A Study on Reference Microphone Selection for Multi-Microphone Speech Enhancement

Jie Zhang, Huawei Chen, Richard C. Hendriks

Research output: Contribution to journalArticleScientificpeer-review

13 Citations (Scopus)
286 Downloads (Pure)


Multi-microphone speech enhancement methods typically require a reference position with respect to which the target signal is estimated. Often, this reference position is arbitrarily chosen as one of the reference microphones. However, it has been shown that the choice of the reference microphone can have a significant impact on the final noise reduction performance. In this paper, we therefore theoretically analyze the impact of selecting a reference on the noise reduction performance with near-end noise being taken into account. Following the generalized eigenvalue decomposition (GEVD) based optimal variable span filtering framework, we find that for any linear beamformer, the output signal-to-noise ratio (SNR) taking both the near-end and far-end noise into account is reference dependent. Only when the near-end noise is neglected, the output SNR of rank-1 beamformers does not depend on the reference position. However, in general for rank-r beamformers with r>1 (e.g., the multichannel Wiener filter) the performance does depend on the reference position. Based on these, we propose an optimal algorithm for microphone reference selection that maximizes the output SNR. In addition, we propose a lower-complexity algorithm that is still optimal for rank-1 beamformers, but sub-optimal for the general rank-r beamformers. Experiments using a simulated microphone array validate the effectiveness of both proposed methods and show that in terms of quality, several dB can be gained by selecting the proper reference microphone.

Original languageEnglish
Article number9272831
Pages (from-to)671-683
Number of pages13
JournalIEEE/ACM Transactions on Audio Speech and Language Processing
Volume29 (2021)
Publication statusPublished - 2020


  • Acoustic distortion
  • Array signal processing
  • low-rank approximation
  • Microphone arrays
  • Microphones
  • multi-channel beamforming
  • Noise reduction
  • reference microphone
  • relative acoustic transfer function
  • Signal to noise ratio
  • Speech enhancement
  • variable span linear filters


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