If you want to understand why the acoustics in buildings and spaces is important, how acoustics can assist with wayfinding, and why designers should consider sound pressure levels and apply technical guidance and standards when designing spaces, read the blog below to see what Centre for Accessible Environments (CAE) Associate Consultant Ron Koorm has to say about those topics and more.
Visiting an early-years nursery to carry out an access audit some time ago, I knocked on the door of the large ‘baby room’ and as the manager opened the door, I was aware something about the space I was about to enter was not quite right…
“You have a problem with acoustics here, don’t you?,” I asked. She acknowledged that a specialist had been booked to give further advice as the reflections of the surfaces in the room gave an uncomfortable echo. Indeed, a section of carpet had to be quickly provided in one corner of the room for staff to dampen the sound(?) in that part of the room.
This was a building constructed less than two years previously, yet communication, and intelligibility of speech, was being compromised here. What was the designer thinking?
Sadly, it is still possible to have a new building signed off today by the authorities, where the floor, wall, and ceiling surfaces have not been designed to properly consider the impact of acoustics on the building users. Poor acoustics can impact many people but particularly those with a degree of hearing-impairment, who are neurodiverse, cognitive impairment or disproportionately affected by poor acoustics.
It’s not that we don’t know how to design buildings and spaces with good acoustics; it’s more that there appears to be inconsistency in the application of design standards and tools to produce a good end-result for the user. Consulting with your building users is a great way to get insight into their needs and aspirations of a more inclusive building and acoustics.
Assisting wayfinding
Just as accessible signage can make a world of difference in finding one’s way around a building or space, effective acoustics can also assist building-users.
Close your eyes and walk around an unfamiliar building with someone assisting you. You should be aware of changes in acoustics, be able to identify larger spaces, perhaps rooms where ceilings are lower, noise transmission from other rooms, etc. This may provide a limited insight into how a blind person or vision-impaired person uses acoustics, often with more acute hearing as a sensory input.
Basic rule: Hard surfaces reflect acoustics; softer surfaces are more absorbent and absorb some of the reflections. Many materials and surfaces fall somewhere in-between. Echo, or more accurately reverberation-time – the decay in seconds, of a sound of a known loudness – is the key item to control in the design process. .
A big cathedral has a high ‘reverb’ time, e.g. 3.5 seconds, a small public library rather less, e.g. 1.5 s. A seated breakout-pod in an office needs a low figure, (0.25 s). When effective communication for users is the aim, absorbent finishes help. .
Applying technical standards
Designers need to apply the relevant technical guidance and standards to ensure that surfaces in buildings and spaces are adequately acoustically dampened or controlled to prevent problems for users.
Think about a lift car, a reception area in a library, a public toilet, swimming pool, partitioned office, church community hall, canteen, GP’s treatment room, dentist’s waiting room. All have different uses, and all different acoustic requirements.
I recommend Design for the Mind PAS 6463:2022, which discusses acoustics in some detail and its impact on people, including those who may be neurodivergent.
Noise and stress
Some studies of equipment can be disturbing to disabled people and others, such as loud electrical hand-dryers. In the UK there is no control for members of the public exposed to them. Studies have identified that some hand-dryers can be approaching loudness of an aircraft jet engine, over 100 dBA.
People most at risk of being impacted by such noises are wheelchair-users, people of small stature, and young children, as their height brings them closer to the loud extract nozzle in many cases, and possibly potential hearing loss over time.
Sound pressure levels
When choosing equipment such as hand-dryers, printers, dishwashers, coffee machines, air-conditioning plant for buildings and spaces, ensure you look at the manufacturer’s technical information sheets.
Check if the sound pressure levels will be acceptable, and compare different makes and models. If in doubt, speak to someone who understands the technical jargon in the literature.
Use consultants
Specialist acoustic treatment consultants can review the architect’s drawings or an existing building and make recommendations to improve the acoustics, making areas more inclusive for everyone.
Uses of multiple induction-hearing-loops need to be carefully checked to ensure there is limited overspill of signal, which could otherwise result in private conversations being overheard.
Diffusion of sound can be controlled with acoustic knowledge, benefitting the user of the room or space. Tests can be conducted prior to, and during occupation.
Finally, whilst CAE may not employ acoustic consultants at time of writing, our access auditors and associate consultants have a good understanding of what is inclusive in terms of acoustics, and what is not. We can point you in the right direction.
Further reading
- BS 8300-2:2018 (11.2 Materials and acoustic design)
- BS8233:2014 Sound Insulation and Noise Reduction for buildings
- BB93: Acoustic design of schools
- Toilet design research recommends low noise hand dryers | Institute of Acoustics
- Hand Dryer Noise level and effect on human hearing (Liu & Wang published 6th December 2019)