bluuebunny/crossref_metadata_2025 huggingface dataset:
Perception of syllable-initial English stops by native Korean listeners
Authors: Kim Mi-Ran , Kluender Keith R. , Lotto Andrew J. , Reed Charles
Published: October 2005

Duration of attenuation in the region of the first formant (F1 cutback) and relative level of aspiration energy are known to be significant acoustic cues used to distinguish voiced from voiceless English stop consonants in initial position. This experiment was designed to test whether Korean listeners distinguish English stops on the same bases as native English listeners. In an identification task, 72 stimuli from six continua ranging perceptually from /da/ to /ta/ were presented to 12 Korean and 12 English subjects. Stimuli were synthesized using a parallel formant synthesizer and varied in duration of F1 cutback (5–82 ns in 7-ms steps), relative amplitude of prevocalic aspiration energy, and fundamental frequency (100, 125, and 150 Hz) of vocalic energy. Longer F1-cutback durations and greater aspiration intensity both significantly increased the proportion of voiceless /ta/ responses for both Korean and English subjects. Only Korean subjects labeled more stops as voiceless when fundamental frequency was higher. [Work supported by NIDCD grant DC-00719 and NSF grant DBS-9258482.]
Effects of speaker, token, and noise variability on the perception of vowels in noise
Authors: Takeuchi Annie H. , Braida Louis D.
Published: October 2005

In tests of speech perception, performance decreases when the stimulus set consists of multiple speakers compared to single-speaker sets [e.g., Mullenix etal., J. Acoust. Soc. Am. 85, 365–378 (1989)]. Similarly, given a single speaker, performance decreases when the stimulus set consists of multiple tokens compared to single-token sets [e.g., Reed etal., J. Rehab. Res. Dev. 28, 67–82 (1991)]. This experiment examined the effect on speech perception when stimulus sets consisted of both multiple speakers and multiple tokens. Listeners identified nine vowels in /bVt/ context masked by noise at a constant instantaneous signal-to-noise ratio. One set of stimuli consisted of three speakers, each producing three tokens. Another set consisted of three speakers, each producing one token, with three different noise samples masking each token. In the baseline conditions, the sets were randomly ordered. In the experimental conditions, the sets were blocked by token, by speaker or noise, or by both token and speaker or token and noise. Averaged across listeners, the effect of token and speaker variability were additive, as were the effects of token and noise variability. However, individual listeners did not always show additivity of variability effects. [Work supported by NIH.]
Detection and recognition of familiar sounds
Authors: Abouchacra Kim S. , Mundis Pamela A. , Haas Ellen C. , Letowski Tomasz R. , Myers Laurie
Published: October 2005

An exploratory study was conducted to determine which acoustical components influence the detection and recognition of 30 familiar sounds (FS). The sounds were categorized as human-, animal-, environment-, or object-producing sounds. Initially, detection thresholds for 20 normal hearing subjects were measured for the 30 FS. Following detection measures, subjects were trained to recognize FS that were presented at a comfortable listening level (40 dB HL). Recognition thresholds were then gathered, beginning at each sound’s detection threshold. Specifically, at detection threshold, a sound was presented and subjects were required to identify the sound. If they could not recognize the sound, listeners were asked to describe ‘‘what’’ was heard (i.e., temporal or spectral components). In increments of 2 dB, the sound was presented and subject’s response recorded. This procedure continued until the level of the sound reached 40 dB HL (training level). Results revealed that the decibel range between detection and recognition averaged 6–10 dB, depending on the sound. At detection threshold, no sounds were recognized; however, subjects predominately heard temporal components of the sound. As levels increased above detection, subjects heard spectral components of the sound prior to its correct recognition. Results suggest that temporal information may play a major role in the detection of sounds, whereas a combination of temporal and spectral information is required for the recognition of familiar, everyday sounds.
Phonetic contrast perception: Predicting human performance from acoustical measures
Authors: Okalidou Areti , Boothroyd Arthur
Published: October 2005

THRIFT is a three-interval forced-choice test of the perception of phonetic contrasts that are embedded in a varying phonetic context. Such parameters as formant frequencies, F0, duration, and intensity were measured for each utterance in a specific recording of THRIFT. Results were used to predict performance of an ideal observer basing oddity decisions on a single acoustic dimension, using (a) a d′ approach with mean differences expressed in relation to token-by-token variability, and (b) an ‘‘oddball’’ approach based on scalar distances among the members of stimulus triads. Reliable perception of some contrasts (e.g., vowel height and place, and consonant voicing) could be attributed to a single acoustic parameter. For other contrasts (e.g., consonant place) no single acoustic parameter was found that could predict reliable perception independent of context. For some contrasts, above-chance performance was predicted for unexpected acoustic parameters that may or may not be specific to this recording. Overall, oddball analysis predicted better performance than d′ analysis, suggesting an advantage for a pre- rather than a postclassification decision strategy. The relative difficulty of contrasts, in terms of predicted perception using single acoustic parameters, parallels the measured performance of deaf children on this test. [Work supported by NIH Grant No. 2PO1DC00178.]
Training transfer in simple psychoacoustic tasks
Authors: Galen Tamara , Delhorne Lorraine , Durlach Nathaniel
Published: October 2005

