“What do you want your building to sound like?”

It’s not the question one might expect. To many, what their building looks like might seem more important than any sound it gives off.

In acoustic design, however, sound is everything. With more offices moving toward open plan layouts and growing numbers of residents living in multi-units close to noisy roads and entertainment venues, the importance of noise control should not be underestimated.

That raises questions about what acoustic design needs to deliver and which technologies and trends are impacting strategies and approaches.

According to Nick Boulter, arts & culture leader at Arup in Australasia, client wishes vary across projects and it is important to ascertain exactly what they are. For this reason, he often starts by asking “what do you want your building to sound like?” This, he says, can generate a bewildered response as clients are not as attuned to thinking as closely about the acoustic features of their building as they are visual features.

“I think it’s a worthwhile thing to ask,” he said. “Not everybody is after the same thing. Understanding what they want and what works for them is important.

“There are lots of standards which you can refer to but the standard isn’t necessarily right for everybody. Ascertaining what is going to work best for the client is an important part of that process’”.

Boulter says a common question involves whether clients wish to go for superior performance or are satisfied with solutions that simply meet National Construction Code requirements. Despite the marketing advantages a superior solution could enable, he says many opt for the latter.

Such an attitude, he says, arises out of an implied presumption that meeting Code requirements guarantees high performance. This, he says, is not necessarily true. NCC requirements, he says, represent a minimum baseline; not necessarily best possible outcome.

Beyond that, Boulter says commercial landlords desire flexibility to cater for a variety of tenants and potential uses for space over time. Often, this could involve putting in a gym – a challenging issue for acoustics in terms of noise and vibration generation. Even where gyms are not included in the original design, Boulter says it is important to allow the structural capacity so as to enable the heavy parts which would be needed to be added should one later be desired.

In residential, Boulter says people expect not to be unduly impacted by outside noise yet be able to generate a reasonable noise volume themselves without being concerned about neighbours.

Danny Boglev, associate director, acoustics team lead – Victoria at AECOM, offers similar thoughts. Acoustic design, he said, must adopt a person-centric approach centred around occupants and must respond to their needs at any point in time. Objectives, therefore, revolve around creating an environment whereby occupants can perform at their optimum whilst providing them with the best amenity possible.

Typically, he says, this is achieved in two ways. First, it is delivered by controlling the impact of any extraneous noise from the environment. Second, in environments such as theatres, concert halls and lecture theatres or videoconferencing rooms, it involves enhancing acoustic performance within that space. Acoustics, Boglev says, is not only about controlling noise but also about utilising acoustic strategies to make something better than it would be.

In practical effect, he says objectives vary across building types. In hospitals, for example, aims revolve around minimising sleep disturbance and facilitating recovery by isolating noise. In offices, objectives surround speech privacy in meeting rooms and control of noise in open plan offices to minimise distraction. In apartments, acoustic goals involve low noise levels in areas intended for living and sleeping. In schools and education, strategies need to support classrooms which are flexible and adaptable.

In considering all this, Boglev says acoustic strategies need to operate in a manner that is congruent with the broader architectural vision for the building.

Matthew Stead, managing director at Resonate Consultants and chairman at the Association of Australasian Acoustical Consultants, meanwhile, says objectives revolve around keeping noise intrusion from outside (road, rail, aircraft and the like), neighbours and heating and air-conditioning to an acceptable level.

Curiously, where acoustic design is effective, he says building occupants will largely remain oblivious to noise related issues.

“If we do a good job, the users of the building don’t notice,” he noted. “Our first aim is that we don’t want them to notice noise intrusion from road, rail and aircraft. Secondly, we don’t want them to notice their neighbour too much and we really don’t want them to notice the air conditioning noise too much either.

“That’s really our design objective. If people don’t notice, then we have done a good job.”

All three stress the importance of acoustics. In offices, effective acoustic design helps workers to remain focused, boosts productivity and helps maintain privacy and confidentiality. Better noise control and the resultant greater comfort for staff also enables companies to reduce turnover and boost employee morale. In residential, good acoustics help deliver better amenity and a more relaxing living experience. In education, good sound performance aids teachers in delivering effective lessons and helps students remain focused. In hospitals, effective acoustic strategies help facilitate patient rest and aid recovery.

Furthermore, acoustic performance impacts not only occupants but developers, sales agents and leasing agents. This is because noise control is one of several factors which affect a building’s performance and thus its attractiveness to purchasers and tenants.

One interesting point which Boulter and Stead talk about is the need to balance too much noise with too much quiet. The latter, they say, can lead to conversations being overheard, compromised privacy and annoyance for those who overhear conversations.

One way to achieve this is sound-masking. This involves introducing a bland sound which is not noticeable in itself but which dulls out other noise. This might be achieved, Stead says, by placing speakers in the ceiling which operate at low volumes which are not easily noticeable.

In terms of trends, developments are happening across several areas.

In residential, Stead says growing density is leading to greater numbers of people living in noisy environments and higher levels of awareness surrounding external noise. This in turn is driving efforts to improve facades through thicker glazing in windows to enhance sound-proofing. In addition, NCC changes a few years back ushered in more stringent requirements in respect of wall acoustic ratings.

