pitch strength of regular interval click trains with different length runs of regular intervals click trains were generated with first and second order statistics following kaernbach and demany j acoust soc am 104 2298 2306 1998 first order intervals are between successive clicks while second order intervals are those between every other click click trains were generated with a repeating alternation of fixed and random intervals which produce a pitch at the reciprocal of the duration of the fixed interval the intervals were then randomly shuffled and compared to the unshuffled alternating click trains in pitch strength comparison experiments in almost all comparisons for the first order interval stimuli the shuffled interval click trains had a stronger pitch strength than the unshuffled interval click trains the shuffled interval click trains only produced stronger pitches for second order interval stimuli when the click trains were unfiltered several experimental conditions and an analysis of runs of regular and random intervals in these click trains suggest that the auditory system is sensitive to runs of regular intervals in a stimulus that contains a mix of regular and random intervals these results indicate that fine structure regularity plays a more important role in pitch perception than randomness and that the long term autocorrelation function or spectra of these click trains are not good predictors of pitch strength

separate mechanisms govern the selection of spectral components for perceptual fusion and for the computation of global pitch the perceptual fusion of harmonics is often assumed to result from the operation of a template mechanism that is also responsible for computing global pitch this dual role hypothesis was tested using frequency shifted complexes these sounds are inharmonic but preserve a regular pattern of equal component spacing the stimuli had a nominal fundamental f0 frequency of 200 hz 20 and were frequency shifted either by 25 0 or 37 5 of f0 three consecutive components 6 8 were removed and replaced with a sinusoidal probe located at one of a set of positions spanning the gap on any trial subjects heard a complex tone followed by an adjustable pure tone in a continuous loop subjects were well able to match the pitch of the probe unless it corresponded with a position predicted by the spectral pattern of the complex peripheral factors could not account for this finding in contrast hit rates were not depressed for probes positioned at integer multiples of the f0 s corresponding to the global pit

structural properties of large scale systems the role of the structural properties of large scale systems for the synthesis of feasible control schemes is investigated the feasibility of considering a state variable as an output control objective of a system is expressed via the concepts of multi input connectability and structural functional controllability it is shown that these concepts can be formulated as mixed integer linear programming milp problems and efficient algorithms are presented for the determination of the above notions as well as for accessibility structural controllability and observability several examples illustrate the concepts and the proposed approach

h2 norm accumulation and its impact on synchronisation of complex dynamical networks this article addresses the h 2 norm accumulation problem of linearly coupled dynamical networks an interesting outer coupling relationship is constructed under which the h 2 norm of the newly constructed network with column input and row output matrices increases exponentially fast in terms of the node number n it increases generally much faster than 2 n when n is large while the h 2 norm of each node is 1 however the h 2 norm of the network with a diffusive coupling is equal to 2 n i e increasing only linearly when the network is stable where 2 is the h 2 norm of a single node and the h 2 norm of the network with antisymmetrical coupling also increases but rather slowly with respect to the node number n other networks with block diagonal input and block diagonal output matrices behave similarly it demonstrates that the changes of h 2 norms in different networks are very complicated despite the fact that the network structures are linear finally the influence of the h 2 norm of the loca

a unitary model of pitch perception a model of the mechanism of residue pitch perception is revisited it is evaluated in the context of some new empirical results and it is proposed that the model is able to reconcile a number of differing approaches in the history of theories of pitch perception the model consists of four sequential processing stages peripheral frequency selectivity within channel half wave rectification and low pass filtering within channel periodicity extraction and cross channel aggregation of the output the pitch percept is represented by the aggregated periodicity function using autocorrelation as the periodicity extraction method and the summary autocorrelation function sacf as the method for representing pitch information it is shown that the model can simulate new experimental results that show how the quality of the pitch percept is influenced by the resolvability of the harmonic components of the stimulus complex these include i the pitch of harmonic stimuli whose components alternate in phase ii the increased frequency difference limen of tones consisting of higher harmonics and iii the influence of a mistuned harmonic on the pitch of the complex as a function of its harmonic number to accommodate these paradigms it was necessary to compare stimuli along the length of the sacf rather than relying upon the highest peak alone these new results demonstrate that the model responds differently to complexes consisting of low and high harmonics as a consequence it is not necessary to postulate two separate mechanisms to explain different pitch percepts associated with resolved and unresolved harmonics

