binaural detection with spectrally nonoverlapping signals and maskers evidence for masking by aural distortion products thresholds were measured for diotic tonal signals in the presence of interaurally delayed bands of gaussian noise when the signal frequency was 525 hz the spectrum of the noise was either below highest frequency 450 hz or above lowest frequency 600 hz the frequency of the signal when the signal frequency was 450 hz the spectrum of the noise was always above the signal frequency lowest frequency 600 hz signals had a 250 ms duration and were temporally centered within the 300 ms long bursts of noise the spectrum level of the noise was 60 db thresholds obtained in all three conditions varied essentially sinusoidally with the interaural delay of the noise for signals below the spectrum of the noise the periodicities within the data were close to but not identical with the periodicities of the signals this outcome is discussed in terms of masking produced by aural distortion products stemming from interactions within the bands of noise cf van der heijden and kohlrausch j acoust soc am 98 3125 3134 1995 for signals above the spectrum of the noise the periodicities in the data suggested that masking was produced by components within the band of noise patterns within the data are also discussed in terms of limitations concerning the magnitude of external delays that can be matched by internal delays that are incorporated in modern models of binaural processing

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

robust auditory localization using probabilistic inference and coherence based weighting of interaural cues robust sound source localization is performed by the human auditory system even in challenging acoustic conditions and in previously unencountered complex scenarios here a computational binaural localization model is proposed that possesses mechanisms for handling of corrupted or unreliable localization cues and generalization across different acoustic situations central to the model is the use of interaural coherence measured as interaural vector strength ivs to dynamically weight the importance of observed interaural phase ipd and level ild differences in frequency bands up to 1 4 khz this is accomplished through formulation of a probabilistic model in which the ild and ipd distributions pertaining to a specific source location are dependent on observed interaural coherence bayesian computation of the direction of arrival probability map naturally leads to coherence weighted integration of location cues across frequency and time results confirm the model s validity through statistical analyses of interaural parameter values simulated localization experiments show that even data points with low reliability i e low ivs can be exploited to enhance localization performance a temporal integration length of at least 200 ms is required to gain a benefit this is in accordance with previous psychoacoustic findings on temporal integration of spatial cues in the human auditory system

the c 3 theorem and a d 2 algorithm for large scale stochastic mixed integer programming set convexification this paper considers the two stage stochastic integer programming problem with an emphasis on instances in which integer variables appear in the second stage drawing heavily on the theory of disjunctive programming we characterize convexifications of the second stage problem and develop a decomposition based algorithm for the solution of such problems in particular we verify that problems with fixed recourse are characterized by scenario dependent second stage convexifications that have a great deal in common we refer to this characterization as the c3 common cut coefficients theorem based on the c3 theorem we develop a decomposition algorithm which we refer to as disjunctive decomposition d2 in this new class of algorithms we work with master and subproblems that result from convexifications of two coupled disjunctive programs we show that when the second stage consists of 0 1 milp problems we can obtain accurate second stage objective function estimates after finitely many steps this result implies the convergence of the d2 algorithm

a family of distributed space time trellis codes with asynchronous cooperative diversity in current cooperative communication schemes to achieve cooperative diversity synchronization between terminals is usually assumed which may not be practical since each terminal has its own local oscillator in this paper based on the stack construction proposed by hammons and el gamal we first construct a family of space time trellis codes for bpsk modulation scheme that is characterized to possess the full cooperative diversity order without the synchronization assumption we then generalize this family of the space time trellis codes from bpsk to higher order qam and psk modulation schemes based on the unified construction proposed by lu and kumar some diversity product properties of space time trellis codes are studied and simplified decoding methods are discussed simulation results are given to illustrate the performance of the newly proposed codes

on the separation of disjunctive cuts disjunctive cuts for mixed integer linear programs mips were introduced by egon balas in the late 1970s and have been successfully exploited in practice since the late 1990s in this paper we investigate the main ingredients of a disjunctive cut separation procedure and analyze their impact on the quality of the root node bound for a set of instances taken from miplib library we compare alternative normalization conditions and try to better understand their role in particular we point out that constraints that become redundant because of the disjunction used can produce over weak cuts and analyze this property with respect to the normalization used finally we introduce a new normalization condition and analyze its theoretical properties and computational behavior along the way we make use of a number of small numerical examples to illustrate some basic and often misinterpreted disjunctive programming features

the effects of randomizing values of interaural disparities on binaural detection and on discrimination of interaural correlation the purpose of this study was to assess whether randomizing roving baseline interaural parameters of binaural stimuli would adversely affect performance in masking level difference and in interaural correlation discrimination paradigms listeners detection thresholds were measured in noso and nos configurations for both broadband 100 3000 hz and narrow band 450 550 hz maskers centered at 500 hz in addition thresholds of interaural decorrelation from a reference correlation of 1 0 were measured for 100 hz wide bands of noise centered at 500 hz data were obtained under conditions in which either values of itd or values of iid were roved both within and across trials data were also collected in the absence of a rove the range of the rove was 500 s for itds and was 6 db for iids the duration of the stimuli was varied between 17 and 310 ms overall the results indicate that independent of duration roving the interaural cues produced small degradations of performance as compared to data ob

