With their twelve loudspeakers built into a sphere, dodecahedrons have an omnidirectional radiation characteristic and are therefore used for acoustic measurements, where the directional sound radiation of conventional loudspeaker boxes is not desired.
In the impedance tube, the surface impedance of an installed specimen is determined at perpendicular sound incidence. The sound absorption coefficient and the reflection factor can be calculated from the surface impedance. With an extension of the impedance tube, the transmission or the sound reduction index of the specimen can also be determined.
Airflow resistance measurement system
The measurement of airflow resistance with m|ars enables a convenient determination of the airflow resistance in quasi-static airflow. The airflow resistance in quasi-static airflow describes the behavior of the specimen at very low air velocities, as typically occur with sound waves.
The microphone array m|multimic is used for reproducible measurement of the sound pressure levels in the spatial head area of the inmates in motor vehicles. The spatial averaging over six microphone positions, which are acoustically independent of each other but still relevant for perception, is of particular importance for the frequency range above 500 Hz.