AES Show 2024 NY

Boom microphones are mostly used in noisy environments and equipped with directional microphones to enhance speech pickup from talkers and suppress noise from surroundings. Theory suggests that using a 2nd order directional microphone array, that is simply a pair of two directional microphones, would greatly increase the amount of far-field noise rejection, with negligibly little degradation of the near-field pickup. We conducted a series of laboratory measurements to validate the theory and assess the feasibility of 2nd order boom microphone applications. The laboratory measurements were designed using Knowles Electronics Manikin for Acoustic Research (KEMAR) with two speakers to play cockpit noise, one being placed on axis of the KEMAR front and one being set to side. A mouth simulator inside KEMAR played artificial voice. The measurements were done at two distances, 6 and 25 mm, from the KEMAR mouth with a 1st order boom microphone, that is a single directional boom microphone, and a 2nd order boom microphone. Spice simulations were also conducted to support the experimental findings. Both the measurements and Spice simulations proved the theory was true until the 2nd order boom microphone was placed near KEMAR. Then, reflections off the KEMAR head degraded the performance of the 2nd order microphone while improving that of the 1st order microphone. The net result shows that the 2nd order microphone is not superior than the 1st order microphone. This article describes details of the theory, our experimental measurements, and the findings.