ABSTRACT
Speech enhancement methods based on microphone array adopt many microphones to record speech signal simultaneously. As spatial information is increased, these methods can increase speech recognition for cochlear implant in noisy environment. Due to the size limitation, the number of microphones used in the cochlear implant cannot be too large, which limits the design of microphone array beamforming. To balance the size limitation of cochlear implant and the spatial orientation information of the signal acquisition, we propose a speech enhancement and beamforming algorithm based on dual thin uni-directional / omni-directional microphone pairs (TP) in this paper. Each TP microphone contains two sound tubes for signal acquisition, which increase the overall spatial orientation information. In this paper, we discuss the beamforming characteristics with different gain vectors and the influence of the inter-microphone distance on beamforming, which provides valuable theoretical analysis and engineering parameters for the application of dual microphone speech enhancement technology in cochlear implants.
Subject(s)
Humans , Algorithms , Cochlear Implants , Equipment Design , Noise , Speech , Speech PerceptionABSTRACT
Microphone array based methods are gradually applied in the front-end speech enhancement and speech recognition improvement for cochlear implant in recent years. By placing several microphones in different locations in space, this method can collect multi-channel signals containing a lot of spatial position and orientation information. Microphone array can also yield specific beamforming mode to enhance desired signal and suppress ambient noise, which is particularly suitable to be applied in face-to-face conversation for cochlear implant users. And its application value has attracted more and more attention from researchers. In this paper, we describe the principle of microphone array method, analyze the microphone array based speech enhancement technologies in present literature, and further present the technical difficulties and development trend.
Subject(s)
Humans , Cochlear Implantation , Cochlear Implants , Speech , Speech PerceptionABSTRACT
Objective The fractional realization of delayed parameters will occurs when using microphone array technology in cochlear implants. To study the design and mismatch feature of fractional delay filter so as to meet the requirement of fractional delay realization in cochlear implants. Methods According to the characteristics of small cochlear implants and delay requirements, a fractional delay filter was designed by least mean square method. Results The fractional delay filtering method based on least mean square interpolation can achieve fractional delay, and can minimize the average error and the mean square error of the whole frequency band. Conclusions The fractional delay filter based on least mean square interpolation has the features of mismatch and high-order flat error, which makes it have theoretical and engineering value and providing a parameter selection method for the design of fractional delay filter.
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Objective To compare medium-term therapeutic effect by bilateral and unilateral puncture plasma coblation nucleoplasty(PCN) in the lumbar disc herniation patients. Methods 90 cases confirmed no significant rupture of annulus fibrosus of lumbar disc herniation by CT or MRI were randomly divided into two groups. Bilateral and unilateral puncture plasma coblation nucleoplasty groups were respectively divided into group A and group B, and compared the JOA scores. Results 82 patients were followed up for 10 ～ 32 months,the average follow-up time was 16.2 months. Preoperative JOA scores of the two groups were not statistically significant(P ＞ 0.05) but the postoperative follow-up JOA scores were higher than preoperative(P ＜0.05) and the JOA scores of group A were higher than group B(P ＜0.05). Conclusion The medium-term therapeutic efficacy of bilateral puncture coblation nucleoplasty was superior to unilateral therpy.
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Objective To study the best extraction method for Radix Salvia Miltiorrhiza effective component. Methods Several extraction methods for Radix Salvia Miltiorrhiza (water decoction, alcohol reflux, ultrasonic extraction and supercritical CO2 extraction) were compared, to optimize the extraction methods by determined of Danshensu and Tanshinone IIA of Radix Salvia Miltiorrhiza. Results Supercritical CO2 extraction had high content of effective component of Danshensu and Tanshinone IIA. Conclusion Supercritical CO2 extraction was the best extraction method for Radix Salvia Miltiorrhiza. This result would be an experimental proof for pre-processing the preparation of Radix Salvia Miltiorrhiza.
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Objective To evaluate the efficacy of Grosse Kempf interlocking intramedullary nailing (Grosse Kempf IIN) and AO plate in the treatment of tibial fractures. Methods A retrospective analysis was done on the recovery of 55 cases with tibial fractures treated with the Grosse Kempf IIN (Group A) and 40 treated with AO plate (Group B) from 1994. Results The 10 26 months follow up showed that the healing rate and the infection rate were 98.2% (54/55) and 1.8% (1/55) respectively in the Group A with a mean healing time for 5.6 months and 90.0% (36/40) and 12.5% (5/40) respectively in the Group B with a mean healing time for 7.5 months. Conclusions The Grosse Kempf IIN has obvious advantage of excellent biodynamics, reliable fixation, simple operation, less trauma on regional blood supply and is more effective in the treatment of tibial fractures than the AO plate. Nevertheless, I IN itself has limitation for further application.
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Object To stuay the quality of seedling leaves cultured from improved variety of Ginkgo biloba L.. Methods The content of terpene lactones in seedling leaves of G. biloba were determined by RP-HPLC-ELSD.Results The content of total terpene lactone producted in Jun. was more than that in Aug., and it was obviously lower in Nov.. The content of terpene lactone in grafting was more than that in seedling. The content of terpene lactone in male trees was more than that in female trees.Conclusion The content of the active components was related to the season of growth, age of tree, raising modes, environment of growth, geographic conditions and others. The evaluation of the content of the main active components BB and GB showed that the quality of seedling leaves cultured from improved variety of G. biloba in Jinagxi is better than that reported by literature.
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This paper introduces a typical network framework based on VPN.With emphasis on network's security and stability,it describes how to construct a remote network based on Internet with VPN by focusing on such facts as security,service quality and expansion,etc.Finally,some natures about VPN both in technique and security are shown.