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

the influence of age and high frequency hearing loss on sensitivity to temporal fine structure at low frequencies l sensitivity to temporal fine structure tfs at low frequencies may be adversely affected by hearing loss at high frequencies even when absolute thresholds at low frequencies are within the normal range however in several studies suggesting this the effects of hearing loss and age were confounded here interaural phase discrimination ipd thresholds for pure tones at 500 and 750 hz were measured for 39 subjects with ages from 61 to 83 yr all subjects had near normal audiometric thresholds at low frequencies but thresholds varied across subjects at high frequencies ipd thresholds were correlated with age ipd thresholds for the test frequency of 750 hz were weakly correlated with absolute thresholds at high frequencies but these correlations became non significant when the effect of age was partialed out the results do not confirm that sensitivity to tfs at low frequencies is influenced by hearing loss at high frequencies independently of age

intensity importance functions for bandlimited monosyllabic words a study was carried out to determine the relative importance to speech intelligibility of different intensities within the speech dynamic range the functions that were derived are analogous to previous descriptions of the relative importance of different frequencies and are referred to here as intensity importance functions iifs they were obtained as follows sharply filtered bands of speech nu6 monosyllabic words were mixed with filtered noise and presented alone or in pairs at 19 signal to noise ratios 25 to 41 db when paired bands were tested the level and signal to noise ratio snr of one band were held constant while the level and snr of the other band were varied the listeners were 100 normal hearers organized into five 20 person groups each group provided speech recognition data for one of five frequency regions 141 562 562 1122 1122 1778 1778 2818 and 2818 8913 hz comparisons of the results for each group indicated that iifs vary with frequency and snr current methods for predicting intelligibility from physical measurements of speech audibility would need to be revised in order to take such findings into consideration

damped oscillatory integrals and boundedness of maximal operators associated to mixed homogeneous hypersurfaces uller abstract we study the boundedness problem for maximal operators in 3 dimen sional euclidean space associated to hypersurfaces given as the graph of c f where f is a mixed homogeneous function which is smooth away from the origin and c is a constant assuming that the gaussian curvature of this surface nowhere vanishes of infinite order we prove that the associated maximal operator is bounded on l p r 3 whenever p h 2 here h denotes a height of the function f defined in terms of its maximum order of vanishing and the weights of homogeneity this result generalizes a corresponding theorem on mixed homogeneous polynomial functions by a iosevich and e sawyer in particular it shows that a certain ellipticity conditon used by these authors is not necessary if c 6 0 our result is sharp

estimates for maximal functions associated with hypersurfaces in ℝ3 and related problems of harmonic analysis we study the boundedness problem for maximal operators mathcal m associated with averages along smooth hypersurfaces s of finite type in 3 dimensional euclidean space for p 2 we prove that if no affine tangent plane to s passes through the origin and s is analytic then the associated maximal operator is bounded on l p left mathbb r 3 right if and only if p h s where h s denotes the so called height of the surface s defined in terms of certain newton diagrams for non analytic s we obtain the same statement with the exception of the exponent p h s our notion of height h s is closely related to a n varchenko s notion of height h for functions such that s can be locally represented as the graph of after a rotation of coordinates

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

the effect of tone vocoding on spatial release from masking for old hearing impaired listeners old hearing impaired listeners generally benefit little from lateral separation of multiple talkers when listening to one of them this study aimed to determine how spatial release from masking srm in such listeners is affected when the interaural time differences itds in the temporal fine structure tfs are manipulated by tone vocoding tvc at the ears by a master hearing aid system word recall was compared with and without tvc when target and masker sentences from a closed set were played simultaneously from the front loudspeaker co located and when the maskers were played 45 to the left and right of the listener separated for 20 hearing impaired listeners aged 64 to 86 srm was 3 7 db smaller with tvc than without tvc this difference in srm correlated with mean audiometric thresholds below 1 5 khz even when monaural tfs sensitivity discrimination of frequency shifts in identically filtered complexes was partialed out suggesting that low frequency audiometric thresholds may be a good indicator of candidacy for hearing aids that preserve itds the tvc difference in srm was not correlated with age pure tone itd thresholds nor fundamental frequency difference limens and only with monaural tfs sensitivity before control for low frequency audiometric thresholds

