Acoustical performance of double-wall active sound packages based on two source-location method

A two source-location method is developed to measure the transmission loss of double-wall active sound packages with piezoelectric ceramics bonded to the excited plate. The results show that (1) Porous materials achieve passively sound-absorbing in the double-wall active sound packages in high frequencies; (2) The optimal secondary source is obtained by using FxLMS algorithm under the minimization of the sound pressure, and the transmission loss of the double-wall active sound packages can be improved in resonance frequencies; (3) To ensure that the measurement error of the transmission loss is less than 5 dB, the microphones must be chosen with the precision within ±0.5 dB, and the distance between them need satisfy some mathematical conditions; (4) When the precision of the microphones is confirmed, the measurement error of the transmission loss is up to the minimum with the distance between the microphones equal to 1/4 wavelength of the interested frequency.