bluuebunny/crossref_metadata_2025 huggingface dataset:
Dispersion-invariant features for classification
Authors: Okopal Greg , Loughlin Patrick J. , Cohen Leon
Published: February 2008

In dispersive propagation, waves from the same source will generally differ depending on how far they have traveled. Accordingly, it is desirable for classification in such environments to either account for propagation effects, or to obtain features that are invariant to such effects. The latter approach is taken in this paper, and features are derived that are unaffected by channel dispersion, per mode. A “local” view of pulse propagation in time-frequency phase space is considered. It is shown that the local duration of a wave, obtained from its time-frequency Wigner distribution, is invariant to dispersion. While higher moments of the Wigner distribution are not invariant to dispersion, the phase space considerations suggest an approach for defining “dispersion-invariant moments” (DIMs) of any order. This approach is also used to define a dispersion-invariant correlation coefficient that can be used for classification. The classification utility of the DIMs, and of the dispersion-invariant correlation coefficient, is evaluated via simulations of acoustic scattering from steel shells in a dispersive channel model (Pekeris waveguide). Receiver operating characteristic curves quantify the improved discriminability of the DIMs versus ordinary temporal moments, and of the dispersion-invariant correlation coefficient versus the ordinary correlation coefficient.
Effect of room absorption on human vocal output in multitalker situations
Authors: Nijs Lau , Saher Konca , den Ouden Daniël
Published: February 2008

People increase their vocal output in noisy environments. This is known as the Lombard effect. The aim of the present study was to measure the effect as a function of the absorption coefficient. The noise source was generated by using other talkers in the room. A-weighted sound levels were measured in a 108m3 test room. The number of talkers varied from one to four and the absorption coefficients from 0.12 to 0.64. A model was introduced based on the logarithmic sum of the level found in an anechoic room plus the increasing portion of noise levels up to 80dB. Results show that the model fits the measurements when a maximum slope of 0.5dB per 1.0dB increase in background level is used. Hence Lombard slopes vary from 0.2dB∕dB at 50dB background level to 0.5dB∕dB at 80dB. In addition, both measurements and the model predict a decrease of 5.5dB per doubling of absorbing area in a room when the number of talkers is constant. Sound pressure levels increase for a doubling of talkers from 3dB for low densities to 6dB for dense crowds. Finally, there was correspondence between the model estimation and previous measurements reported in the literature.
Determination of superior surface strains and stresses, and vocal fold contact pressure in a synthetic larynx model using digital image correlation
Authors: Spencer Mychal , Siegmund Thomas , Mongeau Luc
Published: February 2008

Stresses and strains within the vocal fold tissue may play a critical role in voice fatigue, in tissue damage and resulting voice disorders, and in tissue healing. In this study, experiments were performed to determine mechanical fields on the superior surface of a self-oscillating physical model of the human vocal folds using a three-dimensional digital image correlation method. Digital images obtained using a high-speed camera together with a mirror system were used to measure displacement fields, from which strains, strain rates, and stresses on the superior surface of the model vocal folds were computed. The dependence of these variables on flow rate was established. A Hertzian impact model was used to estimate the contact pressure on the medial surface from superior surface strains. A tensile stress dominated state was observed on the superior surface, including during collision between the model folds. Collision between the model vocal folds limits the medial-lateral stress levels on the superior surface, in conjunction with compressive stress or contact pressure on the medial surface.
Multilevel modeling of between-speaker and within-speaker variation in spontaneous speech tempo
Authors: Quené Hugo
Published: February 2008

Speech tempo (articulation rate) varies both between and within speakers. The present study investigates several factors affecting tempo in a corpus of spoken Dutch, consisting of interviews with 160 high-school teachers. Speech tempo was observed for each phrase separately, and analyzed by means of multilevel modeling of the speaker’s sex, age, country, and dialect region (between speakers) and length, sequential position of phrase, and autocorrelated tempo (within speakers). Results show that speech tempo in this corpus depends mainly on phrase length, due to anticipatory shortening, and on the speaker’s country, with different speaking styles in The Netherlands (faster, less varied) and in Flanders (slower, more varied). Additional analyses showed that phrase length itself is shorter in The Netherlands than in Flanders, and decreases with speaker’s age. Older speakers tend to vary their phrase length more (within speakers), perhaps due to their accumulated verbal proficiency.
Broadband acoustic scattering measurements of underwater unexploded ordnance (UXO)
Authors: Bucaro J. A. , Houston B. H. , Saniga M. , Dragonette L. R. , Yoder T. , Dey S. , Kraus L. , Carin L.
Published: February 2008

In order to evaluate the potential for detection and identification of underwater unexploded ordnance (UXO) by exploiting their structural acoustic response, we carried out broadband monostatic scattering measurements over a full 360° on UXO’s (two mortar rounds, an artillery shell, and a rocket warhead) and false targets (a cinder block and a large rock). The measurement band, 1–140kHz, includes a low frequency structural acoustics region in which the wavelengths are comparable to or larger than the target characteristic dimensions. In general, there are aspects that provide relatively high target strength levels (∼−10 to −15dB), and from our experience the targets should be detectable in this structural acoustics band in most acoustic environments. The rigid body scattering was also calculated for one UXO in order to highlight the measured scattering features involving elastic responses. The broadband scattering data should be able to support feature-based separation of UXO versus false targets and identification of various classes of UXO as well.
Localization cues with bilateral cochlear implants
Authors: Seeber Bernhard U. , Fastl Hugo
Published: February 2008

