The Potential for Phononic Sound Diffusers (PSD)

摘要

Although periodic-structures theory gave rise to sound diffusers almost 40 years ago, it has been only in recent years when several authors regarded the possible application of a particular kind of periodic structure, phononic crystals, in the field on room acoustics. This paper explores the possible application of periodic structures used as sound diffusers in rooms. Preliminary simulations, carried out with FDTD, shows that due to the inherent time spreading provided by a periodic structure, they can be used to reduce, or even to eliminate, pernicious effects associated with the low frequency modes of the room. Recently, there has been growing interest in studying acoustic and elastic waves in periodic composite materials [1, 2]. Due to the periodicity of the structure, there can be ranges of frequency in which waves cannot propagate, giving rise to sonic band gaps. They are analogous to photonic band gaps in photonic crystals. Such materials are called, by analogy, sonic or phononic crystals. Interest in sonic crystals comes from the rich physics of acoustic and elastic systems, where both the density and the velocity contrast affect wave scattering and propagation. These characteristics, together with the potential for developing accurate theoretical models, make sonic crystals promising for fundamental studies of wave properties in strongly scattering materials.