quantifying the effects of fast acting compression on the envelope of speech fast acting compression has several effects on the envelope of speech signals especially when a target and a background are mixed together three measures of the envelope are described which can be used to quantify these changes 1 within signal modulation correlation or coherence the degree of correlation or coherence of the envelope on a db scale of a single source across different frequency regions which is reduced by fast acting compression 2 fidelity of envelope shape the degree to which the envelope shape of the target speech in different frequency channels is preserved following compression and 3 across signal modulation correlation or coherence asmc the extent to which the target and background acquire a common component of modulation when they are compressed together which becomes greater in absolute value more negative when the target and background are compressed together values of these measures are presented and compared with intelligibility scores obtained using stimuli processed with a noise vocoder so as to preserve mainly envelope cues in a limited number of frequency channels the results suggest that the dominant factor affecting intelligibility is asmc

children learn separate aspects of speech production at different rates evidence from spectral moments one theoretical perspective on speech development holds that segmental structure gradually emerges in the utterances of children as their first words realized as roughly specified patterns of gesture are differentiated into patterns of precisely specified and carefully coordinated gestures the purpose of the present study was to test one aspect of this theoretical position namely that children s articulatory gestures are not as precisely specified as are those of adults in addition a related hypothesis was tested namely that some patterns of gesture achieve adultlike precision sooner than others to test these hypotheses the first third and fourth spectral moments were derived for fricative s and and for stop burst t and k noises in the speech samples of children 3 to 7 years of age and of adults first spectral moments for fricatives showed stronger consonant effects i e s vs for adults than for children s samples this acoustic finding replicated a previous result ni

variational inference for large scale models of discrete choice discrete choice models are commonly used by applied statisticians in numerous fields such as marketing economics finance and operations research when agents in discrete choice models are assumed to have differing preferences exact inference is often intractable markov chain monte carlo techniques make approximate inference possible but the computational cost is prohibitive on the large datasets now becoming routinely available variational methods provide a deterministic alternative for approximation of the posterior distribution we derive variational procedures for empirical bayes and fully bayesian inference in the mixed multinomial logit model of discrete choice the algorithms require only that we solve a sequence of unconstrained optimization problems which are shown to be convex one version of the procedures relies on a new approximation to the variational objective function based on the multivariate delta method extensive simulations along with an analysis of real world data demonstr

response to articulation index predictions for hearing impaired listeners with and without cochlear dead regions j acoust soc am 111 2545 2548 2002 rankovic j acoust soc am 111 2545 2548 2002 argues that the ai calculated according to fletcher s method gives good predictions of speech intelligibility for subjects with high frequency hearing loss listening to amplified speech regardless of the presence or absence of dead regions she suggests further that it seems premature to introduce a clinical test for identifying dead regions because it is not clear what information is gained beyond what is obtainable by calculating the ai i argue that in fact the ai is not accurate in predicting the incremental benefit of amplifying frequencies well above the estimated edge frequency fe of a dead region for five out of nine cases application of the ai leads to the prediction that amplification of frequencies well above fe would improve speech scores by 10 15 in fact the largest improvement was 7

a galerkin interface stabilisation method for the advection diffusion and incompressible navier stokes equations abstract a stabilised galerkin finite element method for the advection diffusion and incompressible navier stokes equations is presented which inherits features of both discontinuous and continuous galerkin methods the problem of interest is posed element wise with weakly imposed dirichlet boundary conditions the dirichlet boundary condition is supplied by a function on element boundaries which is determined such that weak continuity of the flux is assured the approach allows the natural incorporation of upwinding at element boundaries which is typical of discontinuous galerkin methods while retaining the same number of global degrees of freedom as for a continuous galerkin method the formulation also stabilises mixed incompressible problems which use equal order interpolations for linear elements only minor modifications are required to existing continuous finite element codes and the link to other stabilised methods is elaborated the method is supported by a range of numerical examples which demonstrate stability with minimal numerical dissipation

the complex watson distribution and shape analysis the complex watson distribution is an important simple distribution on the complex sphere which is used in statistical shape analysis we describe the density obtain the integrating constant and provide large sample approximations maximum likelihood estimation and hypothesis testing procedures for one and two samples are described the particular connection with shape analysis is discussed and we consider an application examining shape differences between normal and schizophrenic brains we make some observations about bayesian shape inference and finally we describe a more general rotationally symmetric family of distributions

clustering on the unit hypersphere using von mises fisher distributions several large scale data mining applications such as text categorization and gene expression analysis involve high dimensional data that is also inherently directional in nature often such data is l2 normalized so that it lies on the surface of a unit hypersphere popular models such as mixtures of multi variate gaussians are inadequate for characterizing such data this paper proposes a generative mixture model approach to clustering directional data based on the von mises fisher vmf distribution which arises naturally for data distributed on the unit hypersphere in particular we derive and analyze two variants of the expectation maximization em framework for estimating the mean and concentration parameters of this mixture numerical estimation of the concentration parameters is non trivial in high dimensions since it involves functional inversion of ratios of bessel functions we also formulate two clustering algorithms corresponding to the variants of em that we derive our approach provides a theoretical basis for the use of cosine similarity that has been widely employed by the information retrieval community and obtains the spherical kmeans algorithm kmeans with cosine similarity as a special case of both variants empirical results on clustering of high dimensional text and gene expression data based on a mixture of vmf distributions show that the ability to estimate the concentration parameter for each vmf component which is not present in existing approaches yields superior results especially for difficult clustering tasks in high dimensional spaces

a new finite element formulation for computational fluid dynamics viii the galerkin least squares method for advective diffusive equations abstract galerkin least squares finite element methods are presented for advective diffusive equations galerkin least squares represents a conceptual simplification of supg and is in fact applicable to a wide variety of other problem types a convergence analysis and error estimates are presented

an analysis of the discontinuous galerkin method for a scalar hyperbolic equation we prove lp stability and error estimates for the discontinuous galerkin method when applied to a scalar linear hyperbolic equation on a convex polygonal plane domain using finite element analysis techniques we obtain l2 estimates that are valid on an arbitrary locally regular triangulation of the domain and for an arbitrary degree of polynomials lp estimates for p 2 are restricted to either a uniform or piecewise uniform triangulation and to polynomials of not higher than first degree the latter estimates are proved by combining finite difference and finite element analysis techniques

finite element methods for linear hyperbolic problems abstract we give a survey of some recent work by the authors on finite element methods for convectiondiffusion problems and first order linear hyperbolic problems

effect of spatial separation extended bandwidth and compression speed on intelligibility in a competing speech task the benefit for speech intelligibility of extending the bandwidth of hearing aids was assessed when the target speech sentences and background two talkers were co located or spatially separated also the relative benefits of slow and fast compression were assessed sixteen hearing impaired hi subjects with mild to moderate high frequency hearing loss and eight normal hearing nh subjects were tested the target and interfering sounds were recorded using a kemar manikin and were located at 60 azimuth either co located or spatially separated simulated binaural hearing aid processing using five channel slow or fast compression was performed offline with gains set individually for each hi subject upper cutoff frequencies were 5 7 5 or 10 khz processed stimuli were presented via headphones for both nh unaided and hi subjects there was no significant effect of cutoff frequency for the co located condition but a small but significant benefit from increasing the cutoff frequency from 5 to 7

an analysis of the embedded discontinuous galerkin method for second order elliptic problems the embedded discontinuous galerkin methods are obtained from hybridizable discontinuous galerkin methods by a simple change of the space of the hybrid unknown in this paper we consider embedded methods for second order elliptic problems obtained from hybridizable discontinuous methods by changing the space of the hybrid unknown from discontinuous to continuous functions this change results in a significantly smaller stiffness matrix whose size and sparsity structure coincides with those of the stiffness matrix of the statically condensed continuous galerkin method it is shown that this computational advantage has to be balanced against the fact that the approximate solutions for the scalar variable and its flux lose each a full order of convergence indeed we prove that if polynomials of degree k ge1 are used for the original hybridizable discontinuous galerkin method its approximations to the scalar variable and its flux converge with order k 2 and k 1 respectively whereas those of the corresponding embedded discontinuous galerkin method converge with orders k 1 and k respectively only we also provide numerical results comparing the relative efficiency of the methods