analytical expressions for the envelope correlation of certain narrow band stimuli analytical solutions are presented for the correlation between the envelopes of certain narrow band stimuli which are typically used in binaural research these stimuli are either the sum of an in phase masker and an out of phase signal or they are two partially correlated noises because an envelope has a nonzero mean the solutions differ depending on whether the envelope correlation is expressed as the normalized cross correlation or as the normalized cross covariance pearson product moment correlation the envelope correlation depends on the statistics of the masker and the signal whereas the waveform correlation depends on neither this influence only disappears for the normalized envelope cross correlation provided that the correlation is close to one in this case the normalized envelope cross correlation is equal to the square root of the waveform correlation the results for two partially correlated noise bands are also of relevance for experiments dealing with monaural envelope discrimination and comodulation masking release

relating interaural difference sensitivities for several parameters measured in normal hearing and hearing impaired listeners just noticeable differences jnds in interaural time delay itd interaural level difference ild and interaural cross correlation icc were measured with low and high frequency noise bands over multiple sessions for 10 normal hearing nh and 11 hearing impaired hi listeners individual subject thresholds tended to improve with training then stabilize measured jnds varied over these experienced listeners for both subject groups and all tasks group jnds were seldom predictable from hearing level individual listeners jnds were highly correlated across frequency for each task and group except for icc in the hi listeners further itd jnds almost always significantly correlated with ild jnds within a group finally although the icc jnds always significantly correlated with the itd or ild jnds for the nh listeners they often did not for the hi listeners these findings suggest that little information about binaural sensitivity is added for nh listeners with multiple itd ild and icc measures for hi listeners however while itd and ild measures are well correlated information is added with icc measures in general the results suggest that less information is added with jnd measures for nh listeners 15 significant correlations than for hi listeners six significant correlations

perceptual separation of concurrent speech sounds absence of across frequency grouping by common interaural delay three experiments and a computational model explored the role of within channel and across channel processes in the perceptual separation of competing complex broadband sounds which differed in their interaural phase spectra in each experiment two competing vowels whose first and second formants were represented by two discrete bands of noise were presented concurrently for identification experiments 1 and 2 showed that listeners were able to identify the vowels accurately when each was presented to a different ear but were unable to identify the vowels when they were presented with different interaural time delays itds i e listeners could not group the noisebands in different frequency regions with the same itd and thereby separate them from bands in other frequency regions with a different itd experiment 3 demonstrated that while listeners were unable to exploit a difference in interaural delay between the pairs of noisebands listeners could identify a vowel defined by interaurally decorrelated noisebands when the other two noisebands were interaurally correlated a computational model based upon that of durlach j acoust soc am 32 1075 1076 1960 showed that the results of these and other experiments can be interpreted in terms of a within channel mechanism which is sensitive to interaural decorrelation thus the across frequency integration which occurs in the lateralization of complex sounds may play little role in segregating concurrent sounds

predicting binaural speech intelligibility using the signal to noise ratio in the envelope power spectrum domain this study proposes a binaural extension to the multi resolution speech based envelope power spectrum model mr sepsm jorgensen ewert and dau 2013 j acoust soc am 134 436 446 it consists of a combination of better ear be and binaural unmasking processes implemented as two monaural realizations of the mr sepsm combined with a short term equalization cancellation process and uses the signal to noise ratio in the envelope domain snrenv as the decision metric the model requires only two parameters to be fitted per speech material and does not require an explicit frequency weighting the model was validated against three data sets from the literature which covered the following effects the number of maskers the masker types speech shaped noise ssn speech modulated ssn babble and reversed speech the masker s azimuths reverberation on the target and masker and the interaural time difference of the target and masker the pearson correlation coefficient between the simulated spee

a unified construction of space time codes with optimal rate diversity tradeoff the problem of constructing space time st block codes over a fixed desired signal constellation is considered in this situation there is a tradeoff between the transmission rate as measured in constellation symbols per channel use and the transmit diversity gain achieved by the code the transmit diversity is a measure of the rate of polynomial decay of pairwise error probability of the code with increase in the signal to noise ratio snr in the setting of a quasi static channel model let n sub t denote the number of transmit antennas and t the block interval for any n sub t spl les t a unified construction of n sub t spl times t st codes is provided here for a class of signal constellations that includes the familiar pulse amplitude pam quadrature amplitude qam and 2 sup k ary phase shift keying psk modulations as special cases the construction is optimal as measured by the rate diversity tradeoff and can achieve any given integer point on the rate diversity tradeoff curve an estimate of the coding gain realized is given other results presented here include i an extension of the optimal unified construction to the multiple fading block case ii a version of the optimal unified construction in which the underlying binary block codes are replaced by trellis codes iii the providing of a linear dispersion form for the underlying binary block codes iv a gray mapped version of the unified construction and v a generalization of construction of the ary case corresponding to constellations of size sup k items ii and iii are aimed at simplifying the decoding of this class of st codes