abnormal processing of temporal fine structure in speech for frequencies where absolute thresholds are normal the identification of nonsense syllables that were lowpass filtered at 1 5khz was compared for subjects with normal hearing and subjects with mild to severe hearing loss at high frequencies but with normal or near normal hearing at low frequencies absolute thresholds were mostly within the normal range 20db hearing level for both groups for frequencies below 1 5khz performance was assessed with intact speech speech that had been processed to preserve only temporal envelope cues in a few frequency bands e speech and speech that had been processed to remove envelope cues as far as possible while preserving temporal fine structure cues again in a few frequency bands tfs speech for the intact speech and e speech the hearing impaired subjects performed slightly more poorly than the normal hearing subjects but this effect was significant only for the intact speech for the tfs speech the hearing impaired subjects performed significantly more poorly than the normal hearing subjects with 12 out o

the importance for speech intelligibility of random fluctuations in steady background noise spectrally shaped steady noise is commonly used as a masker of speech the effects of inherent random fluctuations in amplitude of such a noise are typically ignored here the importance of these random fluctuations was assessed by comparing two cases for one speech was mixed with steady speech shaped noise and n channel tone vocoded a process referred to as signal domain mixing sdm this preserved the random fluctuations of the noise for the second the envelope of speech alone was extracted for each vocoder channel and a constant was added corresponding to the root mean square value of the noise envelope for that channel this is referred to as envelope domain mixing edm it removed the random fluctuations of the noise sinusoidally modulated noise and a single talker were also used as backgrounds with both sdm and edm speech intelligibility was measured for n 12 19 and 30 with the target to background ratio fixed at 7 db for sdm performance was best for the speech background and worst for the steady noise for edm this pattern was reversed intelligibility with steady noise was consistently very poor for sdm but near ceiling for edm demonstrating that the random fluctuations in steady noise have a large effect

exact results for the one dimensional asymmetric exclusion model the asymmetric exclusion model describes a system of particles hopping in a preferred direction with hard core repulsion these particles can be thought of as charged particles in a field as steps of an interface as cars in a queue several exact results concerning the steady state of this system have been obtained recently the solution consists of representing the weights of the configurations in the steady state as products of non commuting matrices

a min plus derivation of the fundamental car traffic law we give deterministic and stochastic models of the traffic on a circular road without overtaking from this model the mean speed is derived as an eigenvalue of the min plus matrix describing the dynamics of the system in the deterministic case and as the lyapunov exponent of a min plus stochastic matrix in the stochastic case the eigenvalue and the lyapunov exponent are computed explicitly from these formulas we derive the fundamental law that links the flow to the density of vehicles on the road numerical experiments using the maxplus toolbox of scilab confirm the theoretical results obtained

relations between frequency selectivity temporal fine structure processing and speech reception in impaired hearing frequency selectivity temporal fine structure tfs processing and speech reception were assessed for six normal hearing nh listeners ten sensorineurally hearing impaired hi listeners with similar high frequency losses and two listeners with an obscure dysfunction od tfs processing was investigated at low frequencies in regions of normal hearing through measurements of binaural masked detection tone lateralization and monaural frequency modulation fm detection lateralization and fm detection thresholds were measured in quiet and in background noise speech reception thresholds were obtained for full spectrum and lowpass filtered sentences with different interferers both the hi listeners and the od listeners showed poorer performance than the nh listeners in terms of frequency selectivity tfs processing and speech reception while a correlation was observed between the monaural and binaural tfs processing deficits in the hi listeners no relation was found between tfs processing and frequency selectivity the effect of noise on tfs processing was not larger for the hi listeners than for the nh listeners finally tfs processing performance was correlated with speech reception in a two talker background and lateralized noise but not in amplitude modulated noise the results provide constraints for future models of impaired auditory signal processing

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

the effect of interaural delay of the masker on masking level differences in young and old adults diotic sono thresholds and dichotic s pi n pi tau thresholds were measured for young and old adults using a 500 hz pure tone signal and broadband burst masking noise at 37 db spl hz in the dichotic condition both the signal and the masker were phase reversed and the masker was presented with an interaural delay of 0 25 0 5 0 75 1 1 25 1 5 1 75 2 3 or 5 ms masking level differences mlds were determined by subtracting dichotic thresholds from diotic thresholds the sono thresholds for the old subjects did not differ significantly from those for the young subjects however when mlds were plotted as a function of delay the pattern of results differed significantly between young and old subjects this difference in pattern was completely accounted for in terms of a delay line version of durlach s equalization and cancellation ec model n i durlach in foundations of modern auditory theory edited by j v tobias academic new york 1972 b a schneider and p m zurek j acoust soc am 86 1756 1763 1989 by assuming that temporal jitter increases with internal delay in young subjects but that it does not vary with the amount of internal delay in old subjects

