the normalized correlation accounting for binaural detection across center frequency bernstein and trahiotis l r bernstein and c trahiotis j acoust soc am 100 1754 1763 1996 recently reported the results of experiments designed to determine the form of interaural correlation that accounts for listeners sensitivities to interaural disparities within high frequency stimuli overall those results demonstrated that listeners abilities to discriminate changes in the interaural correlation of the envelope from a base correlation of 1 0 were well accounted for by the use of the normalized correlation the purpose of this study was to determine how well the normalized correlation computed subsequent to half wave rectification and low pass filtering could account for binaural detection data at low intermediate and high frequencies respectively in a four interval two alternative task listeners detected which interval contained a tone between 500 hz and 2 khz added antiphasically to diotic 100 hz wide noise nos nonsignal intervals contained the tone added homophasically noso performance was measured for signal to noise ratios between 30 and 30 db results indicated that a low pass filter function based on physiological measures of synchrony in cochlear nerve fibers in conjunction with the assumption of half wave square law rectification accounted for typically 80 of the variance in the behavioral data

lateralization of bands of noise as a function of combinations of interaural intensitive differences interaural temporal differences and bandwidth listeners indicated the intracranial position of bands of noise from 50 to 400 hz in width for several combinations of interaural intensitive differences iid and interaural temporal differences itd and or interaural phase differences ipd all itd and ipd combinations produced an interaural delay of 1500 s at the center frequency of the noise the interaural phase spectra were constructed to produce several patterns of putative cross correlation functions potency of iids depended greatly on particular combinations of bandwidth itd and ipd for some combinations changing the iid by only 3 db resulted in large shifts in laterality sometimes moving the image from near one ear to near the other the complex interactions observed make the results incompatible with the traditional notion that iids simply act as weights or scalars rather iids act in two distinct manners 1 as independent scalar quantities and 2 by interacting with specific combinations of bandwidth and itd ipd which is believed to reflect an action within the cross correlation surface

lateralization of complex binaural stimuli a weighted image model this article describes a new model that predicts the subjective lateral position of bandpass stimuli it is assumed as in other models that stimuli are bandpass filtered and rectified and that the rectified outputs of filters with matching center frequencies undergo interaural cross correlation the model specifies and utilizes the shape and location of assumed patterns of neural activity that describe the cross correlation function individual modes of this function receive greater weighting if they are straighter describing consistent interaural delay over frequency and or more central describing interaural delays of smaller magnitude this weighting of straightness and centrality is used by the model to predict the perceived laterality of several types of low frequency bandpass stimuli with interaural time delays and or phase shifts including bandpass noise amplitude modulated stimuli with time delayed envelopes and bandpass filtered clicks this model is compared to other theories that describe lateralization in terms of the relative contributions of information in the envelopes and fine structures of binaural stimuli

analysis of generalized synchronization in directionally coupled chaotic phase coherent oscillators by local minimal fluctuations the method of local minimum fluctuation is proposed to analyze generalized synchronization in directionally coupled chaotic phase coherent oscillators it is shown that the emergence of generalized synchronization is manifested by the qualitative changes in the statistic of local minimum fluctuations of the receiver oscillator

the combination of interaural information across frequencies lateralization on the basis of interaural delay three experiments were carried out that employed low frequency tone complexes with interaural delays that varied across the frequency domain in the first experiment threshold interaural delays were measured for three tone complexes for which one two or all three components were delayed the center frequency was 750 hz and the frequency spacing f between components was 20 50 100 250 or 450 hz for all f s the presence of two diotic components elevated the threshold interaural delays obtained for the third component relative to that obtained for a pure tone of the same frequency in the second experiment observers made left right judgments regarding the direction of movement of signals for which two components were delayed by 25 s to the left ear during one interval and to the right ear during the other interval while a third component of a variable time difference was delayed to the opposite side as the tone pair subjects reported single intracranial images during each interval and the data showed that interaural delays of one component to one ear could be offset by interaural delays of the other two components to the other ear in the final experiment threshold interaural delays were measured for five tone complexes in which one two three four or five components were delayed the center frequency was 750 hz and f was fixed at 100 hz thresholds decreased in a linear fashion as the number of delayed components increased falling by about a factor of 5 as the number of delayed components went from one to five these results are consistent with spectrally synthetic binaural processing with the lateral position of intracranial images determined by a combination of interaural information across the spectrum these effects could be brought about by a linear combination of the outputs of frequency specific cross correlation networks or by a wideband cross correlation of the signals at the two ears

