Bark scale

The human auditory system consists of a series of bandpass filters (filters that have a certain centre frequency and that attenuate signals more the more they deviate from that centre frequency). The bandwidth of these auditory filters increases with higher frequencies and the precision of the frequency perception decreases. Taking into account this property of the human auditory system, the Bark scale is, like the semitone scale and the ERB scale, a perceptually realistic scale of frequency.

Comment
The following conversion should be applied to transform frequency values (F) into Bark values:

Bark= [ (26.81*F) / (1960+F) ] - 0.53

Link
Utrecht Lexicon of Linguistics