author = {J. Bitzer and K.U. Simmer and K.-D. Kammeyer},
  year = {1999},
  month = {May},
  title = {Multi-Microphone Noise Reduction Techniques for Hands-Free Speech Recognition - A Comparative Study},
  pages = {171-174},
  address={Tampere, Finland},
  abstract={In this paper we will describe different multi-microphone noise reduction techniques as for example front-end systems for a command speaker-independent word recognizer in an office environment. Our focus lies on examining the recognition rate if the noise source is not gaussian and stationary, but a second speaker in the same room. In this case standard noise reduction techniques like spectral subtraction will fail, and only multi-microphone techniques can raise the recognition rate by using the spatial information of the speakers. We will compare the delay-and-sum-beamformer, different superdirective solutions and the post-filter approach. Our results show that these techniques are the right choice for hands–free speech recognition systems. Furthermore, we will give a deeper insight into the superdirective design for microphone arrays.},
  booktitle={Robust Methods for Speech Recognition in Adverse Conditions (ROBUST 99)}