Dual-channel modulation energy metric for direct-to-reverberation ratio estimation

Non-intrusive estimators for acoustic parameters like the direct-to-reverberation ratio (DRR) are useful tools but still perform weakly as shown in the acoustic characterization of environments (ACE) challenge. In this paper, we develop a novel dual-channel metric based on the modulation energy domain for DRR estimation. In contrast to established modulation based single-channel metrics like the speech-to-reverberation modulation energy ratio (SRMR), we exploit the spatial information from two microphones as well as the temporal dynamics in the modulation energy domain. The developed metric shows a strong linear correlation to the DRR, which allows a simple mapping. It is shown that the metric is robust against the microphone array configuration, room characteristics and the speech signal. The proposed metric is compared to a reference method based on the spectral variance of the room transfer functions, and both metrics are evaluated using simulated and measured data. In our experiments, the proposed metric achieved a higher correlation and lower RMSE compared the reference method, and outperforms existing SRMR based DRR estimators.