Personal audio with multiple dark zones
Matthew Jones, Stephen J. Elliott · The Journal of the Acoustical Society of America · 2008
This work considers providing personal audio for a listener by use of a local array of acoustic sources driven in such a way as to maintain the reproduced levels in one seat, in the so-called "bright zone," while minimizing the levels experienced by others sitting close by, in the so-called "dark zones." Multiple dark zones are considered both adjacent to and in front of the listener, initially using monopole simulations to investigate three different control strategies, and it is shown that a particular orientation of two sources is able to provide good control over the dark zones in these directions. It is shown that minimizing the sound power radiated by the local array while constraining the reproduced level in the bright zone is an effective method of achieving isolation when the dark zones are numerous. The findings of the investigations are used to design an optimal source arrangement, for which the isolation performance is improved by about 20 dB up to 1 kHz, which is verified with Boundary Element Method (BEM) models and predictions based on measured responses.