interaural correlation discrimination from diffuse field reference correlations just noticeable differences in interaural correlation jnds from diffuse sound field reference correlations are obtained in a three interval three alternative forced choice procedure jnds are measured for positive and negative deviations from nine narrowband reference conditions stimuli are 1 equivalent rectangular bandwidth wide noise bursts with center frequencies between 165 and 1500 hz the frequency dependent reference correlation ref is determined by the simulated interaural correlation under ideal diffuse sound field conditions results show that the interaural correlation at threshold for deviation toward the positive correlation range follows the reference curve in a nonlinear fashion for deviation toward the negative correlation range the interaural correlation at threshold is further afar the reference curve and does not markedly resemble its trend the results indicate that the previously found asymmetry for correlation discrimination from uncorrelated broadband stimuli to the pos

an extended trapezoidal formula for the diffusion equation abstract a finite difference scheme for the diffusion equation that has enjoyed great popularity is the crank nicolson scheme 1 based on the classical trapezoidal formula for integration in time for problems with discontinuities in the boundary conditions and the initial conditions the crank nicolson scheme can give unwanted oscillations in the computed solution we present an alternative scheme based on the extended trapezoidal formula for integration in time the resulting extended trapezoidal formula finite difference scheme etf fds is third order in time unconditionally stable and unlike the crank nicolson scheme etf fds can cope with discontinuities in the boundary conditions and the initial conditions as demonstrated by the numerical examples considered

on the generation of mono implicit runge kutta nystro m methods by mono implicit runge kutta methods mono implicit runge kutta methods can be used to generate implicit runge kutta nystrom irkn methods for the numerical solution of systems of second order differential equations the paper is concerned with the investigation of the conditions to be fulfilled by the mono implicit runge kutta mirk method in order to generate a mono implicit runge kutta nystrom method mirkn that is p stable one of the main theoretical results is the property that mirk methods in standard form cannot generate mirkn methods in standard form of order greater than 4 many examples of mirkn methods generated by mirk methods are presented

numerical solution of the generalized burger s equation via spectral spline methods abstract in this paper we present a mixed spectral spline approach to solve the generalized burger s equation gbe the method is based on a chebyshev spectral approximation in combination with 3 point spline collocation methods the proposed method is accomplished by starting with chebyshev spectral approximation for the highest order derivative in the x direction and generating approximations to the lower order derivatives in the x direction through successive integration of the highest order derivative the problem is then reduced to a system of ordinary differential equations in the t direction which will be treated by 3 point spline collocation methods

detection of the break in interaural correlation is affected by interaural delay aging and center frequency this study investigated whether interaural integration is affected by introducing an interaural delay in experiment 1 both younger adults with normal hearing and older adults in the early stages of presbycusis were able to detect a transient break in interaural correlation bic in the temporal middle of interaurally correlated wideband noises however their duration thresholds for detecting the bic became larger with increasing interaural time difference itd from 0 to 6 ms and the threshold increase for older participants was larger than that for younger participants in experiment 2 to investigate whether the effect of changing itd on the bic detection is frequency dependent 1 3 octave narrowband noises with various center frequencies were used as stimuli results show that the duration threshold for detecting the bic was higher for high frequency noises than for low frequency noises also with increasing itd from 0 to 4 ms the threshold increase was larger for high frequency noises than for low frequency noises the results suggest that there are age and frequency related temporal declines in maintaining fine structure signals for interaural integration these declines may affect the recognition of sound sources in reverberant environments

stabilization of nonlinear systems in the plane abstract it is shown that every small time locally controllable system in the plane can locally be asymptotically stabilized by employing locally holder continuous feedback laws as essentially was conjectured by e sontag an explicit algorithm for the construction of such feedback laws is given

detection of static and dynamic changes in interaural correlation this study examines the relation between a static and a dynamic measure of interaural correlation discrimination 1 the just noticeable difference jnd in interaural correlation and 2 the minimum detectable duration of a fixed interaural correlation change embedded within a single noise burst of a given reference correlation for the first task jnds were obtained from reference interaural correlations of 1 1 and from 0 interaural correlation in either the positive or negative direction for the dynamic task duration thresholds were obtained for a brief target noise of 1 1 and 0 interaural correlation embedded in reference marker noise of 1 1 and 0 interaural correlation performance with a reference interaural correlation of 1 was significantly better than with a reference correlation of 1 similarly when the reference noise was interaurally uncorrelated discrimination was significantly better for a target correlation change towards 1 than towards 1 thus for both static and dynamic tasks interaural correlation discrimination in the positive range was significantly better than in the negative range using the two measures the length of a binaural temporal window was estimated its equivalent rectangular duration erd was approximately 86 ms and independent of the interaural correlation configuration