This paper reports preliminary results about the extent to which the learning curve in one psychoacoustic task is altered by practice in another psychoacoustic task. The primary interest in training transfer is motivated by the idea that variations in training transfer across tasks is closely related to structural properties of the perceptual system under consideration and, therefore, that results on training transfer should be useful in forming hypotheses about these properties. The tasks considered in this studies are frequency and intensity discrimination and the variables across which training transfer is being measured include, in addition to frequency versus intensity and left ear versus right ear, reference frequency, reference intensity, and increment size. [The authors are indebted to Lucia Vaina of Boston University for inspiring this research by informing them of equivalent work currently being conducted in the area of visual psychophysics.]
Transfer of learning in a sequence discrimination task
Authors: Barsz Kathy
Published: October 2005

Listeners discriminated sequences differing in tonal order. These sequences had a moderate frequency range between the tones and were presented in blocks which included either vary narrow range sequences or very wide range sequences. The standard sequence was either fixed throughout a block or varied randomly on each trial. Thus the moderate range sequences were discriminated under four different conditions: In the context of narrow range sequences with a fixed standard, in the context of wide range sequences with a fixed standard, in the context of narrow range sequences with a random standard, and in the context of wide range sequences with a random standard. The performance of listeners who practiced with one of the conditions was compared to the performance of listeners who practiced in all of the conditions. It was found that listeners exposed to all the conditions benefited more from practice, and were more likely to be affected by whether the moderate range sequences were presented with narrow or wide range sequences. Performance was generally better when the standard sequence was fixed throughout a block of trials, but this effect was much larger for the listeners who heard all the conditions. It is argued that, while hearing easier conditions, listeners develop strategies which can aid them in more difficult conditions.
Adaptive multi-level substructuring for computing acoustic radiation and scattering from complex structures
Authors: Bennighof Jeffrey K. , DSouza Paul D. , Kaplan Matthew F. , Subramaniam Murugan , Tutt J. Christopher
Published: October 2005

An adaptive method for computing acoustic radiation and scattering from complex structures is presented. The method uses a multi-level substructuring decomposition of a structure’s finite element model, in which the structure is partitioned into several substructures, and each of these is partitioned into its own substructures, and so on. For each substructure, the finite element representation is transformed to a new one in terms of a quasistatic dependence of internal degrees of freedom on interface and excited ones, complemented with response in substructure fixed-interface modes of vibration. This allows for model reduction in the form of modal truncation for substructures on various levels. The order of the model is reduced to the number of degrees of freedom excited by either the acoustic fluid or applied excitations, plus the number of modes included. An adaptive procedure is used to determine which substructure modes should be included in the structure model. The acoustic fluid is represented with a boundary element model, and the procedure for coupling the structure and fluid models is described. The method is demonstrated on numerical examples in three dimensions. [Work supported by ONR.]
Extension of the surface variational principle to nonaxisymmetric response of submerged thin shells of revolution
Authors: Ginsberg Jerry H. , Wu Kuangcheng
Published: October 2005

Previously, the surface variational principle (SVP) was implemented for rigid and elastic submerged structures under axisymmetric excitations. More recent developments extended SVP to address nonaxisymmetric problems of acoustic radiation and scattering situations for rigid bodies of revolution. In this presentation, SVP is applied jointly with Hamilton’s principle governing nonaxisymmetric responses of elastic thin shells of revolution. Complex Fourier expansions of the azimuthal dependence are combined with Ritz expansions of the spatial dependence to represent the displacement field and surface pressure. This representation is equivalent to a wave-number decomposition of the surface response into a series of helical-type waves. By enforcing continuity of normal velocity on the fluid–structure interface, a set of coupled algebraic equations is formed for each azimuthal harmonic. Problems addressed here are radiation due to arbitrary loading, and scattering associated with arbitrary incidence of a plane wave on a stationary elastic thin shell. The rigid body modes are included in the scattering case. Numerical results are assessed for the convergence qualities of an SVP simulation, particularly regarding series length requirement as the frequency is increased. [Work support by ONR.]
The use of a statistical energy analysis to predict spatial distribution response
Authors: Weissman Karen , Manning Jerome E.
Published: October 2005

A statistical energy analysis (SEA) response level represents a spatial average over the subsystem and a frequency average over a particular bandwidth. If the SEA response is viewed as a modal amplitude for a given bandwidth, this amplitude can be combined with mode shapes obtained from measured data or a finite element model to map the spatial distribution of the response along the subsystem. This paper documents the development of such a procedure for using SEA to predict the spatial distribution of the response. The procedure is applied to a model of a typical component-loaded panel in a spacecraft. Mode shapes are measured during a shake test on a mock up of the spacecraft panel.
Evolution of energy methods for calculation of engineering structures vibration
Authors: Nikiforov Alexei S.
Published: October 2005

