Qiaochu Li - Assignment 5 Acoustic Research

Acoustics generally refers to the qualities that determine the ability of an enclosure (as an auditorium) to reflect sound waves in such a way as to produce distinct hearing, or the science that studies these qualities. In the specific field of architecture, it typically involves the study of speech intelligibility, speech privacy and music quality in the built environment. Architectural acoustic is also by large the science of engineering.

The science of acoustics for interior space is the science of controlling a room's surfaces based on sound absorbing and reflecting properties. Excessive reverberation time, which can be calculated, can lead to poor speech intelligibility. Interior building surfaces can be constructed of many different materials and finishes. Ideal acoustical panels are those without a face or finish material that interferes with the acoustical infill or substrate.
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)

Acoustics and Sound Systems in Architectural Design provides 7 tips for creating the best aural experience in architecture:

1) Watch out for SOUND REFLECTIONS. Straight surfaces reflect sounds back into the central space making sound clarity muddy.
2) Select ACOUSTICAL TREATMENT carefully. Different materials absorb sound frequencies differently. Make sure your acoustical treatments are absorbing the right sound frequencies.
3) Diminish ECHOES when necessary. Be aware that sounds traveling within 30 milliseconds of each other are perceived without echo. Sounds traveling after the 30 millisecond threshold become echoes of the original sound.
4) Don’t let other building systems get in the way. NOISE CONTROL is important to keep in check as other building systems (like HVAC systems) operate. Keep such clashing noises to a minimum.
5) Keep objects or other OBSTRUCTIONS out of the way. Objects that obstruct a sound path can block high frequency sounds. (Low frequency sounds can bend around objects.)
6) Get good PATTERN CONTROL. Make sure sound systems for a room get good sound coverage. This will prevent feed-back and other sound distortions.
7) For out-of-the-way listening areas get DISTRIBUTED SOUND SYSTEMS. Such “delay-fill” speakers operate with an electronic delay so the sound matches and is synchronized.

An architectural/sculptural project that particularly interests me is the Aeolus – Acoustic Wind Pavilion by Luke Jerram. Designed to make audible the shifting patterns of the wind and visually amplify the ever changing sky, the acoustic and optical pavilion is a large musical instrument. It is an Aeolian harp, designed to resonate and sing with the wind without any electrical power or amplification. Vibrations in strings attached to some of the tubes are transferred through skins covering the tops of the pavilion, and projected down through the tubes towards the viewer standing beneath the arch. The stings register the shifting landscape of wind around the artwork. The aim is for the public to be able to visualize this shifting wind map by interpreting the sound around them.

Sources:
http://en.wikipedia.org/wiki/Architectural_acoustics
http://sensingarchitecture.com/649/7-design-tips-for-best-architectural-acoustics/
http://www.aia.org/aiaucmp/groups/aia/documents/pdf/aiab089217.pdf