Discrete representation of perceptual structure underlying consonant confusions

The perceptual representation of speech is generally assumed to be discrete rather than continuous, pointing to the need for general discrete analytic models to represent observed perceptual similarities among speech sounds. The INDCLUS (INdividual Differences CLUStering) model and algorithm [J.D. Carroll and P. Arabie, Psychometrika 48, 157-169 (1983)] can provide this generality, representing symmetric three-way similarity data (stimuli X stimuli X conditions) as an additive combination of overlapping, and generally not hierarchial, clusters whose weights (which are numerical values gauging the importance of the clusters) vary both as a function of the cluster and condition being considered. INDCLUS was used to obtain a discrete representation of underlying perceptual structure in the Miller and Nicely consonant confusion data [G.A. Miller and P.E. Nicely, J. Acoust. Soc. Am. 27, 338-352 (1955)]. A 14-cluster solution accounted for 82.9% of total variance across the 17 listening conditions. The cluster composition and the variations in cluster weights as a function of stimulus degradation were interpreted in terms of the common and unique perceptual attributes of the consonants within each cluster. Low-pass filtering and noise masking selectively degraded unique attributes, especially the cues for place of articulation, while high-pass filtering degraded both unique and common attributes. The clustering results revealed that perceptual similarities among consonants are accurately modeled by additive combinations of their specific and discrete acoustic attributes whose weights are determined by the nature of the stimulus degradation.     

Identification of a parametric loudspeaker system using an adaptive Volterra filter

Due to the parametric acoustic array effect in air, the input audible signal of a parametric loudspeaker system can be reproduced with high directivity at the target region. However, the reproduced audible signal suffers from harmonic distortion, which is the by-product of nonlinear interaction between the primary waves. In order to investigate this inherent nonlinear phenomenon, a nonlinear system identification model is developed based on an adaptive Volterra filter. Unlike the conventional loudspeaker, the nonlinear characteristic of a parametric loudspeaker system is dependent on several primary parameters in nonlinear acoustics, which include the initial pressure of the primary waves, the observing distance and angle, as well as ambient temperature and relative humidity. By using a truncated Volterra series up to the 2nd-order kernel, numerical simulations are conducted to develop a system model with one group of parameters and examine the quadratic nonlinear intensity for different parameters’ settings. Experimental measurements, which take into account of emitter’s response, are carried out to verify the modeling result and evaluate the model performance. Based on the Volterra system model, the sound pressure level and the harmonic distortion can be accurately predicted.     

扬声器锥壳的全频段强迫振动解

解析和数值研究了扬声器锥壳全频段的轴对称强迫振动。给出了典型低频段、典型转点频段和典型高频段的显式位移解析解、特征频率方程和轴向导纳表达式。解析结果与数值计算和实验结果结果非常吻合。在典型低频段,振动完全是纵波型的。在典型转点频段,全域的纵波运动和转点外侧域的横波运动共存,谐振和反谐振频率方程相应呈现出无矩解和弯曲解的耦合特性。在典型高频段,全域的纵波运动和横波运动互相独立,相应出现2组独立的纵波和横波固有频率。     

The underlying linear dynamics of some positive polynomial systems

The conditions of structural dynamical similarity of two special classes of positive polynomial nonlinear systems, the class of quasi-polynomial systems (Brenig (1988) [1]) and that of reaction kinetic networks with mass action kinetics (Horn and Jackson (1972) [2]) are investigated in this Letter. It is shown that both system classes have an underlying reduced linear dynamics. By applying the theory of X-factorable systems (Samardzija et al. (1989) [9]), it can be shown that the reduced linear dynamics is qualitatively similar to the original one within the positive orthant when the original nonlinear system has a unique positive equilibrium point.     

An analytical model for a dodecahedron loudspeaker applied to the design of omni-directional loudspeaker arrays

The dodecahedron (12 sided) loudspeaker is used extensively for acoustic measurements as an approximation to an omni-directional sound source, for example in building acoustics and automotive applications. In many instances its use is favoured above other omni-directional source approximations e.g. open pipe because of its greater power. However, analysis by other authors has shown that the radiation deviates from omni-directional above a certain frequency. In this paper an analytical model of the sound pressure field generated by a dodecahedron loudspeaker is constructed. The sound pressure field generated by the model is then compared with measured data and good agreement is demonstrated. Having established and validated the model, it is adapted to form alternative spherical loudspeaker arrays based on Platonic and Archimedean solid geometry and also a number of spherical packing routines. The aim of the analysis is to determine the optimal geometry for an omni-directional source using pistonic loudspeakers.The analysis shows that constructive interference of the pressure field across the spherical baffle surface and not individual loudspeaker pistonic radiation characteristics is the most significant factor with respect to deviations from omni-directional radiation for a complete spherical array. Consequently, loudspeaker elements which physically occupy the spherical baffle surface to their maximum extent provide the most extended frequency range of omni-directional operation. The most optimal spherical array distribution is shown to be the dodecahedron.     