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

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

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

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

maximal averages over hypersurfaces and the newton polyhedron abstract using some resolution of singularities and oscillatory integral methods in conjunction with appropriate damping and interpolation techniques l p boundedness theorems for p 2 are obtained for maximal averages over hypersurfaces in r n for n 2 these estimates are sharp in various situations including the convex hypersurfaces of finite line type considered by several authors as a corollary we also give a generalization of the result of sogge and stein that for some finite p the maximal operator corresponding to a hypersurface whose gaussian curvature does not vanish to infinite order is bounded on l p for some finite p analogous estimates are proven for fourier transforms of surface measures and these are sharp for the same hypersurfaces as the maximal operators

estimates for maximal functions associated to hypersurfaces in ℝ with height 2 part i deutsche forschungsgemeinschaft dfg grant mu 761 11 1 national science foundation grant no dms 1440140

benefit of high rate envelope cues in vocoder processing effect of number of channels and spectral region in cochlear implants or vocoder simulations of cochlear implants the transmission of envelope cues at high rates related to voice fundamental frequency f0 may be limited by the widths of the filters used to form the channels and or by the cutoff frequency flp of the low pass filters used for envelope extraction the effect of varying flp in tone and noise vocoders was investigated for channel numbers n from 6 to 18 as n increased the widths of the channels decreased the value of flp was 45hz envelope or e filter or 180hz pitch or p filter the following combinations of cutoff frequencies were used for channels below and above 1500hz respectively ee pe ep and pp results from a competing talker task showed that the tone vocoder led to better intelligibility than the noise vocoder the pp condition led to the best intelligibility and the ee condition to the worst for n 6 intelligibility was better for condition pe than for condition ep for n 18 the reverse was true the results

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

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

discrimination of interaural temporal disparities by normal hearing listeners and listeners with high frequency sensorineural hearing loss thresholds of ongoing interaural time difference itd were obtained from normal hearing and hearing impaired listeners who had high frequency sensorineural hearing loss several stimuli a 500 hz sinusoid a narrow band noise centered at 500 hz a sinusoidally amplitude modulated 4000 hz tone and a narrow band noise centered at 4000 hz and two criteria equal sound pressure level eq spl and equal sensation level eq sl for determining the level of stimuli presented to each listener were employed the itd thresholds and slopes of the psychometric functions were elevated for hearing impaired listeners for the two high frequency stimuli in comparison to a the listener s own low frequency thresholds and b data obtained from normal hearing listeners for stimuli presented with eq spl interaurally the two groups of listeners required similar itds to reach threshold when stimuli were presented at eq sls to each ear for low frequency stimuli the itd thresholds of the hearing impaired listener were

on the number of channels needed to understand speech recent studies have shown that high levels of speech understanding could be achieved when the speech spectrum was divided into four channels and then reconstructed as a sum of four noise bands or sine waves with frequencies equal to the center frequencies of the channels in these studies speech understanding was assessed using sentences produced by a single male talker the aim of experiment 1 was to assess the number of channels necessary for a high level of speech understanding when sentences were produced by multiple talkers in experiment 1 sentences produced by 135 different talkers were processed through n 2 n 16 number of channels synthesized as a sum of n sine waves with frequencies equal to the center frequencies of the filters and presented to normal hearing listeners for identification a minimum of five channels was needed to achieve a high level 90 of speech understanding asymptotic performance was achieved with eight channels at least for the speech material used in this study the outcome of experiment 1 demonstrated that the number of channels needed to reach asymptotic performance varies as a function of the recognition task and or need for listeners to attend to fine phonetic detail in experiment 2 sentences were processed through 6 and 16 channels and quantized into a small number of steps the purpose of this experiment was to investigate whether listeners use across channel differences in amplitude to code frequency information particularly when speech is processed through a small number of channels for sentences processed through six channels there was a significant reduction in speech understanding when the spectral amplitudes were quantized into a small number 8 of steps high levels 92 of speech understanding were maintained for sentences processed through 16 channels and quantized into only 2 steps the findings of experiment 2 suggest an inverse relationship between the importance of spectral amplitude resolution number of steps and spectral resolution number of channels

