Improving head-related impulse response measured in noisy environments with spatio-temporal frequency analysis

A new noise reduction method based on spatio-temporal frequency analysis is proposed that can be applied to head-related impulse response (HRIR), which is an impulse response between the sound source and the ear canal entrance. HRIR measurement is some times conducted in spaces which are not free fields, such as sound proof chambers with low reverberation. Conventional noise reduction methods such as synchronous averaging need multiple measurements under an identical measurement condition. However, taking many measurements requires much time, and subjects must be patient. Therefore, a noise reduction method which requires fewer measurements is needed. In our proposed method, noises are sup pressed using a two-dimensional filter that is designed in the spatio temporal frequency domain. Two experiments were conducted to improve the signal-to-noise ratio (SNR). The maximum SNR improvement achieved 1.28 dB, and the HRIRs measured in high reverberation were also improved, indicating that the proposed method effectively improved HRIRs without multiple measurements.