A complete guide to architectural acoustics

Architectural acoustic design is a branch of engineering concerning sound within buildings and the design of structures and elements to achieve good acoustic conditions. The design is usually developed by acoustic consultants – such as our fantastic team here at CPW, headed up by Jon Willmott.

What is architectural acoustics?

Architectural acoustics or building acoustics refers to the study and design of how sound is transmitted and managed within a space and how people interact with it, to enhance its function or their enjoyment of the space. A person’s interaction with architectural acoustics can be observed in a range of different ways, such as reverberation, noise disturbance, speech privacy or speech intelligibility.
A range of design elements contribute to a building’s acoustic condition, such as its internal geometry, surface finishes and separating constructions. Some of the challenges involved in architectural acoustics include balancing the demands of architectural aesthetics, functional use and even building location.

Why is good architectural acoustics important?

Good acoustic conditions allow people to enjoy a space as it is intended without the need to compromise their behaviour. In residential apartments for example, we aim to provide appropriate conditions for sleep such that residents don’t have to worry about noise disturbance from a neighbour where they might have considered wearing earplugs. Within an office lobby, good conditions would allow people to converse without having to raise their voice to be heard above other occupants.

Acoustic comfort is essential to a person’s physical and mental health. Good acoustic design can preserve hearing, decrease stress and anxiety. It aids a person’s rest and recovery, assists their productivity at work and improves their enjoyment of leisure and cultural activities.

The acoustics of a concert hall for example have nuanced design considerations. The shape and material choice of surfaces within the hall need to provide good reinforcement to the musicians to aid their performance. They also need to provide an audio experience for the audience which accentuates the performance with good clarity and without disruptive reverberation. Concert halls are commonly located in urban environments which have notable noise and vibration sources. The design of the building envelope and structural foundations should seek to eliminate these so that they are not perceptible within the concert hall.

The reality is that any new development should be designed to account for the noise environment in which it is to be located. In addition, new developments have the potential of adding noise sources to the environment, and the design of the new development should seek to control noise emission such that it does not prejudice the existing environment or nearby developments.

For this reason, there are statutory requirements for controlling noise for various development types. In addition, there are a broad range of guidance documents which provide design advice and performance criteria for developments, including British Standard 8233 British Council for Offices Guidance, Health Technical Memorandum 08-01 for healthcare buildings or the Building Bulletin 93 Acoustic Performance Standards for Schools.

By considering the importance of architectural acoustics early on in a project, we can help to avoid costly alterations further down the line.

What are the key elements of architectural acoustics?

Building materials

The materials within a building can be used to control the internal conditions. Absorptive materials, commonly porous or textured can reduce sound reverberation, typically used where communication or sound recording, comfort or audio performance are important. Sound insulating materials, such as walls and floors are often designed to reduce noise transfer between internal spaces, improving privacy and reducing disturbance. Reflective and diffusive materials, normally hard and non-porous, can be used to reinforce or spread sound throughout a space so that it carries further and more evenly.

Building envelope

The building envelope refers to the outer structure of a building, which houses all the inside elements and shields them from the environment. The building envelope covers many individual pieces, most notably glazing, ventilation grilles, roofs and solid facades. The acoustic design of these elements should be tailored to achieve the target internal conditions in the context of the external noise environment. For example, where the external environment contains significant low-frequency noise, such as that from a night-club, then the building envelope should be designed accordingly to mitigate the specific noise source. Vice-versa, for developments that are to house loud activities or events such as arenas, theatres or factories, noise egress through the building envelope is also key to a building’s design.

Interior structure

The interior structure of a building comprises foundations, floors, and walls. All of these elements can be designed to reduce noise and vibration transfer through or around the building’s structure. Specific attention is paid to the junctions between these elements, such as where internal walls or floors meet the external building envelope or where building services or structural elements penetrate key separating walls or floors.

Building services noise and vibration

Mechanical equipment such as elevators, generators and heating, ventilation and air conditioning (HVAC) systems contain moving parts such as air-moving fans. Such building services equipment has the potential to create noise and vibration. They and their surrounding structures must be designed so that their noise and vibration doesn’t disturb the internal and external receptors.

Sound masking

Sound masking refers to the use of ambient sounds to cover up unwanted noise. Unwanted noise can take many forms, it could be speech where privacy demands are high or environmental noise where noise disturbance demands are high. Specific masking sounds can be used where the frequency content of the noise in question is well understood.

What assessments are included within architectural acoustics?

Site suitability

Most new developments require an assessment to determine its suitability in the proposed location. Regarding architectural acoustics, this commonly includes assessments relating to the building envelope and proposed ventilation strategies with respect to controlling external noise and vibration intrusion within the development.

This assessment will help inform the location of buildings, rooms and uses within the site, for example locating noise sensitive bedrooms away from high noise sources and locating less-sensitive rooms/uses in the higher noise areas. The assessment will assist with the design of the external building envelope, including construction build-ups and dimensions of elements such as glazing. It may also influence the internal architectural acoustic design via internal surfaces and structures used to control noise and vibration from external sources.

Sound insulation predictions

Using industry developed empirical formula, predictions can be undertaken for noise transfer between rooms to assist with the sound insulation specification of separating elements. Advice can be provided relating to the construction and make-up of the separating elements and where improvement can best be made.

Acoustic modelling and auralisation simulations

3D computer software packages can be used to model internal room acoustics and external noise propagation. External noise propagation modelling can be used when appraising the site suitability of a development. Internal 3D acoustic modelling uses complex ray-tracing algorithms in order to predict the room acoustic conditions (reverberation times, sound mapping, speech intelligibility) or the electroacoustic output from a loudspeaker system within a space.

Internal noise level predictions

By using industry developed empirical formula, predictions can be undertaken for estimating internal noise levels within buildings from a range of noise sources. Internal ambient noise levels can see contributions from external noise ingress via the façade, ventilation systems, roof and building structure. Noise contributions from building services systems which have numerous individual elements are also considered. Other contributions could come from internal noise transfer from other areas of the building as well as noise generated by occupants and the equipment they may be using.

Room acoustic predictions

Calculations and 3D acoustic modelling can be used to predict the room acoustic conditions of a space, including the reverberation time, speech intelligibility, speech clarity and the extent of sound mixing within a space. We can even undertake auralisations, enabling us to understand how a space will sound and allowing us to better describe the impact of certain designs. Such predictions help us inform the internal shape and materials to be used within a building.

On-site testing

Tests can be undertaken within buildings to verify performance of existing or new spaces. Measurements are often undertaken for sound insulation, reverberation times and internal ambient noise levels. Other types of tests can also be undertaken for more nuanced scenarios.

Building Regulations and certification assessments; BREEAM, WELL, Home Quality Mark

Building Regulations relating to acoustics are applicable to residential developments and schools. In addition, certification schemes for buildings commonly include credits for the acoustic design and performance of a building. Compliance is commonly evidenced through detailed reporting of the design and are verified by on-site completion testing.

Get in contact with our architectural acoustics consultants

Get in touch and talk to one of our acoustic consultants today to see how we can help you. No matter the scale or size of the project, our team of experienced and fully qualified acoustic experts can deliver specialist design for a variety of projects, from masterplans to individual studios.

Find out more about our acoustic services.

A guide to architectural acoustics

What is architectural acoustics?