• Advanced - because it's solid state circuitry and digital masking source are contained within one master unit to control zones of up to 1600 m² each.

• Independent Control: each Zone is independently controlled from a source from within the zone or at a central location.

• Flexible - each speaker unit has a seperate volume adjustment so that any unit can be adjusted as special conditions dictate. Volume levels and tone are easily adjusted for an entire zone

Applications:
Educational	Commercial	Local Government	Hospitals
Schools Universities	Boardrooms Music Studios Cinemas Function Rooms Laboratories Workshops	Libraries Gymnasiums Sports and Recreational	Wards Waiting Rooms Theatres Lobbies

Effective soundmasking requires specialist competencies with a thorough technical understanding of building acoustics, psychoacoustics and advanced electroacoustics.

Soundmasking system design should be designed in conjunction with other building acoustic measures for a properly co-ordinated, reliable and lowest total cost-of ownership, installation.

An appropriately designed soundmasking system can significantly simplify and reduce the cost of passive measures (such as lighter screening) and is generally more amenable to open plan spaces. The building acoustics will dictate acoustic behaviour and in conjunction with the electroacoustic design, how the soundmasking will propagate.

Psychoacoustics determines how we perceive the result. The whole basis for soundmasking design is fundamentally and diametrically the opposite of traditional sound system design techniques for high intelligibility speech. After all, soundmasking is intended to limit the intelligibility of a conversion beyond locally designated work area, but not in a stressful way - in fact by improving the 'acoustic comfort zone'.

This is one reason why traditional sound contractors struggle with the concept - many techniques are the opposite of their instinctive skills.

When confronted by sound contractor advice that they've tried soundmasking systems and that they don't work - remember that what theyíre really telling you is just that they can't make them work. Common sense would suggest dealing with a reputable soundmasking specialist.

Combining soundmasking with PA or EWIS must involve compromises and should avoided at all costs. The most likely outcome is a system that meets neither requirement satisfactorily.

High intelligibility PA can usually be achieved with significantly fewer loudspeakers are specifically designed for that purpose than for soundmasking. They should be separately designed and installed. However given the significant installation costs for most sites, roughing in both at the same time by the same contractor should offer significant savings. Also, PA and EWIS normally have substantially higher audio power requirements (can be 30 dB more).

The concept of an 'acoustic comfort zone' is to minimise the background dynamic range, so that many typical background sounds (like a dropped pencil or tapping keyboard) are less noticeable or stark. Soundmasking initially rose to prominence in the age of telex machines and mechanical typewriters, was subsequently employed to improve conversational privacy or confidentiality and is more recently considered as a valuable tool to fine tune the background spectrum, particularly with the prevalence of quieter mechanical services and open-plan layouts.

The masking source itself must not be at a consciously noticeable level or distractive in nature. It must be sufficiently random so that no pattern can be discerned, as the human brain has a powerful ability to build a pattern from the slightest of triggers (known as a psychoacoustic phantom effect).

White noise is only a generic term - in fact each installation requires its own spectral profile which is rarely anything like 'white noise'. White noise, being equal energy per time slice (as distinct from 'pink' with equal energy per octave band) carries most of energy in the highest octaves rather than the lower octaves where most of the spectral masking is required. For minimalist masking, the masking sources must be as close as possible to the same bands as the noises to be masked.

The greater the spectral deviation (between the noise and the mask), the higher the masking level must be. This underscores the significance of psychoacoustics in soundmasking - similar to the basis for efficient audio compression.

Mechanical noise sources although have traditionally been expected to offer a masking capability, are in fact quite problematic - it must be remembered that they are designed for their mechanical tasks, not for their acoustic properties. There is little or no control of their spectral makeup and there can be significant patterns in the sound (you just 'get what you get' ). Air handling systems are basically many interconnected large organ pipes with inherent resonances and other undesirable acoustic artefacts that can lead to an uncomfortable working environment. Active soundmasking, on the other hand, has a completely controllable spectral content, without compromising the air handling design.

In our energy-conscious age, it is comforting that soundmasking is one of the most energy efficient building systems available, often an entire office block may only consume the equivalent of a single fluorescent luminare. Purpose designed soundmasking generators will normally be considerably more efficient than racks of discrete commercial power amplifiers and equalizers (that normally waste far more energy than is output on the speaker lines). For this reason, it is usually more practical to operate a system with a dedicated soundmask generator 24 hours a day rather than fitting timeclocks or concerning about BAS scheduling control. The system will therefore always be available without having to guess unexpected after-hours usage, unlike the major energy demands of HVAC.

An artificially quiet environment, such as heavily acoustically insulated, can be even more uncomfortable as human hearing is highly adaptive to the lower levels - so many other things will be distinctly and distractively audible. Virtually no office equipment can be totally 'quiet' (ie, below the threshold of hearing 0 dB), but their low acoustic spectra will be effectively amplified with the lack of other noise sources that would normally mask them. Similarly, many 'passive' tasks such as reading documents (lightly turning pages) or noises from writing implements will be very noticeable. In other words, it is a very unnatural environment. The lower levels are still fully audible and still characterised by uncontrolled spectral content and patterns but with potentially higher dynamic range and therefore likely to uncomfortable environments

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Phone: +64 (9) 236 8076
Fax: +64 (9) 236 8039
Email: accsol@xtra.co.nz

PO Box 29-220, Greenwoods Corner, Auckland, New Zealand.