auditory spatial resolution in horizontal vertical and diagonal planes minimum audible angle maa and minimum audible movement angle mama thresholds were measured for stimuli in horizontal vertical and diagonal 60 degrees planes a pseudovirtual technique was employed in which signals were recorded through kemar s ears and played back to subjects through insert earphones thresholds were obtained for wideband high pass and low pass noises only 6 of 20 subjects obtained wideband vertical plane maas less than 10 degrees and only these 6 subjects were retained for the complete study for all three filter conditions thresholds were lowest in the horizontal plane slightly but significantly higher in the diagonal plane and highest for the vertical plane these results were similar in magnitude and pattern to those reported by perrott and saberi j acoust soc am 87 1728 1731 1990 and saberi and perrott j acoust soc am 88 2639 2644 1990 except that these investigators generally found that thresholds for diagonal planes were as good as those for the horizontal plane the present results are consistent with the hypothesis that diagonal plane performance is based on independent contributions from a horizontal plane system sensitive to interaural differences and a vertical plane system sensitive to pinna based spectral changes measurements of the stimuli recorded through kemar indicated that sources presented from diagonal planes can produce larger interaural level differences ilds in certain frequency regions than would be expected based on the horizontal projection of the trajectory such frequency specific ild cues may underlie the very good performance reported in previous studies for diagonal spatial resolution subjects in the present study could apparently not take advantage of these cues in the diagonal plane condition possibly because they did not externalize the images to their appropriate positions in space or possibly because of the absence of a patterned visual field

integration of monaural and binaural evidence of vowel formants the intelligibility of speech is sustained at lower signal to noise ratios when the speech has a different interaural configuration from the noise this paper argues that the advantage arises in part because listeners combine evidence of the spectrum of speech in the across frequency profile of interaural decorrelation with evidence in the across frequency profile of intensity to support the argument three experiments examined the ability of listeners to integrate and segregate evidence of vowel formants in these two profiles in experiment 1 listeners achieved accurate identification of the members of a small set of vowels whose first formant was defined by a peak in one profile and whose second formant was defined by a peak in the other profile this result demonstrates that integration is possible experiment 2 demonstrated that integration is not mandatory insofar as listeners could report the identity of a vowel defined entirely in one profile despite the presence of a competing vowel in the other profile the presence of the competing vowel reduced accuracy of identification however showing that segregation was incomplete experiment 3 demonstrated that segregation of the binaural vowel in particular can be increased by the introduction of an onset asynchrony between the competing vowels the results of experiments 2 and 3 show that the intrinsic cues for segregation of the profiles are relatively weak overall the results are compatible with the argument that listeners can integrate evidence of spectral peaks from the two profiles

lateralization of large interaural delays two experiments explored the limits of listeners abilities to interpret large interaural time delays itds in terms of laterality in experiment 1 just noticeable differences jnd s were measured using an adaptive procedure for various reference itds of gaussian noise between 0 and 3000 microseconds the jnd s increased gradually with reference itd for reference itds between 0 microsecond and 700 microseconds then rose sharply to plateau at much higher jnd s for the remainder of the standard itds tested 1000 3000 microseconds the second experiment tested left right discrimination of gaussian noise that was interaurally delayed up to 10 000 microseconds and high pass filtered to cutoff frequencies between 0 hz broadband and 3000 hz there was good discrimination 62 significantly above chance p 0 05 for broadband and 500 hz high pass cutoff stimuli for all itds up to 10 000 microseconds and for itds up to at least 3000 microseconds for higher high pass cutoff frequencies these results indicate that laterality cues are discriminable at much larger itds than are experienced in free field listening even in the absence of energy below 3 khz

temporal pitch perception and the binaural system two experiments examined the relationship between temporal pitch and more generally rate perception and auditory lateralization both used dichotic pulse trains that were filtered into the same high 3900 5400 hz frequency region in order to eliminate place of excitation cues in experiment 1 a 1 s periodic pulse train of rate fr was presented to one ear and a pulse train of rate 2fr was presented to the other in the synchronous condition every other pulse in the 2fr train was simultaneous with a pulse in the opposite ear in each trial subjects concentrated on one of the two binaural images produced by this mixture they matched its perceived location by adjusting the interaural level difference ild of a bandpass noise and its rate pitch was then matched by adjusting the rate of a regular pulse train the results showed that at low fr e g 2 hz subjects heard two pulse trains of rate fr one in the higher rate ear and one in the middle of the head at higher fr 25 hz subjects hea

interaural correlation discrimination ii relation to binaural unmasking many theoretical models of binaural interaction assume that sensitivity to interaural correlation underlies binaural unmasking this paper explores the extent to which sensitivity to changes in interaural correlation implied by results from binaural detection experiments are consistent with sensitivity to changes in interaural correlation measured directly in correlation discrimination experiments the vehicle for this exploration is a simplified model of the underlying processes assumed by many models of binaural unmasking for the detection of narrow band signals in the presence of broadband noise consideration is given to psychometric function slopes detection thresholds bandwidth effects duration effects level effects and interaural parameter effects although many of the results obtained from our analysis are consistent with the notion that the cue in binaural detection tasks is a change in interaural correlation some significant inconsistencies are noted

a modified lift and project procedure in recent years the lift and project approach has been used successfully within a branch and cut framework to solve large difficult pure and mixed 0 1 programs that have resisted solution efforts by pure branch and bound codes the approach uses a linear description in a higher dimensional space of the convex hull of the disjunctive set created by imposing one or several 0 1 conditions by solving a linear program derived from this higher dimensional representation the cut generating linear program cglp the standard lift and project procedure obtains a deepest cut in a well defined sense we propose a modification of cglp that allows us to generate not just one deepest cut but a class of cuts with desirable properties each at the cost of one extra pivot in the optimal tableau of the modified cglp

