Automatic Quality Estimation for ASR System Combination
Table 7: WER[%] (↓) scores of the enhanced channels.
['WER of Enhanced Channels Enhancment-ASR', 'WER of Enhanced Channels DT05', 'WER of Enhanced Channels ET05']
In distant speech recognition, it is common to combine the signals recorded by a microphone array in order to generate an enhanced signal. MVDR processing is included in the baseline system provided by CHiME-3 organizers Barker et al. The peaks of SRP-PHAT are then tracked over time using the Viterbi algorithm (see also Loesch and Yang ) We apply both methods to combine the signals from the 5 microphones and then we transcribe the resulting signals by using the two aforementioned baseline ASR systems. An interesting achievement with this approach is the significant improvement of hypothesis-level combination with respect to the signal-level combination. It is important to remark that the QE-informed ROVER also significantly improves the performance of the enhanced channels when combining less than eight transcriptions. As mentioned before, probably due to the high performance difference between the enhanced and raw channels, we do not observe the same gain at higher levels.