spectral pattern harmonic relations and the perceptual grouping of low numbered components mistuning a harmonic increases its salience and produces an exaggerated change in its pitch the effects on component grouping of spectral pattern global pitch and local harmonicity were explored using these phenomena stimuli were either harmonic f0 200 hz or frequency shifted by 25 of f0 component 1 or 2 was replaced by one of a set of sinusoidal probes in the same spectral region listeners either matched the probe pitch by adjusting the frequency of a pure tone experiments 1 and 3 or matched the probe loudness by adjusting the level of a tone of identical frequency experiment 2 probe positions corresponding to greatest perceptual fusion were estimated from the variations in pitch shift and loudness across frequency both measures gave similar estimates for harmonic stimuli fusion was greatest at harmonic values for shifted stimuli fusion was greatest close to the suboctave 225 hz and the frequency 450 hz of component 2 the latter value moved downwards to near 433 hz 2 3 ratio with component 3 when component 1 was removed together these results indicate that the lowest component of a shifted complex is grouped by local harmonicity whereas the higher components are grouped by common spectral spacing global pitch did not influence component grouping

auditory perceptual interpretation of the vowel an account of the simple vowels of american english will be given in terms of the author s auditory perceptual theory data from many sources will be used to illustrate and support this view in addition to theoretical suggestions concerning an auditory perceptual transformation and a segmentation rule the perceptualized spectral patterns associated with the nonretroflex vowels will be shown to fall into regions within a slab in a three dimensional auditory perceptual space these regions form a vowel map that by simple rotations can be related to various vowel charts such as those of jones pike or fant while the presentheory is an elaboration of traditional formant ratio theory it will be shown that a concept of a perceptual reference is needed not only for talker normalization but also to disambiguate vowels not distinguished by simple formant ratio theory additionally loci for the retroflex and nasalized vowels illustrate the utility of describing vowel spectra by five numbers combined into three dimensions simple f1 by f2 descriptions are not adequate except for enigmatophiles work supported by nincds and afosr

iterated rippled noise discrimination at long durations iterated rippled noise irn was used to study discrimination of irn stimuli with a lower number of iterations from irn stimuli with a higher number of iterations as a function of stimulus duration 100 2000 ms such irn stimuli differ in the strength of the repetition pitch in some cases the gain used to generate irn stimuli was adjusted so that both irn stimuli in the discrimination task had the same height of the first peak in the autocorrelation function or autocorrelogram in previous work involving short duration irn stimuli 500 ms listeners were not able to discriminate between irn stimuli that had different numbers of iterations but the same height of the first peak in the autocorrelation function in the current study irn discrimination performance improved with increases in duration even in cases when the height of the first peak in the autocorrelation was the same for the two irn stimuli thus future studies involving discrimination of irn stimuli may need to use longer durations 1 s or greater than those that have been used in the past

does fundamental frequency discrimination measure virtual pitch discrimination studies of pitch perception often involve measuring difference limens for complex tones dlcs that differ in fundamental frequency f0 these measures are thought to reflect f0 discrimination and to provide an indirect measure of subjective pitch strength however in many situations discrimination may be based on cues other than the pitch or the f0 such as differences in the frequencies of individual components or timbre brightness here dlcs were measured for harmonic and inharmonic tones under various conditions including a randomized or fixed lowest harmonic number with and without feedback the inharmonic tones were produced by shifting the frequencies of all harmonics upwards by 6 25 12 5 or 25 of f0 it was hypothesized that if dlcs reflect residue pitch discrimination these frequency shifted tones which produced a weaker and more ambiguous pitch than would yield larger dlcs than the harmonic tones however if dlcs reflect comparisons of component pitches or timbre they should no

a central spectrum model a synthesis of auditory nerve timing and place cues in monaural communication of frequency spectrum a probabilistic psychophysical model for monaural communication from the auditory nerve to the brain is given in the form of a tonotopic display of stimulus spectrum termed central spectrum the model builds upon prior research demonstrating the potential of neural timing cues from the auditory nerve for conveying information on complex spectra and was designed to meet the quantified demands of the psychophysics of frequency measurement the central spectrum magnitude at each frequency is determined by the response of the auditory nerve fiber with characteristic frequency matching that frequency an interval histogram from each fiber is passed through a filter matched to the characteristic frequency of the fiber this output versus characteristic frequency defines the central spectrum detailed analysis demonstrates that efficient probabilistic processing of the central spectrum describes known psychophysical properties of frequency measurement in discrimination and periodicity pitch experiments psycho

structural control of single input rank one bilinear systems a bilinear dynamical system can be used to represent the model of a network in which the state obeys linear dynamics and the input is the edge weight of certain controlled edges in the network we present algebraic and graph theoretic conditions for the structural controllability of a class of bilinear systems with a single control where the input matrix is rank one subsequently we use these conditions given a system state graph to develop an algorithm to design the location of controlled edges the input matrix such that the system is structurally controllable

