title: Adaptive speech enhancement using directional microphone in a 4-T MRI scanner.
abstract: OBJECTIVE
  To evaluate the effectiveness of the proposed adaptive speech enhancement (ASE) system for the magnetic resonance imaging (MRI) environment to reduce the loud scanning noise without disrupting the communication between patients and MRI operators.
  
  
  METHODS
  The developed system employed the idea of differential directional microphones for measuring and distinguishing the speech signals and MRI acoustic noises simultaneously. Two-stage adaptive filters with normalized least mean square algorithms were adopted. Two common MRI scanning sequences, echo planar imaging (EPI) and gradient echo multi-slice (GEMS), were tested using a 4T MRI scanner.
  
  
  RESULTS
  A total of 1.4 and 3.3 dB speech enhancements quantified by the cepstral distance assessment were achieved for the speech signal contaminated with the EPI and GEMS noises, respectively. The speech signal was noticeably recovered, and a clear speech waveform was observed after treated with the ASE system. Furthermore, a non-adaptive post-processing approach [i.e. simply using spectral subtraction (SS) technique] was also adopted to process the abovementioned results. Additional reductions were achieved for the non-coherent MRI acoustic noises.
  
  
  CONCLUSIONS
  The results showed that combining the proposed ASE system along with the SS approach has a great potential for treating MRI acoustic noise to guarantee an effective communication from patient to MRI operators.
authors.affiliation: Department of Mechanical and Materials Engineering, University of Cincinnati, P.O. Box 210072, Cincinnati, OH, 45221, USA.
authors.forename: Guohua
authors.initials: G
authors.lastname: Sun
authors.affiliation: Department of Mechanical and Materials Engineering, University of Cincinnati, P.O. Box 210072, Cincinnati, OH, 45221, USA.
authors.forename: Mingfeng
authors.initials: M
authors.lastname: Li
authors.affiliation: Department of Mechanical and Materials Engineering, University of Cincinnati, P.O. Box 210072, Cincinnati, OH, 45221, USA.
authors.forename: Brent W
authors.initials: BW
authors.lastname: Rudd
authors.affiliation: Department of Mechanical and Materials Engineering, University of Cincinnati, P.O. Box 210072, Cincinnati, OH, 45221, USA.
authors.forename: Teik C
authors.initials: TC
authors.lastname: Lim
authors.affiliation: Center for Imaging Research, University of Cincinnati, 231 Albert Sabin Way, Suite E685 MSB, P.O. Box 670583, Cincinnati, OH, 45267, USA.
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Osterhage
authors.affiliation: Center for Imaging Research, University of Cincinnati, 231 Albert Sabin Way, Suite E685 MSB, P.O. Box 670583, Cincinnati, OH, 45267, USA.
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Fugate
authors.affiliation: Department of Biomedical, Chemical, and Environmental Engineering, University of Cincinnati, P.O. Box 670048, Cincinnati, OH, 45221, USA. jing-huei.lee@uc.edu.|Center for Imaging Research, University of Cincinnati, 231 Albert Sabin Way, Suite E685 MSB, P.O. Box 670583, Cincinnati, OH, 45267, USA. jing-huei.lee@uc.edu.
authors.forename: Jing-Huei
authors.initials: JH
authors.lastname: Lee
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D006747:Hospital Communication Systems; D021621:Imaging, Three-Dimensional / Q000295:instrumentation*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D009622:Noise / Q000517:prevention & control*; D013018:Sound Spectrography / Q000295:instrumentation*; D013068:Speech Production Measurement / Q000295:instrumentation*
keywords: Active noise control; Adaptive speech enhancement; MRI acoustics; Noise; Sound