performance in several binaural interaction experiments the relationship between interaural correlation discrimination and binaural detection was investigated using common experimental procedures and common subjects psychometric functions were obtained for four normal hearing subjects at 500 and 4000 hz using third octave noise signals for the correlation discrimination experiment and pure tone signals and third octave noise maskers for the detection experiment results from these two measurements which were compared by expressing the signal to noise ratio as an equivalent change in interaural correlation support the idea that interaural correlation discrimination and binaural detection are closely related since large intersubject differences in binaural performance were observed in these experiments interaural time interaural intensity and monaural intensity discrimination were measured in a second experiment the results of the second experiment show large intersubject differences for the interaural tasks but not for the monaural task

an evaluation of models for diotic and dichotic detection in reproducible noises several psychophysical models for masked detection were evaluated using reproducible noises the data were hit and false alarm rates from three psychophysical studies of detection of 500 hz tones in reproducible noise under diotic n0s0 and dichotic n0s conditions with four stimulus bandwidths 50 100 115 and 2900 hz diotic data were best predicted by an energy based multiple detector model that linearly combined stimulus energies at the outputs of several critical band filters the tone plus noise trials in the dichotic data were best predicted by models that linearly combined either the average values or the standard deviations of interaural time and level differences however these models offered no predictions for noise alone responses the decision variables of more complicated temporal models including the models of dau et al 1996a j acoust soc am 99 3615 3622 and breebaart et al 2001a j acoust soc am 110 1074 1088 were weakly correlated with subjects responses comparisons of the dependencies of each model on envelope and fine structure cues to those in the data suggested that dependence upon both envelope and fine structure as well as an interaction between them is required to predict the detection results

minimum audible angles in the horizontal and vertical planes effects of stimulus onset asynchrony and burst duration the effects of burst duration and stimulus onset asynchrony soa the onset onset time difference on the minimum audible angle maa were measured in the horizontal and vertical planes using high pass noise bursts four listeners were tested with two burst durations 10 and 50 ms and five soas 25 50 100 200 and 400 ms using an adaptive paradigm in both planes maas were lowest at burst duration 50 ms and the maas decreased exponentially with soa although the effect of burst duration was generally larger in the vertical plane than in the horizontal plane the plane of presentation did not affect the relationship between soa and maa

the influence of different segments of the ongoing envelope on sensitivity to interaural time delays the auditory system is sensitive to interaural timing disparities in the fine structure and the envelope of sounds each contributing important cues for lateralization in this study psychophysical measurements were conducted with customized envelope waveforms in order to investigate the isolated effect of different segments of a periodic ongoing envelope on lateralization one envelope cycle was composed of the four segments attack flank hold duration decay flank and pause duration which were independently varied to customize the envelope waveform the envelope waveforms were applied to a 4 khz sinusoidal carrier and just noticeable envelope interaural time differences were measured in six normal hearing subjects the results indicate that attack durations and pause durations prior to the attack are the most important stimulus characteristics for processing envelope timing disparities the results were compared to predictions of three binaural lateralization models based on the normalized cross correlation coefficient two of the models included an additional stage to mimic neural adaptation prior to binaural interaction involving either a single short time constant 5 ms or a combination of five time constants up to 500 ms it was shown that the model with the single short time constant accounted best for the data

a new way to account for binaural detection as a function of interaural noise correlation the purpose of this communication is to describe a new method for predicting masking level differences mlds as a function of the interaural correlation of the masking noise the general idea is to decompose a binaural noise masker having an arbitrary value of interaural correlation into two parts an no constituent and an n pi constituent it is shown that the amount of masking produced by a noise having an arbitrary interaural correlation is equal to the addition of the masking effects produced by the no and n pi constituents that compose the masker the new approach was used to generate predictions of mlds for n rho s pi and n rho so conditions those predictions accounted for 98 of the variance in the classical data of robinson and jeffress j acoust soc am 35 1947 1952 1963 finally it is shown that the additivity of masking method is mathematically equivalent to assuming that binaural detection consists of a stage of errorless binaural processing preceded by a corrupted representation of the stimulus

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

a lift and project cutting plane algorithm for mixed 0 1 programs we propose a cutting plane algorithm for mixed 0 1 programs based on a family of polyhedra which strengthen the usual lp relaxation we show how to generate a facet of a polyhedron in this family which is most violated by the current fractional point this cut is found through the solution of a linear program that has about twice the size of the usual lp relaxation a lifting step is used to reduce the size of the lp s needed to generate the cuts an additional strengthening step suggested by balas and jeroslow is then applied we report our computational experience with a preliminary version of the algorithm this approach is related to the work of balas on disjunctive programming the matrix cone relaxations of lovasz and schrijver and the hierarchy of relaxations of sherali and adams

