The SILENT Treatment

Michael Wallace, Sto Technical Consultant for Acoustics

When it comes to acoustics in buildings, many people have a basic misunderstanding of the principles involved, and this generally stems from a lack of knowledge of the differences between reflected sound, noise transference and vibration. This can seriously inhibit the creation of effective acoustic solutions, so it’s important to set the record straight if we’re to create practical acoustic environments in buildings.

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If we look at noise transference, this refers to sounds that originate in one room and then spread to an adjoining space, perhaps via a poorly constructed partition wall, or by vibrating through a building component. Reflected sound however – also known as attenuation and reverberation – refers to sound generated within a space which then reflects off any hard, impervious surfaces such as walls, floors and ceilings.

In a poorly designed acoustic environment communication can be difficult. The clarity and intelligence of speech can be impaired as the sound is ‘blurred’ by the fluttering and echoes that will probably be present, and this can be a real problem, especially for those who may already have hearing issues. Vowels and consonants are often lost in the general noise of the room, and this can even make the space unusable.

This problem is especially serious in places like schools, universities, restaurants and mixed-use spaces. Swimming pools are another prime example – large open spaces filled with hard surfaces and a large water surface area, all of which can damage the pool’s acoustic performance.

Designing with your ears

To avoid these sorts of problems designers need to ‘design with their ears’ and make acoustic considerations a key issue right from the outset. They need to think about absorbing noise, echoes and resonances within the spaces where they originate, and consider such things as the size, height, volume and shape of their intended design. Other factors include the presence of any hard, reflective surfaces and the furnishings used within the space.

Remember that every building presents its own unique acoustic challenge, and so there is no standard formulaic solution that is guaranteed to solve the problem. Each case demands a bespoke solution, and that is why it’s important to engage the services of an acoustic engineer who will be able to develop an acoustic model of the space and provide reliable guidance. They will ensure that your acoustic solution complies with all the current legislative requirements, and their advice can remove the need for any costly retro-fitting which might otherwise be needed later on.

Another key to success is to involve a reputable acoustic systems manufacturer in the project as early as possible. They will be able to guide you through the different acoustic systems available on today’s market and help you select the most appropriate solution that will perform both acoustically and aesthetically. The manufacturer will be able to create independent acoustic graphs for your project so that the acoustic engineer can model the varying frequencies and then advise on the requirements for each individual space.

The manufacturer should also be able to offer support on-site and advise on how their system can work with the many different features such as light fittings, bulkheads and access panels that will need to be accommodated. They will make recommendations on substrate preparation and final finishing, and some will also have trained, authorized installers who will provide the highest quality of installation.

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A good acoustic system manufacturer will advise on how best to accommodate light fittings, diffusers and ceiling bulkheads.

Looking good

Although effective acoustic performance is a prime requirement, aesthetic considerations are also important, and the two elements should work together. Conventional acoustic systems have traditionally used a metal grid infilled with acoustic boards, or boards perforated with multiple holes and used in conjunction with mineral wool quilts. Unfortunately, these solutions restrict the design potential of the room involved and they do tend to become unsightly over time.

However, modern homogeneous alternatives are now available and these allow the creation of monolithic and seamless finishes which combine excellent acoustic performance with the ability to satisfy the modern trend for clean, uncluttered lines. This type of solution really highlights the fact that where architects and clients have adventurous visions for the interiors of their buildings, todays modern acoustic systems can translate those visions into reality without compromising on the acoustic performance.

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