Selected subjects with bilateral cochlear implants (CIs) showed excellent horizontal localization of wide-band sounds in previous studies. The current study investigated localization cues used by two bilateral CI subjects with outstanding localization ability. The first experiment studied localization for sounds of different spectral and temporal composition in the free field. Localization of wide-band noise was unaffected by envelope pulsation, suggesting that envelope-interaural time difference (ITD) cues contributed little. Low-pass noise was not localizable for one subject and localization depended on the cutoff frequency for the other which suggests that ITDs played only a limited role. High-pass noise with slow envelope changes could be localized, in line with contribution of interaural level differences (ILDs). In experiment 2, processors of one subject were raised above the head to void the head shadow. If they were spaced at ear distance, ITDs allowed discrimination of left from right for a pulsed wide-band noise. Good localization was observed with a head-sized cardboard inserted between processors, showing the reliance on ILDs. Experiment 3 investigated localization in virtual space with manipulated ILDs and ITDs. Localization shifted predominantly for offsets in ILDs, even for pulsed high-pass noise. This confirms that envelope ITDs contributed little and that localization with bilateral CIs was dominated by ILDs.
Perception of clear fricatives by normal-hearing and simulated hearing-impaired listeners
Authors: Maniwa Kazumi , Jongman Allard , Wade Travis
Published: February 2008

Speakers may adapt the phonetic details of their productions when they anticipate perceptual difficulty or comprehension failure on the part of a listener. Previous research suggests that a speaking style known as clear speech is more intelligible overall than casual, conversational speech for a variety of listener populations. However, it is unknown whether clear speech improves the intelligibility of fricative consonants specifically, or how its effects on fricative perception might differ depending on listener population. The primary goal of this study was to determine whether clear speech enhances fricative intelligibility for normal-hearing listeners and listeners with simulated impairment. Two experiments measured babble signal-to-noise ratio thresholds for fricative minimal pair distinctions for 14 normal-hearing listeners and 14 listeners with simulated sloping, recruiting impairment. Results indicated that clear speech helped both groups overall. However, for impaired listeners, reliable clear speech intelligibility advantages were not found for non-sibilant pairs. Correlation analyses comparing acoustic and perceptual data indicated that a shift of energy concentration toward higher frequency regions and greater source strength contributed to the clear speech effect for normal-hearing listeners. Correlations between acoustic and perceptual data were less consistent for listeners with simulated impairment, and suggested that lower-frequency information may play a role.
Three wave mixing test of hyperelasticity in highly nonlinear solids: Sedimentary rocks
Authors: D’Angelo R. M. , Winkler K. W. , Johnson D. L.
Published: February 2008

Measurements of three-wave mixing amplitudes on solids whose third order elastic constants have also been measured by means of the elasto-acoustic effect are reported. Because attenuation and diffraction are important aspects of the measurement technique results are analyzed using a frequency domain version of the KZK equation, modified to accommodate an arbitrary frequency dependence to the attenuation. It is found that the value of β so deduced for poly(methylmethacrylate) (PMMA) agrees quite well with that predicted from the stress-dependent sound speed measurements, establishing that PMMA may be considered a hyperelastic solid, in this context. The β values of sedimentary rocks, though they are typically two orders of magnitude larger than, e.g., PMMA’s, are still a factor of 3–10 less than those predicted from the elasto-acoustic effect. Moreover, these samples exhibit significant heterogeneity on a centimeter scale, which heterogeneity is not apparent from a measurement of the position dependent sound speed.
Effects of spectro-temporal modulation changes produced by multi-channel compression on intelligibility in a competing-speech task
Authors: Stone Michael A. , Moore Brian C. J.
Published: February 2008

These experiments are concerned with the intelligibility of target speech in the presence of a background talker. Using a noise vocoder, Stone and Moore [J. Acoust. Soc. Am. 114, 1023–1034 (2003)] showed that single-channel fast-acting compression degraded intelligibility, but slow compression did not. Stone and Moore [J. Acoust. Soc. Am. 116, 2311–2323 (2004)] showed that intelligibility was lower when fast single-channel compression was applied to the target and background after mixing rather than before, and suggested that this was partly due to compression after mixing introducing “comodulation” between the target and background talkers. Experiment 1 here showed a similar effect for multi-channel compression. In experiment 2, intelligibility was measured as a function of the speed of multi-channel compression applied after mixing. For both eight- and 12-channel vocoders with one compressor per channel, intelligibility decreased as compression speed increased. For the eight-channel vocoder, a compressor that only affected modulation depth for rates below 2Hz still reduced intelligibility. Experiment 3 used 12- or 18-channel vocoders. There were between 1 and 12 compression channels, and four speeds of compression. Intelligibility decreased as the number and speed of compression channels increased. The results are interpreted using several measures of the effects of compression, especially “across-source modulation correlation.”
Sounds and vibrations in the frozen Beaufort Sea during gravel island construction
Authors: Greene Charles R. , Blackwell Susanna B. , McLennan Miles Wm.
Published: February 2008

