人工耳蜗植入者音乐感知研究

目前,大部分人工耳蜗使用者在安静情况下的言语感知能力基本达到较高水平,然而其音乐感知能力尚未达到理想水平,音乐感知研究已成为目前人工耳蜗领域主要关注的研究方向之一。主要探讨人工耳蜗使用者音乐感知研究的研究方法、材料,并分析影响其音乐感知能力的主要因素。对音乐的四大要素即音高、时长、响度及音色等的研究进展进行讨论,从信息的传输和接收间的关系分析影响人工耳蜗植入者音乐感知的因素。对现有的主、客观测试以及调查问卷等研究手段进行总结。综合分析了目前音乐感知研究的进展,并对未来的研究发展方向进行展望。     

神经营养因子与人工耳蜗的实验研究

综述了在听觉神经系统中，神经营养因子与听力损伤、电刺激、突触疲劳的关系；介绍了神经营养因子保护听觉的分子机制，及神经营养因子在人工耳蜗研究中的应用前景和意义。     

人工耳蜗信号处理策略研究

人工耳蜗是一种帮助重度和极重度听力损失者恢复听觉的电子装置。人工耳蜗信号处理策略是人工耳蜗的关键技术之一,决定了人工耳蜗电极输出的信号特征。介绍了电刺激听觉机理,按照时间顺序对主要的人工耳蜗信号处理策略进行介绍,并从听觉感知模型理论的角度对过去40年中在人工耳蜗信号处理策略研究上取得的进展进行深入探讨,最后对未来的人工耳蜗信号处理策略的研究方向提出展望。     

压电型人工耳蜗的实验研究

系统研究了不同特性的压电陶瓷植入耳蜗及其植入位置对听阈变化的影响，实验结果表明，植入材料的机电耦合系数和电容越大，听阈下降越明显；陶瓷片置于鼓介中内侧贴于螺旋神经表面成功率最高。充分证实了压电陶瓷片植入耳蜗可模拟毛细胞进行声电转换，刺激听神经引起听觉，提高聋耳的呼力这一新构想是成功的。     

基于压电效应的人工耳蜗的实验研究

为了提高聋耳的听力, 将压电材料植入到耳蜗内, 利用压电效应直接将声波转化为电信号刺激听神经, 以提高听力. 本研究通过未极化与极化的高灵敏性压电陶瓷的对比, 从体外模拟实验中的声电响应曲线和动物体内植入实验的结果中得到: 未极化的压电陶瓷没有压电响应, 而极化后的压电陶瓷能够将声音信号转化为电信号, 证实了压电陶瓷的压电特性的确可以刺激动物的听神经, 从而降低听阈阈值. 比较了压电陶瓷与压电高分子之间的差异, 结果表明压电高分子也可以刺激听神经来提高听力.     

人工耳蜗使用者音乐感知评估系统的设计

该文的目的是设计一套适用于我国人工耳蜗使用者的音乐感知评估系统。所选评估内容包括听辨测试和问卷调查,用以考察人工耳蜗使用者对音乐要素的辨识能力和其聆听感受。听辨测试包括5种不同音色和3个频率范围的音高最小可辨差阈、音高方向分辨和旋律轮廓识别测试;调查问卷包括音乐背景和听赏水平问卷及音乐体验问卷。3名人工耳蜗使用者和6名正常听力者参加了系统验证测试,听辨测试结果与国外类似研究具有可比性。问卷调查的结果显示了音乐教育背景、主观聆听感受与听辨测试之间的联系。     

基于COTS的人工耳蜗体外语音处理器设计与实现

人工耳蜗是目前治疗深度或重度耳蜗性聋的唯一有效的办法,由体外语音处理器和植入体组成。介绍了一种基于商用现货原则（COTS,Commercial-Off-The-Shelf）的低功耗人工耳蜗体外语音处理器的设计与实现：系统选用低功耗立体声A/D芯片CS53L21实现前端处理和采集语音信号;利用通用16位定点DSP芯片TMS320VC5502实现语音处理CIS算法;借用RFID射频芯片MLX90121向植入体传输能量并与其进行双向数据通信。     

