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Sensors 2016, 16(1), 50; doi:10.3390/s16010050

A Novel Method for Speech Acquisition and Enhancement by 94 GHz Millimeter-Wave Sensor

Department of Biomedical Engineering, Fourth Military Medical University, Xi’an 710032, China
College of Control Engineering, Xijing University, Xi’an 710123, China
Shaanxi University of Technology, Hanzhong 723001, China
These authors contributed equally to this work.
Author to whom correspondence should be addressed.
Academic Editor: Vittorio M. N. Passaro
Received: 9 September 2015 / Revised: 10 December 2015 / Accepted: 23 December 2015 / Published: 31 December 2015
(This article belongs to the Section Remote Sensors)
View Full-Text   |   Download PDF [2471 KB, uploaded 31 December 2015]   |  


In order to improve the speech acquisition ability of a non-contact method, a 94 GHz millimeter wave (MMW) radar sensor was employed to detect speech signals. This novel non-contact speech acquisition method was shown to have high directional sensitivity, and to be immune to strong acoustical disturbance. However, MMW radar speech is often degraded by combined sources of noise, which mainly include harmonic, electrical circuit and channel noise. In this paper, an algorithm combining empirical mode decomposition (EMD) and mutual information entropy (MIE) was proposed for enhancing the perceptibility and intelligibility of radar speech. Firstly, the radar speech signal was adaptively decomposed into oscillatory components called intrinsic mode functions (IMFs) by EMD. Secondly, MIE was used to determine the number of reconstructive components, and then an adaptive threshold was employed to remove the noise from the radar speech. The experimental results show that human speech can be effectively acquired by a 94 GHz MMW radar sensor when the detection distance is 20 m. Moreover, the noise of the radar speech is greatly suppressed and the speech sounds become more pleasant to human listeners after being enhanced by the proposed algorithm, suggesting that this novel speech acquisition and enhancement method will provide a promising alternative for various applications associated with speech detection. View Full-Text
Keywords: radar speech; 94 GHz MMW; speech enhancement; empirical mode decomposition; mutual information entropy radar speech; 94 GHz MMW; speech enhancement; empirical mode decomposition; mutual information entropy

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

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Chen, F.; Li, S.; Li, C.; Liu, M.; Li, Z.; Xue, H.; Jing, X.; Wang, J. A Novel Method for Speech Acquisition and Enhancement by 94 GHz Millimeter-Wave Sensor. Sensors 2016, 16, 50.

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