modified backward differentiation methods of the adams type based on exponential interpolation abstract for the numerical solution of first order differential equations multistep methods of the adams type are established which integrate exactly the functions exp kx x j j 0 1 n where k is a parameter these methods have stepsize dependent coefficients which also depend on k within each integration segment one can choose for k the value which minimizes in a certain sense the local truncation error in this way the new method leads to highly accurate results in comparison with the classical methods of the adams type especially when the solution of the differential equation shows an exponential behaviour numerical examples are provided to illustrate this

extended double stride l stable methods for the numerical solution of odes abstract usmani and agarwal 1 had proposed construction of extended one step higher than two order a stable methods by coupling classical linear multistep methods lmms following on their idea in the present paper we describe a class of extended double stride methods based on simpson s rule which are fourth order and l stable

asymptotic stabilization of a class of smooth two dimensional systems this paper studies the asymptotic stabilizability of two dimensional control systems the class under consideration includes c infty systems that satisfy a certain genericity assumption and all real analytic systems necessary and sufficient conditions for feedback stabilization using continuous feedback and a sufficient condition for c 1 feedback stabilization are given this latter condition is given in terms of an inequality involving two indices if the direction of the inequality is changed an obstruction to c infty feedback stabilizability is obtained a subclass of polynomial systems is also studied and given complete necessary and sufficient conditions for global asymptotic stabilization using c 1 feedback

spatial mapping of intracranial auditory events for various degrees of interaural coherence the broadening and splitting of auditory events in dichotic listening conditions with various degrees of interaural coherence are discussed by using a psychoacoustical mapping method it has been possible to observe broadening and splitting for a wide range of stimuli including broadband pink noise as well as bandpass noises with different relative bandwidths and center frequencies the spatial extents of the auditory events decrease with increasing center frequencies for bandpass stimuli of constant relative bandwidth the number of partial events for bandpass stimuli decreases with increasing degrees of interaural coherence these results are for example of interest with respect to auditory spaciousness in architectural acoustics

multistride l stable fourth order methods for the numerical solution of odes recently chawla et al 1 have obtained a one parameter family of double stride l stable methods of fourth order by the coupling of three linear multistep methods lmms here we present an alternative derivation technique based on mono implicit runge kutta mirk methods the mirk method provides a framework within which all families of double and triple stride l stable methods of fourth order can be expressed the well established theory for runge kutta methods can then be used to derive these families in a straightforward manner

a class of stabilized extended one step methods for the numerical solution of odes abstract to overcome the order barrier imposed by a stability on linear multistep methods lmms usmani and agarwal 1 had constructed a third order a stabilized extended one step method by coupling two lmms in the present paper we introduce a class of extended one step methods generalizing the method of usmani and agarwal methods of this class of orders three and four which are a and or l stable have been given previously in 2 3 it is natural to ask the maximum attainable order for methods of this class which are also a stable or l stable the purpose of this paper is to show that the maximum attainable order of a method in this class is five we derive fifth order extended one step methods and show the existence of sub families of these methods which are a stable or l stable these methods are illustrated by considering two numerical examples

interaural correlation and the binaural summation of loudness the effect of interaural correlation on the loudness for noisebands was measured using a loudness matching task in naive listeners the task involved a sequence of loudness comparisons for which the intensity of one stimulus in a given comparison was varied using a one up one down adaptive rule the task provided an estimate of the level difference in decibels for which two stimulus conditions have equal loudness giving measures of loudness difference in equivalent decibel units dbequiv concurrent adaptive tracks measured loudness differences between 1 0 and 1 and between these binaural stimuli and the monaural case for various noisebands for all noisebands monaural stimuli required approximately 6db higher levels than 1 for equal loudness for most noisebands 1 and 1 were almost equal in loudness with 1 being slightly louder in the majority of measurements while 0 was about 2dbequiv louder than 1 or 1 however noisebands with significant high frequency energy showed smaller differences for 3745 4245hz 0 was only about 0 85dbequiv louder than 1 and for 100 5000hz it was non significantly louder perhaps 0 7dbequiv

perceived lateral position of narrow band noise in hearing impaired and normal hearing listeners under conditions of equal sensation level and sound pressure level the perceived lateral position of narrow band noise nbn was studied in a graphic pointer task as a function of the method of compensation for interaural threshold asymmetries in hearing impaired and normal hearing subjects the method of compensation consisted of equal sensation level eqsl or equal sound pressure level eqspl at the two ears within the same subject the nbn signals were presented at 11 center frequencies with interaural intensity differences iids that varied from 20 to 20 db when equalizing by sl the perceived lateral position is essentially linearly dependent on the degree and direction of asymmetry in asymmetric normal hearing and hearing impaired listeners equalizing by spl shows no such dependency but produces images that are lateralized close to the midline these results reveal that subjects may have adapted to their threshold asymmetries these results will be discussed in terms of the fitting of binaural hearing aids

