AES 5th International Conference on Automotive Audio

This paper investigates the perceived spatial extent of a local active noise control (ANC) system for different types of disturbances. Several publications have determined size and shape of the zone of quiet for various arrangements, primarily for pure-tone diffuse sound fields, through analytical and numerical methods. However, these studies have often overlooked human perception, focusing solely on technical properties. Therefore, a listening experiment has been conducted to determine the perceived size of the zone of comfort in a scenario close to reality, using an active headrest setup. Several operational frequency limits for different types and directions of broadband disturbances are examined. Within this experiment, lateral transitions to the front and head rotations at the target position have been considered. Statistically consolidated subjective ratings exhibit limits of around 2 cm to 4 cm for lateral transitions, with an expected decrease towards higher frequencies. When comparing participants’ answers to measurements, the majority of the median responses converge at a point with loudness reduction of 20%. The rotational limits of 7° to 15° are not as dependent on frequency, but rather on the distinct perception of the secondary sources and the loudness reduction as well.