Intensity Based Spatial Soundfield Reproduction Using an Irregular Loudspeaker Array

Abstract

Sound intensity is an acoustic quantity closely linked with human perception of sound location, and it can be controlled to create a high level of realism to humans in soundfield reproduction systems. In this paper, we present an intensity matching technique to optimally reproduce sound intensity over a continuous spatial region using an irregular loudspeaker array. This avoids several known limitations in the previous works on intensity based soundfield reproduction, such as a single sweet spot for the listener and a regular loudspeaker geometry that is difficult to implement in real-world applications. In contrast to the previous works, the new technique uses a cost function we built to optimize sound intensity over space by exploiting spatial sound intensity distributions. The spatial sound intensity distribution is represented by spherical harmonic coefficients of sound pressure, which are widely used to describe a spatial soundfield. Compared to the conventional spatial soundfield reproduction method of pressure matching in the spherical harmonic domain and the HOA max-rE decoding method optimizing sound intensity at a single position, we show that the intensity matching technique has better overall performance with two different irregular loudspeaker layouts through simulations. The impact of microphone noise on reproduction performance is also assessed. Finally, we carry out perceptual localization experiments to validate the proposed method.

3D Multizone Soundfield Reproduction in a Reverberant Environment Using Intensity Matching Method

“…In [21], we have shown that accurate reconstruction of sound intensity guarantees a good localization perception within the target region by perceptual experiments. As the first objective performance measure, we define the relative error of sound intensity as…”

“…where N L is the number of loudspeakers. Note that here we assume incoherent superposition of loudspeaker signals [21].…”

“…with the desired intensity vector I d (x, k) and the reproduced intensity vector I a (x, k), respectively, atx. Note that here we only consider the real part of sound intensity which represents the propagating sound energy and shows the direction of propagation [21].…”

“…However, these intensity based works are all restricted to a single reproduction position, and therefore perception degrades when listeners are moved from this exact reproduction position. Recently, we proposed an intensity matching technique to optimally reproduce sound intensity over a continuous spatial region using a non-uniformly placed loudspeaker array [21], which allows listeners to freely move over the region with good perception.…”

“…In this paper, we extend [21] to multiple spatial zones, concurrently taking room acoustics into consideration. Our aim is to psychoacoustically create the impression of the desired sound in each spatial zone by controlling sound intensity within the zone.…”