streamline upwind petrov galerkin formulations for convection dominated flows with particular emphasis on the incompressible navier stokes equations abstract a new finite element formulation for convection dominated flows is developed the basis of the formulation is the streamline upwind concept which provides an accurate multidimensional generalization of optimal one dimensional upwind schemes when implemented as a consistent petrov galerkin weighted residual method it is shown that the new formulation is not subject to the artificial diffusion criticisms associated with many classical upwind methods the accuracy of the streamline upwind petrov galerkin formulation for the linear advection diffusion equation is demonstrated on several numerical examples the formulation is extended to the incompressible navier stokes equations an efficient implicit pressure explicit velocity transient algorithm is developed which accomodates several treatments of the incompressibility constraint and allows for multiple iterations within a time step the effectiveness of the algorithm is demonstrated on the problem of vortex shedding from a circular cylinder at a reynolds number of 100

spectral moments vs discrete cosine transformation coefficients evaluation of acoustic measures distinguishing two merging german fricatives the results of the quantification of the acoustic differences between german c and in three speaker groups with varying contrast realizations are presented data for two speaker groups were collected in berlin and kiel where the contrast is still realized data for a third group were collected in berlin from speakers of hood german a youth style multiethnolect spoken by adolescents in multilingual and multicultural neighborhoods of berlin where the contrast has weakened or is even lost a forced choice perception test showed that listeners reliably differentiate these two fricatives in minimal pairs produced by the speakers from berlin and kiel but fail to do so for the productions of the hood german speakers the acoustic analysis reveals that spectrally the fricatives are very similar in all varieties the spectral moments center of gravity standard deviation kurtosis skewness fail to reveal the differences between the fricatives that are apparent from visual inspection of the spectra and the perceived auditory differences analyses of the discrete cosine transformation coefficients however better quantify these differences this study suggests that minute differences between fricatives that vary between speaker groups may be captured more reliably with discrete cosine transformations compared to spectral moments the results of the quantification of the acoustic differences between german c and in three speaker groups with varying contrast realizations are presented data for two speaker groups were collected in berlin and kiel where the contrast is still realized data for a third group were collected in berlin from speakers of hood german a youth style multiethnolect spoken by adolescents in multilingual and multicultural neighborhoods of berlin where the contrast has weakened or is even lost a forced choice perception test showed that listeners reliably differentiate these two fricatives in minimal pairs produced by the speakers from berlin and kiel but fail to do so for the productions of the hood german speakers the acoustic analysis reveals that spectrally the fricatives are very similar in all varieties the spectral moments center of gravity standard deviation kurtosis skewness fail to reveal the differences between the fricatives that are apparent from visual inspection of the spectra and

an anisotropic a priori error analysis for a convection dominated diffusion problem using the hdg method abstract this paper deals with the a priori error analysis for a convection dominated diffusion 2d problem when applying the hdg method on a family of anisotropic triangulations it is known that in this case boundary or interior layers may appear therefore it is important to resolve these layers in order to recover if possible the expected order of approximation in this work we extend the use of hdg method on anisotropic meshes in this context when the discrete local spaces are polynomials of degree k 0 this approach is able to recover an order of convergence k 1 2 in l 2 for all the variables under certain assumptions on the stabilization parameter and family of triangulations numerical examples confirm our theoretical results

unified hybridization of discontinuous galerkin mixed and continuous galerkin methods for second order elliptic problems we introduce a unifying framework for hybridization of finite element methods for second order elliptic problems the methods fitting in the framework are a general class of mixed dual finite element methods including hybridized mixed continuous galerkin nonconforming and a new wide class of hybridizable discontinuous galerkin methods the distinctive feature of the methods in this framework is that the only globally coupled degrees of freedom are those of an approximation of the solution defined only on the boundaries of the elements since the associated matrix is sparse symmetric and positive definite these methods can be efficiently implemented moreover the framework allows in a single implementation the use of different methods in different elements or subdomains of the computational domain which are then automatically coupled finally the framework brings about a new point of view thanks to which it is possible to see how to devise novel methods displaying very localized and simple mortaring techniques as well as methods permitting an even further reduction of the number of globally coupled degrees of freedom

constraint energy minimizing generalized multiscale discontinuous galerkin method abstract numerical simulation of flow problems and wave propagation in heterogeneous media has important applications in many engineering areas however numerical solutions on the fine grid are often prohibitively expensive and multiscale model reduction techniques are introduced to efficiently solve for an accurate approximation on the coarse grid in this paper we propose an energy minimization based multiscale model reduction approach in the discontinuous galerkin discretization setting the main idea of the method is to extract the non decaying component in the high conductivity regions by identifying dominant modes with small eigenvalues of local spectral problems and define multiscale basis functions in coarse oversampled regions by constraint energy minimization problems the multiscale basis functions are in general discontinuous on the coarse grid and coupled by interior penalty discontinuous galerkin formulation the minimal degree of freedom in representing high contrast features is achieved through the design of local spectral problems which provides the most compressed local multiscale space we analyze the method for solving darcy flow problem and show that the convergence is linear in coarse mesh size and independent of the contrast provided that the oversampling size is appropriately chosen numerical results are presented to show the performance of the method for simulation on flow problem and wave propagation in high contrast heterogeneous media

spectral moments versus bark cepstrum classification of children s voiceless stops spectral moments have been shown to be effective in deriving acoustic features for classifying voiceless stop release bursts k forrest g weismer p milenkovic and r n dougall j acoust soc am 84 115 123 1988 in this study we compared the classification of stops p t and k based on spectral moments with classification based on an equal number of bark cepstrum coefficients the speech tokens were 446 instances each of utterance initial p t and k sampled from utterances produced by 208 children 6 to 8 years old linear discriminant analysis lda was used to classify the three stops based on four analysis frames from the initial 40 ms of each token the best classification based on spectral moments used all four spectral moment features and all four time intervals and yielded 75 6 correct classification the best classification based on bark cepstrum yielded 83 4 correct also using four coefficients and four time frames differences between these results and previous classi

density estimation for protein conformation angles using a bivariate von mises distribution and bayesian nonparametrics interest in predicting protein backbone conformational angles has prompted the development of modeling and inference procedures for bivariate angular distributions we present a bayesian approach to density estimation for bivariate angular data that uses a dirichlet process mixture model and a bivariate von mises distribution we derive the necessary full conditional distributions to fit the model as well as the details for sampling from the posterior predictive distribution we show how our density estimation method makes it possible to improve current approaches for protein structure prediction by comparing the performance of the so called whole and half position distributions current methods in the field are based on whole position distributions as density estimation for the half positions requires techniques such as ours that can provide good estimates for small datasets with our method we are able to demonstrate that half position data provides a better approximation for the distribution of conformational angles at a given sequence position therefore providing increased efficiency and accuracy in structure prediction

dual scale galerkin methods for darcy flow abstract the discontinuous galerkin dg method has found widespread application in elliptic problems with rough coefficients of which the darcy flow equations are a prototypical example one of the long standing issues of dg approximations is the overall computational cost and many different strategies have been proposed such as the variational multiscale dg method the hybridizable dg method the multiscale dg method the embedded dg method and the enriched galerkin method in this work we propose a mixed dual scale galerkin method in which the degrees of freedom of a less computationally expensive coarse scale approximation are linked to the degrees of freedom of a base dg approximation we show that the proposed approach has always similar or improved accuracy with respect to the base dg method with a considerable reduction in computational cost for the specific definition of the coarse scale space we consider raviart thomas finite elements for the mass flux and piecewise linear continuous finite elements for the pressure we provide a complete analysis of stability and convergence of the proposed method in addition to a study on its conservation and consistency properties we also present a battery of numerical tests to verify the results of the analysis and evaluate a number of possible variations such as using piecewise linear continuous finite elements for the coarse scale mass fluxes