the relative strength of the tone and noise components in iterated rippled noise rippled noise is constructed by delaying a random noise and adding it back to the original iterated rippled noise irn is constructed by repeating the delay and add process irn produces a two component perception i e a buzzy tone with a pitch equal to the reciprocal of the delay and a background noise that sounds like the original random noise the perceived tone noise ratio increases with the number of iterations the effective tone noise ratio in irn sounds with 1 16 iterations was measured in a discrimination matching experiment each irn was paired with a range of standard sounds having varying proportions of a broadband noise and a complex tone to find the point where their perceived tone noise ratios are the same the experiment shows that the tone noise ratio of the matching standard increases 3 8 db per doubling of the number of iterations in the irn stimulus spectral models of auditory perception explain the pitch of irn in terms of peaks in the region of the first five to eight harmonic

an autocorrelation model with place dependence to account for the effect of harmonic number on fundamental frequency discrimination fundamental frequency f0 difference limens dls were measured as a function of f0 for sine and random phase harmonic complexes bandpass filtered with 3 db cutoff frequencies of 2 5 and 3 5 khz low region or 5 and 7 khz high region and presented at an average 15 db sensation level approximately 48 db spl per component in a wideband background noise fundamental frequencies ranged from 50 to 300 hz and 100 to 600 hz in the low and high spectral regions respectively in each spectral region f0 dls improved dramatically with increasing f0 as approximately the tenth harmonic appeared in the passband generally f0 dls for complexes with similar harmonic numbers were similar in the two spectral regions the dependence of f0 discrimination on harmonic number presents a significant challenge to autocorrelation ac models of pitch in which predictions generally depend more on spectral region than harmonic number a modification involving a lag window is proposed and tested restricting the ac repr

determination of the generic rank of structural matrices abstract a new algorithm for determining the generic rank of structural matrices is presented the use of the algorithm in determining whether a system is structurally controllable is discussed and it is found to be adaptable to the much wider problem of control system synthesis such as the elimination of excess manipulated variables or control objectives

psychophysical evidence against the autocorrelation theory of auditory temporal processing nowadays it is widely believed that the temporal structure of the auditory nerve fibers response to sound stimuli plays an important role in auditory perception an influential hypothesis is that information is extracted from this temporal structure by neural operations akin to an autocorrelation algorithm the goal of the present work was to test this hypothesis the stimuli consisted of sequences of unipolar clicks that were high pass filtered and mixed with low pass noise so as to exclude spectral cues in experiment 1 interfering clicks were inserted in an otherwise periodic isochronous click sequence each click belonging to the periodic sequence was followed after a random portion of the period by one interfering click this disrupted the detection of temporal regularity even when the interfering clicks were 5 db less intense than the periodic clicks experiments 2 4 used click sequences that showed a single peak in their autocorrelation functions for some sequences this peak originated from first order temporal regularities that is from the temporal relations between consecutive clicks for other sequences the peak originated instead from second order regularities relative to nonconsecutive clicks the detection of second order regularities appeared to be much more difficult than the detection of comparable first order regularities overall these results do not tally with the current autocorrelation models of temporal processing they suggest that the extraction of temporal information from a group of closely spaced spectral components makes no use of time intervals between nonconsecutive peaks of the amplitude envelope

generic controllability theorems for descriptor systems this paper presents an extension of the structural controllability theorem to the case of structured descriptor systems sds a major difficulty in this problem is the loss of independence among the entries of the system matrices this difficulty is resolved by introducing the idea of column structured matrices csm first the paper defines and characterizes c and r controllability for descriptor systems then the generic controllability theorem is proved extending the structural controllability theorem to column structured systems css finally based on this result necessary conditions and sufficient conditions for generic r and c controllability are obtained the result gives a complete characterization of generic controllability for sds with nonsingular e and a partial solution for the case of singular e

periodic groups covered by transitive subgroups of finitary permutations or by irreducible subgroups of finitary transformations let x be either the class of all transitive groups of finitary permutations or the class of all periodic irreducible finitary linear groups we show that almost primitive x groups are countably recognizable while totally imprimitive x groups are in general not countably recognizable in addition we derive a structure theorem for groups all of whose countable subsets are contained in totally imprimitive x subgroups it turns out that totally imprimitive p groups in the class x are countably recognizable

optimization model for generic rank determination of structural matrices abstract a simple and rigorous approach that determines the generic rank of a structural matrix is presented this approach is based upon an integer linear programming ilp formulation which features the property of total unimodularity in the set of constraints the integer linear programming formulation of the proposed approach with the addition of integer cuts can be used to identify all the structurally redundant equations and or excess columns of a system this approach can also be used as a systematic tool to search for all the possible not necessarily feasible sets of controlled and manipulated variables of large scale control systems the features of the proposed algorithm are illustrated through a representative set of example problems

simple algebraic algorithm for determination of the generic rank of structured systems within the framework of structural controllability a new simple algebraic algorithm for determining the generic rank of a structured pair a b is presented