Energy methods (for example, statistical energy analysis) are used for a calculation of various engineering structures (ships, aircraft, cars, etc.) for a long time. Methods by Westphal and by Maidanik and Lyon proposed by them in 1950–1960 led to make calculations by a numerical solution of algebraical equations systems. Recently the method of equivalent plates was proposed to determine a distribution of vibration energy on a surface of structure elements by using differential equations similar to heat conductivity ones. Sometimes solutions of these equations can be received in analytical form. Equations of energy balance are formulated in a general form. Coupling coefficients in Westphal’s and Maidanik–Lyon’s forms are solved for diffusive fields of bending waves. Limitations for the use of these coefficients are discussed in reference to a frequency range and difference of thickness of jointed plates. Examples of the use of Westphal’s and Maidanik–Lyon’s methods are shown. Some examples of an analytical solution of equations for equivalent plates method are shown for various boundary conditions. Solutions received by Westphal’s and equivalent plates methods are compared.
Frequency-time analysis of pulse propagation in elastic plates excited by frequency-modulated chirp excitations
Authors: Stepanishen P. R. , Huynh Q. , Greene T.
Published: October 2005

The response of elastic plates that are excited by pulsed frequency-modulated chirp force excitations is analyzed using both short time Fourier spectrum and wavelet packet time-frequency (t-f) methods. Both longitudinal and flexural wave propagation is addressed using thick plate theory. Space-time pulsed responses are obtained using integral transform methods and subsequently analyzed using t-f methods. Advantages and disadvantages of the t-f methods in terms of resolution in the t-f plane are presented. Several interesting results for the amplitudes and pulse durations of the propagating elastic waves are presented. The responses are shown to differ significantly depending on the slope of the chirp; however, the results are readily interpreted in light of the group velocities of the waves. Most importantly, the use of t-f methods to determine the dispersion characteristics of the waves will be presented. The potential use of such methods for complex structures will be discussed. [Work supported by ONR.]
A tale of two approaches: The response of a beaded string
Authors: Maidanik G. , Dickey J.
Published: October 2005

In one approach, the response is given by the superposition of two terms. The first is merely the response of the unbeaded infinite string. The remaining terms involve elements of the first term mingled with parameters that describe the beads; e.g., the impedance that each bead presents to the infinite string and the position of that bead on the string. In the other approach, the bays (portions of the string that lie between adjacent beads) are treated as individual dynamic systems. These dynamic systems are coupled at the beads. The model is then a cascade of coupled one-dimensional dynamic systems. In this approach, the response is a vector composed of the response in each bay. The response vector is composed of the superposition of a direct response vector and a reverberant response vector. The reverberant response itself is composed of two distinct terms. The formalisms in the two approaches appear very different although they yield identical responses when subjected to the same external drive. This identity in the responses is illustrated by computations. Unlike the Sommerfeld–Watson transformation that relates the modal and the wave approaches to describing the response of a finite string, as yet, no analogeous analytical transformation is found to relate the two approaches of concern here.
Transformation of SH wave into a Stoneley wave under weak distortion of a crystal lattice of the material of an elastic isotropic space
Authors: Rossikhin Yuriy A. , Shitikova Marina V.
Published: October 2005

The problem on transformation of a volume SH wave propagating along an isotropic elastic space into a Stoneley wave in the consequence of the conversion of this space into a three-layered medium by small variations in material elastic moduli in a portion of the space is considered. The three-layered medium of two types has been investigated: A weakly anisotropic layer of cubic symmetry between two isotropic half-spaces and an isotropic layer between two slightly anisotropic half-spaces of cubic symmetry. In doing so, the elastic moduli of an isotropic material and isotropic parts of the moduli of a weakly anisotropic material are the same. Small anisotropic additions to the isotropic elastic moduli are entered by various means, so that velocities of SH waves in the slightly anisotropic materials with cubic symmetry obtained in such a way may be smaller, bigger, or equal to the velocity of SH waves in the corresponding isotropic material. It is shown that in those cases when the Stoneley wave exists, it refers to a weakly inhomogeneous quasitransverse wave of SH type, because among three displacement components weakly decaying with depth, the transverse one, which is parallel to the interface of three mediums, predominates.
Acoustic studies of magnetic fluids
Authors: Sokolov Victor V.
Published: October 2005