the importance of temporal fine structure information in speech at different spectral regions for normal hearing and hearing impaired subjects speech reception thresholds srts were measured for target and competing speech signals processed to contain variable amounts of temporal fine structure tfs information signals were filtered into 30 1 erb n wide channels where erb n refers to the bandwidth of normal auditory filters which were either tone vocoded preserving temporal envelope information extracted using the hilbert transform or left unprocessed containing both tfs and envelope information improvements in srt were compared when tfs was progressively introduced starting with the high or low frequency channels the results suggest some redundancy in the tfs information across frequency regions in a second experiment the signal was divided into five 6 erb n wide spectral regions four of which were tone vocoded the remaining region was either absent creating a spectral notch or was present and unprocessed srts were measured for normal hearing and hearing impaired subjects conditions where all channels were vocoded or unprocessed were also included normal hearing subjects benefited similarly when tfs information was added to each region suggesting that tfs information is important over a wide frequency range hearing impaired subjects benefited less although the benefit varied across subjects benefit from tfs information in speech was correlated with a psychophysical measure of tfs sensitivity obtained at two center frequencies

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

maximal averages over surfaces letmf x supt 0 f t d x denote the maximal operator associated with surface measured on a smooth surfaces we prove that ifsis convex and has finite order contact with its tangent lines then m is bounded onlp rn p 2 if and only ifd x h 1 l1 loc s for all tangent planeshnot passing through the origin letm f x supt 0 f t d x be the maximal operator associated with a nonisotropic dilation tof surface measured we prove that m often behaves far better than m due to a rotational curvature in the time parametert

piecewise linear concave dynamical systems appearing in the microscopic traffic modeling motivated by microscopic traffic modeling we analyze dynamical systems which have a piecewise linear concave dynamics not necessarily monotonic we introduce a deterministic petri net extension where edges may have negative weights the dynamics of these petri nets are uniquely defined and may be described by a generalized matrix with a submatrix in the standard algebra with possibly negative entries and another submatrix in the minplus algebra when the dynamics is additively homogeneous a generalized additive eigenvalue is introduced and the ergodic theory is used to define a growth rate in the traffic example of two roads with one junction we compute explicitly the eigenvalue and we show by numerical simulations that these two quantities the additive eigenvalue and the average growth rate are not equal but are close to each other with this result we are able to extend the well studied notion of fundamental traffic diagram the average flow as a function of the car density on a road to the case of roads with a junction and give a very simple analytic approximation of this diagram where four phases appear with clear traffic interpretations simulations show that the fundamental diagram shape obtained is also valid for systems with many junctions

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

the effects of age and cochlear hearing loss on temporal fine structure sensitivity frequency selectivity and speech reception in noise temporal fine structure tfs sensitivity frequency selectivity and speech reception in noise were measured for young normal hearing nhy old normal hearing nho and hearing impaired hi subjects two measures of tfs sensitivity were used the tfs lf test interaural phase difference discrimination and the tfs2 test discrimination of harmonic and frequency shifted tones these measures were not significantly correlated with frequency selectivity after partialing out the effect of audiometric threshold suggesting that insensitivity to tfs cannot be wholly explained by a broadening of auditory filters the results of the two tests of tfs sensitivity were significantly but modestly correlated suggesting that performance of the tests may be partly influenced by different factors the nho group performed significantly more poorly than the nhy group for both measures of tfs sensitivity but not frequency selectivity suggesting that tfs sensitivity declines with age in the absence of elevated audiometric thresholds or broadened auditory filters when the effect of mean audiometric threshold was partialed out speech reception thresholds in modulated noise were correlated with tfs2 scores but not measures of frequency selectivity or tfs lf test scores suggesting that a reduction in sensitivity to tfs can partly account for the speech perception difficulties experienced by hearing impaired subjects

discrimination of interaural envelope correlation and its relation to binaural unmasking at high frequencies listeners sensitivity to interaural correlation of the envelope of high frequency waveforms and whether such sensitivity might account for detectability in a masking level difference paradigm were assessed thresholds of interaural envelope decorrelation from a reference correlation of 1 0 were measured for bands of noise centered at 4 khz and bandwidths ranging from 50 1600 hz decorrelation of the envelope was achieved by mixing two independent narrow band noises separately with the same listeners noso and nos detection thresholds were measured for maskers of the same center frequency and bandwidths for bandwidths of noise up to about 400 hz listeners were similarly sensitive to interaural decorrelation in both types of task however for bandwidths greater than 400 hz or so while sensitivity in the discrimination task was unaffected sensitivity was reduced in the nos conditions additional data suggested that listeners were able to maintain their sensitivity independent of bandwidth in the discrimination task by focusing on binaural information within select spectral regions of the stimuli