Underwater and airborne sounds and ice-borne vibrations were recorded from sea-ice near an artificial gravel island during its initial construction in the Beaufort Sea near Prudhoe Bay, Alaska. Such measurements are needed for characterizing the properties of island construction sounds to assess their possible impacts on wildlife. Recordings were made in February–May 2000 when BP Exploration (Alaska) began constructing Northstar Island about 5km offshore, at 12m depth. Activities recorded included ice augering, pumping sea water to flood the ice and build an ice road, a bulldozer plowing snow, a Ditchwitch cutting ice, trucks hauling gravel over an ice road to the island site, a backhoe trenching the sea bottom for a pipeline, and both vibratory and impact sheet pile driving. For all but one sound source (underwater measurements of pumping) the strongest one-third octave band was under 300Hz. Vibratory and impact pile driving created the strongest sounds. Received levels of sound and vibration, as measured in the strongest one-third octave band for different construction activities, reached median background levels <7.5km away for underwater sounds, <3km away for airborne sounds, and <10km away for in-ice vibrations.
Geoacoustic inversion by mode amplitude perturbation
Authors: Poole Travis L. , Frisk George V. , Lynch James F. , Pierce Allan D.
Published: February 2008

This paper introduces a perturbative inversion algorithm for determining sea floor acoustic properties, which uses modal amplitudes as input data. Perturbative inverse methods have been used in the past to estimate bottom acoustic properties in sediments, but up to this point these methods have used only the modal eigenvalues as input data. As with previous perturbative inversion methods, the one developed in this paper solves the nonlinear inverse problem using a series of approximate, linear steps. Examples of the method applied to synthetic and experimental data are provided to demonstrate the method’s feasibility. Finally, it is shown that modal eigenvalue and amplitude perturbation can be combined into a single inversion algorithm that uses all of the potentially available modal data.
Stresses and displacements for some Rayleigh-type surface acoustic waves propagating on an anisotropic half space
Authors: Royer Daniel
Published: February 2008

Specific relations between mechanical displacements and stresses for Rayleigh-type surface acoustic waves propagating on an anisotropic half space are demonstrated. For 16 symmetry configurations belonging to the orthorhombic, tetragonal, hexagonal and cubic systems, involving only two displacement and stress components, it is shown that the ratio between the shear and normal stresses inside the propagation media is equal to the ratio between the normal and in-plane displacement components at the free surface. This result generalizes the previous one obtained in the case of an isotropic solid [W. Hassan and P. B. Nagy, J. Acoust. Soc. Am. 104, 3107–3110 (1998)].
Assessing the pitch structure associated with multiple rates and places for cochlear implant users
Authors: Stohl Joshua S. , Throckmorton Chandra S. , Collins Leslie M.
Published: February 2008

Cochlear implant subjects continue to experience difficulty understanding speech in noise and performing pitch-based musical tasks. Acoustic model studies have suggested that transmitting additional fine structure via multiple stimulation rates is a potential mechanism for addressing these issues [Nie et al., IEEE Trans. Biomed. Eng. 52, 64–73 (2005); Throckmorton et al., Hear. Res. 218, 30–42 (2006)]; however, results from preliminary cochlear implant studies have been less compelling. Multirate speech processing algorithms previously assumed a place-dependent pitch structure in that a basal electrode would always elicit a higher pitch percept than an apical electrode, independent of stimulation rate. Some subjective evidence contradicts this assumption [H. J. McDermott and C. M. McKay, J. Acoust. Soc. Am. 101, 1622–1630 (1997); R. V. Shannon, Hear. Res. 11, 157–189 (1983)]. The purpose of this study is to test the hypothesis that the introduction of multiple rates may invalidate the tonotopic pitch structure resulting from place-pitch alone. The SPEAR3 developmental speech processor was used to collect psychophysical data from five cochlear implant users to assess the tonotopic structure for stimuli presented at two rates on all active electrodes. Pitch ranking data indicated many cases where pitch percepts overlapped across electrodes and rates. Thus, the results from this study suggest that pitch-based tuning across rate and electrode may be necessary to optimize performance of a multirate sound processing strategy in cochlear implant subjects.
Effects of an air-layer-subdivision technique on the sound transmission through a single plate
Authors: Toyoda Masahiro , Kugo Hajime , Shimizu Takafumi , Takahashi Daiji
Published: February 2008