interaural correlation sensitivity sensitivity to differences in interaural correlation was measured for 1 3 erb wide bands of noise using a 2ifc task at six frequencies 250 500 750 1000 1250 and 1500 hz the sensitivity index d was measured for discriminations between a number of fixed pairs of correlation values cumulative d functions were derived for each frequency and condition the d for discriminating any two values of correlation may be recovered from the cumulative d function by the difference between cumulative d s for these values two conditions were employed the noisebands were either presented in isolation narrow band condition or in the context of broad contiguous flanking bands of correlated noise fringed condition the cumulative d functions showed greater sensitivity to differences in correlation close to 1 than close to 0 at low frequencies but this difference was less pronounced in the fringed condition also a more linear relationship was observed when cumulative d was plotted as a function of the equivalent signal to noise ratio snr in db for each correlation value rather than directly against correlation the equivalent snr was the snr at which the interaural correlation in an nos stimulus would equal the interaural correlation of the noise used in the experiment the maximum cumulative d declined above 750 hz this decline was steeper for the fringed than for the narrow band condition for the narrow band condition the total cumulative d was variable across listeners all cumulative d functions were closely fitted using a simple two parameter function the complete data sets averaged across listeners from the fringed and narrow band conditions were fitted using functions to describe the changes in these parameters over frequency in order to produce an interpolated family of curves that describe sensitivity at frequencies between those tested these curves predict the spectra recovered by the binaural system when complex sounds such as speech are masked by noise

cones of matrices and set functions and 0 1 optimization it has been recognized recently that to represent a polyhedron as the projection of a higher dimensional but simpler polyhedron is a powerful tool in polyhedral combinatorics a general method is developed to construct higher dimensional polyhedra or in some cases convex sets whose projection approximates the convex hull of 0 1 valued solutions of a system of linear inequalities an important feature of these approximations is that one can optimize any linear objective function over them in polynomial time in the special case of the vertex packing polytope a sequence of systems of inequalities is obtained such that the first system already includes clique odd hole odd antihole wheel and orthogonality constraints in particular for perfect and many other graphs this first system gives the vertex packing polytope for various classes of graphs including t perfect graphs it follows that the stable set polytope is the projection of a polytope with a polynomial number of facets an extension o

minimum audible angle thresholds for broadband noise as a function of the delay between the onset of the lead and lag signals minimum audible angle maa thresholds were determined for six experienced subjects using a two alternative forced choice adaptive paradigm broadband pink noise from a single generator was led to two identical speakers the two sources were activated sequentially each for a period of 10 ms the subject s task was to indicate whether the second lag sound came from a source to the right or left of the first lead sound the delay between the onset of the lead and the onset of the lag signal interstimulus onset interval isoi was systematically varied from 1 ms both 10 ms signals were concurrently active for 9 ms to 200 ms for a given isoi the spatial separation was varied adaptively to determine the maa a 450 improvement in auditory spatial resolution was evident as the isoi increased from 1 to 150 ms a further increase in the isoi had no systematic effect on spatial resolution these results indicate that there is a minimum integration period between 100 150 ms for the resolution of spatial

on constructions of algebraic space time codes with am psk constellations satisfying rate diversity tradeoff constructions of space time codes having amplitude modulated phase shift keying am psk constellations are presented in this paper the first construction termed p radii construction is obtained by extending hammons dyadic dual radii construction to the cases when the size of the constellation is a power of a prime p p ges 2 the resultant code is optimal with respect to the rate diversity tradeoff and has an am psk constellation with signal points distributed over p concentric circles in the complex plane i e there are p radii also contained in this paper is the identification of rich classes of nontrivial subset subcodes of the newly constructed space time codes and it is shown that these subset subcodes are again all optimal finally a new generalization of the super unified construction by hammons is presented it is shown that codes obtained from several previously known constructions are subset subcodes of the one derived from this generalized construction

mixed 0 1 programming by lift and project in a branch and cut framework we investigate the computational issues that need to be addressed when incorporating general cutting planes for mixed 0 1 programs into a branch and cut framework the cuts we use are of the lift and project variety some of the issues addressed have a theoretical answer but others are of an experimental nature and are settled by comparing alternatives on a set of test problems the resulting code is a robust solver for mixed 0 1 programs we compare it with several existing codes on a wide range of test problems it performs as well as or better than some of the best currently available mixed integer programming codes

rate diversity tradeoff of space time codes with fixed alphabet and optimal constructions for psk modulation we show that for any q spl times m space time code s having a fixed finite signal constellation there is a tradeoff between the transmission rate r and the transmit diversity gain spl nu achieved by the code the tradeoff is characterized by r spl les q spl nu 1 where q is the number of transmit antennas when either binary phase shift keying bpsk or quaternary phase shift keying qpsk is used as the signal constellation a systematic construction is presented to achieve the maximum possible rate for every possible value of transmit diversity gain

interaural correlation discrimination i bandwidth and level dependence measurements of interaural cross correlation jnds from two reference correlations at several bandwidths were obtained for constant total power and constant spectral power gaussian noise at a reference correlation of 1 the results indicate that for bandwidths less than or equal to 115 hz the jnd remains at a constant value of approximately 0 004 and monotonically increases discrimination performance degrades to approximately 0 04 as bandwidth increases above 115 hz at a reference correlation of 0 the jnd decreases discrimination performance improves from approximately 0 7 to 0 35 as the bandwidth increases from 3 to 115 hz and remains at a constant value of approximately 0 35 for bandwidths greater than 115 hz a decrease in the spectral level causes an increase in the jnds at a reference correlation of 1 and no change in the jnds at a reference correlation of 0 of the three models tested none is able to completely describe all of the empirical results

