On the improvement of modulation features using multi-microphone energy tracking for robust distant speech recognition

In this work, we investigate robust speech energy estimation and tracking schemes aiming at improved energy-based multiband speech demodulation and feature extraction for multi-microphone distant speech recognition. Based on the spatial diversity of the speech and noise recordings of a multi-microphone setup, the proposed Multichannel, Multiband Demodulation (MMD) scheme includes: 1) energy selection across the microphones that are less affected by noise and 2) cross-signal energy estimation based on the cross-Teager energy operator. Instantaneous modulations of speech resonances are estimated on the denoised energies. Second-order frequency modulation features are measured and combined with MFCCs achieving improved distant speech recognition on simulated and real data recorded in noisy and reverberant domestic environments.