New and better loudness compensation has been designed based on the differences between the Equal Loudness Level Contours (ELLC) in ISO 226:2003. Sound productions are normally being mixed at a high Mixing Level (ML) in dB but often played at lower Listening Level (LL), which means that the perceived frequency balance will be changed both for LL lower or higher than ML. The differences in ELLC ask for a level based equalization using fractional-order filters. A designing technique for both analog and digital fractional-order filters has been developed. The analog solution is based on OPAMs and the digital solution is realized in a 16/32 bit fixed point DSP and could be implemented in any sound producing system.
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