AN ACTIVE LOUDSPEAKER POINT SOURCE FOR THE MEASUREMENT OF HIGH QUALITY WIDE BAND ROOM IMPULSE RESPONSES

摘要

For different measurements in acoustics, loudspeaker sources are required. Especially in room acoustics and building acoustics, it is commonplace to excite the room with random noise, MLS-signals or swept-sine signals (ISO 18233 [1]) to achieve a reproducible and stable measurement situation. The most common source is the so-called dodecahedron loudspeaker, which is an almost spherical cabinet comprising 12 individual speaker systems that receive identical signals. The resulting spherical sound field is limited to an upper frequency where the distance between adjacent loudspeaker membranes becomes close to half the wavelength. For building acoustics, loudspeakers with a cabinet size of 40 to 50 cm diameter are common and hence the omnidirectional cut-off frequency lies below 1 kHz [8].