Electro-acoustics is the interface between audio and acoustics, and the outcome is the quality of amplified sound at the listeners' ears.
Sound system performance is inextricably linked with the acoustics of the venue. Probably the most important task of electro-acoustic design is to minimise the excitation of the acoustics by the sound system while still delivering even coverage, intelligibility and bandwidth for all to hear.
Coverage, intelligibility and frequency response can be predicted in advance, the design optimised before installation, and then verified upon completion. This work can be realised with much more certainty than in the past, giving assurance to the venue owners, delivering quality to the patrons, and saving money in the long run.
David has been intimately engaged in this process for thirty years, developing processes and innovations at the forefront of the industry, and delivering quality technical, budgetary and aesthetic outcomes.
While he was Technical Manager for Sound, AV and Electronics at the Sydney Opera House, he was able to achieve:
• rewiring of all audio and video stage systems.
• new sound systems for the Concert Hall and Opera Theatre.
• installation of a new Stage Management System.
• design and construction of 'The Studio' and ‘The Recording Studio’ where he oversaw the acoustic specification, sound, AV and communications systems design & installation; functional and operational configuration and layout, wiring, and equipping.
Completed 2014: design and commissioning of all foyer sound systems for the Sydney Opera House as well as performance spaces and sound for the Green Room and 133 back of house zones.
All models are wrong, but some can be useful.
EASE is a convenient tool for analysing conceptual models and visualising sound propagation through virtual venues.
The design process is a creative process ... carried out by humans, not machines. EASE does not design sound systems, however it is very useful.
EASE modelling has become synonymous with sound system design, however it is only one of many tools available to sound system designers. EASE is a convenient tool for analysing conceptual models and visualising sound propagation through virtual venues.
EASE modelling is increasingly becoming the standard 'proof of concept' for responses to tenders for large projects such as theatres and stadiums.
1. WORK OUT WHAT YOU NEED TO ACHIEVE
Determine what the sound system is required to reproduce?
• live music: rock, musical theatre, jazz, classical
• replay of pre-recorded material: clubbing, theatre SFX, dance theatre
• speech: conveying information
This will inform the bandwidth and SPL/headroom requirements.
Who is the target audience?
• how many
• how old
This will inform the quality required and determine how much sound system cost can be amortised per door ticket.
There are three essential performance criteria for sound system design:
• SOUND STAGE - the virtual sound field that is created by the loudspeakers and becomes the illusion of the size, shape and position of the performers on stage, and consequently the focus of the audience's attention.
• SPL CAPABILITY - how loud it can go.
• COVERAGE - how much of the audience gets 'acceptable' sound.
There are two other important criteria:
• INTELLIGIBILITY - how understandable the spoken word is, how clear music sounds.
• ACOUSTIC GAIN - how much amplification can be applied before the onset of acoustic feedback.
These performance criteria set the targets for the design process.
2. DESIGN PROCESS
While it's actually a lot more complicated than it sounds, sound system design can be distilled down to three tasks:
• selection of loudspeaker types
• positioning and aiming them at the audience
• adjusting level / equalisation / delay
These design tasks are carried out in a 3-D electro-acoustic model so that the design can be adjusted and optimised before practical implementation. The industry standard for modelling is EASE (although there are other packages available).
ORDER OF WORKS
1. choose loudspeaker components according to required SPL.
2. position these loudspeakers in the model according to Sound Stage requirement.
3. aim the loudspeakers and assess the resultant Coverage.
4. add speakers and/or change models to those with more suitable radiation patterns, to achieve the required Coverage.
5. assess Intelligibility.
if Intelligibility is insufficient, do one or all of the following:
• reduce loudspeaker overlap
• deploy loudspeakers with tighter and better controlled radiation pattern
• move loudspeakers closer to the audience
• add delay speakers
• Iterate this process until a satisfactory outcome is achieved.
3. THE RESULTS
A sound system that is fit for purpose ... does the job you need it to do.
The journey through the maze of specifications and regulations is simplified and understandable, and the responsibility for a specialised technology is taken off your shoulders.
Compliance with tender specifications and building regulations is assured.
The resultant sound quality is commensurate with the application ... opera quality for opera houses, announcement quality for car parks.
Satisfied patrons - satisfied hirers.