asymptotic stabilization of two dimensional real analytic systems abstract we investigate the local asymptotic stabilizability of a real analytic control system around an equilibrium point and give necessary and sufficient conditions for local asymptotic stabilization using continuous feedback

adding an integrator for the stabilization problem abstract we study the relationship between the following two properties p1 the system x f x y y v is locally asymptotically stabilizable and p2 the system x f x u is locally asymptotically stabilizable where x r n y r dayawansa martin and knowles have proved that these properties are equivalent if the dimension n 1 here using the so called control lyapunov function approach a we propose another more constructive and somewhat simpler proof of dayawansa martin and knowles s result b we show that in general p1 does not imply p2 for dimensions n larger than 1 c we prove that p2 implies p1 if some extra assumptions are added like homogeneity of the system by using the latter result recursively we obtain a sufficient condition for the local asymptotic stabilizability of systems in a triangular form

generating partially correlated noise a comparison of methods there are three standard methods for generating two channels of partially correlated noise the two generator method the three generator method and the symmetric generator method these methods allow an experimenter to specify a target cross correlation between the two channels but actual generated noises show statistical variability around the target value numerical experiments were done to compare the variability for those methods as a function of the number of degrees of freedom the results of the experiments quantify the stimulus uncertainty in diverse binaural psychoacoustical experiments incoherence detection perceived auditory source width envelopment noise localization lateralization and the masking level difference the numerical experiments found that when the elemental generators have unequal powers the different methods all have similar variability when the powers are constrained to be equal the symmetric generator method has much smaller variability than the other two

frequency dependency of the relationship between perceived auditory source width and the interaural cross correlation coefficient for time invariant stimuli previous research has indicated that the relationship between the interaural cross correlation coefficient iacc of a narrow band sound and its perceived auditory source width is dependent on its frequency however this dependency has not been investigated in sufficient detail for researchers to be able to properly model it in order to produce a perceptually relevant iacc based model of auditory source width a series of experiments has therefore been conducted to investigate this frequency dependency in a controlled manner and to derive an appropriate model three main factors were discovered in the course of these experiments first the nature of the frequency dependency of the perceived auditory source width of stimuli with an iacc of 1 was determined and an appropriate mathematical model was derived second the loss of perceived temporal detail at high frequencies caused by the breakdown of phase locking in the ear was found to be relevant and the model was modified accordingly using rectification and a low pass filter finally it was found that there was a further frequency dependency at low frequencies and a method for modeling this was derived the final model was shown to predict the experimental data well

an extended trapezoidal formula for the diffusion equation in two space dimensions abstract we describe a locally one dimensional lod time integration scheme for the diffusion equation in two space dimensions ut uxx uyy based on the extended trapezoidal formula etf the resulting lod etf scheme is third order in time and is unconditionally stable we describe the scheme for both dirichlet and neumann boundary conditions we then extend the lod etf scheme for nonlinear reaction diffusion equations and for the convection diffusion equation in two space dimensions numerical experiments are given to illustrate the obtained scheme and to compare its performance with the better known lod crank nicolson scheme while the lod crank nicolson scheme can give unwanted oscillations in the computed solution our present lod etf scheme provides both stable and accurate approximations for the true solution

numerical methods based on extended one step methods for solving optimal control problems in this article we develop extended one step methods for solving the dynamic system of optimal control problems governed by ordinary differential equations the control variables are approximated by polynomial functions the proposed problem is reduced to either a constrained or unconstrained minimization problem according to the nature of the dynamic system and the given conditions numerical results and comparisons with other methods are presented

stabilization of planar nonlinear systems by polynomial feedback control abstract in this paper some new results are obtained for the problem of local asymptotic stabilization of planar nonlinear systems by polynomial feedback controls the results are obtained by reducing the problem to that of asymptotic stabilization of a one dimensional system by a particular class of continuous feedback controls it is shown constructively that if the one dimensional system is asymptotically stabilize by such a feedback control then the corresponding two dimensional system is asymptotically stabilize by a polynomial feedback control

extended one step time integration schemes for convection diffusion equations abstract we first describe a one parameter family of unconditionally stable third order time integration schemes for the convection diffusion equation u t cu x vu xx based on the extended trapezoidal formulas of usmani and agarwal 1 interestingly there exists a method that is fourth order as well as unconditionally stable we then describe a one parameter family of unconditionally stable fourth order time integration schemes based on the extended simpson rules of chawla et al 2 again there exists a method that is fifth order as well as unconditionally stable the stability and accuracy of the obtained methods are tested and compared with the widely used method of crank nicolson by considering three problems of practical interest

an a stable extended trapezoidal rule for the integration of ordinary differential equations abstract we examine a single step implicit integration algorithm which is obtained by a modification of the well known trapezoidal rule the obtained new method is a third order numerical process and preserves the property of a stability of the trapezoidal rule numerical examples involving stiff linear systems of first order differential equations are also included to demonstrate the practical usefulness of this new integration procedure