This report is a summary of the acoustic studies of magnetic fluids performed by the author and his co-workers. A first investigation applied acoustic spectroscopy methods with the nonmagnetized samples of magnetic fluid. The ultrasonic frequency was varied in the range 3–50 MHz. The velocity of the ultrasound was shown to decreased nonlinearly with the growth of the magnetic particle concentration. The elastic properties are defined mainly by the type of base fluid. In high-concentrated magnetic fluid, ultrasound velocity dispersion was found. The knowledge of frequency dependence of the absorption coefficient made it possible to estimate the applicability of known mechanisms of ultrasonic energy dissipation for the magnetic fluids. A second investigation was of the magnetic field influence upon the acoustic properties of the magnetic fluids. The external uniform magnetic field caused the formation of the needlelike structures. It leads to the breakdown of rotational invariance, and the magnetic fluid becomes acoustically anisotropic. Examination of the angular dependence of ultrasound attenuation indicates that it is the same as the nematic liquid crystal. Current theories are shown not to predict the observed experimental data. The electromagnetic effect accompanying the propagation of the ultrasound waves through a magnetic fluid was examined. This effect can be used for the determination of ultrasound velocity and of the average size of particles of magnetic fluids.
Simultaneous availability of absolute-intensity and relative-intensity cues in profile analysis
Authors: Turner Matthew , Berg Bruce G. , Southworth Curt
Published: October 2005

This study examined observer’s decision strategies in profile analysis experiments when cues based on both absolute-intensity and across-channel relative-intensity information were simultaneously available. The standard, in a 2IFC task, consisted of five equal-intensity tones, centered at 1000 Hz and ranging from 200 Hz to 5 kHz; the signal was an intensity increment added to the center tone. Two observers were initially trained in single-tone intensity discrimination tasks; another was trained in profile analysis tasks. In the first condition, unlike typical profile tasks, the overall level was not varied (e.g., roving-level procedure) thus making absolute-intensity and relative-intensity cues available. Spectral weight estimates for single tone trained observers were positive for all components of the stimulus. These results are consistent with absolute-intensity comparisons. Next, when a roving level procedure was used, spectral weight estimates changed to a pattern indicative of across-channel comparisons. Finally, when absolute intensity cues were again made available to the observers, they continued to use across-channel comparisons. The profile trained observer had constant (across-channel) weights which did not change. This suggests that observers choice of cues can be affected by training or previous listening experience. [Work supported by ONR.]
The role of component-relative entropy in the discrimination of simultaneous tone complexes
Authors: Lutfi Robert A. , Doherty Karen D.
Published: October 2005

Results are reported from a number of experiments investigating the effects of stimulus uncertainty on the discrimination of simultaneous multitone complexes. The results are generally consistent with the predictions of a model in which average threshold for the detection of a change in a single component is related to that component’s relative entropy (CoRe) in the complex [R. A. Lutfi, J. Acoust. Soc. 94, 748–758 (1993)]. In different experiments, target thresholds are found to be linearly related to CoRE for manipulations of target level, number of targets, number of context tones, and the relative degree of level perturbation on the tones from trial to trial. In most cases, the slopes of the functions are close to the theoretical value of b=−1.0, as predicted by strict application of the model. In the few cases where the slopes deviate significantly from this value, the slopes are much smaller in absolute magnitude. Compared to studies where the model has been previously applied the estimates of slopes are also substantially smaller in absolute magnitude, ‖b‖=1.0 versus 3.0. The difference in estimates is likely due to a difference in methodology used in these studies. [Research supported by NIDCD.]
Selective attention to spectral-temporal regions of auditory patterns
Authors: Watson Charles S. , Li Xiaofeng , Kidd Gary R. , Zheng Yijian
Published: October 2005

Training to attend selectively to certain spectral-temporal components of fourtonalpatterns has been found to have only slight effects on discrimination performance [Port etal., J. Acoust. Soc. Am. 93, 2315(A) (1993)]. In a new version of this experiment, a novel pattern (ten 50-ms tones, 300 3 kHz in frequency) was presented on each trial. One group of listeners was trained to discriminate changes in the early low-frequency region of the patterns, a second group in the late high-frequency regions, and a control group was trained with changes occurring throughout the patterns. Training was conducted for ten sessions, followed by testing at all spectral-temporal positions. Effects of selective training were much more substantial than in the earlier four-pattern experiment. Under the high stimulus-uncertainty conditions, attentional training yields the predicted results: Discrimination is relatively improved for trained, compared to untrained regions. An unexpected result was that the control group’s performance was significantly more accurate than that of earlier selective-attention group. It is possible that efforts to selectively attend to some spectral-temporal region of an unfamiliar pattern may reduce overall discrimination performance, compared to that achieved when listening for any change in the pattern. [Work supported by AFOSR.]
Temporal and spectral processing in increment detection
Authors: Eddins David A.
Published: October 2005

Increment detection for narrow-band noise can be enhanced by adding flanking noise bands remote in frequency. With flanking bands present, spectral analyses reveal the increment to produce a change in spectral shape and temporal analyses correspondingly reveal an increase in the envelope amplitude of the incremented band. This experiment was designed to identify the auditory cue(s), temporal or spectral, underlying increment detection with flanking bands. Performance was compared for random noises, having pronounced envelope fluctuations, and low-noise noises, having minimal envelope fluctuations. All noises were 10-Hz wide. The incremented band, centered at 2500 Hz, was presented either alone or with four flanking bands (1500, 2000, 3000, and 3500 Hz). The five noises had either coherent or incoherent temporal envelopes. Conditions having a ±10-dB within-trial random level variation were also included. Coherent flanking bands always facilitated increment detection for random but not low-noise noise, suggesting a temporal rather than a spectral basis for the improved detection. With the random level variation, thresholds were lower for incoherent than single-band conditions, suggesting the use of spectral shape cues. [Research supported by NIH.]
What aspects of the envelope are relevant for detection of amplitude modulation?
Authors: Strickland Elizabeth A. , Viemeister Neal F.
Published: October 2005

