ARCHITECTURAL AND BUILDING ACOUSTICS
Room and building acoustics are an important aspect of new-build and redevelopment projects (including residences, schools, hospitals, hotels, offices, sports and leisure, entertainment, retail, industry, theatres and cinemas) as they can have a significant impact on health and wellbeing, productivity and communication.
Our acoustic consultants work closely with architects, designers and contractors to develop the acoustic design of a build through each design stage, sometimes all the way through to completion, including sound insulation pre-completion or commissioning testing of the finished building. Our team of acoustic consultants has many years of experience in acoustic design and specification of sound insulation measures for walls, floors, ventilation and glazing.
What are room and building acoustics?
Room and building acoustics (together called architectural acoustics) relate to the control of sound and vibration as it travels through buildings, as well as the sound characteristics within individual rooms.
Sound and vibration transfer within a building commonly occurs via walls, floors, structural elements such as steel beams and building services (ductwork, pipes, risers etc). Noise sources requiring consideration may originate outside the building (e.g. traffic noise, railway vibration) or be generated within the building itself (e.g. music noise, building services noise).
Room acoustics relates to sound propagation and decay within enclosed rooms such as small offices and meeting rooms, and within larger spaces such as lobbies, atria, lecture theatres and large auditoria.
Setting and achieving criteria for room and building acoustics is often a requirement for receiving credits under certification schemes such as BREEAM, where a suitably qualified acoustic consultant is required to be part of the design team from the early stages to ensure the available credits are achieved from concept right through to completion.
In addition to certification schemes, Part E of the Building Regulations requires the control of sound transfer within dwellings and achieving this often requires careful consideration of building acoustics during the design and construction phase, together with pre-completion acoustic testing to confirm compliance.
Building acoustics and sound insulation
The main acoustic parameter for building acoustics is sound insulation, where the transfer of sound (usually considered noise) is minimised as much as possible and in accordance with any applicable acoustic regulations and design criteria.
Building noise is considered in its two primary forms: airborne noise (noise that is generated in the air, such as voices or music) and structure-borne noise (noise that is generated by excitation of the building structure, such as footfall impacts from a floor above, or vibrating plant fixed to a wall).
Effectively controlling all potential noise sources in a building involves working closely with architects and building engineers to develop specifications for building materials (façade build-ups, glazing and curtain walling specifications, wall and floor constructions). Equally important is the consideration of construction detailing at junctions between building elements.
The main consideration or acoustic parameter for room acoustics is reverberation time (RT), which is a measurement of the time it takes for sound to decay within a space.
Shorter RTs result in quieter noise levels and better speech intelligibility, and are generally the goal for most spaces. However, exceptionally short RTs are not necessarily preferable and can result in poor projection of speech across a room (e.g. a large classroom or school hall), or a lack of liveliness and atmosphere in bars and restaurants. Shorter RTs are achieved by the inclusion of areas of acoustically absorbent surface finishes throughout the space.
Longer RTs are generally preferable within music venues such as concert halls, theatres and nightclubs where, up to a certain point, they can contribute to a variety of desirable subjective impressions relating to loudness, energy, warmth, envelopment, intimacy and excitement.
Room acoustic predictions for most spaces can be carried out reliably and accurately by acoustic consultants based on the simple relationship between a room’s volume and the total absorption area of its surface finishes. However, whether reduction or enhancement of reverberation is the goal, room acoustics in large or geometrically complex spaces, or where speech intelligibility is critical, can be harder to accurately appraise. These cases often require the use of specialist room modelling software to accurately predict the way sound will behave within a space.
Computer modelling provides much greater confidence in the prediction of room acoustics for complex and large spaces or in critical listening environments. Auralisation of rooms may also be undertaken which allows for different options to be simulated aurally so that designers, clients and end users can actually listen to the space long before it is built.
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