Control of a dual-layer loudspeaker array for the generation of private sound

A dual-layer loudspeaker array has been constructed and controlled in order to ensure directional radiation over only one hemisphere of the region surrounding the array. This enables the generation of a “private sound field” for one or a few persons situated in a certain spatial region relative to the array. The paper compares the performance of two conceptually different types of algorithm. The performance of the control algorithms have been compared theoretically and investigated by using computer simulations. The same control algorithms and the simulations have been experimentally verified with the prototype dual-layer array composed of 16 loudspeakers. Excellent agreement between experiment and theory is achieved

Optimization-based reproduction of diffuse audio objects

The creation of a diffuse sound event from a single audio signal is an important signal processing task, for instance in spatial audio reproduction or audio coding. Current algorithms based on decorrelation filters or frequency-dependent panning typically cause artifacts due to transients or time-domain aliasing. In this paper, we propose an optimization-based approach to diffusion that creates a set of filters to approximate a desired distribution of frequency-dependent propagation directions to create the perception of a diffuse sound field with a multi-channel audio system. Thus, the diffusion can be optimally adapted to a specific reproduction scenario. In addition, the transient response can be purposefully improved by imposing constraints on the time-domain filter coefficients

Individual Listening Zone with Frequency-Dependent Trim of Measured Impulse Responses

Acoustic Contrast Control (ACC) has been widely used to achieve individual audio delivery in shared environments. The effectiveness of this method is reduced when the control is performed in reverberant environments. Even if control filters are computed using measured transfer functions, the robustness of the system is affected by the presence of reverberation in the plant matrix. In this paper a new optimization method is presented to improve the ACC algorithm by applying a frequency-dependent windowing of the measured impulse response used for the filter computation, thus removing late reflections. The effects of this impulse response optimization are presented by means of sound zoning results obtained from experimental measurements performed in a car cabin