In a previous paper, detection thresholds for amplitude modulation at a ‘‘signal’’ modulation frequency (4, 16, 100, and 400 Hz) in the presence of a ‘‘masker’’ modulation frequency (2 to 800 Hz) were presented, when the carrier was a broadband noise [Strickland and Viemeister, J. Acoust. Soc. Am. Suppl. 1 86, S11 (1989)]. Broad tuning for modulation frequency was found, and for maskers half or twice the signal modulation frequency, threshold depended on the relative phases of the signal and masker modulators. Although this tuning has been taken as evidence for ‘‘channels’’ for modulation frequency, phase effects would not be predicted by such a mechanism. In the present study these results were used to determine what aspects of envelopes listeners might use in making decisions. Simulations were performed using the envelope detector model (bandpass filtering, half-wave rectification, and low-pass filtering) with decisions based on envelope statistics that have been used to predict other data. These statistics were (1) rms power, (2) ratio of maximum to minimum amplitude (max/min), (3) crest factor, (4) fourth moment, and (5) average slope. The max/min statistic was successful at predicting the major trends in the data, including tuning, without requiring the presence of modulation frequency channels. [Work supported by NIDCD Grant No. DC00110.]
The detection of modulation and the discrimination of modulation type
Authors: Sek Aleksander , Moore Brian C. J.
Published: October 2005

Psychometric functions were measured for the detection of amplitude modulation (AM) or frequency modulation (FM), using a two-alternative forced-choice (2AFC) task. Carrier frequencies (fc) were 125, 1000, and 6000 Hz, and modulation rates (g) were 2, 5, and 10 Hz. Then, pairs of values of AM and FM were selected that would be equally detectable, and psychometric functions were measured for the discrimination of AM from FM, again in a 2AFC task. For fc=125 and 1000 Hz and g=10 Hz, some subjects were essentially unable to discriminate AM from FM when the detectability of the modulation was relatively low. For g=2 Hz, some subjects identified the type of modulation as well as they detected the modulation. For a carrier frequency of 6000 Hz, the effect of modulation rate varied across subjects, but there was still a trend for poorer discrimination of modulation type at the highest modulation rate. We suggest that FM detection at a 10-Hz modulation rate is based largely on changes in excitation level for all carrier frequencies. For a 2-Hz modulation rate, and for the two lowest carrier frequencies, an extra mechanism, possibly based on phase locking, may play a role in the detection and discrimination of FM.
Selective attention in the discrimination of narrow-band sounds
Authors: Southworth Curt , Berg Bruce G.
Published: October 2005

The ability to discriminate changes in narrow-band sounds by selectively attending to level, pitch, and envelope cues is examined. The listener’s task is to detect an increment in the level of a 1000-Hz component of an equal-amplitude, three-tone complex with sidebands at 960 and 1040 Hz. Spectral weights are estimated according to the method of COSS analysis [B. G. Berg, J. Acoust. Soc. Am. 86, 1743–1746 (1989)] for five experimental conditions. Following a baseline condition of minimal instruction, listeners are instructed to discriminate the stimuli according to differences in loudness, pitch, and roughness. The final condition involves procedures intended to limit the information available to a process of envelope discrimination. Spectral weight estimates reveal that different listeners employ different cues in the absence of specific instructions of strict physical manipulations of the stimuli (e.g., baseline condition). Moreover, changes in spectral weight patterns indicate that narrow-band sounds are discriminable on the basis of multiple auditory processes that are subject to a mechanism of selective attention. Weight estimates closely follow the predicted weight patterns for models that simulate discriminations on the basis of level, pitch, and envelope cues. [Work supported by ONR.]
Detection of frequency modulation in steady and gliding tones
Authors: Zhang Tao , Feth Lawrence L. , Krishnamurthy Ashok K.
Published: October 2005