Many studies on the sound transmission through a single plate have been carried out theoretically and experimentally. The transmission-loss characteristics, in general, follow mass law. Therefore, increasing mass of a plate is a fundamental measure to improve the insulation performance. This method, however, has limitations and might not be a reasonable alternative in current standards. Furthermore, the transmission loss at the critical frequency of coincidence is deteriorated significantly even if the mass is rather large. In this paper, the effect of the air-layer-subdivision technique is studied in detail from the viewpoint of the sound transmission problem of a single plate. An analytical model of an infinite single plate with a subdivided layer is considered and the improvement of the transmission loss is estimated. The limitations of the technique are clarified with some parametric studies. In order to validate the predictions, an experiment was carried out. The transmission loss of a glass board with the air layer subdivided by acryl partitions was measured in the experiment. They were in good agreement with the theoretical ones near and above the coincidence.
Effects of low-frequency biasing on spontaneous otoacoustic emissions: Amplitude modulation
Authors: Bian Lin , Watts Kelly L.
Published: February 2008

The dynamic effects of low-frequency biasing on spontaneous otoacoustic emissions (SOAEs) were studied in human subjects under various signal conditions. Results showed a combined suppression and modulation of the SOAE amplitudes at high bias tone levels. Ear-canal acoustic spectra demonstrated a reduction in SOAE amplitude and growths of sidebands while increasing the bias tone level. These effects varied depending on the relative strength of the bias tone to a particular SOAE. The SOAE magnitudes were suppressed when the cochlear partition was biased in both directions. This quasi-static modulation pattern showed a shape consistent with the first derivative of a sigmoid-shaped nonlinear function. In the time domain, the SOAE amplitudes were modulated with the instantaneous phase of the bias tone. For each biasing cycle, the SOAE envelope showed two peaks each corresponded to a zero crossing of the bias tone. The temporal modulation patterns varied systematically with the level and frequency of the bias tone. These dynamic behaviors of the SOAEs are consistent with the shifting of the operating point along the nonlinear transducer function of the cochlea. The results suggest that the nonlinearity in cochlear hair cell transduction may be involved in the generation of SOAEs.
Annoyance and disturbance of daily activities from road traffic noise in Canada
Authors: Michaud David S. , Keith Stephen E. , McMurchy Dale
Published: February 2008

This study evaluated road traffic noise annoyance in Canada in relation to activity interference, subject concerns about noise and self-reported distance to a major road. Random digit dialing was employed to survey a representative sample of 2565 Canadians 15years of age and older. Respondents highly annoyed by traffic noise were significantly more likely to perceive annoyance to negatively impact health, live closer to a heavily traveled road and report that traffic noise often interfered with daily activities. Sex, age, education level, community size and province had statistically significant associations with traffic noise annoyance. High noise annoyance consistently correlated with frequent interference of activities. Reducing noise at night (10pm–7am) was more important than during the rest of the day.
Influence of microarchitecture alterations on ultrasonic backscattering in an experimental simulation of bovine cancellous bone aging
Authors: Apostolopoulos K. N. , Deligianni D. D.
Published: February 2008

An experimental model which can simulate physical changes that occur during aging was developed in order to evaluate the effects of change of mineral content and microstructure on ultrasonic properties of bovine cancellous bone. Timed immersion in hydrochloric acid was used to selectively alter the mineral content. Scanning electron microscopy and histological staining of the acid-treated trabeculae demonstrated a heterogeneous structure consisting of a mineralized core and a demineralized layer. The presence of organic matrix contributed very little to normalized broadband ultrasound attenuation (nBUA) and speed of sound. All three ultrasonic parameters, speed of sound, nBUA and backscatter coefficient, were sensitive to changes in apparent density of bovine cancellous bone. A two-component model utilizing a combination of two autocorrelation functions (a densely populated model and a spherical distribution) was used to approximate the backscatter coefficient. The predicted attenuation due to scattering constituted a significant part of the measured total attenuation (due to both scattering and absorption mechanisms) for bovine cancellous bone. Linear regression, performed between trabecular thickness values and estimated from the model correlation lengths, showed significant linear correlation, with R2=0.81 before and R2=0.80 after demineralization. The accuracy of estimation was found to increase with trabecular thickness.
Using beamforming and binaural synthesis for the psychoacoustical evaluation of target sources in noise
Authors: Song Wookeun , Ellermeier Wolfgang , Hald Jørgen
Published: February 2008

The potential of spherical-harmonics beamforming (SHB) techniques for the auralization of target sound sources in a background noise was investigated and contrasted with traditional head-related transfer function (HRTF)-based binaural synthesis. A scaling of SHB was theoretically derived to estimate the free-field pressure at the center of a spherical microphone array and verified by comparing simulated frequency response functions with directly measured ones. The results show that there is good agreement in the frequency range of interest. A listening experiment was conducted to evaluate the auralization method subjectively. A set of ten environmental and product sounds were processed for headphone presentation in three different ways: (1) binaural synthesis using dummy head measurements, (2) the same with background noise, and (3) SHB of the noisy condition in combination with binaural synthesis. Two levels of background noise (62, 72dB SPL) were used and two independent groups of subjects (N=14) evaluated either the loudness or annoyance of the processed sounds. The results indicate that SHB almost entirely restored the loudness (or annoyance) of the target sounds to unmasked levels, even when presented with background noise, and thus may be a useful tool to psychoacoustically analyze composite sources.
Temporal weights in the level discrimination of time-varying sounds
Authors: Pedersen Benjamin , Ellermeier Wolfgang
Published: February 2008

