03Apr/18

Wave Field Synthesis

However, the most promising system nowadays to provide a sensation of sound immersion in a vast area is the so-called Wave Field Synthesis ( WFS ), whose fundamental difference is that the sound field is synthesized using a system of loudspeaker arrays for the entire audience area, eliminating the preferred listening area. In this way, a listener can perceive the same sound sensation anywhere in the listening area. Also, WFS synthesizes the acoustic field that a listener would see in the actual listening area, including naturally all the localization tails and effects that the wave would cause in the listener.

This technique of sound reproduction, which is based on the propagation of waves, consists of recreating an acoustic field within a volume from the signals recorded on a surface, by analogy to holography and according to the Huygens principle. According to this, a wavefront of a point source behaves as a set of several secondary sources, which in practice are replaced by loudspeakers. Thus, the algorithm for calculating the signals with which each of the speakers is fed takes the audio signal that would arrive from the virtual source to each secondary source as the data source. Therefore, the WFS system must consider numerous data such as source coordinates, number of fronts and side speakers, speaker spacing, etc.

One of the distinctive characteristics of the surround above audio systems is the suppression of the preferred listening point. This feature is very desirable for various multimedia applications, such as real-time video conferencing, in which multiple participants located at different locations in a room interacting with other remote participants, also spatially distributed in a place. The sense of realism is assured by providing listeners with the amplitude and direction of arrival of any sound message that comes to them, both from the speakers in the same room, as well as from the remote office.

However, there are still open problems to solve, which are currently being studied by researchers, and are based on the practical simplification of the technique. The distribution of secondary sources is not infinitely dense and continuous, but a finite set of individual loudspeakers that receive limited band signals and which, in turn, form a limited reproduction area in space. These two effects compromise the performance of real systems, creating imperfections in the generated wave above a limiting frequency, called spatial aliasing frequency.…