pitch strength of iterated rippled noise when the pitch is ambiguous two versions of a cascade of delay gain following delay and add circuits were used to generate iterated rippled noise irn stimuli irn stimuli produce a repetition pitch whose pitch strength relative to the noise percept can be varied by changing the type of circuit the attenuation or the number of iterations in the circuit the repetition pitch of irn is different when the delayed noise is subtracted gain 0 to the undelayed noise in the case of subtraction irn pitch is often ambiguous having two or more pitches listeners were asked to use pitch strength to discriminate between various pairs of irn stimuli generated with different gains different network circuits and different number of iterations for most conditions the gain was less than one the data were described by a description based on an exponential function of the largest peak of the autocorrelation function of irn stimuli w a yost j acoust soc am 100 511 518 1996 processed such that the spectral dominance region is emphasized these results suggest that the strength of the pitch of irn stimuli can be described by temporal processing mechanisms as might be revealed by autocorrelation

perception of the pitch of unresolved harmonics by 3 and 7 month old human infants three month olds discriminate resolved harmonic complexes on the basis of missing fundamental mf pitch in view of reported difficulty in discriminating unresolved complexes at 7 months and striking changes in the organization of the auditory system during early infancy infants ability to discriminate unresolved complexes is of some interest this study investigated the ability of 3 month olds 7 month olds and adults to discriminate the pitch of unresolved harmonic complexes using an observer based method stimuli were mf complexes bandpass filtered with a 12 db octave slope combined in random phase presented at 70 db sound pressure level spl for 650 ms with a 50 ms rise fall with a pink noise at 65 db spl the conditions were 1 low unresolved harmonics 2500 4500 hz based on mfs of 160 and 200 hz and 2 high unresolved harmonics 4000 6000 hz based on mfs of 190 and 200 hz to demonstrate mf discrimination participants had to ignore spectral changes in complexes with the same fundamental and respond only when the fundamental changed nearly all infants tested categorized complexes by mf pitch suggesting discrimination of pitch extracted from unresolved harmonics by 3 months adults also categorized the complexes by mf pitch although musically trained adults were more successful than musically untrained adults

pitch discrimination of harmonic complex signals residue pitch or multiple component discriminations two models for pitch discrimination of harmonic complex sounds are discussed a multiple band probability summation model using comparisons among component frequencies and a model in which residue pitches are compared the second model is based on goldstein s optimum processor pitch theory j acoust soc am 54 1496 1516 1973 and is distinguished from the multiple band model by an internal noise process pitch difference limens from 2i2afc tasks show that when the test signals comprise corresponding harmonics relative pitch difference limens are less than the smaller relative difference limens for the component frequencies which is consistent with the multiple band model the absence of corresponding harmonics significantly reduces relative pitch discriminability this effect supports the model on goldstein s theory it appears that residue pitch comparisons are not used for pitch discrimination between sounds with corresponding components rather comparisons based on residue pitch are only employed where there are no common resolved components in the signals to be discriminated

pitch strength and pitch dominance of iterated rippled noises in hearing impaired listeners reports using a variety of psychophysical tasks indicate that pitch perception by hearing impaired listeners may be abnormal contributing to difficulties in understanding speech and enjoying music pitches of complex sounds may be weaker and more indistinct in the presence of cochlear damage especially when frequency regions are affected that form the strongest basis for pitch perception in normal hearing listeners in this study the strength of the complex pitch generated by iterated rippled noise was assessed in normal hearing and hearing impaired listeners pitch strength was measured for broadband noises with spectral ripples generated by iteratively delaying a copy of a given noise and adding it back into the original octave band pass versions of these noises also were evaluated to assess frequency dominance regions for rippled noise pitch hearing impaired listeners demonstrated consistently weaker pitches in response to the rippled noises relative to pitch strength in normal hearing listeners

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

algorithms to verify generic causality and controllability of descriptor systems graph theoretic algorithms are developed for determining generic causality and controllability of structured descriptor systems sds s for the case of nonsingular e a completely graph theoretic characterization of generic controllability of sds s is developed the case of singular e is partially resolved with graph theoretic characterization of necessary conditions and sufficient conditions for generic causality and controllability developed separately although not stated explicitly these results can be easily translated into a graph theoretic algorithm to test for generic observability of sds s

a new algorithm for determining structural controllability the physical meaning of structural controllability is explored and is used as the basis for deriving a now algorithm for determining the controllability of linear multi input time invariant processes with ill defined parameter values the algorithm can be used in system design studies to specify the number of inputs required and their points of application to ensure plant controllability a flow chart is provided for implementing the algorithm on a digital computer however it is shown that in many cases structural controllability can be determined without computational aids and this is an advantage compared with the techniques suggested by earlier workers