To determine how listeners weight different portions of the signal when integrating level information, they were presented with 1-s noise samples the levels of which randomly changed every 100ms by repeatedly, and independently, drawing from a normal distribution. A given stimulus could be derived from one of two such distributions, a decibel apart, and listeners had to classify each sound as belonging to the “soft” or “loud” group. Subsequently, logistic regression analyses were used to determine to what extent each of the ten temporal segments contributed to the overall judgment. In Experiment 1, a nonoptimal weighting strategy was found that emphasized the beginning, and, to a lesser extent, the ending of the sounds. When listeners received trial-by-trial feedback, however, they approached equal weighting of all stimulus components. In Experiment 2, a spectral change was introduced in the middle of the stimulus sequence, changing from low-pass to high-pass noise, and vice versa. The temporal location of the stimulus change was strongly weighted, much as a new onset. These findings are not accounted for by current models of loudness or intensity discrimination, but are consistent with the idea that temporal weighting in loudness judgments is driven by salient events.
Speech recognition in noise as a function of highpass-filter cutoff frequency for people with and without low-frequency cochlear dead regions
Authors: Vinay  , Baer Thomas , Moore Brian C. J.
Published: February 2008

Regions in the cochlea with very few functioning inner hair cells and/or neurons are called “dead regions” (DRs). Previously, we measured the recognition of highpass-filtered nonsense syllables as a function of filter cutoff frequency for hearing-impaired people with and without low-frequency (apical) DRs [J. Acoust. Soc. Am. 122, 542–553 (2007)]. DRs were diagnosed using the TEN(HL) test, and psychophysical tuning curves were used to define the edge frequency (fe) more precisely. Stimuli were amplified differently for each ear, using the “Cambridge formula.” The present study was similar, but the speech was presented in speech-shaped noise at a signal-to-noise ratio of 3dB. For subjects with low-frequency hearing loss but without DRs, scores were high (65–80%) for low cutoff frequencies and worsened with increasing cutoff frequency above about 430Hz. For subjects with low-frequency DRs, performance was poor (20–40%) for the lowest cutoff frequency, improved with increasing cutoff frequency up to about 0.56fe, and then worsened. As for speech in quiet, these results indicate that people with low-frequency DRs are able to make effective use of frequency components that fall in the range 0.56fe to fe, but that frequency components below 0.56fe have deleterious effects.
Vibration modeling of structural fuzzy with continuous boundary
Authors: Friis Lars , Ohlrich Mogens
Published: February 2008

From experiments it is well known that the vibration response of a main structure with many attached substructures often shows more damping than structural losses in the components can account for. In practice, these substructures, which are not attached in an entirely rigid manner, behave like a multitude of different sprung masses each strongly resisting any motion of the main structure (master) at their base antiresonance. The “theory of structural fuzzy” is intended for modeling such high damping. In the present article the theory of fuzzy structures is briefly outlined and a method of modeling fuzzy substructures examined. This is done by new derivations and physical interpretations are provided. Further, the method is extended and simplified by introducing a simple deterministic approach to determine the boundary impedance of the structural fuzzy. By using this new approach, the damping effect of the fuzzy with spatial memory is demonstrated by numerical simulations of a main beam structure with fuzzy attachments. It is shown that the introduction of spatial memory reduces the damping effect of the fuzzy and in certain cases the damping effect may even be eliminated completely.
A probabilistic framework for landmark detection based on phonetic features for automatic speech recognition
Authors: Juneja Amit , Espy-Wilson Carol
Published: February 2008

A probabilistic framework for a landmark-based approach to speech recognition is presented for obtaining multiple landmark sequences in continuous speech. The landmark detection module uses as input acoustic parameters (APs) that capture the acoustic correlates of some of the manner-based phonetic features. The landmarks include stop bursts, vowel onsets, syllabic peaks and dips, fricative onsets and offsets, and sonorant consonant onsets and offsets. Binary classifiers of the manner phonetic features—syllabic, sonorant and continuant—are used for probabilistic detection of these landmarks. The probabilistic framework exploits two properties of the acoustic cues of phonetic features—(1) sufficiency of acoustic cues of a phonetic feature for a probabilistic decision on that feature and (2) invariance of the acoustic cues of a phonetic feature with respect to other phonetic features. Probabilistic landmark sequences are constrained using manner class pronunciation models for isolated word recognition with known vocabulary. The performance of the system is compared with (1) the same probabilistic system but with mel-frequency cepstral coefficients (MFCCs), (2) a hidden Markov model (HMM) based system using APs and (3) a HMM based system using MFCCs.
Effects of moderate cochlear hearing loss on the ability to benefit from temporal fine structure information in speech
Authors: Hopkins Kathryn , Moore Brian C. J. , Stone Michael A.
Published: February 2008