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

binaural interference in lateralization thresholds for interaural time and level differences listeners discriminated changes in either interaural time differences itds or interaural level differences ilds in one noise band the target in the presence or absence of an uninformative spectrally remote second noise band the interferer the noise bands had center frequencies of 500 and 4000 hz and bandwidths of 50 and 400 hz respectively when one band was a target the other served as an interferer the interferer was presented either diotically or dichotically with itds or ilds that varied randomly across intervals interference was defined as occurring if the target thresholds were elevated in the presence of an interferer for itd discrimination interference was greater for the 4000 hz target than for the 500 hz target but for ild discrimination interference for the 500 hz target was greater than or equal to that obtained for the 4000 hz target larger interference effects were obtained when the interferer itd or ild was randomly varied revealing that interference can be large not only for high frequency targets but also for low frequency targets with high frequency interferers the data are consistent with a model in which listeners combine lateral position across frequency with interaural information weighted according to the accuracy with which positions are encoded in each frequency region

why do transposed stimuli enhance binaural processing interaural envelope correlation vs envelope normalized fourth moment high frequency transposed stimuli have been shown to yield enhanced processing of ongoing interaural temporal disparities itds this paper concerns determining which aspect or aspects of the envelopes of such stimuli mediate enhanced resolution of itd behavioral measures and quantitative analyses utilizing special classes of transposed stimuli show that the internal interaural envelope correlation accounts both qualitatively and quantitatively for the enhancement in contrast the normalized fourth moment of the envelope y which provides an index of the degree to which the envelopes of high frequency stimuli fluctuate does not lead to a successful accounting of the data

localization of sound in rooms v binaural coherence and human sensitivity to interaural time differences in noise binaural recordings of noise in rooms were used to determine the relationship between binaural coherence and the effectiveness of the interaural time difference itd as a cue for human sound localization experiments showed a strong monotonic relationship between the coherence and a listener s ability to discriminate values of itd the relationship was found to be independent of other widely varying acoustical properties of the rooms however the relationship varied dramatically with noise band center frequency the ability to discriminate small itd changes was greatest for a mid frequency band to achieve sensitivity comparable to mid band the binaural coherence had to be much larger at high frequency where waveform itd cues are imperceptible and also at low frequency where the binaural coherence in a room is necessarily large rivalry experiments with opposing interaural level differences ilds found that the trading ratio between itd and ild increasingly favored the ild as coherence decreased suggesting that the perceptual weight of the itd is decreased by increased reflections in rooms

the normalized interaural correlation accounting for nospi thresholds obtained with gaussian and low noise masking noise recently j acoust soc am 103 2578 2589 1998 and j acoust soc am 103 2573 2577 1998 independently reported that greater masking of interaurally phase reversed s tones was produced by diotic low noise noise than by diotic gaussian noise based on quantitative analyses eddins and barber suggested that their results could not be accounted for by assuming that listeners judgments were based on constant criterion changes in the normalized interaural correlation produced by adding the s signal to the diotic masker in particular they showed that a model like the one previously employed by j acoust soc am 100 3774 3784 1996 predicted an ordering of thresholds between the conditions of interest that was opposite to that observed bernstein and trahiotis computed the normalized interaural correlation subsequent to half wave square law rectification and low pass filtering the parameters of which were chosen to mimic peripheral auditory processing in this report it is demonstrat

extracting straight lines this paper presents a new approach to the extraction of straight lines in intensity images pixels are grouped into line support regions of similar gradient orientation and then the structure of the associated intensity surface is used to determine the location and properties of the edge the resulting regions and extracted edge parameters form a low level representation of the intensity variations in the image that can be used for a variety of purposes the algorithm appears to be more effective than previous techniques for two key reasons 1 the gradient orientation rather than gradient magnitude is used as the initial organizing criterion prior to the extraction of straight lines and 2 the global context of the intensity variations associated with a straight line is determined prior to any local decisions about participating edge elements

on the use of the normalized correlation as an index of interaural envelope correlation the purpose of the present study was to obtain new empirical observations that would help determine the form of interaural envelope correlation that accounts for listeners sensitivity to binaural information conveyed by high frequency stimuli in a four interval two alternative task listeners detected which interval contained a 4 khz tone added antiphasically to diotic 200 hz wide noise nos the nonsignal intervals contained the tone added homophasically noso discriminability d was measured as a function of s n for values between 30 and 30 db for all s ns overall level was 70 db spl using a similar procedure listeners were also tested in direct discrimination tasks where changes in envelope correlations were produced in one of two manners first changes in the normalized interaural envelope correlation were produced by varying the degree to which the envelopes covaried this was accomplished by mixing two independent gaussian noises second changes in the normalized interaural envelope correlation were produced by adding dc values to the envelopes of the stimuli overall in both experiments listeners ability to discriminate changes in interaural envelope correlation from a base correlation of 1 0 was well accounted for by the normalized correlation it is also shown that the normalized correlation of the envelope accounts for classic data concerning discriminability of interaural time differences at high frequencies as a function of depth of modulation

