Personal spatial audio in cars: development of a loudspeaker array for multi-listener transaural reproduction in a vehicle

Abstract

High quality consumer audio products are well established, however, research into improving the performance and functionality of car audio systems is still growing. This project attempts to enhance the capabilities of in-car audio by combining personal and spatial audio technologies via an array of loudspeakers to reproduce separate spatial audio for both the driver and the front passenger of a car.

A MATLAB model of the array has been developed, including source directivity and first order reflections, and the parameters obtained from this acoustic model were used to aid the design of the array. The physical array was CNC milled out of aluminium to create a sleek, high quality product and contained 27 nominally identical loudspeakers. The array was tested using filters created from both modelled and measured transfer functions, created using the least mean squares (LMS) algorithm to control the pressure at four control points.

The array was tested in both an anechoic chamber and a car to assess its performance in terms of crosstalk cancellation between control points corresponding to the positions of the listeners’ ears. It was found that the array performed very well in anechoic conditions creating 25 - 45 dB of Crosstalk Cancellation (CTC) between 300 Hz and 11 kHz, and even with the addition of several reflections in the car environment, it was still found to perform well with 18 - 40 dB of CTC over the same frequency range.

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Identifiers

ORCID for Charles House: orcid.org/0000-0002-9653-3594

ORCID for Jordan Cheer: orcid.org/0000-0002-0552-5506

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