Large-scale aeroacoustic simulation and non-linear 1-D modeling of bass-reflex loudspeakers

In a bass-reflex loudspeaker, a port (or vent) enhances the low-frequency response through Helmholtz resonance. However, at high sound pressure levels, the airflow near the port tip can generate vortices, leading to noise and distortion. This paper introduces an aeroacoustic computational method to simulate the noise and distortion in bass-reflex loudspeakers, with results showing reasonable agreement with experimental data. The aeroacoustic computational results, based on large eddy simulation, demonstrate that considering the three-dimensional nature of vortices is essential for accurately predicting the associated harmonic distortion and noise. Furthermore, a one-dimensional modeling approach is introduced to capture the nonlinear distortion caused by the vena-contracta effect in the port, which qualitatively matches experimental results. The 1-D modeling results show that accounting for the asymmetry of the flow at the port tips is essential for reproducing even-order distortion.