L-Acoustics V-DOSC, Руководство оператора

Страница: 16 / 158

L-ACOUSTICS V-DOSC Manual Version 4 6/29/2005 Page 16 of 158
Apart from coverage precision and predictability, another significant benefit of V-DOSC is the fact that
the system effectively extends the nearfield region at higher frequencies (the nearfield is defined as the
region where cylindrical wavefront propagation applies and the farfield is the region where spherical
wavefront propagation occurs – see Appendix 5 for further details).
As pictured in Figure 4, cylindrical wave propagation results in a 3 dB reduction in SPL with doubling
of distance as opposed to the 6 dB reduction that is typical of conventional systems that radiate
spherical wavefronts.
Figure 4: Cylindrical versus spherical wave propagation
Due to it’s ability to generate cylindrical wavefronts, V-DOSC has different attenuation properties
than conventional systems and should not be evaluated in terms of the classical "$ / kilowatt"-ratio.
Comparing SPL predictions according to standard calculations is also not meaningful since V-DOSC
produces a combination of cylindrical and spherical wavefront propagation that must be evaluated
using specific calculations.
Aside: Conventional modeling techniques cannot accurately simulate WST-based systems such as ARCS,
KUDO, dV-DOSC or V-DOSC. For WST-based products, L-ACOUSTICS has worked with the developers of
EASE and CATT to integrate proprietary SOUNDVISION modeling techniques into these industry-standard
room acoustics modeling programs.
When curved V-DOSC arrays are employed there is a combination of cylindrical and spherical
propagation. This combined propagation, together with the actual shape of the audience allows the
wavefront to be focused so that tonal balance and sound pressure levels are evenly distributed
throughout the listening area. Although pure cylindrical wave propagation is not always in effect, 3 dB
reduction with doubling of distance can still be obtained along with extension of the nearfield if WST
Condition 4 is respected - this is an important aspect of WST and the reason why correct focus of V-
DOSC on the audience is so important.
Psychoacoustically, nearfield extension allows one to walk a considerable distance from a V-DOSC
system with only a small difference in SPL due to the system’s unconventional attenuation rate.
Effectively, more of the audience experiences nearfield listening, enjoying higher fidelity, improved