analytical expressions for the envelope correlation of narrow band stimuli used in cmr and bmld research analytical solutions are presented for the correlation between the envelopes of certain narrow band stimuli that are typically used in experiments on binaural unmasking and on comodulation masking release cmr these stimuli consist of two maskers with identical envelopes and a signal that is added to one of the maskers if the two maskers have the same center frequency and are presented to the right and left ear the stimulus resembles a binaural mosm condition if the two maskers have different center frequencies we have a cmr condition with one flanking band the solutions for the envelope correlation differ depending on whether the envelope correlation is expressed as normalized cross correlation or as normalized cross covariance pearson product moment correlation the envelope correlation depends on the statistics of the masker and the signal whereas the waveform correlation depends on neither this influence only disappears for the normalized envelope cross correlation provided that the masker level is much higher than the signal level in this case the envelope cross correlation is approximately equal to the square root of the waveform correlation it is argued that the different properties of both types of envelope correlation are of relevance for cmr research

the binaural temporal window in adults and children this study investigated the binaural temporal window in adults and children 5 10 5 years of age detection thresholds were estimated for a brief interaurally out of phase s 500hz pure tone signal masked by bandpass 100 2000hz gaussian noise in one set of conditions the masker was consistently either in phase no or out of phase n in another set of conditions the masker changed abruptly in interaural phase non or n no and threshold was estimated at a range of delays with respect to the phase transition masked thresholds were also obtained in further conditions where the masker interaural phase was steady and the signal was of long duration age effects obtained with dynamic maskers could be accounted for by positing that children have a binaural temporal window with a relatively prolonged leading edge or that the children position the binaural temporal window relatively late with respect to the signal modeling of the reduced masking level difference shown by children for a brief s signa

binaural detection as a function of interaural correlation and bandwidth of masking noise implications for estimates of spectral resolution detection thresholds were measured for an antiphasic s 500 hz tone masked by a binaural noise as a function of the bandwidth of the noise several values of interaural correlation of the masking noise were used ranging from 1 to 1 the bandwidth dependence of the thresholds showed a pattern consistent with a 100 hz wide critical band for most values of interaural correlation even for those values which resulted in a considerable binaural release of masking only when the interaural correlation of the masking noise was very close to or equal to unity was the bandwidth dependence of the thresholds in accord with an approximately 300 hz wide binaural critical band measured in previous studies our analysis of the data calls into question the commonly stated notion that binaural processing is characterized by a wider critical band than is monaural processing

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

measurements of the binaural temporal window using a detection task two experiments investigated the shape of the binaural temporal window using a detection task in experiment 1 a 10 ms tone burst was presented binaurally out of phase during a burst of white noise which changed from being interaurally uncorrelated to correlated and back to uncorrelated the tone occurred during the correlated portion of the noise in one interval of each 2i fc trial detection thresholds were recorded using a 2 down 1 up adaptive procedure thresholds were measured for different durations of correlated noise 0 960 ms frequencies of tone burst 125 250 500 and 1000 hz and levels of noise 20 30 40 and 50 db spl hz window shapes based on nine candidate functions were fitted to the data using the assumption that the binaural masking release was related to the overall interaural correlation of noise admitted by the window fitted windows included both a forward and a backward lobe gaussian functions tended to give closer fits than exponential and rounded exponential functions and simple functions gave more parsimonious fits that those which included dynamic range limiting terms using simple gaussian fits the shape of the window was largely independent of frequency and level and the windows for individual listeners had equivalent rectangular durations ranging from 55 to 188 ms the asymmetry was variable although forward lobes were generally shorter than backward lobes experiment 2 ruled out the possibility that the forward lobe might be an artefact caused by distraction of the listener when the interaural phase change in the noise closely followed the signal in this experiment the out of phase tone was presented during a burst of partially correlated noise which changed after a variable interval to a fully correlated noise thresholds for detecting the tone rose i e performance worsened as the interval was increased distraction would have produced the opposite effect

binaural processing model based on contralateral inhibition iii dependence on temporal parameters this paper and two accompanying papers breebaart et al j acoust soc am 110 1074 1088 2001 110 1089 1104 2001 describe a computational model for the signal processing of the binaural auditory system the model consists of several stages of monaural and binaural preprocessing combined with an optimal detector simulations of binaural masking experiments were performed as a function of temporal stimulus parameters and compared to psychophysical data adapted from literature for this purpose the model was used as an artificial observer in a three interval forced choice procedure all model parameters were kept constant for all simulations model predictions were obtained as a function of the interaural correlation of a masking noise and as a function of both masker and signal duration furthermore maskers with a time varying interaural correlation were used predictions were also obtained for stimuli with time varying interaural time or intensity differences finally binaural forward maskin

