Perception of loudness changes induced by a phononic crystal in specific frequency bands

Abstract

To study the influence of classical phononic crystal (PC) structures on the acoustical characteristics of a sound source, a combined acoustics/perceptual analysis is conducted on a PC specially designed to exhibit several spectral and wave vector properties in different audible frequency ranges. The properties, confirmed by both numerical calculations and experiments, consist in both partial and absolute band gaps, as well as a negative refraction band. A psychoacoustic feature, namely the loudness in third-octave bands, is estimated from numerical simulations of the acoustic field behind the crystal. Additional perceptual tests are conducted to evaluate the efficiency of the PC slab. In the frequency range of the band gaps, sound stimuli filtered by the PC’s impulse response are perceived as softer than stimuli resulting from a free-field propagation (FF), they also are perceived as equally (or close to equally) loud than sounds attenuated by a free-standing rigid wall (FS). In the frequency range of the focalization (negative refraction), PC sound stimuli sound louder than both FS and FF sound stimuli. The possibility of designing an efficient sound barrier based on the considered PC is finally discussed.