Speech reception thresholds (SRTs) were measured with a competing talker background for signals processed to contain variable amounts of temporal fine structure (TFS) information, using nine normal-hearing and nine hearing-impaired subjects. Signals (speech and background talker) were bandpass filtered into channels. Channel signals for channel numbers above a “cut-off channel” (CO) were vocoded to remove TFS information, while channel signals for channel numbers of CO and below were left unprocessed. Signals from all channels were combined. As a group, hearing-impaired subjects benefited less than normal-hearing subjects from the additional TFS information that was available as CO increased. The amount of benefit varied between hearing-impaired individuals, with some showing no improvement in SRT and one showing an improvement similar to that for normal-hearing subjects. The reduced ability to take advantage of TFS information in speech may partially explain why subjects with cochlear hearing loss get less benefit from listening in a fluctuating background than normal-hearing subjects. TFS information may be important in identifying the temporal “dips” in such a background.
Impact of ocean variability on coherent underwater acoustic communications during the Kauai experiment (KauaiEx)
Authors: Song Aijun , Badiey Mohsen , Song H. C. , Hodgkiss William S. , Porter Michael B. ,   the KauaiEx Group
Published: February 2008

During the July 2003 acoustic communications experiment conducted in 100m deep water off the western side of Kauai, Hawaii, a 10s binary phase shift keying signal with a symbol rate of 4kilosymbol∕s was transmitted every 30min for 27h from a bottom moored source at 12kHz center frequency to a 16 element vertical array spanning the water column at about 3km range. The communications signals are demodulated by time reversal multichannel combining followed by a single channel decision feedback equalizer using two subsets of array elements whose channel characteristics appear distinct: (1) top 10 and (2) bottom 4 elements. Due to rapid channel variations, continuous channel updates along with Doppler tracking are required prior to time reversal combining. This is especially true for the top 10 elements where the received acoustic field involves significant interaction with the dynamic ocean surface. The resulting communications performance in terms of output signal-to-noise ratio exhibits significant change over the 27h transmission duration. This is particularly evident as the water column changes from well-mixed to a downward refracting environment.
The pulse-train auditory aftereffect and the perception of rapid amplitude modulations
Authors: Gutschalk Alexander , Micheyl Christophe , Oxenham Andrew J.
Published: February 2008

Prolonged listening to a pulse train with repetition rates around 100Hz induces a striking aftereffect, whereby subsequently presented sounds are heard with an unusually “metallic” timbre [Rosenblith et al., Science 106, 333–335 (1947)]. The mechanisms responsible for this auditory aftereffect are currently unknown. Whether the aftereffect is related to an alteration of the perception of temporal envelope fluctuations was evaluated. Detection thresholds for sinusoidal amplitude modulation (AM) imposed onto noise-burst carriers were measured for different AM frequencies (50–500Hz), following the continuous presentation of a periodic pulse train, a temporally jittered pulse train, or an unmodulated noise. AM detection thresholds for AM frequencies of 100Hz and above were significantly elevated compared to thresholds in quiet, following the presentation of the pulse-train inducers, and both induced a subjective auditory aftereffect. Unmodulated noise, which produced no audible aftereffect, left AM detection thresholds unchanged. Additional experiments revealed that, like the Rosenblith et al. aftereffect, the effect on AM thresholds does not transfer across ears, is not eliminated by protracted training, and can last several tens of seconds. The results suggest that the Rosenblith et al. aftereffect is related to a temporary alteration in the perception of fast temporal envelope fluctuations in sounds.
Gap detection in modulated noise: Across-frequency facilitation and interference
Authors: Grose John H. , Buss Emily , Hall Joseph W.
Published: February 2008

This study tested the hypothesis that a detection advantage for gaps in comodulated noise relative to random noise can be demonstrated in conditions of continuous noise and salient envelope fluctuations. Experiment 1 used five 25-Hz-wide bands of Gaussian noise, low-fluctuation noise, and a noise with increased salience of the inherent fluctuations (staccato noise). The bands were centered at 444, 667, 1000, 1500, and 2250Hz, with the gap signal always inserted in the 1000-Hz band. Results indicated that a gap detection advantage existed in continuous comodulated noise only for Gaussian and staccato noise. Experiment 2 demonstrated that the advantage did not exist for gated presentation. This experiment also showed that the advantage bore some similarity to comodulation masking release. However, differences were also noted in terms of the effects of the number of flanking bands and the absence of a detection advantage in gated conditions. The detrimental effect of a gated flanking band was less pronounced for a comodulated band than for a random band. This study indicates that, under some conditions, a detection advantage for gaps carried by a narrow band of noise can occur in the presence of comodulated flanking bands of noise.
Vibrational frequencies and tuning of the African mbira
Authors: McNeil L. E. , Mitran S.
Published: February 2008

The acoustic spectrum of the mbira, a musical instrument from Africa that produces sound by the vibration of cantilevered metal rods, has been measured. It is found that the most prominent overtones present in the spectrum have frequencies that are approximately 5 and 14 times the lowest frequency. A finite-element model of the vibration of the key that takes into account the acoustic radiation efficiency of the various normal modes reveals that the far-field power spectrum is dominated by modes involving predominately transverse motion of the key. Modes involving longitudinal motion do not radiate efficiently, and therefore contribute little to the sound produced. The high frequencies of the dominant overtones relative to the fundamental make it unlikely that the tunings of the mbira that are used by expert musicians are determined by matching the fundamental frequencies of the upper keys with the overtones of the lower keys.
Adaptive wave field synthesis
Authors: Gauthier Philippe-Aubert
Published: February 2008