the influence of interaural stimulus uncertainty on binaural signal detection this paper investigated the influence of stimulus uncertainty in binaural detection experiments and the predictions of several binaural models for such conditions masked thresholds of a 500 hz sinusoid were measured in an n s condition for both running and frozen noise maskers using a three interval forced choice 3ifc procedure the nominal masker correlation varied between 0 64 and 1 and the bandwidth of the masker was either 10 100 or 1000 hz the running noise thresholds were expected to be higher than the frozen noise thresholds because of stimulus uncertainty in the running noise conditions for an interaural correlation close to 1 no difference between frozen noise and running noise thresholds was expected for all values of the masker bandwidth these expectations were supported by the experimental data for interaural correlations less than 1 0 substantial differences between frozen and running noise conditions were observed for bandwidths of 10 and 100 hz two additional conditions were tested to further investigate the influence of stimulus uncertainty in the first condition a different masker sample was chosen on each trial but the correlation of the masker was forced to a fixed value in the second condition one of two independent frozen noise maskers was randomly chosen on each trial results from these experiments emphasized the influence of stimulus uncertainty in binaural detection tasks if the degree of uncertainty in binaural cues was reduced thresholds decreased towards thresholds in the conditions without any stimulus uncertainty in the analysis of the data stimulus uncertainty was expressed in terms of three theories of binaural processing the interaural correlation the ec theory and a model based on the processing of interaural intensity differences iids and interaural time differences itds this analysis revealed that none of the theories tested could quantitatively account for the observed thresholds in addition it was found that in conditions with stimulus uncertainty predictions based on correlation differ from those based on the ec theory

the effects of signal duration on noso and nosπ thresholds at 500 hz and 4 khz a two interval two alternative temporal forced choice procedure was used to measure noso and nos masked thresholds with 500 hz and 4 khz tonal signals the duration of the signal was either 10 20 40 or 320 ms the maskers were 200 hz wide bands of gaussian noise centered at the frequency of the signal and presented continuously decreasing the duration of the 500 hz tonal signal resulted in a modest increase 1 5 db or so in the masking level difference mld measured between noso and nos conditions in contrast decreasing the duration of the 4 khz tonal signal resulted in a substantial decrease 4 5 db or so in the mld comparisons of the data with thresholds predicted from analyses based on windows of temporal integration provided quantitatively acceptable accounts of the data the data obtained in the nos condition at 4 khz which are novel and were of primary interest were well accounted for in a statistical sense however there were small but systematic discrepancies between the predictions and the data those discrepancies although small in magnitude suggest that binaural temporal integration at high frequencies where the envelopes of the stimuli convey the information may be inherently different from both monaural temporal integration and binaural temporal integration at low frequencies

interaural correlation and loudness when the same sound is presented to both ears rather than to just one a phenomenon called binaural summation occurs in which the overall loudness is greater than when either ear is individually stimulated the present investigation focused on the effect of interaural correlation on this phenomenon an adaptive matching paradigm was used to measure the difference in intensity between monotic diotic uncorrelated and anticorrelated bands of noise needed to equate them in loudness the results for 460 540 hz bands showed 1 consistent with binaural summation diotic noise was matched to monotic noise that was 4 6 db more intense and 2 uncorrelated noise was matched to diotic noise that was 2 0 db more intense anticorrelated and diotic noises did not differ significantly in intensity when matched in loudness similar results were observed for 100 900 hz bands 1 was extended to 6 5 db and 2 remained at 2 0 db but anticorrelated noise was now matched to diotic noise that was 1 0 db more intense f

nonanticipative duality relaxations and formulations for chance constrained stochastic programs we propose two new lagrangian dual problems for chance constrained stochastic programs based on relaxing nonanticipativity constraints we compare the strength of the proposed dual bounds and demonstrate that they are superior to the bound obtained from the continuous relaxation of a standard mixed integer programming mip formulation for a given dual solution the associated lagrangian relaxation bounds can be calculated by solving a set of single scenario subproblems and then solving a single knapsack problem we also derive two new primal mip formulations and demonstrate that for chance constrained linear programs the continuous relaxations of these formulations yield bounds equal to the proposed dual bounds we propose a new heuristic method and two new exact algorithms based on these duals and formulations the first exact algorithm applies to chance constrained binary programs and uses either of the proposed dual bounds in concert with cuts that eliminate solutions found by the subproblems the second exact method is a branch and cut algorithm for solving either of the primal formulations our computational results indicate that the proposed dual bounds and heuristic solutions can be obtained efficiently and the gaps between the best dual bounds and the heuristic solutions are small

the effect of burst duration interstimulus onset interval and loudspeaker arrangement on auditory apparent motion in the free field the illusion of auditory apparent motion aam was examined in order to determine the burst durations and interstimulus onset intervals isois at which aam is heard when spatial information regarding source location was varied in the first experiment aam was examined in the free field under monaural and binaural listening conditions aam was heard at the same burst duration isoi combinations for both listening conditions but the location of the lead source could be determined only under binaural listening in the second experiment aam was measured with two and three sound sources the number of sources did not affect the burst duration isoi combinations that produced aam but did affect the determination of the location of the lead source in the third experiment aam was tested when the sources were located in the median plane the sources were located either at 0 and 180 azimuth or both at 0 azimuth one in the horizontal plane and one 20 above the location of the speakers did not affect the timing requirements for the perception of aam only the timing requirements for the detection of the lead source in the fourth experiment aam was measured when the vertical separation between the sources was either 2 5 or 20 aam was heard at both separations even though 2 5 is less than the vertical maa in each of these experiments only burst duration and isoi determined whether motion was heard localization cues were important only for the determination of the direction of motion

