Perceptual Properties of Local Sound Field Synthesis

• Applicant: Professor Dr.-Ing. Sascha Spors
• Subject Area: Acoustics
• Term: from 2017 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 326746201

Techniques for Sound Field Synthesis (SFS) use a large number of loudspeakers in order to reproduce virtual sound fields. Contrary to perceptually motivated reproduction techniques, such as stereophony, SFS traditionally aims at a physically correct synthesis of the desired sound field over an extended listening area. Wave Field Synthesis (WFS) and Near-Field Compensated Higher Order Ambisonics (NFC-HOA) are two well-known SFS techniques. Practical implementations cause systematic artifacts in the synthesized sound field that are a consequence of a departure from theoretical requirements. The most prominent deviation is the employment of a finite number of discrete loudspeakers as opposed to the continuous distributions of secondary sources that the theory requires. The artifacts that result from the spatial discretization are referred to as spatial aliasing. These effects are perceptually relevant as they may lead to a position dependent coloration and localization errors for different listening positions. The findings with regard to the spatial and the timbral properties of conventional SFS techniques constitute a dilemma: WFS allows for a good localization within the whole listening area, while spatial aliasing causes significant coloration. NFC-HOA avoids coloration at the center of the loudspeaker distribution at the cost of decreased timbral and spatial fidelity for off-centre positions. Techniques for Local Sound Field Synthesis (LSFS) also aim at a physically correct synthesis but limit the listening area to a smaller local region in order to increase the reproduction accuracy. Based on physical analyzes, LSFS methods offer a promising alternative to improve spatial reproduction with regard to these aspects. The main objective of this proposal is to evaluate the Perceptual Properties of LSFS. The outcome of this analysis can be used to improve the overall quality of Sound Field Synthesis techniques.

• DFG Programme: Research Grants