Boulter agrees that greater density is creating challenges. One area revolves around friction between different user types – especially that which occurs where new residents move into apartments close to evening entertainment venues. Under normal circumstances, he says those creating noise would assume responsibility for keeping this to a reasonable level. With venues in many cases having been there first, however, operators are increasingly pushing back on ideas they should outlay possibly hundreds of thousands of dollars to cater for those who willingly choose to live nearby noisy venues.

Residential is where noise from above affects occupants on floors below poses another challenge. This can be disturbing, Boulter says, where people take out carpet and put down timber or tile flooring. In such cases, people below can start to hear considerable noise notwithstanding that the original acoustic solution might have been NCC compliant.

This is potentially problematic, Boulter says, amid growing use of cross-laminated-timber. As things stand, he says it is difficult to derive a good standard of acoustic performance whilst using exposed CLT.

One problem involves the standard for testing impact noise (footfalls, chair scrapes and the like). Borrowing largely from standards used in Europe and Japan, this relies upon a tapping machine which produces a controlled tapping on the floor and measures how much of that is echoed downstairs. For practical reasons, the tapping delivered by the machine is light and is nowhere near the noise generated by people. Thus you can have situations where solutions are Code compliant but far from ideal.

Stead agrees that there are problems in this area. He says the ACCC has instituted a star rated scheme which rates the performance of the building from an acoustic perspective.

In offices, Stead says the trend toward activity based workspaces is driving consultants to tailor acoustic solutions to the needs of specific spaces. Quiet workspaces, teleconferencing areas and the like need to be quieter and require greater soundproofing compared other spaces such as lunch rooms, he says.

In terms of technologies, Stead notes there is a trend toward denser types of plasterboard along with a growing use of acoustic panels which provide noise absorption. A new type of product in this area called EcoPanel is made from recycled PET bottles and is serving as a newer and greener alternative.

Boulter, meanwhile, says developers are driving acoustic performance to help achieve higher ratings in the increasingly popular WELL rating scheme which incorporates a number of aspects which pertain to acoustics. The most recent edition of Green-Star had also taken the welcome step of having different criteria for naturally ventilated buildings – a welcome change from a previous situation under which the rating requirements would have been failed simply because somebody opens a window.

One trend which Boulter says has potential but is yet to work comprehensively is active noise control. This noise-cancelling technology is becoming more common in domestic headphones and has been around for a while in aircraft. Though there have been ideas for new products on Kickstarter, the notion of being able to flick a switch and have it work comprehensively in an open room has thus far proved to be elusive, he says.

Boulter also talks about active architecture (otherwise often known as artificial reverberation), which helps to make a room sound larger compared to its actual size. This is promising in event venues, where it could enable an acoustically dead theatre to give the sense that the orchestra is playing in a much larger environment such as a concert hall.

As mentioned above, systems to perform noise masking are becoming cheaper, more sophisticated, more mainstream and better able to cater for a wider array of office environments.

Boglev, meanwhile, adopts a bolder focus and sees opportunities to combine acoustics with technology advances in other areas.

First, acoustics could be combined with augmented reality and virtual reality. This, he says, will complement current abilities to predict acoustic performance with those to ‘hear’ what the building will actually sound like. In a similar way to that in which people can don VR headset and ‘walk’ through spaces to see how these will look, Boglev says there are opportunities to add sound to this experience. Those would ‘hear’ what the building is likely to sound like. This could enable architects, for example, to present the likely acoustic aspects of different design options to developers in a more intuitive way.

Likewise, developers, sales agents and leasing agents will be empowered to provide more immersive experiences whereby prospective purchasers or tenants could use VR to experience the building from a sound perspective as well as a visual perspective.

In a different sphere, acoustics could be combined with the Internet of Things in noise sensitive environments where major highways, rail lines or industrial facilities are located nearby residential or public space facilities. Capturing noise and vibration levels in real-time, Boglev says, could be used to raise alerts about any immediate noise issues requiring attention, identify areas where noise mitigation strategies are needed and provide an accountability tool to report noise emission levels as they occur.

As a result of all this, Boglev says technology will deliver opportunities for acoustic consultants to further entrench and embed their position as indispensable members of design teams. Consultants, he said, will be able to demonstrate the value of their services in a manner which is more intuitive and more easily understood.

“With this emerging technology, we are not only able to provide different services, but we are able to add value to our existing services and make them far more tangible than they were in the past,” he said.

“In the past, we would have only numbers and technical information which could be hard for clients to understand. If you tell a client that we are going to design your building to 21 degrees Celsius, they understand what that feels like. If we say we are going to design your room to 40 or 45 decibels, they don’t know how loud that will be.

“Distilling that technical information to something which is easier to understand will be extremely valuable. Being able to hear what the results are and see things happen in real time will mean that people are no longer relying on a set of numbers.”

Boulter says acoustics deserves greater consideration in building design.

“The way I see it is that people often concentrate on the visual and not on the audible,” he said.

“People look at what a building looks like and will spend a lot of money making it look nice. It seems to be an anathema for people to start spending money on making it sound nice.

“But as soon as you go in to a building, it (sound) is one of the things which you react to. You instantly pick up the acoustic of the space as part of the experience.

“That tends to get forgotten, but is part of making a space work.”