interaural fluctuations and the detection of interaural incoherence iii narrowband experiments and binaural models in the first two articles of this series reproducible noises with a fixed value of interaural coherence 0 992 were used to study the human ability to detect interaural incoherence it was found that incoherence detection is strongly correlated with fluctuations in interaural differences especially for narrow noise bandwidths but it remained unclear what function of the fluctuations best agrees with detection data in the present article ten different binaural models were tested against detection data for 14 and 108 hz bandwidths these models included different types of binaural processing independent interaural phase difference interaural level difference lateral position and short term cross correlation several preprocessing transformations of the interaural differences were incorporated compression of binaural cues temporal averaging and envelope weighting for the 14 hz bandwidth data the most successful model postulated that incoherence is detected via fluctuations of interaural phase and interaural level processed by independent centers that model correlated with detectability at r 0 87 that model proved to be more successful than short term cross correlation models incorporating standard physiologically based model features r 0 78 for the 108 hz bandwidth data detection performance varied much less among different waveforms and the data were less able to distinguish between models

diversity product properties of lu kumar s space time codes in this paper we show that the diversity products of the full transmit diversity space time block codes proposed by lu kumar we call them lu kumar s codes with quadratic amplitude modulation qam constellations are lower bounded by 4 we present a sufficient condition on the minimum hamming weight of the linear binary full rank space time code such that this lower bound is met we show that the special lu kumar codes does satisfy the sufficient condition and therefore the diversity products of the special lu kumar codes are 4 where ldquospecialrdquo means that the linear binary full rank space time codes are not general but specially constructed by lu kumar

detectability of time varying interaural correlation in narrow band noise stimuli in a two interval forced choice task observers discriminated a binaural noise whose interaural correlation r varied according to the function r t m cos 2 fmt from an interaurally uncorrelated noise nu r t 0 0 the former stimulus produces a perceptual binaural flutter where the flutter rate is equal to the modulation frequency fm and the amount of flutter corresponds to m the stimuli were 0 4 octave wide gaussian noises with center frequencies of 500 1000 2000 or 4000 hz presentation levels were 70 75 db spl duration was 1 0 s for a given modulation frequency the peak interaural correlation m was varied in a blocked procedure and thresholds were estimated as that value of m required for 75 discriminability plotting thresholds as a function of fm yields a modulation function which can be interpreted as an attenuation characteristic of the binaural system for the 500 hz stimulus thresholds increased from m 0 28 at fm 1 hz to m 0 80 at fm 50 hz for higher frequenc

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

the contribution of static and dynamically varying itds and iids to binaural detection this paper investigates the relative contribution of various interaural cues to binaural unmasking in conditions with an interaurally in phase masker and an out of phase signal mos pi by using a modified version of multiplied noise as the masker and a sinusoid as the signal conditions with only interaural intensity differences iids only interaural time differences itds or combinations of the two were realized in addition the experimental procedure allowed the presentation of specific combinations of static and dynamically varying interaural differences in these conditions with multiplied noise as masker the interaural differences have a bimodal distribution with a minimum at zero iid or itd additionally by using the sinusoid as masker and the multiplied noise as signal a unimodal distribution of the interaural differences was realized through this variation in the shape of the distributions the close correspondence between the change in the interaural cross correlation and the size of the interaural differences is no longer found in contrast to the situation for a gaussian noise masker domnitz and colburn j acoust soc am 59 598 601 1976 when analyzing the mean thresholds across subjects the experimental results could not be predicted from parameters of the distributions of the interaural differences the mean the standard deviation or the root mean square value a better description of the subjects performance was given by the change in the interaural correlation but this measure failed in conditions which produced a static interaural intensity difference the data could best be described by using the energy of the difference signal as the decision variable an approach similar to that of the equalization and cancellation model

on the theory of space time codes for psk modulation the design of space time codes to achieve full spatial diversity over fading channels has largely been addressed by handcrafting example codes using computer search methods and only for small numbers of antennas the lack of more general designs is in part due to the fact that the diversity advantage of a code is the minimum rank among the complex baseband differences between modulated codewords which is difficult to relate to traditional code designs over finite fields and rings we present general binary design criteria for psk modulated space time codes for linear bpsk qpsk codes the rank of binary projections of the unmodulated codewords as binary matrices over the binary field is a sufficient design criterion full binary rank guarantees full spatial diversity this criterion accounts for much of what is currently known about psk modulated space time codes we develop new fundamental code constructions for both quasi static and time varying channels these are perhaps the first general constructions other than delay diversity schemes that guarantee full spatial diversity for an arbitrary number of transmit antennas

revision extension and evaluation of a binaural speech intelligibility model this study presents revision extension and evaluation of a binaural speech intelligibility model beutelmann r and brand t 2006 j acoust soc am 120 331 342 that yields accurate predictions of speech reception thresholds srts in the presence of a stationary noise source at arbitrary azimuths and in different rooms the modified model is based on an analytical expression of binaural unmasking for arbitrary input signals and is computationally more efficient while maintaining the prediction quality of the original model an extension for nonstationary interferers was realized by applying the model to short time frames of the input signals and averaging over the predicted srt results binaural srts from 8 normal hearing and 12 hearing impaired subjects incorporating all combinations of four rooms three source setups and three noise types were measured and compared to the model s predictions depending on the noise type the parametric correlation coefficients between observed and predicted srts were 0 80 0 93 for normal hearing subjects and 0 59 0 80 for hearing impaired subjects the mean absolute prediction error was 3 db for the mean normal hearing data and 4 db for the individual hearing impaired data 70 of the variance of the srts of hearing impaired subjects could be explained by the model which is based only on the audiogram