Previous work in this lab has developed a short-term IWAIF model for auditory frequency discrimination of dynamic signals. In this presentation we will report further tests of the model. The STEP versus GLIDE discrimination task used previously [Feth etal., J. Acoust. Soc. Am. Suppl. 1 86, S222 (1989); Madden, J. Acoust. Soc. Am. 95, 454–462 (1994)] has been replaced by an FM detection task. Sinusoidal FM of the GLIDE tone can be substituted for the STEP signal [Feth etal., J. Acoust. Soc. Am. Suppl. 1 88, S48 (1990)]. Listeners are asked to determine which of two tones is sinusoidally modulated in frequency. In a limiting case, the GLIDE has a slope of zero, that is, it is a steady tone. The detection task then is similar to FM detection. To reduce the influence of absolute frequency discrimination on the listeners’ performance, the experiment was run using roving frequency. For every interval of each 2Q, 2AFC trial, the starting frequency of the signal was selected from a uniform random distribution. Preliminary results indicate that performance in the task is similar to FM detection when the ‘‘unmodulated’’ signal is a GLIDE. However, the modulation index of the just detectable FM is approximately four times larger than the index for a steady reference tone. A comparison of IWAIF model predictions with listener performance will also be given. [Work supported by a grant from AFOSR.]
Pitches of concurrent vowels
Authors: Assmann Peter F. , Paschall D. Dwayne
Published: October 2005

When two vowels on different fundamental frequencies (F0’s) are presented concurrently, listeners can often report which vowel has the higher pitch. However, when the duration of the vowels is brief, listeners are more likely to misidentify the vowels and/or rank their pitches incorrectly. Four experienced listeners matched the pitches evoked by pairs of concurrent vowels whose durations were either 200 or 50 ms. The reference stimuli were pairwise combinations of the vowels /i/, /a/, /u/, /æ/, and /hooked backward eh/. One F0 was 100 Hz; the other was 0, 0.25, 0.5, 1, 2, or 4 semitones higher. When the F0 difference was less than one semitone, the majority of listeners’ matches clustered around the mean of the two F0’s, and they generally reported only one pitch. With larger F0 differences, 50-ms vowels generated more variable matching histograms than 200-ms stimuli. With 200-ms stimuli, listeners were more likely to report two pitches and their matches were more often clustered around the two F0’s. However, consistent evidence of bimodality emerged only for 200-ms stimuli with the largest F0 separation of four semitones. These results indicate that the pitches of concurrent vowels emerge less clearly when the stimuli are brief. [Work supported by NIDCD.]
The pitches of mistuned harmonics
Authors: Lin Jian-Yu , Hartmann William Morris
Published: October 2005

If a single harmonic of a complex tone is mistuned it can be heard as a separate entity. Pitch matching experiments show that the pitch of a mistuned harmonic does not agree with its frequency. The shift in pitch, caused by the complex context, is an exaggeration of the frequency mistuning. The differential pitch shift, for positive versus negative mistuning, is called the ‘‘split.’’ Splits for complex tones with simple spectra were measured by Hartmann and Smith [J. Acoust. Soc. Am. Suppl. 1 85, S109 (1989)]. Experiments reported here, measure splits for complex tones having spectral gaps and other anomalies. Experiments show that splits depend upon partial masking: Components below the mistuned harmonic create large splits; splits increase with increasing stimulus level. Experiments show that splits also depend upon the overall periodicity of the complex: Splits are larger for mistuned harmonics than for nonharmonic interstitials, given identical local spectral environments. Splits are larger for mistuned harmonics with low harmonic number or low fundamental frequency. These observations require revision of the neural timing model for the pitches of mistuned harmonics. [Work supported by the NIDCD, DC00181.]
Repetition detection by untrained listeners presented with very long period recycled noises
Authors: Brubaker Bradley S. , Warren Richard M. , Bashford James A.
Published: October 2005

In 1963 Guttman and Julesz reported that repetition of noise segments could be detected effortlessly for periods up to 1 s, and with difficultly up to 2 s. Bashford etal. (1992) reported that initial cross-modal cueing (100-ms flash, synchronous with a fixed portion of the waveform) allowed experienced listeners to exceed easily this 2-s limit of repetition detection. The present experiment examined whether prior flash cueing would enable untrained listeners to tap in synchrony with the previously highlighted portion of recycled noise segments (RNs) having periods from 2 to 10 s. Accurate synchronous tapping to 10-s RNs was achieved in 48% of the trials. Surprisingly, it was also observed that, without prior cueing, a separate group presented with the same 10-s RNs tapped accurately at a fixed waveform position on 32% of the trials. While taps of the cued group clustered around the previously highlighted positions, taps of the uncued group were distributed randomly. These results indicate that repetition detection by naive listeners is possible well above the two second limit described by Guttman and Julesz (1963). [Work supported by NIH.]
Some evidence that two separate mechanisms encode the F0’s of resolved and unresolved harmonics
Authors: Carlyon Robert P. , Shackleton Trevor M.
Published: October 2005

