Objective and subjective evaluation of musical and speech recordings transmitted by DAB+ system

The results of research on the sound quality of various kinds of music as well as speech signals transmitted via Digital Audio Broadcasting Plus system are presented. The results showed that bitrate values significantly influence the results of quality assessment, i.e. the overall audio quality as well as a timbre are dependent on the bitrate. The additional conclusion is that the CCR method is more accurate for sound assessment for higher bitrate values and this fact has been verified by standard deviation values of obtained results. The speech signals were additionally examined with PESQ method. The results have shown that the assumed quality of 4 MOS for speech could be achieved at 48 kbps. This fact was confirmed by both: subjective and objective research