扬声器的优化设计

基于有限元法发展了扬声器的计算机辅助设计，由此分析了扬声器的振动特征，讨论了各参数对扬声器振动及声辐射的影响，最后地其声压频响的优化措施作了探讨。     

Fractal dimensions in perceptual color space: a comparison study using Jackson Pollock's art

The fractal dimensions of color-specific paint patterns in various Jackson Pollock paintings are calculated using a filtering process that models perceptual response to color differences (L*a*b* color space). The advantage of the L*a*b* space filtering method over traditional red-green-blue (RGB) spaces is that the former is a perceptually uniform (metric) space, leading to a more consistent definition of "perceptually different" colors. It is determined that the RGB filtering method underestimates the perceived fractal dimension of lighter-colored patterns but not of darker ones, if the same selection criteria is applied to each. Implications of the findings to Fechner's "principle of the aesthetic middle" and Berlyne's work on perception of complexity are discussed.     

对我国扬声器研究与产业发展的建议之管见

据统计，我国已经是扬声器单元的生产大国。但是，我国多数扬声器产品还是处在低、中档技术含量的水平，生产厂的研究能力也还相当薄弱和缺乏战略安排，他们的产品开发也多是处在选料装配的状态。     

扬声器锥壳的全频段振动通解

为更好地理解扬声器数值计算结果,解析研究了扬声器锥壳轴对称振动在整个工作频段一致有效的通解,这些解以特殊函数的形式给出。在典型低频段,弯曲解仅表现为边界层效应;在典型转点频段,弯曲解存在于转点的外侧域;在典型高频段,弯曲解覆盖了整个扬声器锥壳。无矩解和弯曲解在转点频段是耦合的,该耦合特性表明在此频段不可能消除分割振动。     

扬声器辐射体旋转薄壳的谐波失真

研究了扬声器辐射体旋转薄壳几何非线性引起的谐波失真。采用摄动法和有限元法确定了2次和3次谐波振型,计算了薄壳材料参数和几何参数对谐波失真的影响。结果表明扬声器薄壳谐波失真的机制是分割振动模态的基波共振和超谐波共振,以基波共振为主。采用高阻尼、大杨氏模量和低密度的振膜材料可以降低振膜谐波失真;厚度对谐波失真的峰值影响不大;锥壳半顶角过大,可使3次谐波明显增大。     

Analysis and prediction of loudspeaker large-signal symptoms

Nonlinear lumped-parameter force factor Bl(x), stiffness K _ms(x) and inductance L _e(x) of electrodynamic loudspeakers change frequency responses and generate some nonlinear effects for large stimulus: harmonic and intermodulation distortion, DC component in diaphragm displacement, instability of vibration and jumping effects. By modeling the nonlinear system under large-signal conditions, relationship between the nonlinear parameters and large-signal behavior can be revealed and help to provide guidance to diagnose loudspeakers. Agreement between the measured and predicted responses of a real loudspeaker validates the modeling and enables new methods for loudspeaker diagnosis.     

Quantum dimensions and irreducible modules of some diagonal coset vertex operator algebras

Letters in Mathematical Physics - In this paper, under the assumption that the diagonal coset vertex operator algebra $$C(L_{mathfrak {g}}(k+l,0),L_{mathfrak {g}}(k,0)otimes L_{mathfrak...     

Acoustical performance of an electrostrictive polymer film loudspeaker

A new type of loudspeaker that generates sound by means of the electrostrictive response of a thin polymer film is described. Electrostrictive polymer film (EPF) loudspeakers are constructed with inexpensive, lightweight materials and have a very low profile. The films are typically silicone and are coated with compliant electrodes to allow large film deformations. Acoustical frequency response measurements from 5 x 5 cm (planar dimensions) prototype EPF loudspeakers are presented. Measurements of harmonic distortion are also shown, along with results demonstrating reduced harmonic distortion achieved with square-root wave shaping. Applications of EPF loudspeakers include active noise control and general-purpose flat-panel loudspeakers.     