电刺激参数与ECAP阈值关系的研究

0引言人工耳蜗是唯一可以帮助感音神经性重度耳聋患者恢复部分听力的装置。人工耳蜗系统中的语音处理策略是将外界的语音信号进行处理后,转换为电信号通过编码的方式发送到植入体并传输到相应的电极刺激耳蜗内残余的听觉神经,目前商用人工耳蜗产品较多采用的连续交错采样法(CIS,Continuous Interleaved Sampling)策略受刺激速率、     

人工海水中铝合金与复合材料T700电偶的腐蚀性能

采用失重法、腐蚀电化学试验方法、电偶腐蚀试验方法,研究了铝合金(Al6061)在人工海水中的耐腐蚀性能和电化学特性及其与环氧碳纤维复合材料T700偶接后的电偶腐蚀敏感性.结果表明,Al6061在人工海水中有一定的电化学腐蚀钝化性;Al6061与T700偶接后,电偶腐蚀使Al6061的腐蚀速度明显加快,人工海水中通入空气使电偶腐蚀程度增大;在T700表面涂敷环氧树脂涂层,能有效控制T700与Al6061之间的电偶腐蚀.     

SBN系列人工晶体的合成与初步研究

以SrNb2O6-BaNb2O6的赝二元体系相图为基础来合成这个体系中的3种物质,根据X射线粉晶衍射图谱中显示数据的分析,发现了相图中的端元相SrNb2O6、BaNb2O6和中间相Sr0.5Ba0.5Nb2O6在结构上的不连续性.计算了3种合成晶体的晶胞参数和化学分子式.     

采用短时傅立叶变换方法的电子耳蜗语音处理技术

电子耳蜗是用有限个电极刺激听神经以恢复全聋人听觉的装置,目前发展的关键目标是研制出可靠、灵活、价格低廉的产品。在介绍了电子耳蜗的原理和语音信号处理方案的发展的基础上,研究了采用短时傅立叶变换方法的电子耳蜗语音处理技术。据此法分析提取参数用以刺激耳蜗内的听神经,使聋人恢复听觉,该技术的优点在于:能根据每个耳聋病人的毛细胞和神经残留多少等情况的不同来灵活的选择刺激参数,达到较好的语音识别效果。     

各频段的时域周期波动信息在中文元音和音调认知中的作用

各种时域包络信息中,周期波动信息能显著增强频谱信息严重受损时的中文音调和句子识别;分析各频段的时域周期波动信息对中文语音识别的作用具有重要的理论和实际意义。为了在不同频段中保留时域周期波动信息,4频段电子耳蜗声学模拟实验使用不同的低通滤波截止频率来提取各频段的时域包络。6种低通滤波截止频率组合包括:4频段都使用50Hz(all-50),4频段都使用500Hz(all-500),4频段中某一频段使用500Hz而其余三频段使用50Hz(ch1-500等)。辨识结果显示:ch4-500组合产生最高的,与all-500组合相似、比all-50组合显著增强的音调识别;而元音识别则不随低通滤波截止频率组合发生显著变化。这表明传递最高频段的时域周期波动信息对增强电子耳蜗使用者的中文音调识别最重要。     

A novel mechanism of cochlear excitation during simultaneous stimulation and pressure relief through the round window

The round window (RW) membrane provides pressure relief when the cochlea is excited by sound. Here, we report measurements of cochlear function from guinea pigs when the cochlea was stimulated at acoustic frequencies by movements of a miniature magnet which partially occluded the RW. Maximum cochlear sensitivity, corresponding to subnanometre magnet displacements at neural thresholds, was observed for frequencies around 20 kHz, which is similar to that for acoustic stimulation. Neural response latencies to acoustic and RW stimulation were similar and taken to indicate that both means of stimulation resulted in the generation of conventional travelling waves along the cochlear partition. It was concluded that the relatively high impedance of the ossicles, as seen from the cochlea, enabled the region of the RW not occluded by the magnet, to act as a pressure shunt during RW stimulation. We propose that travelling waves, similar to those owing to acoustic far-field pressure changes, are driven by a jet-like, near-field component of a complex pressure field, which is generated by the magnetically vibrated RW. Outcomes of research described here are theoretical and practical design principles for the development of new types of hearing aids, which use near-field, RW excitation of the cochlea.     

