Dipl. Ing. Bernd Noack, proAV Consulting
For the first meeting in 2010 organized by the AES
Swiss section, more than 30 people gathered in the
auditorium of at Conservatoire cantonal de musique
et la Haute Ecole de Gestion (CMN & HEG) in
Neuchâtel.
Dipl. Ing. Bernd Noack explained the need for and
the theory of variable acoustics.
Many rooms are designed as multipurpose rooms but
the acoustical environment is often not optimal for all
uses of the room. One can certainly say that there is
no such thing as a good or bad acoustic! It depends
on the use of the room. Mr. Noack explained how we
hear the reflections in rooms and how this influences
speech intelligibility or how we perceive sound in a
concert hall. Several acoustical parameters can be
measured and need to be considered, the RT60 alone
is not sufficient.
Multipurpose rooms can be designed using passive
acoustical changes such as changing the volume,
adding curtains or reverb chambers etc. But these
methods are expensive and often cannot be
retrofitted.
Adding an active variable acoustics can often be the
solution. However, simply adding a reverb to the
room is not sufficient. The system has to recreate the
reflections that the listener would expect from a real
room.
Over the years many differ systems have been
developed and Mr. Noack gave a historical overview
of the development of such systems. The first
systems were passive and used for example
resonating jars in Greek stone-built
theatres. As electronics progressed assisted resonance
systems using relatively simple electronics were
installed for example at the Royal Festival Hall
London in 1964. Later with the development of
digital electronics many different systems were
developed.
Mr. Noack then explained some of the problems
which can arise and also how a well designed active
variable acoustics system can correct acoustical
errors in rooms.
After a pause with an aperitif offered by Avidec AG
some small ensembles from the music school played
various pieces of music. Whilst the music played the
reverb time was changed so that the audience could
judge the effect.
After the official event, the several members of the
audience as well as those involved in organising the
meeting moved on to a nearby restaurant, where
discussions continued. Many thanks to Bernd Noack
for their interesting presentations and to Jörg Steiger
and Pascal Hügli Avidec AG for the organisation and
aperitif. Also thanks to Robi Hersberger from
WSDG-e GmbH for the loan of the omnidiectional
loudspeaker.
The PDF of the presentation can be downloaded from
the web site of the Swiss AES.