binaural speech intelligibility in noise for hearing impaired listeners the effect of head induced interaural time delay itd and interaural level differences ild on binaural speech intelligibility in noise was studied for listeners with symmetrical and asymmetrical sensorineural hearing losses the material recorded with a kemar manikin in an anechoic room consisted of speech presented from the front 0 and noise presented at azimuths of 0 30 and 90 derived noise signals containing either only itd or only ild were generated using a computer for both groups of subjects speech reception thresholds srt for sentences in noise were determined as a function of 1 noise azimuth 2 binaural cue and 3 an interaural difference in overall presentation level simulating the effect of a monaural hearing aid comparison of the mean results with corresponding data obtained previously from normal hearing listeners shows that the hearing impaired have a 2 5 db higher srt in noise when both speech and noise are presented from the front and 2 6 5 1 db less binaural gain when the noise azimuth is changed from 0 to 90 the gain due to ild varies among the hearing impaired listeners between o db and normal values of 7 db or more it depends on the high frequency hearing loss at the side presented with the most favorable signal to noise s n ratio the gain due to itd is nearly normal for the symmetrically impaired 4 2 db compared with 4 7 db for the normal hearing but only 2 5 db in the case of asymmetrical impairment when itd is introduced in noise already containing ild the resulting gain is 2 2 5 db for all groups the only marked effect of the interaural difference in overall presentation level is a reduction of the gain due to ild when the level at the ear with the better s n ratio is decreased this implies that an optimal monaural hearing aid with a moderate gain will hardly interfere with unmasking through itd while it may increase the gain due to ild by preventing or diminishing threshold effects

high order discontinuous galerkin methods with lagrange multiplier for hyperbolic systems of conservation laws in this work we present novel high order discontinuous galerkin methods with lagrange multiplier dglm for hyperbolic systems of conservation laws lagrange multipliers are introduced on the inter element boundaries via the concept of weak divergence static condensation on element unknowns considerably reduces globally coupled degrees of freedom resulting in the stiffness equations in the lagrange multipliers only we first establish stability results and provide conditions on the stabilization parameter which plays an important role in resolving discontinuities as well accuracy tests are then performed which shows optimal convergence in the l2 norm extensive numerical results indicate that the dglm has potentials in delivering high order accurate information for various problems in hyperbolic conservation laws numerical examples include inviscid burgers equations shallow water equations subcritical flow and supercritical upstream subcritical downstream flow and 2d circular dam break and compressible euler equations intersection of mach 3 and sods shock tube

effect of loudness recruitment on the perception of amplitude modulation people with hearing loss of cochlear origin usually display loudness recruitment the rate of growth of loudness level with increasing sound level is greater than for a normally hearing person loudness recruitment has usually been studied with steady sounds of relatively long duration the present study examines how recruitment affects the perception of dynamically varying sounds namely amplitude modulated sinusoids the modulation rates used 4 8 16 and 32 hz were chosen to span the range of the most prominent modulations present in the envelope of speech three subjects with unilateral cochlear hearing loss were used in experiment 1 subjects were required to make loudness matches between 1 khz tones presented alternately to the two ears this was done over a wide range of sound levels experiment 2 used 1 khz carriers that were amplitude modulated the modulation was sinusoidal on a db scale the modulated tones were presented alternately to the two ears and were approximately equally loud in the two ears the modulation depth was fixed in one ear and the subject was required to adjust the modulation depth in the other ear so that the modulation depth appeared equal in the two ears this was done for a range of modulation depths and with the fixed tone presented to both the normal and the impaired ear a given modulation depth in the impaired ear was matched by a greater modulation depth in the normal ear to a first approximation the modulation matching functions were independent of modulation rate furthermore the functions could be predicted reasonably well from the loudness matching results of experiment 1 obtained with steady tones the results are consistent with the idea that loudness recruitment results from the loss of a fast acting compressive nonlinearity that operates in the normal peripheral auditory system possible implications of the results for the use of fast acting compression in hearing aids are discussed

acoustic characteristics of english fricatives this study constitutes a large scale comparative analysis of acoustic cues for classification of place of articulation in fricatives to date no single metric has been found to classify fricative place of articulation with a high degree of accuracy this study presents spectral amplitudinal and temporal measurements that involve both static properties spectral peak location spectral moments noise duration normalized amplitude and f2 onset frequency and dynamic properties relative amplitude and locus equations while all cues except locus equations consistently serve to distinguish sibilant from nonsibilant fricatives the present results indicate that spectral peak location spectral moments and both normalized and relative amplitude serve to distinguish all four places of fricative articulation these findings suggest that these static and dynamic acoustic properties can provide robust and unique information about all four places of articulation despite variation in speaker vowel context and voicing

discontinuous galerkin methods for advection diffusion reaction problems we apply the weighted residual approach recently introduced in f brezzi et al comput methods appl mech engrg 195 2006 pp 3293 3310 to derive discontinuous galerkin formulations for advection diffusion reaction problems we devise the basic ingredients to ensure stability and optimal error estimates in suitable norms and propose two new methods

testing the concept of softness imperception loudness near threshold for hearing impaired ears buus and florentine j assoc res otolaryngol 3 120 139 2002 have proposed that loudness recruitment in cases of cochlear hearing loss is caused partly by an abnormally large loudness at absolute threshold this has been called softness imperception to evaluate this idea loudness matching functions were obtained using tones at very low sensation levels for subjects with asymmetrical hearing loss matches were obtained for a single frequency across ears for subjects with sloping hearing loss matches were obtained between tones at two frequencies one where the absolute threshold was nearly normal and one where there was a moderate hearing loss loudness matching was possible for sensation levels sls as low as 2 db when the fixed tone was presented at a very low sl in an ear or at a frequency where there was hearing impairment it was matched by a tone with approximately the same sl in an ear or at a frequency where hearing was normal e g 2 db sl matched 2 db sl this relationship held for sls up to 4 10 db depending on the subject these results are not consistent with the concept of softness imperception

a discontinuous galerkin method with lagrange multiplier for hyperbolic conservation laws with boundary conditions we introduce a discontinuous galerkin method with lagrange multiplier dglm to approximate the solution to the hyperbolic conservation laws with boundary conditions lagrange multipliers are introduced on the edge face of the element via weak divergence wang and ye 2014 the final global system has reduced numbers of unknowns of the standard dg methods numerical fluxes from finite volume difference method are not considered for the time discretization backward euler difference method is used stability of the approximate solution is proved in energy norm discontinuity of the solution is allowed in the error analysis local error estimates of o hr 12 t with pr e elements rd 12 are derived where h and t are the maximum diameter of the elements and time steps respectively and d is the dimension of the spatial domain the high order approximation is obtained under an appropriate condition on the stabilizing parameter it is shown that the method preserves the property of the local mass conservation an explanation on algorithmic aspects is given

analysis of an interface stabilized finite element method the advection diffusion reaction equation analysis of an interface stabilized finite element method for the scalar advection diffusion reaction equation is presented the method inherits attractive properties of both continuous and discontinuous galerkin methods namely the same number of global degrees of freedom as a continuous galerkin method on a given mesh and the stability properties of discontinuous galerkin methods for advection dominated problems simulations using the approach in other works demonstrated good stability properties with minimal numerical dissipation and standard convergence rates for the lowest order elements were observed in this work stability of the formulation in the form of an inf sup condition for the hyperbolic limit and coercivity for the elliptic case is proved as is order k 1 2 order convergence for the advection dominated case and order k 1 convergence for the diffusive limit in the l 2 norm the analysis results are supported by a number of numerical experiments

