Investigation of Personal Sound Zones by Use of Subarray Division

Köhne, Jonas Bredgaard ; Seindal, Mikkel Solhaug

4. term

Signal Processing and Computing, Master

2020

2020-06-03

121 pages

The project investigates a method of dividing a loudspeaker array into smaller subarrays in order to create higher contrast between to personal sound zones with sub-optimal positions. The weighted pressure matching algorithm is used with a line array to create personal sound zones. Simulation tests showed that an increase in contrast was achieved when turning off loudspeakers. Ray space edge subdivision (RSES), a method, using the ray space transform, to determine which of the loudspeakers that should be turned off was made. The method was tested in a measurement room, with a line array consisting of 39 loudspeakers. Two different sub-optimal setups was tested, setup 1) with the sound zones placed with centers in (0,0.5) and (0,1.5), and setup 2) with centers in (0.25,1.5) and (-0.25,1.5). Both relative to the center of the loudspeaker array. The frequency region of interest is 315-4000 Hz, and is based on the dimensions of the loudspeaker array. The results show that an increase in contrast is achieved when using the proposed method, with an increase in the mean square error. At higher frequencies an increase of up to 12 dB is achieved with the RSES-model, No improvement is seen at the lower frequencies. However the results are very dependent on the specific setup. An informal listening test and spectrograms show that the increase in MSE, is due to small changes in amplitude.

Personal Sound Zones ; Beamforming ; weighted pressure matching ; ray space transform ; ray space subdivision model ; loudspeaker array

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