When you walk into a concert hall, do you notice anything particularly different? Often times, audiences are instantly aware of the unique physical structure of a professional performance space, the moment they step through the entrance. If you want to know why these rooms are special, you must find out what is Architectural Acoustics!
People usually find themselves easily distracted (well, for me at least) by the aesthetic appeal of the various structural aspects of a live concert venue. Hence, it never really occurred to them that the design elements are there for an acoustical function, that benefits the overall experience of the musical performance!
Architectural Acoustics – A Primary Quality Factor
Otherwise known as “room acoustics”, architectural acoustics is a branch of acoustical engineering that deals with the science of achieving good sound quality within a building. Architectural acoustical methods was first applied by Wallace Sabine in the Fogg Museum lecture room. He then used his new found knowledge, to design the acoustics of the Symphony Hall in Boston.
Architectural acoustics is not only about enhancing the quality of sound in a concert hall or recording studio. Its principles are also used to achieve good speech intelligibility in a theatre or restaurant, and to make offices and homes more conducive and pleasant for people to work and live in. Architectural acoustic designs are typically carried out by acoustic consultants.
These are the topics that we’ll be looking into:
- Building skin envelope
- Inter-space noise control
- Interior space acoustics
- Mechanical equipment noise
Building Skin Envelope
Noise often travel through roofs, eaves, walls, windows, doors and penetrations. Hence, noise transmission from building exterior envelope to interior (and vice versa), must be analyzed. Having enough noise control measures in place, will ensure space functionality. These measures are also designed based on building use and local laws.
A simple example would be coming up with an ideal acoustical design for a home which will be built close to a busy highway, or under the flight path of a major airport.
Inter-Space Noise Control
In order to ensure space functionality and speech privacy, noise transmission from one building space to another, must be limited or controlled. In these types of situations, sound often travel through ceilings, room partitions, acoustic ceiling panels (such as wood dropped ceiling panels), doors, windows, flanking, ducting and other penetrations.
Engineers will take into account the possible sources of noise and the path of acoustic transmission, before coming up with solutions. For instance, noise by steps or noise by flow vibrations (air, water). An example would be designing a party wall in an apartment, that will minimize the mutual disturbance due to noise by residents in adjacent apartments.
Interior Space Acoustics
This discipline involves controlling a room’s surfaces by utilizing sound absorbing and reflecting materials. Thus preventing excessive reverberation time, which can result in poor speech intelligibility. Reflections of sound waves create standing waves, which in turn produces natural resonances that can be perceived as a pleasant sensation or an unsettling one.
The reflective surfaces of a room can also be beneficial if they are angled and coordinated in a way that provides good coverage of sound for a listener in a performance hall or music recital space. To understand this concept, try to observe the differences in design between a modern large office meeting room or lecture theatre and a traditional classroom with all hard surfaces.
Sound Absorbing Materials
There are many different materials and finishes used in acoustical treatments. The best acoustical panels are those without a face or finish material that interferes with the acoustical infill or substrate. Fabric covered panels are used to heighten acoustical absorption. Perforated metal sheets or plates also exhibit sound absorbing qualities, and are often used.
Acoustical substrates are often covered over by various finish materials. “Mineral fiber board”, or “Micore”, is a commonly used acoustical substrate. Various finish materials often include fabric, wood or acoustical tile. Fabric can also be wrapped around substrates to create a “pre-fabricated panel”, which typically exhibits good noise absorption properties if laid onto a wall.
There are three ways to improve workplace acoustics and solve workplace sound problems – the ABCs.
- A = Absorb (via drapes, carpets, ceiling tiles, etc.)
- B = Block (via panels, walls, floors, ceilings and layout)
- C = Cover-up (via sound masking)
Mechanical Equipment Noise
Building services noise control is the science of controlling noise produced by:
- ACMV (air conditioning and mechanical ventilation) systems in buildings, termed HVAC in North America
- Electrical generators positioned within or attached to a building
- Any other building service infrastructure component that emits sound.
If the noise generated by these equipment are not adequately controlled, it may lead to an unwanted increase in sound levels within the building, thus reducing speech intelligibility. Common control methods include vibration isolation of mechanical equipment, and sound traps in ductwork. Sound masking can also be created by adjusting HVAC noise to a predetermined level.
That’s about all I have for today folks. Do you notice any differences while working in an acoustically treated room?
Let me know your thoughts down below, and do share this article!