effects of low pass filtering on the intelligibility of speech in noise for people with and without dead regions at high frequencies people with high frequency sensorineural hearing loss differ in the benefit they gain from amplification of high frequencies when listening to speech using vowel consonant vowel vcv stimuli in quiet that were amplified and then low pass filtered with various cutoff frequencies vickers et al j acoust soc am 110 1164 1175 2001 found that the benefit from amplification of high frequency components was related to the presence or absence of a cochlear dead region at high frequencies for hearing impaired subjects without dead regions performance improved with increasing cutoff frequency up to 7 5 khz the highest value tested subjects with high frequency dead regions showed no improvement when the cutoff frequency was increased above about 1 7 times the edge frequency of the dead region the present study was similar to that of vickers et al but used vcv stimuli presented in background noise ten subjects with high frequency hearing loss including eight from the study of vickers et al were tested five had dead regions starting below 2 khz and five had no dead regions speech stimuli at a nominal level of 65 db were mixed with spectrally matched noise amplified according to the cambridge prescriptive formula for each subject and then low pass filtered the noise level was chosen separately for each subject to give a moderate reduction in intelligibility relative to listening in quiet for subjects without dead regions performance generally improved with increasing cutoff frequency up to 7 5 khz on average more so in noise than in quiet for most subjects with dead regions performance improved with cutoff frequency up to 1 5 2 times the edge frequency of the dead region but hardly changed with further increases calculations of speech audibility using a modified version of the articulation index showed that application of the cambridge formula was at least partially successful in making high frequency components of the speech audible for subjects with dead regions and that such subjects often failed to benefit from increased audibility of the speech at high frequencies

analysis of a multiscale discontinuous galerkin method for convection diffusion problems we study a multiscale discontinuous galerkin method introduced in t j r hughes g scovazzi p bochev and a buffa comput meth appl mech engrg 195 2006 pp 2761 2787 that reduces the computational complexity of the discontinuous galerkin method seemingly without adversely affecting the quality of results for a stabilized variant we are able to obtain the same error estimates for the convection diffusion equation as for the usual discontinuous galerkin method we assess the stability of the unstabilized case numerically and find that the inf sup constant is positive bounded uniformly away from zero and very similar to that for the usual discontinuous galerkin method

the negative effect of amplitude compression in multichannel hearing aids in the light of the modulation transfer function the article deals with the question of why multichannel amplitude compression appears to have a negative rather than a positive effect on speech intelligibility by hearing impaired listeners it is argued that the small time constants of amplitude compression diminish the temporal as well as the spectral contrasts in the speech signal according to the modulation transfer function concept this results in reduced intelligibility scores experimental evidence is reviewed indicating that the following two arguments in favor of amplitude compression in case of sensorineural hearing loss are not valid 1 to compensate for the effects of loudness recruitment and 2 to get weak consonants above threshold the author concludes that in multichannel hearing aids automatic gain control with time constants of 0 25 0 5 s should be given preference to amplitude compression

global and local error analysis for the residual free bubbles method applied to advection dominated problems we prove the stability and a priori global and local error analysis for the residual free bubbles rfb finite element method applied to advection dominated advection diffusion problems

acoustic cue weighting in the singleton vs geminate contrast in lebanese arabic the case of fricative consonants this paper is the first reported investigation of the role of non temporal acoustic cues in the singleton geminate contrast in lebanese arabic alongside the more frequently reported temporal cues the aim is to explore the extent to which singleton and geminate consonants show qualitative differences in a language where phonological length is prominent and where moraic structure governs segment timing and syllable weight twenty speakers ten male ten female were recorded producing trochaic disyllables with medial singleton and geminate fricatives preceded by phonologically short and long vowels the following acoustic measures were applied on the medial fricative and surrounding vowels absolute duration intensity fundamental frequency spectral peak and shape dynamic amplitude and voicing patterns of medial fricatives and vowel quality and voice quality correlates of surrounding vowels discriminant analysis and receiver operating characteristics roc curves were used to assess each acoustic cue s contribution to the singleton geminate contrast classification rates of 89 and roc curves with an area under the curve rate of 96 confirmed the major role played by temporal cues with non temporal cues contributing to the contrast but to a much lesser extent these results confirm that the underlying contrast for gemination in arabic is temporal but highlight tense fortis as a secondary feature

burst spectrum as a cue for the stop voicing contrast in american english voicing contrasts in stop consonants are expressed by a constellation of acoustic cues this study focused on a spectral cue present at burst onset in american english labial and coronal stops spectral shape was examined for word initial prevocalic stops of all three places of articulation in a laboratory production study and a large corpus of continuous read speech voiceless labial and coronal stops were found to have greater energy at higher frequencies in comparison to homorganic voiced stops a difference that could not be attributed to aspiration in the voiceless stops or modal phonation in the voiced while no consistent effect was found for dorsal stops this pattern was found with various methods of spectral estimation time averaged and multitaper spectra and measures of spectral energy concentration center of gravity and spectral peak for both linear and auditorily based frequency scales perceptual relevance of the spectral cue was tested in laboratory and online experiments with continua created by crossing burst shape and voice onset time a trading relation was observed such that voiceless identifications were more likely for tokens with higher frequency bursts goodness ratings indicated that burst spectrum influences category typicality for voiceless stops even when voice onset time is unambiguous

horizontal directivity of low and high frequency energy in speech and singing speech and singing directivity in the horizontal plane was examined using simultaneous multi channel full bandwidth recordings to investigate directivity of high frequency energy in particular this method allowed not only for accurate analysis of running speech using the long term average spectrum but also for examination of directivity of separate transient phonemes several vocal production factors that could affect directivity were examined directivity differences were not found between modes of production speech vs singing and only slight differences were found between genders and production levels soft vs normal vs loud more pronounced in the higher frequencies large directivity differences were found between specific voiceless fricatives with s more directional than f in the 4 8 16 khz octave bands

automatically stable discontinuous petrov galerkin methods for stationary transport problems quasi optimal test space norm we investigate the application of the discontinuous petrov galerkin dpg finite element framework to stationary convection diffusion problems in particular we demonstrate how the quasi optimal test space norm improves the robustness of the dpg method with respect to vanishing diffusion we numerically compare coarse mesh accuracy of the approximation when using the quasi optimal norm the standard norm and the weighted norm our results show that the quasi optimal norm leads to more accurate results on three benchmark problems in two spatial dimensions we address the problems associated to the resolution of the optimal test functions with respect to the quasi optimal norm by studying their convergence numerically in order to facilitate understanding of the method we also include a detailed explanation of the methodology from the algorithmic point of view

multiscale phenomena green s functions the dirichlet to neumann formulation subgrid scale models bubbles and the origins of stabilized methods abstract an approach is developed for deriving variational methods capable of representing multiscale phenomena the ideas are first illustrated on the exterior problem for the helmholtz equation this leads to the well known dirichlet to neumann formulation next a class of subgrid scale models is developed and the relationships to bubble function methods and stabilized methods are established it is shown that both the latter methods are approximate subgrid scale models the identification for stabilized methods leads to an analytical formula for the intrinsic time scale whose origins have been a mystery heretofore

a robust wg finite element method for convection diffusion reaction equations this paper proposes and analyzes a weak galerkin wg finite element method for 2 and 3 dimensional convection diffusion reaction problems on conforming or nonconforming polygon polyhedral meshes the wg method uses piecewise polynomial approximations of degrees k k 0 for both the scalar function and its trace on the inter element boundaries we show that the method is robust in the sense that the derived a priori error estimates is uniform with respect to the coefficients for sufficient smooth true solutions numerical experiments confirm the theoretical results

inf sup testing of upwind methods we propose inf sup testing for finite element methods with upwinding used to solve convection diffusion problems the testing evaluates the stability of a method and compactly displays the numerical behaviour as the convection effects increase four discretization schemes are considered the standard galerkin procedure the full upwind method the galerkin least squares scheme and a high order derivative artificial diffusion method the study shows that as expected the standard galerkin method does not pass the inf sup tests whereas the other three methods pass the tests of these methods the high order derivative artificial diffusion procedure introduces the least amount of artificial diffusion copyright 2000 john wiley sons ltd

