中国声学学会五届三次常务理事扩大会议在深圳召开

中国声学学会五届三次常务理事扩大会议于2004年11月21-23日在深圳大学召开。 会议由田静副理事长主持,深圳大学邢副校长出席会议并致欢迎词。杨士莪院士代表中国声学学会五届三次常务理事扩大会议的全体代表对深圳大学给予会议的支持表示感谢。16位常务理事出席了会议(因事未能到会的常务理事委派了代表),中国声学学会名誉理事长应崇福院士参加了会议。各分会秘书列席了会议。 宗健秘书长传达了中国科协关于加强学术交流活动、提高学术会议质量、认真办好学术刊物和学会改     

Stochastic Resonance in an Over-Damped Bias Linear System with Dichotomous Noise

The stochastic resonance in an over-damped bias linear system subject to multiplicative and additive dichotomous noise （DN） is investigated. By using the linear-response theory and the properties of the DN, the exact expressions are found for the signal-to-noise ratio （SNR）. It is shown that the SNR is a non-monotonic function of the correlation time of the additive DN, and it varies non-monotonically with the bias of the external field, the intensity and asymmetry of the multiplicative DN, as well as the external field frequency. Moreover, the SNR depends on the bias of the system, as well as the strength and asymmetry of the additive DN.     

863合成孔径声纳项目通过验收

由中国科学院声学研究所主持研制的国内第一套合成孔径声纳海试样机于2005年底在浙江舟山海域进行的海上试验中获得圆满成功，并于2006年初顺利通过863专家组验收。该样机不仅填补了国内空白，而且主要指标已经达到国际先进水平。     

On study of the theory and algorithm of the three dimensional coupled mode － parabolic equation

A fast algorithm of sound propagation in three dimensional underwater environments is presented. On the basis of the generalized phase integral (WKBZ) theory and the beam displacement ray mode (BDRM) theory, the coupled mode parabolic equation (CMPE) theory of sound propagation in range dependent underwater environment is extended for three dimensional (3D) problems. The CMPE3D solution is expressed in terms of the normal modes in vertical direction and the coupled mode amplitude coefficients in horizontal directions. By using the WKBZ theory and the BDRM theory, the local normal mode analysis can be processed efficiently. A PE-based algorithm, which was implemented in model FOR3D by Lee D et al [“Numerical Ocean Acoustic Propagation in Three Dimensions“, World Scientific, Singapore, 1995] is also adopted to solve the coupled mode amplitude coefficients. Numerical simulations indicate that the efficiency has been greatly improved by using CMPE3D instead of the PE approximations.     

Speech recognition based on a combination of acousticfeatures with articulatory information

The contributions of the static and dynamic articulatory information to speech recognition were evaluated, and the recognition approaches by combining the articulatory information with acoustic features were discussed. Articulatory movements were observed by the Electromagnetic Articulographic System for reading speech, and the speech signals were recorded simultaneously. First, we conducted several speech recognition experiments by using articulatory features alone, consisting of a number of specific articulatory channels, to evaluate the contribution of each observation point on articulators. Then, the displacement information of articulatory data were combined with acoustic features directly and adopted in speech recognition. The results show that articulatory information provides with additional information for speech recognition which is not encoded in acoustic features. Furthermore, the contribution of the dynamic information of the articulatory data was evaluated by combining them in speech recognition. It is found that the second derivative of articulatory information provided quite larger contribution to speech recognition comparing with the second derivative of acoustical information. At last, the combination methods of articulatory features and acoustic ones were investigated for speech recognition. The basic approach is that the Bayesian Network (BN) is added to each state of HMM, where the articulatory information is represented by the BN as a factor of observed signals during training the model and is marginalized as a hidden variable in recognition stage. Results based on this HMM/BN framework show a better performance than the traditional method.     

Experimental studies on the multistage constant modulus array for the estimation of directions-of-arrival

The performance of the multistage Constant Modulus (CM) array, one of the most striking blind beamforming algorithms, for the source Directions-of-Arrival (DOA) estimation was analyzed via computer simulations and water tank experiments, and was compared to that of other DOA estimation algorithms including the ‘non-blind‘ and the ‘blind‘. Firstly, a nominal array model and an array model with gain and phase perturbations were established,respectively. Secondly, the multistage CM array algorithm was described and computer simulations were conducted. Simulation results showed that the multistage CM array could correctly estimate the DOA at the same time when the sources were blindly recovered, and the angle separating ability of the algorithm was beyond the Rayleigh resolution limit. By changing the variance of the array model errors, it was also verified that the multistage CM array was more robust to the errors than some other algorithms mentioned in this paper. Finally, water tank experiments and data processing results were provided. Situations with different array sizes and source angular separations were considered. It was shown that the results were in good agreement with computer simulations. Results of computer simulations and water tank experiments verified that the DOAs of the multiple independent sources could be blindly and robustly estimated with the multistage CM array.     

《应用声学》征稿简则

《应用声学》是声学领域的学术刊物，中国自然科学核心期刊，中国科学引文数据库、中国科技论文统计用刊，国内外公开发行，办刊的宗旨是繁荣应用声学事业，促进新成果的开发与推广，促进科研、工程技术人员与生产实践者之间的相互了解和合作，读者对象是从事声学方面科研、教学、医疗、产品与设备开发、科技管理、企业管理的工作者，以及大专院校学生。