Experimental Study on the Influence of the Sensor and Actuator Arrangement on the Performance of an Active Noise Blocker for a Tilted Window.

Closed windows reduce noise by approximately 20 dB. Unfortunately, they block fresh air circulation at the same time. To solve this problem, an active noise blocker (ANB) has been set up. It consists of a set of microphones and loudspeakers driven by a MIMO FxLMS (multiple input multiple output filtered reference (x) least mean square) controller on the real time processor. The goal of the ANB is to generate sound pressure nodes to stop the transfer of acoustic energy into the room, using a low but sufficient number of secondary loudspeakers placed in the transmission path. This specific local anti-noise measure shall achieve a high global noise reduction inside the room. Preceding numerical studies have shown, that the arrangement of the sensors and actuators of the ANB in the transmission path has significant effect on its performance. This study checks experimentally different combinations of the setup of the system components with regard to their influence on the performance of the ANB. Additionally this study includes the realization of an add-on kit for an already installed window.