the combination of interaural information across frequencies the effects of number and spacing of components onset asynchrony and harmonicitya threshold interaural delays were measured for a single interaurally delayed low frequency target component presented against a background of two four six or eight diotic distractor components in the first experiment a 753 hz target and the flanking distractor components were gated on and off simultaneously in subsequent experiments the distractors were gated on 25 200 ms prior to the target in addition the target and distractor components were given various harmonic configurations in general threshold interaural delays were higher in all conditions in which distractors were present relative to thresholds obtained for the target component in isolation subjects reported that the pitch of the target component was more salient when an onset asynchrony between the target and distractors was present but the components were perceived as occupying a single intracranial position in spite of the various interaural delays across the frequency domain these results suggest that binaural processing of stimuli consisting of a small number of low frequency temporally overlapping components occurs in a spectrally synthetic manner in which interaural information is combined across the spectrum even in situations in which the segregation of pitch information occurs

transition from intermittency to periodicity in lag synchronization in coupled rossler oscillators the dynamical and statistical behavior of lag synchronization in two coupled self sustained chaotic rossler oscillators is reexamined the lack of uniqueness in the conventional characterization of lag synchronization based on the similarity function has caused much skepticism about the existence of lag synchronization we provide an evidence that the emergence of lag synchronization is associated with the transition from on off intermittency to a periodic structure in the laminar phase distribution

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 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

generalized synchronization of chaos in directionally coupled chaotic systems synchronization of chaotic systems is frequently taken to mean actual equality of the variables of the coupled systems as they evolve in time we explore a generalization of this condition which equates dynamical variables from one subsystem with a function of the variables of another subsystem this means that synchronization implies a collapse of the overall evolution onto a subspace of the system attractor in full space we explore this idea in systems where a response system bold y ital t is driven with the output of a driving system bold x ital t but there is no feedback to the driver we lose generality but gain tractability with this restriction to investigate the existence of the synchronization condition bold y ital t phi bold x ital t we introduce the idea of mutual false nearest neighbors to determine when closeness in response space implies closeness in driving space the synchronization condition also implies that the response dynamics is determined by the drive alone and we provide tests for this as well examples are drawn from computer simulations on various known cases of synchronization and on data from nonlinear electrical circuits determining the presence of generalized synchronization will be quite important when one has only scalarmore observations from the drive and from the response systems since the use of time delay or other embedding methods will produce imperfect coordinates in which strict equality of the synchronized variables is unlikely to transpire less

lateralization produced by interaural temporal and intensitive disparities of high frequency raised sine stimuli data and modeling an acoustic pointing task was used to measure extents of laterality produced by combinations of ongoing envelope based interaural temporal disparities itds and interaural intensitive disparities iids of 4 khz centered raised sine stimuli bernstein and trahiotis j acoust soc am 125 3234 3242 2009 while varying parametrically their peakedness depth of modulation and frequency of modulation the study was designed to assess whether iids act as weights within the putative binaural display at high spectral frequencies where the envelopes convey itd information as appears to be the case at low spectral frequencies where the waveforms i e fine structure and envelopes convey itd information the data indicate that envelope based iids do principally act as weights and that they appear to exert their influence on lateral position independently of the influence of itds quantitative analyses revealed that an augmented form of the cross correlation based position variable model of stern and shear j acoust soc am 100 2278 2288 1996 accounted for 94 of the variance in the data this success notwithstanding for a small subset of the data predictions could be improved by assuming that the listeners utilized information within auditory filters having center frequencies above 4 khz

enhancing interaural delay based extents of laterality at high frequencies by using transposed stimuli an acoustic pointing task was used to determine whether interaural temporal disparities itds conveyed by high frequency transposed stimuli would produce larger extents of laterality than itds conveyed by bands of high frequency gaussian noise the envelopes of transposed stimuli are designed to provide high frequency channels with information similar to that conveyed by the waveforms of low frequency stimuli lateralization was measured for low frequency gaussian noises the same noises transposed to 4 khz and high frequency gaussian bands of noise centered at 4 khz extents of laterality obtained with the transposed stimuli were greater than those obtained with bands of gaussian noise centered at 4 khz and in some cases were equivalent to those obtained with low frequency stimuli in a second experiment the general effects on lateral position produced by imposed combinations of bandwidth itd and interaural phase disparities ipds on low frequency stimuli remained when those stimuli were transposed to 4 khz overall the data were fairly well accounted for by a model that computes the cross correlation subsequent to known stages of peripheral auditory processing augmented by low pass filtering of the envelopes within the high frequency channels of each ear