the effects of hearing loss on the contribution of high and low frequency speech information to speech understanding ii sloping hearing loss the speech understanding of persons with sloping high frequency hf hearing impairment hi was compared to normal hearing nh controls and previous research on persons with flat losses hornsby and ricketts 2003 j acoust soc am 113 1706 1717 to examine how hearing loss configuration affects the contribution of speech information in various frequency regions speech understanding was assessed at multiple low and high pass filter cutoff frequencies crossover frequencies defined as the cutoff frequencies at which low and high pass filtering yielded equivalent performance were significantly lower for the sloping hi compared to nh group suggesting that hf hi limits the utility of hf speech information speech intelligibility index calculations suggest this limited utility was not due simply to reduced audibility but also to the negative effects of high presentation levels and a poorer than normal use of speech information in the frequency region with the greatest hearing loss the hf regio

residual free bubbles for advection diffusion problems the general error analysis we develop the general a priori error analysis of residual free bubble finite element approximations to linear elliptic convection dominated diffusion problems subject to homogeneous dirichlet boundary condition optimal order error bounds are derived in various norms using piecewise polynomial finite elements of degree greater than or equal to 1

statistical analysis of word initial voiceless obstruents preliminary data a statistical procedure for classifying word initial voiceless obstruents is described the data set to which the analysis was applied consisted of monosyllabic words starting with a voiceless obstruent each word was repeated six times in the carrier phrase i can say again by each of ten speakers fast fourier transforms ffts using a 20 ms hamming window were calculated every 10 ms from the onset of the obstruent through the third cycle of the following vowel each fft was treated as a random probability distribution from which the first four moments mean variance skewness and kurtosis were computed moments were calculated from linear and bark transformed spectra data were pooled across vowel contexts for speakers of a given gender and input to a discriminant analysis using the moments calculated from the linear spectra 92 of the voiceless stops were classified correctly when dynamic aspects of the stop were included even more important the model constructed from the males data correctly classified about 94 of the voiceless stops produced by the female speakers classification of the voiceless fricatives when all places of articulation were included in the analysis did not exceed 80 correct when the moments from either the linear or bark transformed scales were used however classification of only the voiceless sibilants was 98 correct when the moments from the bark transformed spectra were used as with the stops the classification model held across gender

the variational multiscale method a paradigm for computational mechanics abstract we present a general treatment of the variational multiscale method in the context of an abstract dirichlet problem we show how the exact theory represents a paradigm for subgrid scale models and a posteriori error estimation we examine hierarchical p methods and bubbles in order to understand and ultimately approximate the fine scale green s function which appears in the theory we review relationships between residual free bubbles element green s functions and stabilized methods these suggest the applicability of the methodology to physically interesting problems in fluid mechanics acoustics and electromagnetics

a distribution free method of interval estimation for unsigned directional data summary a method of moments is suggested for large samples of unsigned directional data the point estimators obtained coincide with the natural estimates obtained from maximum likelihood estimation if the data have a bingham distribution however the calculations necessary for interval and regional estimation are considerably simpler the statistical analysis is based upon the asymptotic sampling properties of principal components in nonnormal populations davis 1977 tyler 1981 a numerical example first treated by bingham 1974 is examined and found to yield very similar regional estimates the hypothesis of rotational symmetry is discounted by using a test statistic suggested by watson 1965

blind separation of speech mixtures via time frequency masking binary time frequency masks are powerful tools for the separation of sources from a single mixture perfect demixing via binary time frequency masks is possible provided the time frequency representations of the sources do not overlap a condition we call w disjoint orthogonality we introduce here the concept of approximate w disjoint orthogonality and present experimental results demonstrating the level of approximate w disjoint orthogonality of speech in mixtures of various orders the results demonstrate that there exist ideal binary time frequency masks that can separate several speech signals from one mixture while determining these masks blindly from just one mixture is an open problem we show that we can approximate the ideal masks in the case where two anechoic mixtures are provided motivated by the maximum likelihood mixing parameter estimators we define a power weighted two dimensional 2 d histogram constructed from the ratio of the time frequency representations of the mixtures that is shown to have one peak for each source with peak location corresponding to the relative attenuation and delay mixing parameters the histogram is used to create time frequency masks that partition one of the mixtures into the original sources experimental results on speech mixtures verify the technique example demixing results can be found online at http alum mit edu www rickard bss html

insights into multiple single lower bound approximation for extended variational inference in non gaussian structured data modeling for most of the non gaussian statistical models the data being modeled represent strongly structured properties such as scalar data with bounded support e g beta distribution vector data with unit length e g dirichlet distribution and vector data with positive elements e g generalized inverted dirichlet distribution in practical implementations of non gaussian statistical models it is infeasible to find an analytically tractable solution to estimating the posterior distributions of the parameters variational inference vi is a widely used framework in bayesian estimation recently an improved framework namely the extended vi evi has been introduced and applied successfully to a number of non gaussian statistical models evi derives analytically tractable solutions by introducing lower bound approximations to the variational objective function in this paper we compare two approximation strategies namely the multiple lower bounds mlbs approximation and the single lower bound slb approximation which can be applied to carry out the evi for implementation two different conditions the weak and the strong conditions are discussed convergence of the evi depends on the selection of the lower bound regardless of the choice of weak or strong condition we also discuss the convergence properties to clarify the differences between mlb and slb extensive comparisons are made based on some evi based non gaussian statistical models theoretical analysis is conducted to demonstrate the differences between the weak and strong conditions experimental results based on real data show advantages of the slb approximation over the mlb approximation

a multiscale discontinuous galerkin method with the computational structure of a continuous galerkin method proliferation of degrees of freedom has plagued discontinuous galerkin methodology from its inception over 30 years ago this paper develops a new computational formulation that combines the advantages of discontinuous galerkin methods with the data structure of their continuous galerkin counterparts the new method uses local element wise problems to project a continuous finite element space into a given discontinuous space and then applies a discontinuous galerkin formulation the projection leads to parameterization of the discontinuous degrees of freedom by their continuous counterparts and has a variational multiscale interpretation this significantly reduces the computational burden and at the same time little or no degradation of the solution occurs in fact the new method produces improved solutions compared with the traditional discontinuous galerkin method in some situations

variational multiscale analysis the fine scale green s function projection optimization localization and stabilized methods we derive an explicit formula for the fine scale green s function arising in variational multiscale analysis the formula is expressed in terms of the classical green s function and a projector which defines the decomposition of the solution into coarse and fine scales the theory is presented in an abstract operator format and subsequently specialized for the advection diffusion equation it is shown that different projectors lead to fine scale green s functions with very different properties for example in the advection dominated case the projector induced by the h 1 0 seminorm produces a fine scale green s function which is highly attenuated and localized these are very desirable properties in a multiscale method and ones that are not shared by the l 2 projector by design the coarse scale solution attains optimality in the norm associated with the projector this property combined with a localized fine scale green s function indicates the possibility of effective methods with local character for dominantly hyperbolic problems the constructs lead to a new class of stabilized methods and the relationship between h 1 0 optimality and the streamline upwind petrov galerkin supg method is described

segmental durations in connected speech signals current results two types of analyses have been performed on the measured durations of recordings produced by six talkers reading two scripts of approximately 300 words each the texts the combined visual auditory marking technique and preliminary results were reported earlier by crystal and house j acoust soc am 72 705 716 1982 the average durations and standard deviations of various classes of speech sounds as well as individual speech sounds have been determined and segmental measurements are compared to earlier data and to various pertinent published reports the histograms of the measured durations of various sounds and categories have been fitted with distributions which are equivalently the exit probability sequence for a markov chain or the impulse response of an iir digital filter network