control objective reduction in single input single output control schemes abstract structural analysis techniques have been applied to the problem of eliminating excess control objectives when developing single input single output regulatory control schemes an algorithm is presented for determining whether a control scheme involving fewer observations than control objectives is possible and if so what are feasible minimum sots of observations

maximal unipotent subgroups of finitary linear groups finitary linear groups have been in recent years the subject of intensiveinvestigations the structure of these groups has been studied and nowmuch is known about the locally solvable or locally nilpotent finitary lineargroups or about the locally finite ones a remarkable achievement is forinstance the classification of the simple locally finite finitary linear groups recently completed by j hall

pitch of iterated rippled noise iterated rippled noise irn stimuli are generated by a cascade of delay d gain g and add networks the matched pitch of irn stimuli was determined as a function of the type of network used to generate irn stimuli the delay d 2 4 and 8 ms the number of iterations n 1 2 3 4 6 8 of the delay and add networks and whether the delayed noise was added g 1 to or subtracted g 1 from the undelayed noise the matched pitch of irn stimuli did not depend on the type of network when g 1 addition the matched pitch did not depend on the number of stages of iterations n and was always equal to the reciprocal of the delay 1 d when g 1 subtraction the match pitch depended on n when n 1 the matched pitch of irn stimuli was ambiguous having two pitches in the region of 1 d 10 when n 8 the match pitch was equal to 1 2d this change in the pitch occurred between n 2 and 6 the results are discussed in terms of spectral and temporal models of complex pitch processing a temporal model based on autocorrelation was able to provide quantitative predictions for the pitch of these irn stimuli however a spectral type of model can also account for the pitch of these irn stimuli

further evidence that fundamental frequency difference limens measure pitch discrimination difference limens for complex tones dlcs that differ in f0 are widely regarded as a measure of periodicity pitch discrimination however because f0 changes are inevitably accompanied by changes in the frequencies of the harmonics dlcs may actually reflect the discriminability of individual components to test this hypothesis dlcs were measured for complex tones the component frequencies of which were shifted coherently upward or downward by f 0 25 37 5 or 50 of the f0 yielding fully harmonic f 0 strongly inharmonic f 25 37 5 or odd harmonic f 50 tones if dlcs truly reflect periodicity pitch discriminability they should be larger worse for inharmonic tones than for harmonic and odd harmonic tones because inharmonic tones have a weaker pitch consistent with this prediction the results of two experiments showed a non monotonic dependence of dlcs on f with larger dlcs for f s of 25 or 37 5 than for f s of 0 or 50 of f0 these findings are consistent with

irreducible finitary lie algebras over fields of characteristic zero abstract a lie subalgebralof g l k v is said to befinitaryif it consists of elements of finite rank we show that if char k 0 if dim k vis infinite and iflacts irreducibly onv then the derived algebra oflis simple

discrimination of first and second order regular intervals from random intervals as a function of high pass filter cutoff frequency this study extends the work of kaernbach and demany j acoust soc am 104 2998 2306 1998 in which regular interval stimuli ris click trains with first order intervals could be discriminated from random interval click trains but ris with second order intervals could not kaernbach and demany concluded that their results cast doubt on autocorrelation as a method of analysis for such stimuli the present study investigated the same stimuli but for a variety of filter conditions the results suggest that while ris click trains with first order intervals are more easily discriminated from random interval stimuli than second order interval ris click trains discrimination based on second order intervals is possible except when the stimuli are high pass filtered above 8 khz i e above the spectral region of phase locking

pitch strength of iterated rippled noise two versions of a cascade add attenuate and delay circuit were used to generate iterated rippled noise irn stimuli irn stimuli produce a repetition pitch whose pitch strength relative to the noise percept can be varied by changing the type of circuit the attenuation or the number of iterations in the circuit listeners were asked to use pitch strength to discriminate between various pairs of irn stimuli which differed in the type of network used to generate the sounds the number of iterations and the attenuation in the network a description based on an exponential function of the first peak of the autocorrelation function of irn stimuli is consistent with the results the discrimination data were well fit by a function based on the difference in the exponential functions of the first peak of the autocorrelation functions a magnitude estimation experiment indicated that pitch strength was an exponential function of the height of the first peak in the autocorrelation function these results suggest that the strength of the pitch of irn stimuli is based on temporal processing as might be revealed by autocorrelation

modeling the perception of concurrent vowels vowels with different fundamental frequencies if two vowels with different fundamental frequencies f0 s are presented simultaneously and monaurally listeners often hear two talkers producing different vowels on different pitches this paper describes the evaluation of four computational models of the auditory and perceptual processes which may underlie this ability each model involves four stages i frequency analysis using an auditory filter bank ii determination of the pitches present in the stimulus iii segregation of the competing speech sources by grouping energy associated with each pitch to create two derived spectral patterns and iv classification of the derived spectral patterns to predict the probabilities of listeners vowel identification responses the place models carry out the operations of pitch determination and spectral segregation by analyzing the distribution of rms levels across the channels of the filter bank the place time models carry out these operations by analyzing the periodicities in the wavef