perceptual fusion and fragmentation of complex tones made inharmonic by applying different degrees of frequency shift and spectral stretch global pitch depends on harmonic relations between components but the perceptual coherence of a complex tone cannot be explained in the same way instead it has been proposed that the auditory system responds to a common pattern of equal spacing between components but is only sensitive to deviations from this pattern over a limited range roberts and brunstrom j acoust soc am 104 2326 2338 1998 this hypothesis predicts that spectral fusion will be largely unaffected either by frequency shifting a harmonic stimulus because equal spacing is preserved or by small degrees of spectral stretch because significant deviations from equal spacing only cumulate over large spectral distances complex tones were either shifted by 0 50 of f0 200 hz 10 or stretched by 0 12 of f0 100 hz 10 subjects heard a complex followed by a pure tone in a continuous loop one of the components 2 11 was mistuned by 4 and subjects adjusted the pure tone to match its pitch broadly consistent with our hypothesis frequency shifts had relatively little effect on hit rates and only large degrees of stretch reduced them substantially the implications for simultaneous grouping are explored with reference to an autocorrelation model of auditory processing

lateralization produced by envelope based interaural temporal disparities of high frequency raised sine stimuli empirical data and modeling an acoustic pointing task was used to measure extents of laterality produced by ongoing interaural temporal disparities itds conveyed by the envelopes of 4 khz centered raised sine stimuli while varying parametrically their peakedness depth of modulation and frequency of modulation one purpose of the study was to determine whether such manipulations would produce changes in laterality logically consistent with those found for itd discrimination thresholds reported by bernstein and trahiotis j acoust soc am 125 3234 3242 2009 the data obtained revealed that they did in that 1 increasing depth of modulation peakedness or frequency of modulation between 32 and 128 hz produced smaller threshold itds and greater laterality and 2 increasing frequency of modulation to 256 hz produced modest increases in threshold itds and modest decreases in laterality the extents of laterality measured were successfully accounted for via an augmentation of the cross correlation based position variable modeling approach developed by stern and shear j acoust soc am 100 2278 2288 1996 to account for itd based extents of laterality obtained at low spectral frequencies

the lateralization of simple dichotic pitches a simple dichotic pitch arises when a single narrow band possesses a different interaural configuration from a surrounding broadband noise whose interaural configuration is uniform and correlated such pitches were created by interaurally decorrelating a narrow band experiment 1 or by giving a narrow band a different interaural time difference from the noise experiment 2 using an adaptive forced choice procedure listeners adjusted the interaural intensity difference of pointers to match their lateralization to that of the dichotic pitches the primary determinants of lateralization were the interaural configuration of the broadband noise experiment 1 the center frequency of the narrow band experiment 1 and its interaural configuration experiment 2 the ability of two computational models to predict these results was evaluated a version of the central spectrum model j raatgever and f a bilsen j acoust soc am 80 429 441 1986 incorporating realistic frequency selectivity accounted for the main results of experiment 1 but not experiment 2 a new reconstruction comparison model accounted for the main results of both experiments to accommodate the variables shown to influence lateralization this model segregates evidence of the dichotic pitch from the noise reconstructs the cross correlogram of the noise and compares it with the cross correlogram of the original stimulus

an adaptive contour closure algorithm and its experimental evaluation the potential of edge based complete image segmentation into regions has not gained the due attention in the literature thus far the present paper attempts to explore this potential by proposing an adaptive grouping algorithm to solve the contour closure problem that is the key to a successful edge based complete image segmentation the effectiveness of the proposed algorithm is extensively tested in the range image domain and compared to several region based segmentation methods within a rigorous comparison framework on three range image databases of varying quality acquired by different range scanners it is shown that the proposed approach is able to achieve very appealing performance with respect to both segmentation quality and computation time

the normalized correlation accounting for nosπ thresholds with gaussian and low noise masking noise recently both eddins and barber j acoust soc am 103 2578 2589 1998 and hall et al j acoust soc am 103 2573 2577 1998 demonstrated that low noise noise produced more masking of antipha sic tones than did gaussian noise eddins and barber could not account for this finding by considering changes in the normalized interaural correlation produced by adding antiphasic signals to the diotic maskers they calculated the normalized correlation subsequent to half wave square law rectification and low pass filtering that approach was used successfully by bernstein and trahiotis j acoust soc am 100 3774 3784 1996 to account for binaural detection performance as a function of frequency in this presentation it will be shown that one can account quantitatively for thresholds obtained with low noise noise and with gaussian noise by incorporating a stage of compression prior to rectification and low pass filtering the compressive function employed produces effects similar to tho