Wave field synthesis (WFS) is a sound field reproduction technology which assumes that the reproduction environment is anechoic. A real reproduction space reduces the objective accuracy of WFS. This research involves the improvement of WFS performance by active noise control and adaptive filters. Simulations of sound field reproduction in a three-dimensional space show the physical possibility of progressive sound field reproduction in a closed space on the basis of optimal control of the reproduction errors at a sensor array. The proposed solution is adaptive wave field synthesis (AWFS). The originality of AWFS is the combination of the minimization of the reproduction error along with a penalty for any departure from the WFS solution. AWFS is theoretically analyzed on the basis of singular value decomposition. This suggests that the AWFS underlying mechanism is independent radiation mode control. Two adaptive algorithms for AWFS are developed. An experimental AWFS system is tested in different rooms (hemi-anechoic, laboratory, reverberant). It shows that AWFS performs better than WFS: AWFS significantly reduces the room effects on sound field reproduction. The algorithm based on independent radiation mode control contributes to the enlargement of the effective reproduction region. The thesis is written in French and in English.
A study of modal characteristics and the control mechanism of finite periodic and irregular ribbed plates
Authors: Lin Tian Ran
Published: February 2008

An analytical solution is presented in this paper to investigate the control mechanism and modal characteristics of finite periodic and irregular ribbed plates. Peak responses of a finite periodic ribbed plate were examined where they were grouped into two sets of propagation zones according to the coupling mechanism at beam/plate interfaces. Details of modal characteristics in pass bands of the periodic ribbed plate were elucidated and the control mechanism was discussed. Modes in each pass band that are governed by shear force couplings were characterized by one of the beam flexural modes whose modal responses could be represented approximately by those of the corresponding orthotropic plate modes. Modes in the second set of pass bands were found to retain the resonance frequencies of the corresponding modes of the unribbed base plate. Higher order orthotropic plate modes were also identified, which could not be grouped into any pass bands defined by the classical periodic theory. The control mechanism leading to vibration confinement in disordered and irregular ribbed plates was also discussed. It was found that beam spacing irregularity attributes to localization of the group of modes associated with flexural wave couplings but not the group of modes associated with moment couplings.
Drifters Through Time
Authors: Riding Robert
Published: February 2008

Evolution of Primary Producers in the Sea
.
Paul G. Falkowski and Andrew H. Knoll, Eds.
. Academic Press (Elsevier), Burlington, MA, 2007. 470 pp. $79.95. ISBN 9780123705181.

Approaching the topic from a variety of perspectives--including molecular evolution, phylogenetics, biogeochemistry, marine ecology, and paleontology---the contributors examine the evolution and impact of phytoplankton and the photosynthetic process
DIFFERENTIAL STRUCTURE OF ABELIAN FUNCTIONS
Authors: CHO KOJI , NAKAYASHIKI ATSUSHI
Published: February 2008

The space of Abelian functions of a principally polarized abelian variety (J,Θ) is studied as a module over the ring [Formula: see text] of global holomorphic differential operators on J. We construct a [Formula: see text] free resolution in case Θ is non-singular. As an application, in the case of dimensions 2 and 3, we construct a new linear basis of the space of abelian functions which are singular only on Θ in terms of logarithmic derivatives of the higher-dimensional σ-function.
A LIMIT FORMULA FOR EVEN NILPOTENT ORBITS
Authors: BOŽIČEVIĆ MLADEN
Published: February 2008

Let Gℝ be a real form of a complex, semisimple Lie group G. Assume [Formula: see text] is an even nilpotent coadjoint Gℝ-orbit. We prove a limit formula, expressing the canonical measure on [Formula: see text] as a limit of canonical measures on semisimple coadjoint orbits, where the parameter of orbits varies over the negative chamber defined by the parabolic subalgebra associated with [Formula: see text].
DARBOUX TRANSFORMATION OF THE GREEN FUNCTION FOR THE DIRAC EQUATION WITH THE GENERAL POTENTIAL
Authors: POZDEEVA EKATERINA
Published: February 2008

We consider the Darboux transformation of the Green functions of the regular boundary problem of the one-dimensional stationary Dirac equation. We obtained the Green functions of the transformed Dirac equation with the initial regular boundary conditions. We also obtain the formula for the full trace of the difference of the transformed and initial Green functions of the regular boundary problem of the one-dimensional stationary Dirac equation. We illustrate our findings by the consideration of the Darboux transformation of the Green function on an interval.
NEW INTERPRETATION OF SKYRME THEORY
Authors: CHO Y. M. , PARK B. S. , ZHANG P. M.
Published: February 2008