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

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

the influence of non spatial factors on measures of spatial release from masking this study tested the hypothesis that the reduction in spatial release from masking srm resulting from sensorineural hearing loss in competing speech mixtures is influenced by the characteristics of the interfering speech a frontal speech target was presented simultaneously with two intelligible or two time reversed unintelligible speech maskers that were either colocated with the target or were symmetrically separated from the target in the horizontal plane the difference in srm between listeners with hearing impairment and listeners with normal hearing was substantially larger for the forward maskers deficit of 5 8 db than for the reversed maskers deficit of 1 6 db this was driven by the fact that all listeners regardless of hearing abilities performed similarly and poorly in the colocated condition with intelligible maskers the same conditions were then tested in listeners with normal hearing using headphone stimuli that were degraded by noise vocoding reducing the number of available spectral channels systematically reduced the measured srm and again more so for forward reduction of 3 8 db than for reversed speech maskers reduction of 1 8 db the results suggest that non spatial factors can strongly influence both the magnitude of srm and the apparent deficit in srm for listeners with impaired hearing

sentence reception in noise from one versus two sources effects of aging and hearing loss sentence reception thresholds srts and babble detection thresholds bdts were measured for signals presented from loudspeakers located at 0 deg and 90 deg azimuth in addition the s b ratios necessary to achieve srt in the presence of a 12 talker babble were determined under three conditions in which the speech and babble were presented from the same or spatially separated loudspeakers in the first experiment normal hearing subjects were tested on two occasions the results were highly reliable with standard errors of the test retest differences of less than 1db for all conditions in the second experiment srts bdts and s b ratios were measured for three normal hearing groups 39 40 54 and 55 years and for a fourth group with presbycusis 55 years presbycusics had higher srts and bdts than all other groups regardless of age and the oldest normals had higher thresholds than younger subjects presbycusics required higher s b ratios than any of the normal groups and the oldest normal group needed a higher s b ratio compared to the youngest group all groups demonstrated a significant advantage in s b ratio when the sentences and babble sources were spatially separated compared to when they were presented from the same loudspeaker there was no significant difference in the magnitude of advantage due to spatial separation of speech and noise between the normal groups regardless of age but the presbycusics had significantly smaller advantages than all normals these findings suggest that aging alone does not impair the ability to take advantage of the spatial separation of speech and noise and that the speech reception problems of aging individuals involve various components that depend upon the nature of the listening task

the effect of age on auditory spatial attention in conditions of real and simulated spatial separation the contributions of auditory and cognitive factors to age dependent differences in auditory spatial attention were investigated in conditions of real spatial separation the target sentence was presented from a central location and competing sentences were presented from left and right locations in conditions of simulated spatial separation different apparent spatial locations of the target and competitors were induced using the precedence effect the identity of the target was cued by a callsign presented either prior to or following each target sentence and the probability that the target would be presented at the three locations was specified at the beginning of each block younger and older adults with normal hearing sensitivity below 4khz completed all 16 conditions 2 spatial separation method 2 callsign conditions 4 probability conditions overall younger adults performed better than older adults for both age groups performance improved with target location certainty with a priori tar

inequalities for some maximal functions ii let s be a smooth compact hypersurface in rn and let u be a measure on s absolutely continuous with respect to surface measure for t in r tt denotes the dilate of u by t normalised to have the same total variation as u for f in s rn t f denotes the maximal function supt o l t f we seek conditions on u which guarantee that the a priori estimate ll0 flip clhflip f g s rn holds this estimate entails that the sublinear operator extends to a bounded operator on the lebesgue space lp rn our methods generalise e m stein s treatment of the spherical maximal function 5 a study of riesz operators g functions and analytic families of measures reduces the problem to that of obtaining decay estimates for the fourier transform of u these depend on the geometry of s and the relation between u and surface measure on s in particular we find that there are natural geometric maximal operators limited on lp rn if and only if p e q oo q is some number in 1 oo and may be greater than 2 this answers a question of s wainger posed by stein 61 0 notation and contents the following notation will be used the fourier transform f of a function f on rn is given by f f dxf x e 2 x o e rn rn by b x r we mean the open ball of radius r and centre x the unit sphere in rn is sn 1 we often use polar coordinates p and o with p in 0 x and o in sn by expressions like c cp ck r etc we denote various constants which may vary from line to line and which depend on p k and r and so on these constants will normally also depend on other parameters like n the dimension of the ambient space but we do not mention this dependence explicitly given f in s rn we denote by t secondary 42b10

