Metingen aan speciale akoestische maatregelen in een concertzaal

In a recently constructed concert hall (14400 m3, 1250 seats), problems were encountered initially with solo piano performances. Music critics judged the piano sound as 'weak' and 'swimming in space'. As a remedy, an acoustic reflector to enhance direct sound, in combination with a curtain to reduce reverberant sound were installed. To test the acoustic effectiveness of these measures, KEMAR head recordings of short piano fragments were made at various positions in the hall, both with and without reflector and curtain. Blind two-alternative forced choice 'same-different' listening tests yielded a score, averaged over positions, music fragments and listeners, of 57% correct. Computations of changes in reverberation time and clarity ratio, based on physical measurements with an MLSSA procedure, yielded results that are barely above threshold level according to the literature. All this suggests that the apparent public satisfaction with the acoustic measures may be attributable to factors other than purely acoustical ones.