Speaker
Description
In automotive active noise control (ANC), the secondary path—the transfer from the loudspeaker to the error microphone—has a strong effect on control performance. In real driving, the number of occupants changes often, but its impact on the secondary path has not been studied much through experiments. This paper tests how occupant count changes the secondary-path magnitude and phase in a production passenger car, and how those changes affect ANC. We measure secondary paths under different occupancy conditions while keeping the same loudspeaker–microphone setup, and we compare the results frequency by frequency. We then run ANC using the measured paths to evaluate noise reduction and filter convergence. The results show that occupancy does not change the secondary path in a uniform way across frequency. Instead, some bands show phase spread and noticeable shifts in the transfer response. In those bands, noise attenuation drops and convergence becomes less stable, even when the reference signal has high coherence. These findings suggest that occupancy is a major factor affecting the secondary path in passenger car