Development of a low-cost binaural audio recording system

This article presents the development and evaluation of a low-cost artificial head prototype for binaural audio recording, using electret microphones mounted on a mannequin. The analog front-end, implemented on a custom-printed circuit board, provides both signal amplification and polarization voltage for the capsules. The frequency response of the developed circuit was characterized using an exponential sine sweep and the spectral division method between output signal and excitation signal, revealing a flat magnitude response from 20 Hz to 20 kHz. To address the difference in sensitivity between the left and right ear capsules, an indirect calibration procedure was adopted using a 1 kHz tone at 94 dB SPL from an acoustic calibrator, followed by spectral correction across the full frequency range. The prototype's binaural capabilities were evaluated by measuring interaural level differences (ILDs) for sound sources at various horizontal azimuths. The ILD results demonstrate the prototype's ability to preserve spatial cues relevant to binaural recordings. Although the difference in sensitivity between the left and right ear capsules affects the absolute amplitude balance, the applied correction method proved effective in mitigating this limitation.