Acoustic Research

In acoustic design, it is common for architect’s to hire an outside expert for design consultation based on the building’s needs. The first steps an acoustical engineer will make include performing an acoustical survey, determine use and number of seats, and determine a need for audio systems.  Some specific measurements that are crucial to the design are the background sound level, volume per seat, reverberation time, and the need for adjustable acoustics.

Wallace Sabine, one of the earliest pioneers in the architectural acoustic scene, was the first to take quantitative measures of reverberation, absorption, and sound transmittance.   Reverberation measures how long a sound resonates in a space, particularly useful for the design of concert halls. To put the numbers in perspective, a cathedral ranges from 2-5 seconds of reverberation and a concert hall from 1.2-2.5 seconds.  Which is calculated based on Sabine’s formula:

T (reverberation time) = 0.16 V (volume in meters of space) / A (sum of all absorption)

The Tokyo Opera City Hall, by TAK Architects, relied heavily on the instruction off their acoustical designer Leo Branck. The acoustical design process was tackled in three phases. First, computer simulations traced rays to find the diffraction of reflected surfaces to test the feasibility of a rectangular or pyramidal ceiling shape. Then the architect’s built a wooden model to test the geometry and height of the space, where the reflecting surfaces molded to achieve the desired reverberation. The third phase of acoustic design involved real life testing of an orchestra in the space.