应用于助听器反馈抑制的信噪比自适应滤波算法

针对基于自适应滤波器的助听器反馈抑制系统,该文提出了一种基于信噪比的归一化最小均方误差算法,采用最小值统计法估计误差信号的噪声分量,从而计算出误差信号的信噪比来计算自适应滤波系数的更新步长。当误差信号信噪比越高,语声占主要成分,信号的相关性越强,此时将滤波器的更新步长控制在较小值,减小滤波器的失调量;当信噪比越低时,噪声占主要成分,信号的相关性相对较弱,更新步长取较大值,加快滤波器的收敛速度。在仿真实验中,该文提出的基于信噪比的归一化最小均方误差算法相较于传统算法在平均稳态失调量和稳态失调范围上分别低1 dB和2 dB,其最大稳态增益提高了4 dB,同时具有更快的稳态收敛速度,验证了该文提出算法的有效性。     

分析滚动轴承部分油膜润滑状态的两种计算模型

油膜压降法是应用于滚动轴承部分油膜润滑状态测试的简单而有效的方法。本文根据接触表面的形貌参数及其高度的概率密度函数给出了两种计算油膜压降比与油膜厚度关系的模型——接触电阻模型和接触率模型,并将其计算结果与试验结果进行了对比,发现当油膜较厚而接触峰数很少时,接触率模型的计算值与实测值吻合得较好;在部分油腆较薄而接触峰数很多的情况下,接触电阻模型的计算值比较符合于实测值。     

The Analysis of Mammalian Hearing Systems Supports the Hypothesis That Criticality Favors Neuronal Information Representation but Not Computation

In the neighborhood of critical states, distinct materials exhibit the same physical behavior, expressed by common simple laws among measurable observables, hence rendering a more detailed analysis of the individual systems obsolete. It is a widespread view that critical states are fundamental to neuroscience and directly favor computation. We argue here that from an evolutionary point of view, critical points seem indeed to be a natural phenomenon. Using mammalian hearing as our example, we show, however, explicitly that criticality does not describe the proper computational process and thus is only indirectly related to the computation in neural systems.     

Impact of unilateral hearing loss on sound localization

The impact of unilateral hearing loss on the localization of horizontal plane sound sources ipsilateral and contralateral to the side of the unimpaired ear was examined. Normal-hearing listeners judged the direction of six loudspeakers, separated by 30° and arrayed frontally or laterally on the right side with the right or left ear occluded. The benefit of massed practice over three sequential days was assessed. For the frontal loudspeaker array, azimuthal discrimination on the occluded side was poor but only 30% of sounds were perceived to come from the unoccluded side. For the right lateral array, when the ipsilateral ear was unoccluded, front and back were rarely confused. Accuracy mainly decreased for speakers close to the midline axis, front and back. When the contralateral ear was unoccluded responses were biased toward the rearmost speaker. Practice did not improve performance. The findings were discussed within the context of military operations. They support the need for job-specific hearing standards.     

Head-related transfer function database and its analyses

Based on the measurements from 52 Chinese subjects (26 males and 26 females), a high-spatial-resolution head-related transfer function (HRTF) database with corre- sponding anthropometric parameters is established. By using the database, cues relating to sound source localization, including interaural time difference (ITD), interaural level difference (ILD), and spectral features introduced by pinna, are analyzed. Moreover, the statistical relationship between ITD and anthropometric parameters is estimated. It is proved that the mean values of maximum ITD for male and female are significantly different, so are those for Chinese and western sub- jects. The difference in ITD is due to the difference in individual anthropometric parameters. It is further proved that the spectral features introduced by pinna strongly depend on individual; while at high frequencies (f≥ 5.5 kHz), HRTFs are left-right asymmetric. This work is instructive and helpful for the research on bin- aural hearing and applications on virtual auditory in future.     

从表演者角度论述歌剧院的声学研究和设计

本文从解决歌手与乐队竞争的谜团入手,详述了歌剧院乐队演奏(缺乏高频声)和歌剧唱法(高频的歌手共振峰)的声音特点,进而提出了歌手和乐队之间平衡的声学设计(即放大歌手的歌唱声并适当降低乐队的演奏声,观众听起来歌手和乐队之间的声音保持平衡),重点论述了乐池的声学设计。然后分别从提高表演者的相互听闻(为了合奏的同步性)和提高房间的声反馈(为了控制演奏的响度)进行了论述,得出从表演者角度进行声学研究和设计的重要性。