How does it work?

A small number of microphones (usually four) high above the front of the stage capture the sound.

They feed the stage sound of the performers, orchestra, choir etc. with all of its information such as source location(s) and their tonal quality to the SIAP acoustic processor.

Optionally we can add some ambiance microphones above the audience to have some extra ambiance and interaction between audience and actors.


The SIAP processor is a very powerful sound processing “system”. In this the sound is treated with appropriate time delays, filters and reverberation fine-structure based on the desired acoustic.

For this purpose the processor comprises a large number of independently digital programmable channels.

Because of the large number of channels, it is possible to create more acoustical zones, each with their own envelope and reverberation time.


The SIAP system is very user friendly. No specialist knowledge needs to be at hand to operate the SIAP system. Simply choose between the acoustic presets (optional wireless).

For example: (unamplified) speech as in drama, operetta/light opera, grand opera/classical ballet, chamber music, non-classical unamplified ensemble, chamber orchestra, large orchestra, choir/vocal group, solo piano. Amplified: ambiance, fill-in, surround.

Changing between (movie) surround presets and users presets are just as easily.


The output from the processor generates a “sound blanket” that covers the entire room (and orchestra pit and /or stage). This sound field, that is exactly the same as the reverberation time and corresponding nuances as set in the processor software, forms the optimum acoustic together with the hall itself.

The SIAP system creates this sound field by building up reflections, reverberation etc. in exactly the same way as the natural reflections and reverberation in a hall itself, while keeping the orginal acoustic character “signature” of the room.


This sound is reproduced in the hall through high quality power amplifiers and about 50 to 200 loudspeakers, distributed over the walls and ceiling.

All of these individual loudspeakers contribute for one or two percent of the total contribution which makes each loudspeaker individually unnoticeable to locate.

We like to use high quality loudspeakers with a very wide dispersion and an outstanding polar diagram to create a uniform dense and diffused soundfield.


SIAP’s natural process preserves the natural balance, the correct localization and the timbre of the sound sources on stage (instruments, singers, actors).

With a SIAP system a spectator can close his/her eyes and still localize the source position, which then appears to be exactly correct when the eyes are openend again.

Of course the same correct localization correctness applies to sound sources moving around the stage area (walking singer, actor or musician). At SIAP demonstrations this is always a nice experience.



Acoustic Enhancement

A comprehensive concept


The SIAP system enhances the acoustic of a hall for a single purpose and/or multipurpose use:

Single purpose SIAP acoustic enhancement can for example be improvement of the intelligibility of unamplified speech in a drama theatre or improvement of the acoustics for music in a concert hall, opera house or church.

Multipurpose SIAP acoustic enhancement makes the acoustic of a hall optimally adjustable to a wide range of purposes. For example the acoustic for music can be improved by enhancing the Reverberation Time, envelopment of the sound, spaciousness etc. of a hall that has insufficient reverberation for unamplified (classical) music, or could have some support (“liveliness”) and ambiance for amplified music (pop/jazz/bands): variable acoustics.

The SIAP system is unique because the reverberation which is generated by the processor to increase the reverberation time of an auditorium, is composed of sound reflections like in a real concert hall or opera theatre.

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Church acoustics

Acoustic Divinity


The characteristic acoustics of churches can be very beautiful and desirable, on the other hand, it may have a disadvantage with speech (speech intelligibility). The origin of the churches has led to great musical compositions for organ and singing, among other things, in recent centuries.

Church and music are, as it were, ‘fertilized’. Over time, there are many churches that no longer have the desired acoustics. Often this has to do with building history (such as repair of war damage / alterations by changing use) and the acoustics of these (sometimes ancient churches) have unfortunately been lost in part. For speech, this may be beneficial for music that needs spaciousness it won’t work.

In the absence of a beautiful acoustics, the organ and choir, instrumentalists and singers of the present are not threated optimally (acoustically). They will sound too “dry” due to lack of reverberation.

SIAP has developed an integral solution specifically for churches that are too dry to get the speech (intelligibility) and acoustics (including reverberation time extension) as desired.

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Theatre acoustics

Compelling Perfomances

Theatre acoustics

Theatres are generally built with a short reverberation time, since this is required for good speech intelligibility and is the optimum for amplified sound. Many venues are made as acoustically “dry” as possible because most performances are fully amplified. For reinforced sound a reverberation time somewhere between 0.7 and 1.2 second is ideal. Many elements in a theatre determine the acoustic. Walls and seats can for example provide plenty of absorption and non-parallel walls are an effective means against flutter echos and other undesirable reflections. In addition to the reverberation time there are of course numerous other acoustic parameters which influence the acoustic quality and sound of a theatre auditorium.

Critical spots

In a theatre auditorium – which possesses a beautiful ambience – “difficult” positions can be found.
One can think of under balcony seats (impedance step) or the stage area (side and/ or rear wall reflections).Or a slap-back from the auditorium rear wall or balcony front edge back to the stage. In an acoustic design all these subjects are taken into account to realize an acoustically well-performing theatre.

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Studio acoustics

This must be perfect

Studio acoustics

The success of a studio depends largely on a good (recording) acoustic. A variety of starting pints and possibilities are available to achieve this. For control rooms the “live end – dead end” principle is often applied of the acoustic. The dead-end side of the room serves monitor loudspeakers which have to be able to reproduce an uncoloured sound and with correct source localizations. The live-end side of the room is beneficial for artists who are making music there. Similarly this live-end environment provides supporting ambience to the sound engineer who is giving the recording a beautiful sound. Other design principles for a wide range of applications are of course also used. SIAP can provide a useful acoustic completion.

Recording room

The recording room itself, where the music is made, not only determines the final sound quality, such as “sound stage”. Musicians prefer to experience an inspiring sounding room. Of course can acoustics be “added” to the recording during editing as a reverberation effect.

An appropriate acoustic in the recording room itself which is picked up by beautifully sounding microphones, has its advantages too.

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Suitable For Unamplified Music.

Add the natural early and late reflections to the direct sound to give the audience and the musicians the joyfull experience the way it should.

Suitable For Amplified Music.

Add the proper ambiance to the room to give it a more lively feel, or combine the FoH installation with the SIAP system for optimum results.  

Suitable For 3D Surround.

Create a surround matrix with multi in and outputs. Create a configuration for a show or musical and save it. Incorporate SIAP in an existing environment with surround.