performance evaluation of max automata automata with multiplicities over the max semiring can be used to represent the behavior of timed discrete event systems this formalism which extends both conventional automata and max linear representations covers a class of systems with synchronization phenomena and variable schedules performance evaluation is considered in the worst mean and optimal cases a simple algebraic reduction is provided for the worst case the last two cases are solved for the subclass of deterministic series recognized by deterministic automata deterministic series frequently arise due to the finiteness properties of max linear projective semigroups the mean performance is given by the kolmogorov equation of a markov chain the optimal performance is given by a hamilton jacobi bellman equation

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

gap detection and the precedence effect in young and old adults thresholds for detecting a gap between two gaussian enveloped standard deviation 0 5 ms 2 khz tones were determined in young and old listeners the gap detection thresholds of old adults were more variable and about twice as large as those obtained from young adults moreover gap detection thresholds were not correlated with audiometric thresholds in either group estimates of the width of the temporal window of young subjects based on the detection of a gap between two tone pips were smaller than those typically obtained when a relatively long duration pure tone is interrupted moore et al j acoust soc am 85 1266 1275 1989 because the amount of time it takes to recover from an adapting stimulus is likely to affect gap detection thresholds glasberg et al j acoust soc am 81 1546 1556 1987 smaller estimates of temporal window size would be expected in this paradigm if the amount of adaptation produced by the first tone pip was negligible the larger gap detection thresholds of o

the effect of hearing loss on the resolution of partials and fundamental frequency discrimination the relationship between the ability to hear out partials in complex tones discrimination of the fundamental frequency f0 of complex tones and frequency selectivity was examined for subjects with mild to moderate cochlear hearing loss the ability to hear out partials was measured using a two interval task each interval included a sinusoid followed by a complex tone one complex contained a partial with the same frequency as the sinusoid while in the other complex that partial was missing subjects had to indicate the interval in which the partial was present in the complex the components in the complex were uniformly spaced on the erbn number scale performance was generally good for the two edge partials but poorer for the inner partials performance for the latter improved with increasing spacing f0 discrimination was measured for a bandpass filtered complex tone containing low harmonics the equivalent rectangular bandwidth erb of the auditory filter was estimated using the notched noise

deterministic models for traffic jams abstract we study several deterministic one dimensional traffic models for integer positions and velocities we find the typical high and low density phases separated by a simple transition if positions and velocities are continuous variables the model shows self organized critically driven by the slowest car

dynamic processes in the precedence effect three experiments were conducted to investigate the dependence of echo suppression on the auditory stimulation just prior to a test stimulus subjects sat in an anechoic chamber between two loudspeakers one which presented the lead sound and the other the delayed lag sound in the first experiment subjects reported whether or not they heard an echo coming from the vicinity of the lag loudspeaker during a test click pair in seven of nine listeners perception of the lagging sound was strongly diminished by the presence of a train of conditioning clicks presented just before the test click echo threshold increased subjects were less sensitive to echoes as the number of clicks in the train increased from 3 to 17 for a fixed number of clicks the effect was essentially independent of click rate from 1 s through 50 s and duration of the train from 0 5 through 8 s a second experiment demonstrated a similar buildup of echo suppression with white noise bursts regardless of whether the bursts in the conditioning train were repeated samples of frozen noise or were independent samples of noise using an objective procedure for measuring echo threshold the third experiment demonstrated that both lead and lag stimuli must be presented during the conditioning train in order to produce the buildup of suppression when only the lead sound was presented during the conditioning train the perceptibility of the lag sound during the test burst appeared to be enhanced

