  This paper addresses the combination of complementary parallel speech
recognition systems to reduce the error rate of speech recognition systems
operating in real highly-reverberant environments. First, the testing
environment consists of recordings of speech in a calibrated real room with
reverberation times from 0.47 to 1.77 seconds and speaker-to-microphone
distances of 0.16 to 2.56 meters. We combined systems both at the level of the
DNN outputs and at the level of the final ASR outputs. Second, recognition
experiments with the reverb challenge are also reported. The results presented
here show that the combination of features can lead to WER improvements between
7% and 18% with speech recorded in real reverberant environments. Also, the
combination at DNN-output level is much more effective than at the
system-output level. However, cascading both schemes can still lead to smaller
reductions in WER.