effects of vocalic formant transitions and vowel quality on the english s s boundary the effects of the vocalic portion of fricative vowel syllables on the perception of alveolar and palatal fricatives were examined the fricative noises were synthesized to represent a continuum from s to the vowels ranged from u to i through i and u the vocalic formant transitions were of two types those appropriate to s and those to all stimuli were presented in forced choice labeling tests the boundary between s and for english speaking listeners was found to vary as a function both of transitions and of vowel the effect of the transitions was clear and straightforward an ambiguous fricative noise was heard more often as s before s transitions and as before transitions the quality of the vowel clearly had an effect but the interpretation of the effect in terms of the perception of coarticulation was not clear the responses of listeners who were unfamiliar with languages which use u and or i distinctively were not significantly different from those of listeners who were familiar with such languages

multiscale stabilization for convection dominated diffusion in heterogeneous media abstract we develop a petrov galerkin stabilization method for multiscale convection diffusion transport systems existing stabilization techniques add a limited number of degrees of freedom in the form of bubble functions or a modified diffusion which may not be sufficient to stabilize multiscale systems we seek a local reduced order model for this kind of multiscale transport problems and thus develop a systematic approach for finding reduced order approximations of the solution we start from a petrov galerkin framework using optimal weighting functions we introduce an auxiliary variable to a mixed formulation of the problem the auxiliary variable stands for the optimal weighting function the problem reduces to finding a test space a dimensionally reduced space for this auxiliary variable which guarantees that the error in the primal variable representing the solution is close to the projection error of the full solution on the dimensionally reduced space that approximates the solution to find the test space we reformulate some recent mixed generalized multiscale finite element methods we introduce snapshots and local spectral problems that appropriately define local weight and trial spaces in particular we use energy minimizing snapshots and local spectral decompositions in the natural norm associated with the auxiliary variable the resulting spectral decomposition adaptively identifies and builds the optimal multiscale space to stabilize the system we discuss the stability and its relation to the approximation property of the test space we design online basis functions which accelerate convergence in the test space and consequently improve stability we present several numerical examples and show that one needs a few test functions to achieve an error similar to the projection error in the primal variable irrespective of the peclet number

a comparison of spectral estimation methods for the analysis of sibilant fricatives it has been argued that to ensure accurate spectral feature estimates for sibilants the spectral estimation method should include a low variance spectral estimator however no empirical evaluation of estimation methods in terms of feature estimates has been given the spectra of s and were estimated with different methods that varied the pre emphasis filter and estimator these methods were evaluated in terms of effects on two features centroid and degree of sibilance and on the detection of four linguistic contrasts within these features estimation method affected the spectral features but none of the tested linguistic contrasts

an investigation of locus equations as a source of relational invariance for stop place categorization locus equations were investigated as a potential metric capable of illustrating relational invariance for place of articulation in voiced initial stop consonants independently of vowel context locus equations are straight line regression fits to data points formed by plotting onsets of f2 transitions along the y axis and their corresponding midvowel nuclei along the x axis twenty subjects 10 male and 10 female produced b v t d v t and g v t tokens for ten vowel contexts each cvc token was repeated in a carrier phrase five times yielding 50 tokens per stop place category formant measures were obtained using the macspeech lab ii speech analysis system extremely linear regression functions were found characterized by distinct slopes and y intercepts as a function of place of articulation a discriminant analysis using f2onset and vowel frequencies as predictors showed 82 78 and 67 classification rates for labial alveolar and velar place using derived slope and y intercept values as predictors led to 100 classification into stop place categories a neurobiologically oriented perspective on the invariance issue is developed and a brain based recognition algorithm for stop place integrating burst and f2 trajectory cues is offered

primal stabilized hybrid and dg finite element methods for the linear elasticity problem abstract primal stabilized hybrid finite element methods for the linear elasticity problem are proposed consisting of locally discontinuous galerkin problems in the primal variable coupled to a global problem in the multiplier which is identified with the trace of the displacement field numerical analysis covering both continuous or discontinuous interpolations of the multiplier shows that the proposed formulation preserves the main properties of the associate dg method such as consistency stability boundedness and optimal rates of convergence in the energy norm and in the l 2 norm for adjoint consistent formulations convergence studies confirm the optimal rates of convergence predicted by the numerical analysis presented here and a local post processing technique is proposed to recover stress approximations with improved rates of convergence in h div norm

bayesian estimation of beta mixture models with variational inference bayesian estimation of the parameters in beta mixture models bmm is analytically intractable the numerical solutions to simulate the posterior distribution are available but incur high computational cost in this paper we introduce an approximation to the prior posterior distribution of the parameters in the beta distribution and propose an analytically tractable closed form bayesian approach to the parameter estimation the approach is based on the variational inference vi framework following the principles of the vi framework and utilizing the relative convexity bound the extended factorized approximation method is applied to approximate the distribution of the parameters in bmm in a fully bayesian model where all of the parameters of the bmm are considered as variables and assigned proper distributions our approach can asymptotically find the optimal estimate of the parameters posterior distribution also the model complexity can be determined based on the data the closed form solution is proposed so that no iterative numerical calculation is required meanwhile our approach avoids the drawback of overfitting in the conventional expectation maximization algorithm the good performance of this approach is verified by experiments with both synthetic and real data

a local discontinuous galerkin method for the compressible reynolds lubrication equation abstract we present an extension of the local discontinuous galerkin ldg method introduced in 9 for nonlinear diffusion problems to nonlinear stationary convection diffusion problems we develop a numerical study of the convergence properties of the new method and solve the stationary compressible reynolds lubrication equation under some realistic conditions

within consonant perceptual differences in the hearing impaired ear the consonant recognition of 17 ears with sensorineural hearing loss is evaluated for 14 consonants p t k f s b d g v z m n under four speech weighted noise conditions 0 6 12 db snr quiet one male and one female talker were chosen for each consonant resulting in 28 total consonant vowel test tokens for a given consonant tokens by different talkers were observed to systematically differ in both the robustness to noise and or the resulting confusion groups such within consonant token differences were observed for over 60 of the tested consonants and all hi ears only when hi responses are examined on an individual token basis does one find that the error may be limited to a small subset of tokens with confusion groups that are restricted to fewer than three confusions on average averaging different tokens of the same consonant can raise the entropy of a listener s responses i e the size of the confusion group causing the listener to appear to behave in a less systematic way quantifying these token differences provides insight into hi perception of speech under noisy conditions and characterizes each listener s hearing impairment

protein bioinformatics and mixtures of bivariate von mises distributions for angular data summary a fundamental problem in bioinformatics is to characterize the secondary structure of a protein which has traditionally been carried out by examining a scatterplot ramachandran plot of the conformational angles we examine two natural bivariate von mises distributions referred to as sine and cosine models which have five parameters and for concentrated data tend to a bivariate normal distribution these are analyzed and their main properties derived conditions on the parameters are established which result in bimodal behavior for the joint density and the marginal distribution and we note an interesting situation in which the joint density is bimodal but the marginal distributions are unimodal we carry out comparisons of the two models and it is seen that the cosine model may be preferred mixture distributions of the cosine model are fitted to two representative protein datasets using the expectation maximization algorithm which results in an objective partition of the scatterplot into a number of components our results are consistent with empirical observations new insights are discussed

articulatory acoustic kinematics the production of american english s due to its aerodynamic articulatory and acoustic complexities the fricative s is known to require high precision in its control and to be highly resistant to coarticulation this study documents in detail how jaw tongue front tongue back lips and the first spectral moment covary during the production of s to establish how coarticulation affects this segment data were obtained from 24 speakers in the wisconsin x ray microbeam database producing s in prevocalic and pre obstruent sequences analysis of the data showed that certain aspects of jaw and tongue motion had specific kinematic trajectories regardless of context and the first spectral moment trajectory corresponded to these in some aspects in particular contexts variability due to jaw motion is compensated for by tongue tip motion and bracing against the palate to maintain an invariant articulatory aerodynamic goal constriction degree the change in the first spectral moment which rises to a peak at the midpoint of the fricativ

