Influence of Loudspeaker Distortion on Room Acoustic Parameters

The assessment of the range of uncertainty for room acoustic parameters is an ongoing research topic. ISO 3382 demands the calculation of the uncertainty according to the GUM. However, the separation and determination of the main influence factors and their contribution is still not fully solved. Mainly the position of the sound source and the microphones, [1, 2, 3] background noise [4, 5, 6] and the loudspeaker directivity pattern [7] are currently addressed due to strong deviations observed in the past. In this contribution we explain an existing modeling technique of non-linear systems that is used to simulate the effect of loudspeaker distortion in impulse response measurements. Generic impulse responses are used to simulate a room acoustic measurement. We will analyze which room acoustic parameters are potentially affected. The evaluation of the room acoustic parameters leads to a scenario with controllable degree of loudspeaker distortion without the influence of the other uncertainty factors priorly addressed. This simulation approach is validated by measurement results with different amplifications in auditoria using exponential sweep measurements.