title: A Novel Method for Speech Acquisition and Enhancement by 94 GHz Millimeter-Wave Sensor.
abstract: 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.
authors.affiliation: Department of Biomedical Engineering, Fourth Military Medical University, Xi'an 710032, China. cfm5762@126.com.
authors.forename: Fuming
authors.initials: F
authors.lastname: Chen
authors.affiliation: College of Control Engineering, Xijing University, Xi'an 710123, China. shengli@fmmu.edu.cn.
authors.forename: Sheng
authors.initials: S
authors.lastname: Li
authors.affiliation: Department of Biomedical Engineering, Fourth Military Medical University, Xi'an 710032, China. lichuantao614@126.com.
authors.forename: Chuantao
authors.initials: C
authors.lastname: Li
authors.affiliation: Department of Biomedical Engineering, Fourth Military Medical University, Xi'an 710032, China. lium90@163.com.
authors.forename: Miao
authors.initials: M
authors.lastname: Liu
authors.affiliation: Department of Biomedical Engineering, Fourth Military Medical University, Xi'an 710032, China. lizhaofmmu@fmmu.edu.cn.
authors.forename: Zhao
authors.initials: Z
authors.lastname: Li
authors.affiliation: Department of Biomedical Engineering, Fourth Military Medical University, Xi'an 710032, China. xinyin20130419@163.com.
authors.forename: Huijun
authors.initials: H
authors.lastname: Xue
authors.affiliation: Department of Biomedical Engineering, Fourth Military Medical University, Xi'an 710032, China. fmmujxj@fmmu.edu.cn.
authors.forename: Xijing
authors.initials: X
authors.lastname: Jing
authors.affiliation: Department of Biomedical Engineering, Fourth Military Medical University, Xi'an 710032, China. sheng@mail.xjtu.edu.cn.|Shaanxi University of Technology, Hanzhong 723001, China. sheng@mail.xjtu.edu.cn.
authors.forename: Jianqi
authors.initials: J
authors.lastname: Wang
mesh_terms: D000328:Adult; D000465:Algorithms; D005260:Female; D006801:Humans; D008297:Male; D012815:Signal Processing, Computer-Assisted; D013018:Sound Spectrography; D013060:Speech / Q000145:classification*; D055815:Young Adult
keywords: 94 GHz MMW; empirical mode decomposition; mutual information entropy; radar speech; speech enhancement