Time-domain realisation of model-based rendering for 2.5D local wave field synthesis using spatial bandwidth-limitation

Abstract

Abstract-Wave Field Synthesis aims at a physically accurate synthesis of a desired sound field inside an extended listening area. This area is surrounded by loudspeakers individually driven by their respective driving signals. Recently, the authors have published an approach for so-called Local Wave Field Synthesis which enhances the reproduction accuracy in a limited region by applying a spatial bandwidth limitation in the circular/spherical harmonics domain to the desired sound field. This paper presents an efficient time-domain realisation of the mentioned approach for 2.5-dimensional synthesis scenarios. It focuses on the modelbased rendering of virtual plane waves and point sources. As an outcome, the parametric representation of the driving signals for both source types allows for the reproduction of time-varying acoustic scenarios. This also includes an adaptation to the tracked position of a moving listener. The realisation is compared with conventional Wave Field Synthesis regarding the spatial structure and spectral properties of the reproduced sound field. The results confirm the findings of the prior publication, that the reproduction accuracy can be locally improved with Local Wave Field Synthesis.

Time Domain Sampling of the Radial Functions in Spherical Harmonics Expansions

“…9 (left). For r = 1 m, the spectral accuracy of each discrete-time radial function can be reasonably predicted by (26). For small r, however, the analytical SAR n should be used with care, since the real (numerical) SAR n has strong variations and (26) only follows the overall trend.…”

“…The importance of temporal characteristics is also acknowledged in audio applications, where a bandwidth of about ten octaves is under consideration and the temporal structure is known to have significant impact on human perception of timbre and spaciousness [17][18][19][20]. Time-domain processing scheme was employed in spatial sound recording and reproduction techniques [21][22][23][24][25][26][27] where it was shown to be computationally efficient thus suited for real-time applications.…”

Time Domain Spherical Harmonic Processing with Open Spherical Microphones Recording

“…This work only targets the free-space Green's function, and as a result, the method is highly limited to the application of free space sound field reproduction. In [36], a time domain wave field synthesis method is presented. Although an IFFT is applied to derive the time domain solution, the work still demonstrates that time-domain wave field synthesis can be beneficial to time-varying spatial acoustic applications.…”

Broadband multizone sound rendering by jointly optimizing the sound pressure and particle velocity

“…In recent years, much research effort has also been invested in personalized audio reproduction, i.e., synthesizing individualized acoustic scenes for multiple listeners in different areas of the reproduction room [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]. A prominent use case is given in cars, where the driver could listen to the information provided by a navigation system while all passengers can enjoy their favorite audio content.…”

“…The free-field RIRs are of length 128 samples and the SNRs are determined based on the energies of the clean RIRs and the noise sequences. The broadband reproduction error (MSE) in the bright zone and the broadband level difference ∆L obtained from averaging(23)and(24), respectively, are listed inTable Ifor the three approaches.The table contains resultsfor SNR values of 10 dB, 20 dB, 30 dB, and 60 dB, where only frequencies above 100 Hz are considered for evaluation. As expected, decreasing the SNR results in an increase of the MSE values and a reduction of the level difference.…”