Performances and design of ironless loudspeaker motor structures

This paper presents several kinds of structures of ironless loudspeaker motors. The proposed devices go from simple structures, in terms of manufacturing process, to structures in which the magnet rings can be stacked, with different magnetization directions or values. The structures are studied and compared according to their created induction level and uniformity across the coil displacement range, which are directly linked to the loudspeaker performances (force factor). The model used is the coulombian model of magnets to calculate the magnetic field created, therefore all the calculations are analytical. The paper shows that no structure is universal when it comes to the loudspeaker design: some are well adapted to micro displacements of the coil while other structures are adapted to large displacements.     

Acoustic characteristics of an electrodynamic planar digital loudspeaker

In this paper, an electrodynamic planar loudspeaker driven by a digital signal is experimentally discussed. The digital loudspeaker consists of 22 voice coils, 11 permanent magnets, a diaphragm with streamlined sections molded in plastic, and a suspension made of handmade Japanese paper between the diaphragm and the frame. First, the acoustic responses are affected by the arrangement of the voice coils, so an asymmetric arrangement is studied. This asymmetric arrangement is designed to obtain as flat a frequency response to an analog signal as possible. This arrangement is compared with a symmetric one and results show that the flatness of the frequency response around 1 kHz and 4 kHz is improved and that the sound reproduction band is from 40 Hz to 10 kHz. Second, to evaluate the acoustic responses to a digital signal, the digital loudspeaker is driven with a pulse code modulation signal. Results show that the digital loudspeaker can reproduce pure sound with a total harmonic distortion of less than 5% from 40 Hz to 10 kHz, exceeding this value only in a narrow frequency band near 4 kHz. This digital loudspeaker was demonstrated to have good linearity over its dynamic range of 84 dB.     

电动扬声器悬置系统蠕变效应建模

对电动扬声器悬置系统的蠕变效应进行了分数阶建模。通过将标准线性固体模型中的牛顿黏壶替换为分数阶Abel黏壶,提出了悬置系统分数阶标准线性固体力顺模型。使用Klippel扬声器单元电阻抗激光测量系统,测量了2只具有不同橡胶折环的中频扬声器单元的电阻抗和传递函数(振膜输出位移/输入声压),并采用最小二乘法拟合实测曲线,得到了模型参数。通过与已有的考虑蠕变效应的4参数对数模型和标准线性固体模型拟合结果的对比,结果表明:分数阶标准线性固体模型能够准确描述力顺损耗因数随频率的变化规律,对蠕变效应具有更好的模拟精度。     

四阶带通箱的自回归滑动平均模型

建立扬声器系统的离散时间模型是对其进行数字控制的基础。研究给出了使用LR-2理论优化的四阶带通箱的自回归滑动平均模型,推导其传递函数方程组,构建其时域差分迭代式,形成离散时间形式的表述,用以描述系统的瞬态行为。实验结果表明,与基于状态空间方程的差分求解方法相比,该文给出的自回归滑动平均模型更为稳定精确,对采样率的要求更低。该方法为实现对扬声器的前馈数字控制提供了参考。     

The dimensions of some self-affine limit sets in the plane and hyperbolic sets

In this article we compute the Hausdorff dimension and box dimension (or capacity) of a dynamically constructed model similarity process in the plane with two distinct contraction coefficients. These examples are natural generalizations to the plane of the simple Markov map constructions for Cantor sets on the line. Some related problems have been studied by different authors; however, those results are directed toward generic results in quite general situations. This paper concentrates on computing explicit formulas in as many specific cases as possible. The techniques of previous authors and ours are correspondingly very different. In our calculations, delicate number-theoretic properties of the contraction coefficients arise. Finally, we utilize the results for the model problem to compute the dimensions of some affine horseshoes in ⁿ , and we observe that the dimensions do not always coincide and their coincidence depends on delicate number-theoretic properties of the Lyapunov exponents.     

封闭式扬声器系统空气劲度的非线性研究

从理想气体多变过程的状态方程出发,推导了封闭式扬声器系统的非线性空气劲度的理论公式。研究发现,封闭式扬声器系统的非线性空气劲度与音圈运动位移、有效辐射面积、箱体有效容积和多变系数等主要因素有关。通过实验,分别测量了封闭式扬声器系统与扬声器单元的非线性劲度,二者相减获得封闭式扬声器系统的非线性空气劲度。实测数据与理论计算得到很好的吻合。