Comparison of basic audio quality and timbral and spatial fidelity changes caused by limitation of bandwidth and by down-mix algorithms in 5.1 surround audio systems

The effect on audio quality of controlled multichannel audio bandwidth limitation and selected down-mix algorithms was quantified using one generic attribute (basic audio quality) and three specific attributes (timbral fidelity, frontal spatial fidelity, and surround spatial fidelity). The investigation was focused on the standard 5.1 multichannel audio setup (ITU-R BS.775-1) and was limited to the optimum listening position. The results obtained from a panel of experienced listeners indicate that the basic audio quality of multichannel recordings is more affected by timbral fidelity than by spatial fidelities. Therefore it can be concluded that in the case of broadcasting multichannel audio under highly restricted transmission conditions, it is better, in terms of basic audio quality, to sacrifice spatial fidelity by down-mixing original multichannel audio material to a lower number of broadcast audio channels than to sacrifice the timbral fidelity by transmitting all channels with limited bandwidths.