Wavefront Sculpture Principles - L-Acoustics dV-DOSC Operator's Manual

Figure 1: Wavefield interference for a conventional sound reinforcement system
compared to a sculptured dV-DOSC wavefield

Wavefront Sculpture Principles

As early as 1988, a preliminary system named "Incremental" had proven the feasibility of V-DOSC
and dV-DOSC. From this experimental concept, theoretical research was undertaken by Professor
Marcel Urban and Dr. Christian Heil. The results of this research were presented at the 92nd AES
convention in Vienna, March 1992 (preprint n°3269).
The theory that was developed defines the acoustic coupling conditions required for effectively
arraying individual sound sources. Relevant parameters include: wavelength, the shape of each
source, the surface area of each source and the relative source separation.
In brief, the coupling conditions can be summarized as follows:
An assembly of individual sound sources arrayed with regular separation between the sources on a plane or
curved continuous surface is equivalent to a single sound source having the same dimensions as the total
assembly if one of the two following conditions is fulfilled:
1) Shape: The wavefronts generated by the individual sources are planar and the combined surface area of
the sources fills at least 80% of the total target surface area.
2) Frequency: The step or source separation, defined as the distance between the acoustic centers of the
individual sources, is smaller than half the wavelength over the bandwidth of operation.
These two criteria form the basis of Wavefront Sculpture Technology™ (referred to as WST
throughout this text). For further information, more detailed theory is presented in Appendix 3.
Additional WST Criteria were developed for the AES preprint entitled ''Wavefront Sculpture
Technology'' that was prepared for the 111 th Convention, NYC, Sept 2001 (preprint n°5488). The
first two WST Criteria were re-derived based on an intuitive approach using Fresnel analysis and in
addition it was shown that:
3) The deviation from a flat wavefront must be less than λ /4 at the highest operating frequency (this
corresponds to less than 5 mm curvature at 16 kHz)
dV-DOSC dV-SUB Manual V2.0 Nov 2001 9