R&D Report 1994-04 : Multi-channel sound for HDTV: Subjective tests on sound channel configuration J.A. Fletcher This report describes subjective tests carried out as part of the Eureka 95 project to compare different multi-channel sound systems being considered for use with HDTV. In the tests, the number of sound channels varied from one (mono) to five (three front channels and two surround channels). The improvement in quality obtained by increasing the number of front channels from two to three (adding a centre-front channel) was often similar to that obtained by increasing the number of front channels from one to two. Two-channel stereo was in one case found inferior to mono, presumably because of mislocation of central sound images for off-centre listeners, but three-channel stereo was always preferred to two-channel stereo (and to mono). The improvement obtained by adding one or two surround channels was about half that obtained by adding a centre front channel. On most programme items the use of two surround channels, rather than one, gave a small improvement but only on one programme item was this significant.
