  As for the humanoid robots, the internal noise, which is generated by motors,
fans and mechanical components when the robot is moving or shaking its body,
severely degrades the performance of the speech recognition accuracy. In this
paper, a novel speech recognition system robust to ego-noise for humanoid
robots is proposed, in which on/off state of the motor is employed as auxiliary
information for finding the relevant input features. For this, we consider the
bottleneck features, which have been successfully applied to deep neural
network (DNN) based automatic speech recognition (ASR) system. When learning
the bottleneck features to catch, we first exploit the motor on/off state data
as supplementary information in addition to the acoustic features as the input
of the first deep neural network (DNN) for preliminary acoustic modeling. Then,
the second DNN for primary acoustic modeling employs both the bottleneck
features tossed from the first DNN and the acoustics features. When the
proposed method is evaluated in terms of phoneme error rate (PER) on TIMIT
database, the experimental results show that achieve obvious improvement (11%
relative) is achieved by our algorithm over the conventional systems.