variational multiscale residual based turbulence modeling for large eddy simulation of incompressible flows we present an les type variational multiscale theory of turbulence our approach derives completely from the incompressible navier stokes equations and does not employ any ad hoc devices such as eddy viscosities we tested the formulation on forced homogeneous isotropic turbulence and turbulent channel flows in the calculations we employed linear quadratic and cubic nurbs a dispersion analysis of simple model problems revealed nurbs elements to be superior to classical finite elements in approximating advective and diffusive processes which play a significant role in turbulence computations the numerical results are very good and confirm the viability of the theoretical framework

statistical analysis on high dimensional spheres and shape spaces we consider the statistical analysis of data on high dimensional spheres and shape spaces the work is of particular relevance to applications where high dimensional data are available a commonly encountered situation in many disciplines first the uniform measure on the infinite dimensional sphere is reviewed together with connections with wiener measure we then discuss densities of gaussian measures with respect to wiener measure some nonuniform distributions on infinite dimensional spheres and shape spaces are introduced and special cases which have important practical consequences are considered we focus on the high dimensional real and complex bingham uniform von mises fisher fisher bingham and the real and complex watson distributions asymptotic distributions in the cases where dimension and sample size are large are discussed approximations for practical maximum likelihood based inference are considered and in particular we discuss an application to brain shape modeling

detection of fricatives using s transform two prime acoustic characteristics of fricatives are the concentration of spectral energy above 3 khz and having noisy nature spectral domain approaches for detecting fricatives rely on capturing the information from spectral energy distribution in this work s transform based time frequency representation is explored for detecting fricatives from continuous speech s transform based time frequency representation exhibits a progressive resolution which is tailored for localizing the high frequency events i e onset and offset of fricative regions with time spectral evidence computed from s transform based time frequency representation is observed to perform better compared to the spectral evidence computed from short time fourier transform the existing predictability measure based approach relies on capturing the noisy nature of fricatives a phone level comparative analysis is carried out between s transform and predictability measure based approaches and the phone distribution of the detected fricatives is observed to be complimentary in this work a combination of s transform and predictability based approaches is put forth for detecting fricatives from continuous speech apart from detecting the presence of a fricative the proposed s transform based approach and combined approach exhibit better accuracy in detecting the boundaries of fricatives i e extracting the durational information of fricatives

locally discontinuous but globally continuous galerkin methods for elliptic problems abstract we propose and analyze a stabilized hybrid finite element method for elliptic problems consisting of locally discontinuous galerkin problems in the primal variable coupled to a globally continuous problem in the multiplier numerical analysis shows that the proposed formulation preserves the main properties of the associate dg method such as consistency stability boundedness and optimal rates of convergence in the energy norm and in the l 2 norm for adjoint consistent formulations for using an element based data structure it has basically the same complexity and computational cost of classical conforming finite element methods convergence studies confirm the optimal rates of convergence predicted by the numerical analysis presented here with accuracy equivalent or even better than the corresponding dg approximations

variational inference for watson mixture model this paper addresses modelling data using the watson distribution the watson distribution is one of the simplest distributions for analyzing axially symmetric data this distribution has gained some attention in recent years due to its modeling capability however its bayesian inference is fairly understudied due to difficulty in handling the normalization factor recent development of markov chain monte carlo mcmc sampling methods can be applied for this purpose however these methods can be prohibitively slow for practical applications a deterministic alternative is provided by variational methods that convert inference problems into optimization problems in this paper we present a variational inference for watson mixture models first the variational framework is used to side step the intractability arising from the coupling of latent states and parameters second the variational free energy is further lower bounded in order to avoid intractable moment computation the proposed approach provides a lower bound on the log marginal likelihood and retains distributional information over all parameters moreover we show that it can regulate its own complexity by pruning unnecessary mixture components while avoiding over fitting we discuss potential applications of the modeling with watson distributions in the problem of blind source separation and clustering gene expression data sets

effects of spectro temporal modulation changes produced by multi channel compression on intelligibility in a competing speech task these experiments are concerned with the intelligibility of target speech in the presence of a background talker using a noise vocoder stone and moore j acoust soc am 114 1023 1034 2003 showed that single channel fast acting compression degraded intelligibility but slow compression did not stone and moore j acoust soc am 116 2311 2323 2004 showed that intelligibility was lower when fast single channel compression was applied to the target and background after mixing rather than before and suggested that this was partly due to compression after mixing introducing comodulation between the target and background talkers experiment 1 here showed a similar effect for multi channel compression in experiment 2 intelligibility was measured as a function of the speed of multi channel compression applied after mixing for both eight and 12 channel vocoders with one compressor per channel intelligibility decreased as compression speed increased for the eight channel vocoder a compresso

a multiscale discontinuous galerkin method for convection diffusion reaction problems we provide a general framework of multiscale discontinuous galerkin methods developed in buffa et al 2006 hughes et al 2006 for general second order partial differential equations we establish stability of the method and prove the error estimates

bayesian estimation of the von mises fisher mixture model with variational inference this paper addresses the bayesian estimation of the von mises fisher vmf mixture model with variational inference vi the learning task in vi consists of optimization of the variational posterior distribution however the exact solution by vi does not lead to an analytically tractable solution due to the evaluation of intractable moments involving functional forms of the bessel function in their arguments to derive a closed form solution we further lower bound the evidence lower bound where the bound is tight at one point in the parameter distribution while having the value of the bound guaranteed to increase during maximization we derive an analytically tractable approximation to the posterior distribution which has the same functional form as the assigned prior distribution the proposed algorithm requires no iterative numerical calculation in the re estimation procedure and it can potentially determine the model complexity and avoid the over fitting problem associated with conventional approaches based on the expectation maximization moreover we derive an analytically tractable approximation to the predictive density of the bayesian mixture model of vmf distributions the performance of the proposed approach is verified by experiments with both synthetic and real data

continuous discontinuous galerkin methods stabilized through transfer functions applied to the incompressible elasticity and to the stokes problem abstract in this work we present a family of new continuous discontinuous mixed formulations with interpolation of equal order for velocity and pressure for the stokes problem and incompressible elasticity the degrees of freedom associated to the discontinuous component are eliminated and an approach with computational effort similar to that of the continuous formulation is obtained an analysis of continuity and weak coercivity infsup condition is performed and it is proved that the formulation is continuous and satisfies the infsup condition on an appropriated norm error estimates derived from theorems and the lemma presented are obtained on a similar norm to the one of the gls method numerical experiments with the cavity problem and a smooth solution problem show the robustness of the new formulation

detecting palatalization in spontaneous spoken english we present an analysis of palatalization from s to at word boundaries in uk english previous work has considered the effect of lexical frequency lf on this phenomenon but without combining acoustics and spontaneous speech in one study which we undertake using data gathered from the audio bnc http www phon ox ac uk audiobnc we analyze 5 259 word pairs in five phonological contexts comparing the acoustics of test tokens subject to palatalization e g s in miss you to control tokens containing non alternating s miss it or mission wish it wish you word and segment boundaries were obtained via forced alignment but hand checked we measured the spectral moments and duration of each fricative following vowel duration and formant values were also extracted lf was calculated using the audio bnc we find that the spectral center of gravity cog of s before j miss you is intermediate p 0 01 between those of s and furthermore cog of test tokens correlates negatively with lf indicating increased palatalization in high frequency contexts no control pair exhibits such correlations lf predicts cog even considering speaker gender and other phonetic co predictors this supports the view of palatalization as gestural overlap which increases with lf in casual or fast speech

effects of compression and onset offset asynchronies on the detection of one tone in the presence of another the weaker of two temporally overlapping complex tones can be easier to hear when the tones are asynchronous than when they are synchronous this study explored how the use of fast and slow five channel amplitude compression as might be used in hearing aids affected the ability to use onset and offset asynchronies to detect one signal complex tone when another masking complex tone was presented almost simultaneously a 2 1 compression ratio was used with normal hearing subjects and individual compression ratios and gains recommended by the cam2 hearing aid fitting method were used for hearing impaired subjects when the signal started before the masker there was a benefit of compression for both normal hearing and hearing impaired subjects when the signal finished after the masker there was a benefit of fast compression for the normal hearing subjects but no benefit for most of the hearing impaired subjects except when the offset asynchrony was relatively large 100 ms the benefit of compression probably occurred because the compression improved the effective signal to masker ratio hence reducing backward and forward masking this apparently outweighed potential deleterious effects of distortions in envelope shape and the introduction of partially correlated envelopes of the signal and masker