Based on the proposal that the Skyrme theory is a theory of monopole we provide a new interpretation of Skyrme theory, that the theory can also be viewed as an effective theory of strong interaction which is dual to QCD, where the monopoles (not the quarks) are confined through the Meissner effect. This dual picture leads us to predict the existence of a topological glueball in QCD, a chromoelectric knot which is dual to the chromomagnetic knot in Skyrme theory, whose mass and decay width are estimated to be around 60 GeV and 8 GeV. As importantly, the existence of the magnetic vortex and knot in Skyrme theory strongly indicates that the theory could also be interpreted to describe a very interesting low energy condensed matter physics in a completely different environment. These new interpretations of Skyrme theory puts the theory in a totally new perspective.
CRÈME: AN AUTOMATIC INVARIANT PROVER OF BEHAVIORAL SPECIFICATIONS
Authors: NAKANO MASAHIRO , OGATA KAZUHIRO , NAKAMURA MASAKI , FUTATSUGI KOKICHI
Published: February 2008

We describe a method of automating invariant verification of behavioral specifications, which are algebraic specifications of abstract machines. The proposed method is based on fixed-point computation, which is one of the standard techniques for automatic (invariant) verification. The proposed method has some notable features. Among them are as follow:

(1) the method finds and uses as lemmas state predicates whose invariant proofs may (even mutually) depend on other state predicates whose invariant proofs may not be completed, and

(2) the method finds a counterexample showing that an abstract machine does not satisfy an invariant property if any, which does not need to make the (reachable) state space of the abstract machine finite.

Crème is a tool based on the proposed method. We also report on two case studies in which

(1) Crème proves fully automatically that the NSLPK authentication protocol satisfies the secrecy property and

(2) Crème finds a counterexample showing that the NSPK authentication protocol does not satisfy the secrecy property.
A STATISTICAL METHODOLOGY TO SIMPLIFY SOFTWARE METRIC MODELS CONSTRUCTED USING INCOMPLETE DATA SAMPLES
Authors: CHAN VICTOR K. Y. , WONG W. ERIC , XIE T. F.
Published: February 2008

Software metric models predict the target software metric(s), e.g., the development work effort or defect rates, for any future software project based on the project's predictor software metric(s), e.g., the project team size. Obviously, the construction of such a software metric model makes use of a data sample of such metrics from analogous past projects. However, incomplete data often appear in such data samples. Moreover, the decision on whether a particular predictor metric should be included is most likely based on an intuitive or experience-based assumption that the predictor metric has an impact on the target metric with a statistical significance. However, this assumption is usually not verifiable "retrospectively" after the model is constructed, leading to redundant predictor metric(s) and/or unnecessary predictor metric complexity. To solve all these problems, we derived a methodology consisting of the k-nearest neighbors (k-NN) imputation method, statistical hypothesis testing, and a "goodness-of-fit" criterion. This methodology was tested on software effort metric models and software quality metric models, the latter usually suffers from far more serious incomplete data. This paper documents this methodology and the tests on these two types of software metric models.
A SURVEY OF EXISTING REQUIREMENTS ENGINEERING TECHNOLOGIES AND THEIR COVERAGE
Authors: PARVIAINEN PÄIVI , TIHINEN MAARIT
Published: February 2008

Requirements engineering is a process in which a most diverse set of product demands from a most diverse set of stakeholders has to be considered. Thus, requirements engineering is generally thought of as the most critical and complex process within the development of embedded systems. Over the years, a lot of requirements engineering research has been carried out and reported, but still it seems clear that the industry is struggling with requirements engineering. Why is that, and what should be done to support the industry in tackling its problems? Develop a new method, tailor the existing ones, or better inform the industry of what is available that could help them in their problems? To find some answers, we carried out an inventory of the available requirements engineering technologies, while also looking into their support for requirements engineering. This paper describes the survey and reports our findings indicating that what is most urgently needed is information and evidence of the applicability of the available technologies in different situations, though further development of the technologies is also required.
SCALING LIMITS OF THE CHERN–SIMONS–HIGGS ENERGY
Authors: KURZKE MATTHIAS , SPIRN DANIEL
Published: February 2008

We continue our study in [16] of the Gamma limit of the Abelian Chern–Simons–Higgs energy [Formula: see text] on a bounded, simply connected, two-dimensional domain where ε → 0 and με → μ ∈ [0, +∞]. Under the critical scaling, Gcsh ≈ | log ε2, we establish the Gamma limit when μ ∈ (0,+∞], and as a consequence, we are able to compute the first critical field H1 = H1(U,μ) for the nucleation of a vortex. Finally, we show failure of Gamma convergence when μμ → 0 (this includes the self-dual case). The method entails estimating in certain weak topologies the Jacobian J(uε) = det (∇ uε) in terms of the Chern–Simons–Higgs energy Ecsh.
COMPACTNESS OF A NONLINEAR EIGENVALUE PROBLEM WITH A SINGULAR NONLINEARITY
Authors: ESPOSITO PIERPAOLO
Published: February 2008

We study the Dirichlet boundary value problem [Formula: see text] on a bounded domain Ω ⊂ ℝN. For 2 ≤ N ≤ 7, we characterize compactness for solutions sequence in terms of spectral informations. As a by-product, we give an uniqueness result for λ close to 0 and λ* in the class of all solutions with finite Morse index, λ* being the extremal value associated to the nonlinear eigenvalue problem.