accounting quantitatively for sensitivity to envelope based interaural temporal disparities at high frequencies bernstein and trahiotis 2009 j acoust soc am 125 3234 3242 reported threshold interaural temporal disparities itds conveyed by the envelopes of 4 khz centered raised sine stimuli a raised sine stimulus consists of a carrier modulated by a sinusoid raised to an exponent such stimuli permitted bernstein and trahiotis to vary independently stimulus modulation frequency modulation depth and relative peakedness deadtime an interaural correlation based model that included stages mimicking peripheral auditory processing captured most of the data save for an overestimation of threshold itds obtained when the depth of modulation was 25 and the raised sine exponent was 8 0 the purpose of the present study was 1 to present a quantitative evaluation of how well other measures including normalized envelope fourth moment envelope peakwidth and envelope deadtime might also account for the data reported by bernstein and trahiotis and 2 to present new threshold itds measured while varying factorially depth of modulation raised sine exponent and modulation frequency quantitative analyses of both the prior and the new data showed that the normalized interaural correlation computed subsequent to peripheral auditory processing provided the most accurate predictions importantly the overestimation of threshold itds did not occur when it was assumed that listeners can employ information within off frequency auditory filters

manipulating the straightness and curvature of patterns of interaural cross correlation affects listeners sensitivity to changes in interaural delay the purpose of this study was to test the hypothesis that stimuli characterized by straight trajectories of their patterns of cross correlation foster greater sensitivity to changes in interaural temporal disparities itds than do stimuli characterized by more curved trajectories of their patterns of cross correlation to do so sensitivity to changes in itd was measured as a function of duration using a set of reference stimuli that yielded differing relative amounts of straightness within their patterns of cross correlation while keeping the dominant trajectory at or near midline the relative amounts of straightness were manipulated by employing specific combinations of bandwidth itd and interaural phase disparity ipd of gaussian noises centered at 500 hz the results were consistent with expectations in that the patterning of the threshold itds revealed increasingly poorer sensitivity as greater and greater curvature was imposed on the dominant midline trajectory the variations in threshold itd across the stimulus conditions can be accounted for quite well quantitatively by assuming either that the listeners based their judgments on changes in the position of the most central peak of the cross correlation function or that they based their judgments on changes in the centroid of a second level cross correlation function in a second experiment binaural detection was measured using a subset of the reference stimuli as maskers as expected sensitivity was poorest with the maskers characterized by the greatest curvature which were also those having the lowest interaural correlation

multivalued mappings in generalized chaos synchronization the onset of generalized synchronization of chaos in directionally coupled systems corresponds to the formation of a continuous mapping that enables one to persistently define the state of the response system from the trajectory of the drive system a recently developed theory of generalized synchronization of chaos deals only with the case where this synchronization mapping is a single valued function in this paper we explore generalized synchronization in a regime where the synchronization mapping can become a multivalued function specifically we study the properties of the multivalued mapping that occurs between the drive and response systems when the systems are synchronized with a frequency ratio other than one to one and address the issues of the existence and continuity of such mappings the basic theoretical framework underlying the considered synchronization regimes is then developed

edge expression based on tree structure abstract it is a difficult problem to construct the edge structure of an object from its defective line drawing after the low level image processing phase a tree structure edge expression is proposed in which the tree expresses the contiguous line segments and all the trees constitute a forest for the object some medium level processing algorithms such as line connecting pruning and appending are derived by using the tree structure experiments are conducted which show the advantages of the expression and corresponding algorithms

measures of extents of laterality for high frequency transposed stimuli under conditions of binaural interference our purpose in this study was to determine whether across frequency binaural interference would occur if itd based extents of laterality were measured using high frequency transposed stimuli as targets the results of an earlier study l r bernstein and c trahiotis j acoust soc am 116 3062 3069 2004 which focused on threshold itds rather than extents of laterality suggested that high frequency transposed stimuli might be immune to binaural interference effects resulting from the addition of a spectrally remote low frequency interferer in contrast to the earlier findings the data from this study indicate that high frequency transposed targets are susceptible to binaural interference nevertheless high frequency transposed targets even when presented along with an interferer yielded greater extents of itd based laterality than did high frequency gaussian noise targets presented in isolation that is the enhanced potency of itds conveyed by transposed stimuli persisted even in the