High-Resolution MIMO DRIR Measurements in an Opera Hall

International audienceDirectional room impulse responses (DRIRs) are typically measured with spherical microphone arrays (SMA). When being combined with spherical loudspeaker arrays (SLA), also the directivity of the sound source can be controlled. Such multiple-input multiple-output (MIMO) systems allow for an in-depth analysis of the acoustics of a room. A prototype SMA/SLA system was used to capture 3-D MI-MO DRIRs for several measurement points and under different acoustic conditions at the opera hall of the Salzburg Festival. The SMA consists of 64 microphones on a rigid sound-hard sphere (25 cm diameter). It captures the 3-D sound field up to the spherical harmonic expansion order N=7. The SLA consists of 28 speakers (of three different sizes) on a rigid sound-hard sphere (40 cm diameter). It is equipped with an internal tilt motor and mounted on a remote-controlled turntable. The rotated loudspeaker positions chosen for this measurement approximate a Gaussian sampling of order N=11. To ensure coinciding ranges of operation, the SLA and SMA para-meters were matched using an analytical MIMO system model previously published by some of the authors. The measurement data can be analyzed with respect to per-ceptual and acoustical parameters typically used in architectural acoustics