The art of acoustics

Pinning down the acoustic performance to expect is far more complicated when products don’t do exactly what they say on the tin. Here, Paul Thompson investigates the increasing emphasis on the acoustic performance of buildings and how the industry should respond to this growing demand to ensure product accountability and reliability.

Recent years have seen various studies proclaim the positive – and negative – effect that a workplace environment can have on workforce productivity. Lighting and acoustics have come in for special attention, so by providing the optimum conditions for both, employees will be happy, feel more relaxed and be capable of their best work, meaning productivity will increase.

In the fiercely competitive business world where any gain – marginal or otherwise – can mean the difference between the success or failure of a company, these proven studies making the link between worker wellbeing and productivity have seen the construction, architecture and fit-out of offices and workplaces change markedly.

And, where the acoustics of the workplace can have such a dramatic effect on a company’s bottom line, then greater focus is placed on improving them.

Understanding acoustics

“We are certainly finding that the subject has increased in importance for owners and architects,” said Paige Hodsman, concept development and workplace specialist at acoustic product manufacturer Ecophon. “They are increasingly well briefed on acoustics and understand its complexity.”

She points out that the acoustic performance of a room such as an open plan office is not a black-and-white issue – there are various greys of different hues involved too.

“As well as the space involved, you have to look at the workforce themselves,” continued Ms Hodsman. “People react to sound differently: some work better in quieter spaces, others enjoy background noise. We find that acoustic performance and comfort can change across professions, so engineers might prefer quieter spaces than, perhaps, architects might. There are basic physical steps to improve acoustics that can be made, but the key is to try and design offices that promote ‘activity-based working’ – where you might have different zones within the office designed specifically for different tasks,” she added.

For Ms Hodsman, these basic steps to improve acoustic performance include fitting the best sound-absorbing ceiling as possible and providing soft floor finishes wherever seating is fixed.

In-situ performance

But there are plenty of other products that will afford some level of improvement in a building’s acoustic performance. The difficulty is understanding exactly how these products perform and what level of improvement can be expected once they are fitted, according to FIS technical director Joe Cilia.

“Acoustic performance of products is expressed using data from laboratory tests. These tests measure airborne sound insulation and absorption. However, those results achieved in a laboratory cannot realistically be achieved on-site. There are too many other factors involved,” he explained.

Laboratory tests provide a single figure value on the product’s acoustic performance where flanking sound – the transfer of sound through ducts, holes in a partition or voids beneath a raised floor or suspended ceiling – has been eliminated as much as possible. Rather than a statement of the expected in-situ performance, these test results should be used as guidance for clients, architects and acousticians on the potential that some products have if used in a well-designed space.

Andrew Parkin, global head of acoustics at engineering consultancy Cundall, said: “There is no doubt that acoustic performance varies from laboratory to site. As specialists, we need to be able to offer clear advice to our clients. We are the translators of that information. The acoustician’s job is not to baffle people but to understand exactly what the client needs and then interpret that into a design.”

Ensuring clients understand exactly what that advice means in-situ can be difficult. The only way of really ensuring the design meets expectation is to provide an on-site mock-up. It is an approach that fit-out and refurbishment specialist BW has taken.

Bringing acoustic performance to life for clients

“We will construct mock-ups on-site for our clients. It helps them understand exactly how the building is likely to perform,” said BW’s operations director, Peter Nagle.

“We have had to tailor the provision for some clients on the back of these tests, but it can help us deliver on our clients’ expectations.”

That proactive approach highlights just how important some clients see the issue of acoustics but often they are hindered by other issues. Installations can be compromised from the word go if a property owner or landlord does not give permission for certain work. It can mean a complete rethink on how best to provide the optimum solution for a client.

“There tends to be three variables that have to be considered on each design,” commented Stuart Colam, acoustic advisor at SAS International, adding “Finance, form and function. Depending on how you approach the project, each of these can have greater influence over the final scheme.

“Often, financial pressure will dictate the type of materials used, and this will have an influence on the other variables. The final installation will meet the specification, but it might not look quite as good.”

Early involvement

Ultimately, the best way to ensure a workplace, shop, pub, restaurant performs at its optimum acoustically is to ensure that the acoustician is involved in a project as early as possible in the design process. In Ms Hardman’s opinion, that is RIBA design stage zero.

“Ideally, I would like to see acousticians involved during that strategic appraisal period,” she said.

Perhaps that is a little too much to hope for, but there is no doubt that the sooner the acoustic requirements are addressed, the better for the final scheme.

Mr Parkin from Cundall added: “The sooner acousticians are involved then the lesser the financial impact on a project the acoustic design has. The old saying that the later you are in the contract cycle the more cost you add, the earlier the more value, rings true.”

It is a view echoed by Mr Cilia. “Acoustic performance is not an exact science. There are variables and a holistic approach needs to be taken by designers. Clients need to understand that by bringing acousticians onto a project as early as possible, they will be able to deliver a better solution for them,” he concluded.