Sensitivity (d′) was measured to differences in fundamental frequency (ΔF0’s) between two groups of frequency modulated harmonics, presented simultaneously, where each group was filtered into either a LOW (125–625 Hz), MID (1375–1875 Hz), or HIGH (3900–5400 Hz) frequency region. The first set of experiments measured sensitivity to ΔF0’s between either the LOW and MID groups or the MID and HIGH groups, for baseline F0’s of 88 and 250 Hz, and also measured sensitivity to ΔF0’s between sequentially presented tokens of each individual group. Sensitivity to simultaneous ΔF0’s was best when the combination of frequency region and F0 caused the two groups to be either both resolved or both unresolved by the peripheral auditory system, and worst when the groups different in ‘‘resolvability.’’ Additional experiments showed that the high sensitivity to ΔF0’s between two groups of unresolved harmonics could be attributed to the pitch pulse asynchronies that invariably arise from a ΔF0. A model based on optimum combination of information was applied to the results of the first set of experiments, and succeeded in predicting sensitivity to simultaneous ΔF0’s between two groups of resolved components from that to successive ΔF0’s on the individual groups. However, the model overestimated performance when one group was resolved and the other unresolved. The results suggest that the F0’s of resolved and unresolved harmonics are processed by separate mechanisms, in contrast to the predictions of ‘‘autocorrelation’’ models of F0 encoding.
An entrainment model of human time perception
Authors: McAuley J. Devin
Published: October 2005

A ‘‘biologically inspired’’ entrainment mechanism is presented which captures certain aspects of human time perception. The adaptiveoscillator model has three main properties: (1) a preferred oscillation period, (2) a gradient-descent procedure which incrementally adapts this period so that the oscillator becomes synchronized with ‘‘rhythmic’’ aspects of the stimulus pattern, and (3) a decay term which drives the system back toward its preferred period. To compare model performance to human data, the adaptive oscillator is trained using a simulated 2AFC adaptive-tracking procedure to discriminate tempo changes across a range of interonset intervals (100–1500 ms). It has been shown that human subjects, performing the task described above, exhibit maximum tempo sensitivity between 300–800 ms; increasing the number of isochronous intervals improves thresholds in a roughly uniform way across the investigated range of interonset intervals [Drake and Botte, Percept. Psychophys. 54(3), 277–286 (1993)]. The performance of the model provides a qualitative match to the Drake and Botte data in a more biologically plausible manner than the ‘‘multiple-look’’ model proposed by these authors. [Work supported by NIMH.]
Using physically based models for collision-sound synthesis in virtual environments
Authors: Lee Jeng-Feng , Shen I-Yue , Crouch John , Aviles Walt , Zeltzer David , Durlach Nathaniel
Published: October 2005

Aural attributes of virtual environments have recently received great attention. While much of this work has been focused on spatialization of sound signals, the focus herein is on the synthesis of relevant environmental sounds. In particular, a framework is proposed for the synthesis of collision sounds using physically based models and digital filters. An impulse is fed into a bandpass filter, which is affected by the impact force as the driving source to the filter bank. Each filter bank represents a dominant vibrational mode that contributes to the collision sound. It will be shown how to determine the dominant vibrational modes and their corresponding natural resonant frequencies based on the material density, the Young’s modulus, inertia, and the boundary conditions of the objects involved. A broad range of collision sounds are synthesized to illustrate the use of the physically based models.
Optimization of medical imaging transducers by a piezoelectric computer-aided design system
Authors: Lerch Reinhard , Kaarmann Hans T.
Published: October 2005

The capabilities of a software package developed for the computer-aided design (CAD) of electroacoustic transducers operating under fluid load are reported. The simulation capabilities are mainly based on a combined finite element boundary element technique. The package contains modules for the geometric modeling, pre- and postprocessing tools for supporting the simulation, the numerical analysis software, and an optimization module. Main criteria for the optimization of ultrasonic phased array antennas used for diagnostic imaging are (i) high efficiency in transmit and receive mode (noise), (ii) short ultrasound pulse length (sharpness), (iii) broad radiation pattern (wide field of view). The CAD package was utilized for the determination of the optimal design parameters, such as the geometry of the transducer elements, the characteristics of applied piezoactive and non-piezoactive materials, and features of the electrical interface networks. In practical applications, the design software revealed to be superior to conventional design methods, especially in the final optimization of parameters, such as the refinement of transducer geometry. Furthermore, the understanding of physical phenomena, such as the crosstalk between array elements, is mainly enhanced by utilizing these computer simulations. The improvements in respect to the above optimization criteria obtained by the computer support have been experimentally verified.
Determination of breathing tube position and patency using acoustic reflectometry
Authors: Mansfield Jeffrey P. , Wodicka George R.
Published: October 2005

A new technique for determining the position and patency of tubes placed within the body using acoustic reflectometry was developed. The technique was used to guide and monitor endotracheal tubes (ETT) in four canines requiring breathing assistance during surgery. An incident sound pulse, generated by a small speaker in a tube, was injected into the proximal end of the ETT. The pulse then traveled down the ETT, was emitted into the airways, and the resulting reflections were measured by a microphone as they propagated back up the tube toward the speaker. A characteristic inverted reflection from the airways was measured and its timing was used to determine ETT position or movement. In addition, the reflection from the distal end of the ETT was used to estimate the diameter of the intubated airway. The location and degree of obstruction in the ETT was also estimated. The information provided by the device insured proper tracheal placement, patency, and accurate detection of ETT movement. [Work supported by NSF.]
Design and construction of a flexible dipole woofer
Authors: Canale James , Raichel Daniel R.
Published: October 2005