auditory filter shapes of normal hearing and hearing impaired listeners in continuous broadband noise listeners with sensorineural hearing impairment typically exhibit auditory processing deficits such as reduced frequency and or temporal resolution such deficits may represent separate sequela of auditory pathology or may result directly from the sensitivity loss and the requirement to listen at high levels to assess the impact of increased thresholds on frequency resolution auditory filter characteristics were determined for hearing impaired and normal hearing listeners at 500 and 2000 hz in the presence of continuous broadband noise meant as a rough simulation of hearing loss in the fitting procedure the low frequency skirt of the derived auditory filter was allowed to vary as a function of signal level permitting different filter shapes to be estimated at high versus low signal levels listeners with moderate hearing losses at 2000 hz demonstrated near normal auditory filter shapes for lower signal levels but increasingly broad and asymmetric filters as signal level was raised at 500 hz where hearing losses were mild filter bandwidths increased little at the higher signal levels the presence of broadband noise had essentially no effect on filter shapes of either listener group the filter shape abnormalities demonstrated by listeners with moderate hearing loss which were not observed in normal hearing listeners at the same signal levels indicate that poor frequency resolution in these patients for high intensity stimuli does not follow directly from decreased sensitivity but instead reflects an independent pathology

infinite alternating groups as finitary linear transformation groups abstract degree of a classical group as its natural projective representation degree see 6 2 case 1 of 2 6 is dispensed with using mal cev s local characterization of finite dimensional linear groups and their classification theorem 2 7 mal cev see 13 l l 91 let g be a iocally finite group with adeg g 00 then g is a finite dimensional linear group theorem 2 8 l 2 8 21 let g be an infinite group then is a simple locally finite linear group of finite degree if and only if g is isomorphic to an adjoint group of lie type over an infinite subfield fp the algebraic closure of f for some prime p 3 local characterization of finitary linear groups a theorem of mal cev type mal cev s theorem 2 7 provides a local characterization of locally finite linear groups g of finite degree the property of having a faithful linear representation of degree n passes from the set of finite subgroups of g to g itself under this section we provide a similar result for locally finite simple groups which are linitary linear remember that the linear transformation g of the vector space i is finitary if g fixes pointwise a subspace of finite codimension in v that is the subspace c g v e v 1 vg v has finite codimension in v or equivalently the subspace v g v g 1 1 v e v has finite dimension in v the collection of all linitary members of gl v forms a normal sub group fgl v and a group which is isomorphic to a subgroup of fgl v for some v is sometimes called a finitary linear group

perception of missing fundamental pitch by 3 and 4 month old human infants a hallmark of complex pitch perception is that the pitch of a harmonic complex is the same whether or not the fundamental frequency is present by 7 months infants appear to discriminate on the basis of the pitch of the missing fundamental mf although electrophysiological cortical responses to mf pitch changes have been recorded in infants younger than 7 months no psychophysical studies have been published this study investigated the ability of 3 and 4 month olds to perceive the pitch of mf harmonic complexes based on fundamentals of 160 hz and 200 hz using an observer based method in experiment i to demonstrate mf pitch discrimination 3 and 4 month olds were required to ignore spectral changes in complexes with the same fundamental and to respond only when the fundamental changed in experiment ii a 60 260 hz noise was presented with complexes to mask combination tones at the fundamental frequency in experiment iii complexes were bandpass filtered with a 12 db octave slope to limit use of

prediction of absolute thresholds and equal loudness contours using a modified loudness model the loudness model described by moore et al j audio eng soc 45 224 240 1997 forms the basis for a recent ansi standard for the calculation of the loudness of steady sounds however the model does not give accurate predictions of the absolute thresholds published in a recent iso standard here it is described how the assumed middle ear transfer function in the model can be modified to give more accurate absolute threshold predictions the modified model also gives reasonably accurate predictions of the equal loudness contours published in a recent iso standard

the perceptual tone noise ratio of merged iterated rippled noises with octave harmonic and nonharmonic delay ratios the perceptual tone noise ratio was measured for merged iterated ripple noise stimuli irns in which one of the individual irns always had a delay of 16 ms the second irn was chosen to create merged irns with single octave delay ratios e g 16 ms 8 ms double octave delay ratios e g 16 ms 4 ms harmonic delay ratios e g 16 ms 12 ms and nonharmonic delay ratios e g 16 ms 3 9 ms all stimuli were high pass filtered at 800 hz the tone noise ratio was significantly enhanced for the octave ratios and there was a strong interaction between the single and double octave delay ratios and number of iterations but the perceptual tone noise ratio for nonoctave ratios was determined solely by the number of iterations the pattern of the results can be explained in terms of the height of the largest peak in the summary autocorrelogram meddis and hewitt j acoust soc am 89 2866 2882 1991 provided the model is modified to improve the simulation of the loss of phase locking

