Perceptual Active Equalization of Multi-frequency Noise

In this paper we propose a novel multi-channel active noise equalizer (ANE) when music or speech signals are present inside the same room. Our perceptual ANE (PANE) can benefit from the masking effect of the music emitted carrying out a perceptual equalization (PEQ) of the undesired ambient noise. Our PEQ strategy automatically adapts the spectral profile of the ambient noise recorded at the error microphones to the masking threshold of the audio signal recorded at that same point. We present a real-time experiment carried out in our laboratory that simulates the position of a driver in a car to test the PANE with different audio signals. The experimental results are compared with two alternative strategies: the full cancellation (FC) profile that corresponds to an active noise cancellation strategy, and the hearing threshold (HT) profile that corresponds to an ANE system whose gains mimic the human audibility threshold. Both FC and HT profiles are independent of the music presented in the room. Results show that the noise power measured at the microphones is higher for the PEQ profile, but always below the masking threshold of the music, getting almost unnoticeable. However, the emitted anti-noise power in the case of PEQ is 15 dB lower compared to HT and FC profiles for frequencies above 300 Hz. This performance leads to a reduction of noise pollution in the room and a lower power consumption of the system loudspeakers. In addition, the PEQ profile provided by the novel PANE system is a versatile approach that can reduce the perceived noise as much as the user decides, even reaching the same performance than the HT or FC profiles if needed. Therefore, the PANE system is a versatile real-time alternative to the classic active noise cancellation systems for multi-frequency noise.