Air- and bone-conductive integrated microphones have been introduced by the authors [5,4] for speech enhancement in noisy environments. In this paper, we present a novel technique, called direct filtering, to combine the two channels from the air- and bone-conductive microphone for speech enhancement. Compared to the previous technique, the advantage of the direct filtering is that it does not require any training, and it is speaker independent. Experiments show that this technique effectively removes noises and significantly improves speech recognition accuracy even in highly non-stationary noisy environments.