the perceptual tone noise ratio of merged iterated rippled noises iterated rippled noise irn is constructed by delaying a random noise by d ms adding it back to the same noise and repeating the process iteratively when two irns with the same power but slightly different delays are added together the perceptual tone noise ratio of the merged irn is markedly reduced with respect to that of either of the component irns in this paper the reduction in the perceptual tone noise ratio is measured for irns in which one of the delays is always 16 ms and the other is either 16 0 1 ms or 16 1 1 ms the component irns have the same number of iterations and the number varies across conditions from 4 to 256 the perceptual tone noise ratio is measured using a discrimination matching procedure developed for single irns each merged irn is compared with a range of standard stimuli having varying proportions of a complex tone and a broadband noise patterson et al j acoust soc am 100 3286 3294 1996 for single irns the function relating the signal to noise ratio of the matching standard to the number of iterations in the irn was found to be essentially straight this relationship was explained in terms of the height of the first peak in the autocorrelation of the stimulus wave or by the first peak in the summary autocorrelogram produced by a time domain auditory model for the merged irns in the current experiment the matching point functions are found to have pronounced downward curvature in addition to being well below the function for single irns to account for the reduction in the perceptual tone noise ratio of merged irns the autocorrelation model was extended to include a simple rule for combining adjacent peaks in the autocorrelation function of the wave and the autocorrelogram model was revised to improve the simulation of the loss of phase locking at higher frequencies in the autocorrelogram

pitch discrimination and phase sensitivity in young and elderly subjects and its relationship to frequency selectivity frequency difference limens for pure tones dlfs and for complex tones dlcs were measured for four groups of subjects young normal hearing young hearing impaired elderly with near normal hearing and elderly hearing impaired the auditory filters of the subjects had been measured in earlier experiments using the notched noise method for center frequencies fc of 100 200 400 and 800 hz the dlfs for both impaired groups were higher than for the young normal group at all fc s 50 4000 hz the dlfs at a given fc were generally only weakly correlated with the sharpness of the auditory filter at that fc and some subjects with broad filters had near normal dlfs at low frequencies some subjects in the elderly normal group had very large dlfs at low frequencies in spite of near normal auditory filters these results suggest a partial dissociation of frequency selectivity and frequency discrimination of pure tones the dlcs for the two impaired groups were higher than those for the young normal group at all fundamental frequencies fo tested 50 100 200 and 400 hz the dlcs for the elderly normal group were intermediate at fo 50 hz dlcs for a complex tone containing only low harmonics 1 5 were markedly higher than for complex tones containing higher harmonics for all subject groups suggesting that pitch was conveyed largely by the higher unresolved harmonics for the elderly impaired group and some subjects in the elderly normal group dlcs were larger for a complex tone with lower harmonics 1 12 than for tones without lower harmonics 4 12 and 6 12 for fo s up to 200 hz some elderly normal subjects had markedly larger than normal dlcs in spite of near normal auditory filters the dlcs tended to be larger for complexes with components added in alternating sine cosine phase than for complexes with components added in cosine phase phase effects were significant for all groups but were small for the young normal group the results are not consistent with place based models of the pitch perception of complex tones rather they suggest that pitch is at least partly determined by temporal mechanisms

comments on determining structural controllability abstract focusing on the determination of the generic rank of structural matrices deficiencies in burrows and sahinkaya s 1981 algorithm for determining structural controllability are highlighted

finitary representations and images of transitive finitary permutation groups abstract we characterize the point stabilizers and kernels of finitary permutation representations of infinite transitive groups of finitary permutations moreover the number of such representations is determined

perception of the low pitch of frequency shifted complexes when all of the components in a harmonic complex tone are shifted in frequency by f the pitch of the complex shifts roughly in proportion to f for tones with a small number of components the shift is usually somewhat larger than predicted from pitch theories which has been attributed to the influence of combination tones smoorenburg j acoust soc am 48 924 941 1970 experiment 1 assessed whether combination tones influence the pitch of complex tones with more than five harmonics by using noise to mask the combination tones the matching stimulus was a harmonic complex test complexes were bandpass filtered with passbands centered on harmonic numbers 5 resolved 11 intermediate or 16 unresolved and fundamental frequencies f0s were 100 200 or 400 hz for the intermediate and unresolved conditions the matching stimuli were filtered with the same passband to minimize differences in the excitation patterns of the test and matching stimuli for the resolved condition the matching st

on nonmodular periodic finitary linear groups abstract very recently m s lucido proved that for any prime p a periodic finitary linear p group g of characteristic p is isomorphic to some finitary linear group g 0 of characteristic zero moreover g 0 can be chosen to be irreducible whenever g is irreducible here we offer an alternative proof one that is somewhat shorter more explicit and more elementary we then generalize this result by proving that the same conclusion holds for periodic finitary skew linear p groups of characteristic p that is we replace fields by division rings in the hypotheses this is less elementary

