Designing for Sound

Designing for Sound

Whether the goal is to hear a pin drop in a concert hall, to reduce the drone of airplane engines, or to improve sound clarity in lecture halls, designing physical spaces with superior sound quality is a computational challenge. Duke engineers are developing new engineering tools to improve our acoustic environment.

Did you know?

The quality and volume of sound in a room can bring pleasure or fatigue to the listener. Careful consideration of sound quality in design can make even cavernous spaces feel cozy and comfortable.

Materials such as carpets and tile ceilings absorb sound, while other materials such as wood and masonry may reflect sound. Motors and air conditioning units also introduce noise into acoustic spaces. The traditional approach to predicting the acoustic characteristics of a particular space, to understand its ‘sound landscape,’ is to analyze each and every sound frequency separately. This approach becomes increasingly burdensome as the wider frequency ranges of practical interest are considered. What’s more, the effects of absorbing and reflecting materials become more difficult to precisely predict.

Mechanical engineering faculty Donald Bliss and Linda Franzoni, specialists in structural vibrations and acoustics, are developing computationally efficient analysis tools for predicting and optimizing acoustic spaces. The key to their approach is to analyze the acoustic field as a series of frequency bands. This allows them to evaluate a frequency band’s pressure level and power flow. The behavior of the sound field, and the effect of absorbing, reflecting, and radiating boundaries are all considered.

The team’s approach allows them to take a more statistical point of view and quickly understand what design changes are needed to affect the acoustics of a particular space. The method is unique among emerging energy-based boundary element or finite element methods as it combines analytical insight with computational efficiency, and has lead to new insights into the physical behavior of broadband sound fields. These insights are leading to more direct and efficient design methods.