Development and validation of an automated FEM-based design optimization tool for continuum compliant structures

International Journal of Mechanics and Materials in Design - This paper presents a design optimization method for continuum compliant structures. The developed optimization tool enables automated...     

Preparation and characterization of silk fibroin hydrogel as injectable implants for sustained release of Risperidone

The principal objective of the present study is to achieve a depot formulation of Risperidone by gelation of silk fibroin (SF). For this purpose, hydrochloric acid (HCl)/acetone-based and methanol-based hydrogels were prepared with different drug/polymer ratios (1:3, 1:6, and 1:15). For all the drug-loaded methanol-based hydrogels, gel transition of SF solutions occurred immediately and the gelation time was 1?min, while the gelation time of HCL/acetone-based hydrogels was around 360?min. According to the results obtined from Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) spectra, solvent systems and Risperidone could induce β-sheet structure, but HCL/acetone system had the lowest effect on induction of β-sheets. The crystallinity was increased by increasing the amount of Risperidone, and drug to polymer ratio of 1:3 possessed the highest crystallinity. Thermogravimetric analysis (TGA) indicated that increasing the amount of drug in formulation increased the stability of hydrogels, and methanol-based hydrogel with a ratio of 1:3 had the most stable structure. The release rate of Risperidone from methanol-based hydrogel at ratio of 1:3 was lower than that for HCl/acetone-based one, and it decreased by increasing the amount of Risperidone. The release of Risperidone from methanol hydrogel at ratios 1:3 and 1:6 continued up to 25?d which is acceptable for depot form of Risperidone and shows that the extended release of Risperidone was achieved successfully. In conclusion, SF hydrogel with the ability to respond to the environmental stimuli is an excellent candidate for injectable implants for extended release of Risperidone.     

Development and experimental validation of an overlay mortar with biocide activity

Biodeterioration of concrete by microorganism colonisation may be a problem in several structures, especially in irrigation and hydroelectric canals. The main problem in such structures is the proliferation of algae and cyanobacteria that affect the performance of the structure, increase the maintenance costs and affects its durability. A research was conducted to develop a novel cement-based material with biocide activity that can be used as an overlay mortar in existing structures, such as canals and pipes. With this aim, ten commercial biocides were evaluated in a laboratory campaign to assess the effectiveness of the compounds against the microbial colonisation of concrete. Both mono- and multicomponent formulations were designed from the commercial products, to increase their antimicrobial effect obtaining a set of biocide formulations. The formulations were submitted to a flowchart process to determine their influence on the physical properties of the concrete, evaluate the release of the actives, and their antimicrobial efficiency both before and after accelerated aging processes. During the campaign, some formulations were observed to diminish the strength of the concrete. Such behaviour was normally due to the interaction of the active with the cement hydration process. Other formulations showed a high release of active from the concrete in water, compromising the durability of the treatment. In general, monocomponent formulations did not succeed to fulfill all the requirements, thus multicomponent formulations were analysed. One studied multicomponent formulation presented particularly good results in all properties analysed. This product did not significantly change the properties of concrete and the release of active in water from the concrete was low, while the antimicrobial effects were long lasting.     

Development and validation of an analytical method for tensile strength determination of fibrous bulk solids

The increasing significance of products consisting of elongated particles or fibres along with a lack of understanding flow properties of fibrous bulk solids in processes urge for appropriate test procedures.Therefore, a tensile tester was designed with respect to the special needs in terms of test techniques of those bulk solids. The procedure of tensile strength determination was tested with regard to several possible influencing factors. Following from that, the manner of filling and filling height were identified to have the greatest influence on results. Furthermore, it is shown that the developed load system is capable of improving the repeatability of test results for fibrous bulk solids.Based on the derived standard procedure, systematic tests were carried out on beech and spruce chips in three different fractions each as well as model materials such as polypropylene fibres and differently sized bunches of glass fibres. The biomass materials have been characterised by dynamic image analysis prior to and after experiments resulting in particle size and shape factor distributions. It is found that tensile strength is affected by particle shape, size, roughness and interparticle contact area.