PORTABLE AND FIXED DIFFUSION ACOUSTIC SHELLS
 

INTRODUCTION


When performing at a conventional theatre, symphonic and chamber orchestras, as well soloists and opera singers, encounter problems related to the projection of the sound and voice, due to the noise that is produced on the space of the stage box and the absence of diffusion materials.
The sound that is produced by the orchestra is dispersed heterogeneously in all directions, depending on the instruments. It needs an acoustic shell to channel it towards the audience. In order not to lose the sound level and all the musicality of orchestras, acoustic shells should be placed around them.
To project the sound, it is necessary to install diffusion panels shaped like a shell, open towards the audience, in order to scatter the sound in that direction. The Acoustic Shells can be installed hanging on the stage's ceiling and/or on the floor around the musicians.
Following the research on acoustic panels, JOCAVI® adopted four of its models of acoustic diffusers to create these models of AS® acoustic shells.

Spaces, like theatres and auditoriums, where classic music performances are programmed, are usually big-volume rooms. Thus, due to the noise from the audience and the lack of an acoustic shell, electro-acoustic equipment (microphones, power stages and loudspeakers) is overused in these spaces. Musicians, singers and musical directors do not tend to overuse electro-acoustics in order not to distort the natural colour of the instruments and voices. The use of our AS® acoustic shells increases the natural level of the sound that is genuinely produced by the instruments and naturally increases the level of the acoustic pressure of the room, thus leading to a balanced diffusion throughout the whole range of the sound spectrum.

AS® ACOUSTIC SHELL® - THE BRAND


AS® Acoustic Shell® is a brand that sells highly specialised acoustic shells which are conceived in the laboratories (R&D) of the Portuguese company JOCAVI® Acoustic Panels Lda. The AS® brand belongs to the JOCAVI® Group. We prepare projects to advise on our products by seeking the best shell for each space.
We sell for permanent installation in theatres and auditoriums where the main activity requires the use of these acoustic diffusers. We also carry out the installation and acoustic checking and enter into maintenance contracts for our shells. We are AS® Acoustic Shell®, a company specialised in acoustic diffusion shells.

VERSATILITY OF A SHELL


Unlike the most ancient and original open-air acoustic shells made of stone in roman amphitheatres, today's acoustic shells used in performance rooms have to be versatile and discreet, so that their presence does not hinder the use of the space for the most varied types of performances. Our shells have been developed and built with light and attractive materials, which facilitate as much as possible their practical use. They adapt to the orchestra by increasing the number of the necessary modules and by adjusting their application according to the type of performance. It is a stage equipment that is easily assembled and disassembled and that is imperceptible when it is not being used.

ACOUSTIC BEHAVIOUR


The purpose of acoustic shells is to use both the acoustic energy and sound, which were beforehand wasted in the stage-box, and direct them towards the audience. It is particularly important how this is done. Acoustic shells, which are simply a flat, convex or concave piece of varnished plywood, are normally used. These pieces, due to their big size, return the acoustic energy in very tight angles of incidence. Their scattering coefficient versus frequency is not balanced either, meaning that they do not scatter all frequencies in a uniform way. They scatter high frequencies much more often than medium/low frequencies.
Effectfuser® AcSh®, Dynamicflow® AcSh®, Woodfoil® AcSh® and Plura® AcSh® acoustic shells come from duly characterised JOCAVI®’s acoustic diffusion panels, in order to obtain the best diffusion balance throughout the sound spectrum. Therefore, a good and distributed angular coverage and a better balance of the diffusion values over the several frequencies are obtained.