Room acoustics

Sound masking

Sound masking is a proven technology that Alara-Lukagro has been delivering for a long time now. It is a simple way to improve the acoustic environment in open plan areas or in conference rooms in which privacy should be improved. Speech sounds in open plan areas are often quite disturbing and distracting to personnel. Privacy of speech is not attained in most cases. Attempts to solve this problem by installing partition walls and other acoustic measures are costly and often counterproductive.

Sound masking is an ideal solution that is both effective and inconspicuous and thus preserving the intended open architecture of the architect. It is also suitable for office floors with separate rooms, provided with lightweight partition walls, where sound is causing problems by excessive speech sounds or speech transmission through the lightweight partition walls, via the ventilation system or space above the modular ceiling. This can result in a major cost saving with respect to other measures such as heavier partition walls.

The basic principle of sound masking is simple. In office spaces, electronically generated noise is added to a background sound with a low volume through a series of concealed speakers (in most cases above the false ceiling). The generated sound is a careful mix of frequencies that mask speech and other sounds, for example produced by office machines. The background sound is inconspicuous and is easily accepted by the other people present, making the working environment a more comfortable place to be in.

After the installation, the sound masking system can easily be adapted to achieve an optimal background sound masking for every separate area in the office.

Adjusting an optimal background sound level is desirable to guarantee the privacy and to minimize the distraction. Disturbing work of the office personnel is not so much related to the sound level itself, but rather to the differences between sound levels and the background sound. It is important that the background sound level is not decreased too much. This is crucial for speech frequencies ranging from approximately 400 Hz up to 4 KHz, since sound sources are experienced as highly interfering in that situation. Natural background noise caused by, for instance office ventilation systems and computers is too unpredictable and too tonal to accomplish this function, whereas sound masking is fully controllable, predictable and without dominant frequencies. Sound masking provides for an ideal background sound level for optimal acoustic comfort. It does not increase the level of noise peaks in the room, but effectively fills the low areas in between.

Most important characteristics of sound masking
1. Improved speech privacy and aural comfort
2. Prevention of undesirable eavesdropping
3. No destraction from the objective to create an open-plan office
4. Low costs in relation to other acoustic measures
5. Masking of unwanted sound
6. People who can work in a concentrated and efficient way make less mistakes
7. The sound level can be adapted for every separate area according to your wishes
8. Easy relocation of speakers in case the lay-out of the office is revised
9. Low energy consumption
10. Simple installation and low maintenance
11. Can be combined with paging system or public address system
12. Can be combined with background music.

Figure 2 shows a typical sound spectrum for background noise in offices that corresponds with a NC-value of 34 and is saturated with low frequency noise. Sound masking can provide for a 20 dB masking sound spectrum in the speech frequencies. This will increase the NC-value up to 36, but it will create a more pleasant acoustic environment with a significant improvement of speech privacy.

Applications

• Open office space
• Call centres and help desks
• Privacy in consultation rooms/waiting rooms
• Privacy at counters and reception desks
• Restaurants

Alara-Lukagro attends to the:

• Design
• Installation
• Electronic tuning
• Service

References


Lloyds Bank PLC, Oxford Street, London UK


When the Lloyds Bank in the lively business centre of London was searching for a solution in which the speech privacy of both customers and personnel was to flourish, the sound masking system of Alara-Lukagro was selected. As a result of the tremendous satisfaction with this system, the amount of branch-offices of the Lloyds Bank that utilize this system has increased over 30.

Procter & Gamble applies a worldwide uniform office lay-out. We have been given the opportunity to deliver the sound masking system on many locations, for instance in Switzerland, Belgium, Germany, Turkey and Poland. Dependent on the activities and the amount of masking materials, the area is divided into specific zones. For each zone, the sound level can be adjusted separately.



In addition to the mentioned examples, several offices of the Rabobank in the Netherlands have been provided with sound masking systems. Please contact us for other references.

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Isoleco^® hygienic sound absorption

Alara-Lukagro is dealer of Isoleco^® sound insulating ceilings and baffles. This programme has an impressive record of service with regard to soundproofing hygienic areas.

Hard ceilings, walls and floors are the cause of a relatively long-lasting reverberation in many working accommodations. It seems that in for instance laboratories, meat-packing industries, bottling plants and hospitals, only the use of hard materials is allowed as a result of hygienic requirements. This is the cause of noise pollution which requires a hygienic sound absorption to keep the working environment liveable. Almost all popular materials can not be employed, but Isoleco^® offers a complete product range with solutions and the best guarantee that a strict HACCP policy can be combined with a pleasant acoustic environment.

By selecting Isoleco^® 1000 ceiling boards, the Isoleco^® 2000 ceiling system, Isoleco^® hygienic baffles or Isoleco^® wall absorbers, many solutions to noise problems can be offered. The panels, completely sealed with Tedlar foil, can be delivered in a quality that can be cleaned on a daily basis with pressure and/or cleaning products and is extremely resistant to all types of chemicals. The foil is so thin (0.025 mm) that the acoustic function of the filling remains optimal and can not be penetrated by bacteria, viruses, dirt and humidity at the same time. In addition, Tedlar has excellent UV-resistance and is the least static of all synthetic foils.

The programme contains a number of unique items such as specially developed locking clips, the Multiclip®, which can be applied for baffles in many different ways, integrated lighting (optional), specially extruded aluminium profiles and, last but not least, dummy modules and tape for custom-made items, provided with the same Tedlar foil. In 2006, Isoleco® bears the CE-mark and is thus easily applicable throughout Europe.

Examples of application areas:

• Food industry
• Pharmaceutical industry
• cleanrooms (highest classification)
• Bottling plants and breweries
• Operating rooms

Apply for the comprehensive Isoleco^® documentation, inquire after the enormous amount of possibilities and references Isoleco^® has already proven itself or let us make you an offer, free of obligation. Alara-Lukagro offers you a complete solution including mounting. Simultaneously, other sources of noise can be tackled as well!

Project Nieuwebrug: combination of Isoleco® 1000 ceiling and Isoleco® absorbers.

Isoleco® application in a clean room in the pharmaceutical industry.

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Correction of reverberation and room acoustics

Reverberation can be an enormous problem. Audibility of speech and concentration decrease while absence is increased on the shop floor. Even in culturally used rooms, the well-being and sense of direction deteriorate as a result of bad acoustics.

Alara-Lukagro is acquainted with the problems related to room acoustics. It is decided how a specific room can be improved after consultation with the customer or after indication of a problem by an acoustic consultancy agency. As you are accustomed to, we emphasize the solution in our approach: What do you, as a customer, need to solve your problems? We do not sell measurements and advice as such, but we often perform reverberation measurements. A good solution contains our point of view that: enough is enough, so calculations are part of the deal. That is why!

The choice is then up to you: would you like to select a conventional modular ceiling (sometimes in combination with our sound masking system), the relatively inexpensive but highly effective industrial baffles or an esthetical custom-made solution in which shape, colour and use of material can often only be limited by fantasy itself? As we are both manufacturer and representative of a number of distinguishing manufacturers in the area of room acoustics, we have a lot of freedom to fulfil your wishes.

The reverberation time in a hall like this is sometimes decreased with entire seconds after the application of baffles.

Baffles in a parallel staggered pattern.

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