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

exploring the temporal mechanism involved in the pitch of unresolved harmonics this paper continues a line of research initiated by kaernbach and demany j acoust soc am 104 2298 2306 1998 who employed filtered click sequences to explore the temporal mechanism involved in the pitch of unresolved harmonics in a first experiment the just noticeable difference jnd for the fundamental frequency f0 of high pass filtered and low pass masked click trains was measured with f0 100 to 250 hz and the cut frequency 0 5 to 6 khz being varied orthogonally the data confirm the result of houtsma and smurzynski j acoust soc am 87 304 310 1990 that a pitch mechanism working on the temporal structure of the signal is responsible for analyzing frequencies higher than ten times the fundamental using high pass filtered click trains however the jnd for the temporal analysis is at 1 2 as compared to 2 3 found in studies using band pass filtered stimuli two further experiments provide evidence that the pitch of this stimulus can convey musical information a fourth experiment replicates the finding of kaernbach and demany on first and second order regularities with a cut frequency of 2 khz and extends the paradigm to binaural aperiodic click sequences the result suggests that listeners can detect first order temporal regularities in monaural click streams as well as in binaurally fused click streams

a time domain description for the pitch strength of iterated rippled noise two versions of a cascaded add attenuate and delay circuit were used to generate iterated rippled noise irn stimuli irn stimuli produce a repetition pitch whose strength relative to the noise can be varied by changing the type of circuit the attenuation or the number of iterations in the circuit listeners were asked to discriminate between various pairs of irn stimuli which differed in the type of network used to generate the sounds or the number of iterations n 1 2 3 4 7 and 9 performance was determined for irn stimuli generated with delays of 2 4 and 8 ms and for four bandpass filter conditions 0 2000 250 2000 500 2000 and 750 2000 hz some irn stimuli were extremely difficult to discriminate despite relatively large spectral differences while other irn stimuli produced readily discriminable changes in perception despite small spectral differences these contrasting results are inconsistent with simple spectral explanations for the perception of irn stimuli an explanation based on the first peak of the autocorrelation function of irn stimuli is consistent with the results simulations of the processing performed by the peripheral auditory system i e interval histograms and correlograms produce results which are consistent with the involvement of these temporal processes in the perception of irn stimuli

the role of the envelope in processing iterated rippled noise iterated rippled noise irn is generated by a cascade of delay and add the gain after the delay is 1 0 or delay and subtract the gain is 1 0 operations the delay and add subtract operations impart a spectral ripple and a temporal regularity to the noise the waveform fine structure is different in these two conditions but the envelope can be extremely similar four experiments were used to determine conditions in which the processing of irn stimuli might be mediated by the waveform fine structure or by the envelope in experiments 1 and 3 listeners discriminated among three stimuli in a single interval task irn stimuli generated with the delay and add operations g 1 0 irn stimuli generated using the delay and subtract operations g 1 0 and a flat spectrum noise stimulus in experiment 2 the listeners were presented two irn stimuli that differed in delay 4 vs 6 ms and a flat spectrum noise stimulus that was not an irn stimulus in experiments 1 and 2 both the envelope and waveform fine structure contained the spectral ripple and temporal regularity in experiment 3 only the envelope had this spectral and temporal structure in all experiments discrimination was determined as a function of high pass filtering the stimuli and listeners could discriminate between the two irn stimuli up to frequency regions as high as 4000 6000 hz listeners could discriminate the irn stimuli from the flat spectrum noise stimulus at even higher frequencies as high as 8000 hz but these discriminations did not appear to depend on the pitch of the irn stimuli a control experiment fourth experiment suggests that irn discriminations in high frequency regions are probably not due entirely to low frequency nonlinear distortion products the results of the paper imply that pitch processing of irn stimuli is based on the waveform fine structure

on generalized finitary groups we introduce a wide range of generalized finitary automorphism groups of an arbitrary module m over an arbitrary ring r the largest such subgroup of autrm that we seriously consider here is the subgroup of all r automorphisms g of m such that m g 1 has krull dimension we also consider the subgroup of all r automorphisms g of m such that m g 1 is artinian as an r module the results are vaguely analogous to the genuine finitary case but are somewhat weaker