Tunable sound absorbing and air filtering attenuating device

摘要

Acoustical attenuating devices (52) and method of forming them. The attenuating devices (52) include an exterior layer (64), a sound absorption layer (66), and multiple perforated layers (68) coupled to the sound absorption layer (66). The perforated layers (68) include a perforated structural layer (70) and a perforated substrate layer (72). The perforated structural layer (70) and the perforated substrate layer (72) provide structural stiffness and define multiple resonating tubes (88) that attenuate sound.