what shape is your conjugate a survey of computational convex analysis and its applications computational convex analysis algorithms have been rediscovered several times in the past by researchers from different fields to further communications between practitioners we review the field of computational convex analysis which focuses on the numerical computation of fundamental transforms arising from convex analysis current models use symbolic numeric and hybrid symbolic numeric algorithms our objective is to disseminate widely the most efficient numerical algorithms useful for applications in image processing computing the distance transform the generalized distance transform and mathematical morphology operators partial differential equations solving hamilton jacobi equations and using differential equations numerical schemes to compute the convex envelope max plus algebra computing the equivalent of the fast fourier transform multifractal analysis etc the fields of applications include among others computer vision robot navigation thermodynamics electrical networks medical imaging and network communication

the effect of smoothing filter slope and spectral frequency on temporal speech information it is known that information contained within the filter skirts can provide cues important to speech intelligibility however the role of filter slope during temporal smoothing has received little attention in experiment 1 smoothing filter slope angle was found to have a large effect on the intelligibility of sentences represented by three amplitude modulated sinusoids in experiment 2 the use of temporal cues above 16hz was examined across various regions of the spectrum when increases in rate were presented to individual spectral bands intelligibility only increased when presented in the higher spectral region this result suggests a greater reliance on higher rate cues in this region however intelligibility was greatest when these cues were distributed across the spectrum indicating that their effective use is not restricted solely to this region

moderate cochlear hearing loss leads to a reduced ability to use temporal fine structure information the ability of normally hearing and hearing impaired subjects to use temporal fine structure information in complex tones was measured subjects were required to discriminate a harmonic complex tone from a tone in which all components were shifted upwards by the same amount in hz in a three alternative forced choice task the tones either contained five equal amplitude components non shaped stimuli or contained many components but were passed through a fixed bandpass filter to reduce excitation pattern changes shaped stimuli components were centered at nominal harmonic numbers n 7 11 and 18 for the shaped stimuli hearing impaired subjects performed much more poorly than normally hearing subjects with most of the former scoring no better than chance when n 11 or 18 suggesting that they could not access the temporal fine structure information performance for the hearing impaired subjects was significantly improved for the non shaped stimuli presumably because they could benefit from spectral cues it is proposed that normal hearing subjects can use temporal fine structure information provided the spacing between fine structure peaks is not too small relative to the envelope period but subjects with moderate cochlear hearing loss make little use of temporal fine structure information for unresolved components

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

on adapted coordinate systems the notion of an adapted coordinate system for a given real analytic function introduced by v i arnol d plays an important role for instance in the study of asymptotic expansions of oscillatory integrals in two dimensions a n varchenko gave sufficient conditions for the adaptness of a given coordinate system and proved the existence of an adapted coordinate system for analytic functions without multiple components varchenko s proof is based on a two dimensional resolution of singularities result in this article we present a more elementary approach to these results which is based on the puiseux series expansion of roots of the given function this approach is inspired by the work of d h phong and e m stein on the newton polyhedron and oscillatory integral operators it applies to arbitrary real analytic functions and even to arbitrary smooth functions of finite type in particular we show that varchenko s conditions are in fact necessary and sufficient for the adaptedness of a given coordinate system and that adapted coordinates always exist in two dimensions even in the smooth finite type setting for analytic functions a construction of adapted coordinates by means of puiseux series expansions of roots has already been carried out in work by d h phong e m stein and j a sturm on the growth and stability of real analytic function as we learned after the completion of this paper in contrast to their work however our proof more closely follows varchenko s algorithm for the construction of an adapted coordinate system which turns out to be useful for the extension to the smooth setting

use of high rate envelope speech cues and their perceptually relevant dynamic range for the hearing impaired the ability of hearing impaired hi listeners to use high rate envelope information in a competing talker situation was assessed in experiment 1 signals were tone vocoded and the cutoff frequency fc of the envelope extraction filter was either 50 hz e filter or 200 hz p filter the channels for which the p or e filter was used were varied intelligibility was higher with the p filter regardless of whether it was used for low or high center frequencies performance was best when the p filter was used for all channels experiment 2 explored the dynamic range over which hi listeners made use of high rate cues in each channel of a vocoder the envelope extracted using fc 16 hz was replaced by the envelope extracted using fc 300 hz either at the peaks or valleys with a parametrically varied switching threshold for a target to background ratio of 5 db changes in speech intelligibility occurred mainly when the switching threshold was between 8 and 8 db relative to the channel root mean square level this range is similar in width to but about 3 db higher in absolute level than that found for normal hearing listeners despite the reduced dynamic range of the hi listeners