a high order discontinuous galerkin method with skeletal multipliers for convection diffusion reaction problems abstract a discontinuous galerkin method with skeletal multipliers dgsm is developed for diffusion problem skeletal multiplier is introduced on the edge face of each element through the definition of a weak divergence and a weak derivative in the method the local weak formulation is derived by weakly imposing the dirichlet boundary condition and continuity of fluxes and solutions on the edges faces the global weak formulation is then obtained by adding all the local problems equivalence of the weak formulation and the original problem is proved stability of dgsm is shown and an error estimate is derived in a broken norm a dgsm for linear convection diffusion reaction problems is also derived an explanation on algorithmic aspects is given some numerical results are presented singularities due to discontinuities in the diffusion coefficients are accurately approximated internal boundary layers are well captured without showing spurious oscillations robustness of the method in increasingly small diffusivity is demonstrated on the whole domain

spectral dynamics of sibilant fricatives are contrastive and language specific previous research has extensively investigated the spectral properties of sibilant fricatives with little consideration to how these properties vary over time to investigate such spectro temporal variation productions of english s and and of japanese s and in word initial prevocalic position were elicited from adult native speakers the spectral dynamics of these productions were analyzed in terms of a psychoacoustic measure of peak frequency peak erbn number peak erbn number was computed at 17 evenly spaced points across each fricative production the resulting peak erbn number trajectories were analyzed with orthogonal polynomial growth curve models to determine how peak frequency varied temporally within each fricative three analyses compared 1 the english sibilants to each other 2 the japanese sibilants to each other and 3 english s to japanese s the results indicated that in both english and japanese the sibilant fricatives differ acoustically in terms of both static i e overall level and dynamic i e shape aspects of the peak erbn number trajectories furthermore english s and japanese s exhibited language specific differences in the shape but not overall level of peak erbn number trajectories

continuous discontinuous galerkin methods applied to elasticity problems abstract a new family of coupled continuous discontinuous galerkin formulations is presented and analyzed in this paper these formulations have some distinguishing properties support to all boundary conditions without differentiating whether the condition is dirichlet or not the continuous part of the formulations can use the discontinuous part to have better accuracy and robustness properties and the discontinuous part has the same stabilized properties of common discontinuous galerkin methods a new promising stability parameter is introduced and its effects analyzed in the numerical experiments some important results related to the stability of the formulations associated with the polynomial degree adopted for the continuous component are also shown

nonlinear frequency compression influence of start frequency and input bandwidth on consonant and vowel recognitiona by varying parameters that control nonlinear frequency compression nfc this study examined how different ways of compressing inaudible mid and or high frequency information at lower frequencies influences perception of consonants and vowels twenty eight listeners with mild to moderately severe hearing loss identified consonants and vowels from nonsense syllables in noise following amplification via a hearing aid simulator low pass filtering and the selection of nfc parameters fixed the output bandwidth at a frequency representing a moderately severe 3 3 khz group ms or a mild to moderate 5 0 khz group mm high frequency loss for each group n 14 effects of six combinations of nfc start frequency sf and input bandwidth by varying the compression ratio cr were examined for both groups the 1 6 khz sf significantly reduced vowel and consonant recognition especially as cr increased whereas recognition was generally unaffected if sf increased at the expense of a higher cr vowel recognition detriments for group ms were moderately correlated with the size of the second formant frequency shift following nfc for both groups significant improvement 33 50 with nfc was confined to final s and z and to some vcv tokens perhaps because of listeners limited exposure to each setting no set of parameters simultaneously maximized recognition across all tokens

nonparametric bayesian density estimation on manifolds with applications to planar shapes statistical analysis on landmark based shape spaces has diverse applications in morphometrics medical diagnostics machine vision and other areas these shape spaces are non euclidean quotient manifolds to conduct nonparametric inferences one may define notions of centre and spread on this manifold and work with their estimates however it is useful to consider full likelihood based methods which allow nonparametric estimation of the probability density this article proposes a broad class of mixture models constructed using suitable kernels on a general compact metric space and then on the planar shape space in particular following a bayesian approach with a nonparametric prior on the mixing distribution conditions are obtained under which the kullback leibler property holds implying large support and weak posterior consistency gibbs sampling methods are developed for posterior computation and the methods are applied to problems in density estimation and classification with shape based predictors simulation studies show improved estimation performance relative to existing approaches

multiscale stabilization for convection diffusion equations with heterogeneous velocity and diffusion coefficients abstract we present a new stabilization technique for multiscale convection diffusion problems stabilization for these problems has been a challenging task especially for the case with high peclet numbers our method is based on a constraint energy minimization idea and the discontinuous petrov galerkin formulation in particular the test functions are constructed by minimizing an appropriate energy subject to certain orthogonality conditions and are related to the trial space the resulting test functions have a localization property and can therefore be computed locally we will prove the stability and present several numerical results our numerical results confirm that our test space gives a good stability in the sense that the solution error is close to the best approximation error

cs decomposition based bayesian subspace estimation in numerous applications it is required to estimate the principal subspace of the data possibly from a very limited number of samples additionally it often occurs that some rough knowledge about this subspace is available and could be used to improve subspace estimation accuracy in this case this is the problem we address herein and in order to solve it a bayesian approach is proposed the main idea consists of using the cs decomposition of the semi orthogonal matrix whose columns span the subspace of interest this parametrization is intuitively appealing and allows for non informative prior distributions of the matrices involved in the cs decomposition and very mild assumptions about the angles between the actual subspace and the prior subspace the posterior distributions are derived and a gibbs sampling scheme is presented to obtain the minimum mean square distance estimator of the subspace of interest numerical simulations and an application to real hyperspectral data assess the validity and the performances of the estimator

discontinuous hp finite element methods for advection diffusion reaction problems we consider the hp version of the discontinuous galerkin finite element method dgfem for second order partial differential equations with nonnegative characteristic form this class of equations includes second order elliptic and parabolic equations advection reaction equations as well as problems of mixed hyperbolic elliptic parabolic type our main concern is the error analysis of the method in the absence of streamline diffusion stabilization in the hyperbolic case an hp optimal error bound is derived here we consider only advection reaction problems which satisfy a certain standard positivity condition in the self adjoint elliptic case an error bound that is h optimal and p suboptimal by frac 1 2 a power of p is obtained these estimates are then combined to deduce an error bound in the general case for elementwise analytic solutions the method exhibits exponential rates of convergence under p refinement the theoretical results are illustrated by numerical experiments

evaluation of a method for enhancing interaural level differences at low frequencies a method called binaural enhancement for enhancing interaural level differences at low frequencies based on estimates of interaural time differences was developed and evaluated five conditions were compared all using simulated hearing aid processing 1 linear amplification with frequency response shaping 2 binaural enhancement combined with linear amplification and frequency response shaping 3 slow acting four channel amplitude compression with independent compression at the two ears agc4ch 4 binaural enhancement combined with four channel compression be agc4ch and 5 four channel compression but with the compression gains synchronized across ears ten hearing impaired listeners were tested and gains and compression ratios for each listener were set to match targets prescribed by the cam2 fitting method stimuli were presented via headphones using virtualization methods to simulate listening in a moderately reverberant room the intelligibility of speech at 60 azimuth in the presence of competing speech on the opposite side of the head at 60 azimuth was not affected by the binaural enhancement processing sound localization was significantly better for condition be agc4ch than for condition agc4ch for a sentence but not for broadband noise lowpass noise or lowpass amplitude modulated noise the results suggest that the binaural enhancement processing can improve localization for sounds with distinct envelope fluctuations