal distances. Above about 500 Hz this scale is more or less equal to a logarithmic frequency axis. Below 500 Hz the Bark scale becomes more and more linear."
The scale ranges from 1 to 24 and corresponds to the first 24 critical bands of hearing.Julius O. Smith III and Jonathan S. Abel. "The Bark Frequency Scale", CCRMA.Stanford.edu.
It is related to, but somewhat less popular than, the mel scale, a perceptual scale of pitches judged by listeners to be equal in distance from one another.
Bark scale critical bands
Number Center frequency (Hz) Cut-off frequency (Hz) Bandwidth (Hz) 20 1 50 100 80 2 150 200 100 3 250 300 100 4 350 400 100 5 450 510 110 6 570 630 120 7 700 770 140 8 840 920 150 9 1000 1080 160 10 1170 1270 190 11 1370 1480 210 12 1600 1720 240 13 1850 2000 280 14 2150 2320 320 15 2500 2700 380 16 2900 3150 450 17 3400 3700 550 18 4000 4400 700 19 4800 5300 900 20 5800 6400 1100 21 7000 7700 1300 22 8500 9500 1800 23 10500 12000 2500 24 13500 15500 3500 Since the direct measurements of the critical bands are subject to error, the values in this table have been generously rounded.
In his letter "Subdivision of the Audible Frequency Range into Critical Bands", Zwicker states: "These bands have been directly measured in experiments on the threshold for complex sounds, on masking, on the perception of phase, and most often on the loudness of complex sounds. In all these phenomena, the critical band seems to play an important role. It must be pointed out that the measurements taken so far indicate that the critical bands have a certain width, but that their position on the frequency scale is not fixed; rather, the position can be changed continuously, perhaps by the ear itself." Thus the important attribute of the Bark scale is the width of the critical band at any given frequency, not the exact values of the edges or centers of any band.
Conversions To convert a frequency f (Hz) into Bark use:
or (Traunmüller, 1990)
or (Wang, Sekey & Gersho, 1992)"Sonification seminar – 10/9/03", CCRMA.Stanford.edu.
See also Luminosity function, which describes the average sensitivity of the human eye to light of different wavelengths. Fletcher–Munson curves Equivalent rectangular bandwidth, the ERB scale Critical bands
References
External links
Smith and Abel – Bark and ERB Bilinear Transforms (1999) Auditory scales of frequency representation