Computer Programmes for Calculating Loudness from Third-Octave Band Levels or from Critical Band Levels

The preparation of computer programmes for calculating loudness is described according to Zwicker's graphical procedure that is recommended by the ISO in R 532 B. An endeavour is made to base the programmes on the psychoacoustic foundations of the procedure rather than on the recommended graphs alone. The necessary data and conclusions for this objective are specified and are shown to facilitate programming and to improve the precision of loudness calculations.

In comparison with third-octave band levels, critical band levels will lead to more accurate results, and so also, a programme to process the latter has been prepared. The basic data and relations are specified so as to support programming in both cases in any convenient programming language. Programmes that are ready for use have been written in FORTRAN IV and are introduced together with instructions for the user. Moreover, correct application is also demonstrated by an example. Execution of the programmes does not result in total loudness alone. Additionally, detailed information about the contribution of each third-octave band or each critical band is made available.