A design for a flexible dipole woofer [M. Allen, Speaker Builder 2/93, 10–13 (1993)] was modified to include additional acoustical features to facilitate better projection of sound into the room. The actual design of the woofer uses two large (91.5 cm×55.9 cm) Mylar or propylene sheets laminated on a foam pad, instead of a suspended cone. This design should eliminate resonances associated with traditional speaker cones to yield clearer bass sound. The planar woofer is mounted on a rectangular frame with rounded edges to eliminate diffraction. The result is a quality, low cost woofer system which can be augmented by an array of tweeters mounted to one side.
An optimized loudspeaker array for home theater surround sound
Authors: Starobin Bradley M.
Published: October 2005

The special requirements imposed by home theater on the performance characteristics of the surround channel loudspeaker system are several. Primarily, they entail combinations of radiation pattern, and placement/orientation (with respect to room boundaries and the seating area) which give rise to both the facilitation of a pronounced impression of acoustic spaciousness and, somewhat incongruously, the provision of the subtle directional cues for appropriate localization. A single-enclosure, six-element array has been designed to meet these requirements. The geometry, phasing, and passbands of the array elements together account for the system’s complex, multipolar radiation pattern, which is characterized by an angular region of reduced output. This radiation null is directed into the seating area, thereby preventing easy localization to the enclosure. The system’s acoustic spaciousness, as evidenced by measurements of interaural cross correlation, is compared to that of more traditional surround loudspeaker arrangements. [Work supported by Thomson Consumer Electronics.]
The resonance acoustic generators on the base of a cylindrical cavity and revolving drum
Authors: Sviyazheninov Eugene D.
Published: October 2005

Resonance generators of acoustic vibrations are developed from viscous heat-conductive compressible gas vibration research; and from specific applicable inventions that are intended to generate sonic and ultrasonic frequency mechanical vibrations at the expense of the store of steady energy of compressed gas, using the resonance properties of acoustic cylindrical cavities. The cylindrical shape provides the monochromaticity of the generating signal, picking off the cavity’s axis while exiting through the axial slots on its surface. The resonance phenomenon affords optimal pumping of the fixed frequency oscillating power to the sonic screened system. The resonance generators convert the steady mechanical energy of gas to sound or ultrasound vibrations by a highly simple original method. In comparison with currently available generators (mechanical, electromechanical, electromagnetic, electrodynamic, hydraulic, pneumatic, etc.), the proposed acoustic generators are considerably easier to produce, operate, and maintain, and are more reliable, highly competing with them in efficiency. The most closely related design in conception is the radial siren, containing coaxially mounted cylindrical stator, rotor with openings and drive. With the important strengths of the prototype, among which are construction simplicity, high reliability, and large unit power, its weaknesses are bandwidth-duration product, operation instability, and moderate efficiency. This can be improved by laying the resonance condition into the device foundation.
Analysis of concurrent timbres with an auditory model
Authors: Sandell Gregory J.
Published: October 2005

Concurrently sounding timbres (two or more instruments playing on the same or different pitches) sometimes yield unexpected qualities of sound which are exploited in orchestration. A model simulating spectrum analysis by the human auditory periphery is used to explore the differing contributions of individual instruments to the sum sound. Signals are passed through a bank of overlapping bandpass filters whose center frequency spacing corresponds to equal physical distances along the basilar membrane. Thus sinusoidal components do not fall into single ‘‘bins’’ as in a Fourier analysis, but rather spread excitation over a large number of channels. Some partials are resolved in separate channels while other partials are processed in a single channel with others, leading to interactions that determine the overall timbre of the combination. Sampled musical instrument tones are combined into concurrent arrangements and analyzed with the method.
Additive analysis and synthesis using partial tracking, spectral envelopes, and inverse fast Fourier transform
Authors: Rodet X. , Depalle P. , Garcia G.
Published: October 2005

Additive methods developed and used at IRCAM and CNMAT are presented. Analysis includes new techniques to find spectral peaks, estimate their parameters, track partial sinusoids, and separate sinusoidal components from the residual considered as noise. Partials are tracked by identifying trajectories in successive set of spectral peaks using a combinatorial hidden Markov model. Control is made easier by use of spectral envelopes instead of the classical time functions. Characteristic features of sounds are given in term of fundamental frequency, spectral envelopes for amplitude, phase, deviation from harmonicity, noise components, etc. This procedure renders user control much more economical and efficient. To reduce the computational cost of the synthesis algorithm, a method has been developed that is based on the short-time Fourier model of a sound signal allowing for the synthesis and control of hundreds of sinusoidal partials and noise components in real time on a desktop computer without custom hardware. Very high quality sound examples are obtained showing that a limited cost real-time multitimbral instrument can easily be designed based on inverse FFT. This would have all the possibilities of present day synthesizers, plus many others such as the precise modifications of sampled sounds, speech, and singing voice synthesis.