Fundamentals of Architectural Acoustics
Architectural Acoustics evaluates interactions between people and sound, indoors and outdoors with the aim of using the information garnered to develop acoustical design criteria for architecture and planning. Architectural acoustics is the technology of designing spaces and systems that meet our auditory needs; deals with sound in and around buildings of varying functions. It creates designs that enable efficient distribution of desirable sound and the exclusion of undesirable sound (noise). It achieves these through two categories: soundproofing and acoustical treatment. Architectural Acoustics studies sound in homes and other buildings and the design of those structures for optimal acoustic performance.
Elements of Architectural Acoustics
- Building envelope
- Interior structure
- Building materials
- Selection of equipment
- Sound masking
Building envelope is the outer shell of a structure that shields it from wind, water, heat, light, noise and other elements of the outside world. It is often designed to absorb sound and reduce noise.
This comprises the interiors of a building such as rooms, ceiling, walls, floors, doors, windows and ducts which are constructed to reduce noise or produce a desired acoustic environment. An example of this is a theatre that is shaped to allow sound to flow unobstructed from the stage to all seats and to prevent sound from echoing back.
Some building materials are selected for their sound properties such as reflection, absorption, refraction, diffraction and transmission of sound. An example is a party wall between two apartments that contain layers of sound insulation that absorbs noise.
This is the selection of suitable equipment based on their quiet mechanical operation, lack of noisy beeps and other features that produce noise. An example of this is an elevator.
Sound masking refers to ambient sounds that absorb noise or electronic noise control that generates noise-canceling waveform in real-time in response to sound.
Properties of Architectural Acoustics
The properties of architectural acoustics include sound absorption and sound diffusion.
- Sound absorption
- Sound diffusion
Acoustic absorption is the ratio of absorbed sound intensity by a material to the intensity of the sound source. Sound waves are absorbed by the objects they hit. Different materials offer different levels of absorption, and frequencies ranges behave in their own unique waves. Higher frequencies are more easily absorbed, while lower frequencies can pass through objects. This means that lower frequencies are often far more difficult to control. Absorbent materials like foam, sound absorbing panels, etc. certainly help, but those large waves have to go somewhere!
There are sophisticated devices and calculations for determining materials that absorb what frequencies, and all of these come into play when designing a room with acoustics in mind – or simply adding treatments to a space to improve acoustic properties.
This is the method of spreading sound energy with a diffuser to improve sound in a space. Diffusion spreads the reflected sound energy in a room and reduces the harmful effects of strong echo and reverberation. One type of diffusor is a curved panel, often with a fabric cover, which can be easily placed on walls and ceilings. These types of panels have the advantage of uniformly spreading flat-wall reflections that would otherwise be combined with original sound waves to create destructive interference. In a concert hall, for example, diffusion panels are used to enhance the richness of sound and help create a sense of spaciousness.
How the Properties Work
Installation of absorbers and diffusers in a space reduces the level of undesirable noise, in the form of echo and reverberation. Noise is a relative term and can range from low levels of intrusive sound in a quiet environment to loud sounds in an already noisy environment.