bluuebunny/crossref_metadata_2025 huggingface dataset:
The effects of high intensity pure tone on visual field, eye fixation, pupil size, and visual false positive and negative errors
Authors: Aazh Hashir , Nouraeinejad Ali , Peyvandi Ali Asghar , Gachkar Latif
Published: October 2013

Our aim in this study is to evaluate the effects of pure tone on visual field, pupil size, eye fixation, and visual false positive and negative errors. Thirty-two young adult subjects with normal hearing and normal visual acuity were tested in this study. Measurements were performed over two test sessions. In one session visual factors were measured in quiet, and another measurement was performed during presenting a pure tone (1000 Hz, 100-dB HL) binaurally via a headphone. The statistical program SPSS10 was used for all analyses. Fixation loss was significantly lower (better) in quiet condition compared with continuous pure tone condition, and other visual factors had no significant differences in the two conditions. As a conclusion it can be stated that changes in attentional focus which result from altered levels of arousal or autonomic system activity during presenting a high intensity pure tone affect on fixation of the eye. However, it is suggested that these effects are possibly related to stress caused by sound masking the hearing of speech and other wanted environmental sounds, and not from some direct autonomic system arousal by sound.
Development of the positional presumption system of sound source which combines sound source information and picture image
Authors: Yasuhiro Yamashita
Published: October 2013

The development of the positional presumption system of sound sources which combines sound information and picture images has been done by using five microphones. The calculation of the positional presumption of the sound source is obtained by calculating the time difference from the cross spectrum of the output of several microphones. There was a tendency that the direction presumption varies by enlarging the elevation of the position of the sound source and the receiving sound point. It is thought that this cause is influenced by the ground level reflection. We tried to separate the reflected sound and the removed method was shown. In addition, the methods of improving the calculation accuracy in consideration of the acoustic impedance of the ground surface were shown, and compared.
A comparison of middle ear acoustic admittance in adults and 3-week-old infants based on multifrequency tympanometry
Authors: Polka Linda , Shahnaz Navid , Zeitouni Anthony
Published: October 2013

The assessment of newborn hearing requires information on middle ear status yet the interpretation of tympanometry in newborns is unclear. This study aims to further our understanding of acoustic admittance in the newborn middle ear. Multifrequency tympanograms were recorded from sixteen 3-week-old infants (30 ears) and sixteen young normal-hearing adults (30 ears). Tympanometry was conducted using the Virtual 310 middle ear analyzer using 9 probe tone frequencies between 226 and 1000 Hz at roughly 100 Hz intervals. All infants passed a hearing screening using automated ABR (Algo II) shortly after birth (within 24 h) and again at 3-weeks of age. At 226 Hz, admittance tympanograms had a single peak in all adult ears while 60% of infant ears had multiple peaks or irregular patterns. At 1000 Hz admittance tympanograms had a single peak for 74% of infant ears while 78% of adult ears showed multiple peak or irregular patterns. Analyses of tympanometric shape (using the Vanhuyse classification scheme), as well as static admittance, static susceptance, and static conductance also reveal differences in adult and infant middle ear function. Implications for the clinical application of tympanometry in the first month of life will be discussed.
Estimates of the strength of repetition pitch in infants
Authors: Clarkson Marsha G. , Zettler Cynthia M. , Follmer Michelle J. , Takagi Michael J.
Published: October 2013

To measure the strength of the pitch of iterated rippled noise (IRN), 24 7- to 8-month-olds and 24 adults were tested in an operant conditioning procedure. To generate IRN, a 500-ms Gaussian noise was delayed by 5 or 6 ms (pitches of 200 and 166 Hz) and added to the original noise for 16 iterations. IRN stimuli having one delay were presented repeatedly, and on signal trials the delay changed for 6 s. Overall stimulus level roved from 63–67 dBA. Infants learned to turn their heads toward the sound, and adults learned to press a button when the delay of the stimulus changed. Testing started with IRN stimuli having 0 dB attenuation (i.e., maximal pitch strength). Then, stimuli having weaker pitches (i.e., progressively greater attenuation applied to the delayed noise) were presented. Strength of pitch can be quantified as the maximum attenuation for which pitch can be discerned. For each subject, threshold attenuation for pitch strength was extrapolated as the 71% point on a psychometric function depicting percent-correct performance as a function of attenuation. Mean thresholds revealed that the pitch percept was significantly weaker for infants (6.9 dB) than for adults (19.1 dB).
Listening strategies used by normal-hearing adults during loudness estimation
Authors: Leibold Lori J. , Werner Lynne A.
Published: October 2013

This study describes individual differences in the weight normal-hearing adults give to the frequency components of a complex sound when performing loudness estimation. In addition, the relationship between listening strategy and loudness was examined. A multi-tone complex (1000, 2000, and 4000 Hz) was presented for 500 ms to the left ear of seven normal-hearing adults. The level of each tone was selected independently and randomly from a rectangular distribution ranging in 10 dB steps from 40 to 80 dB SPL on each of 500 presentations. In the nonselective condition, subjects provided a numerical estimate of the loudness of the complex. In selective conditions, listening strategy was controlled by instructing subjects to attend to a single target frequency. Relative weights for each subject were estimated by normalizing the raw correlations calculated from the level of each component and the subjects magnitude estimate for each trial. Results for the nonselective condition revealed individual differences in subjects’ weighting functions. In contrast, similar weighting functions were observed in the selective conditions, with subjects giving the greatest weight to the target frequency. The loudness growth data can best be described by weighting the intensity of each frequency component prior to determining the loudness growth.
Distinguishing feature misperception from illusory conjunctions in spatially distributed musical tones
Authors: Hall Michael D. , Wieberg Kimberly
Published: October 2013

Recent questions have been raised in the visual search literature concerning whether illusory conjunctions of correctly registered features occur (indicating a feature integration process) or are an artifact of feature misperception. The current investigation raised and addressed similar questions for findings of auditory illusory conjunctions using simultaneous, spatially distributed musical tones. Two experiments were conducted where musically trained listeners identified pairs of tones that reflected possible combinations of two instrument timbres with two pitches. Experiments differed in the spatial separation between simultaneous tones to potentially evaluate the effects of distance on feature perception/integration. In Experiment 1 tones were presented to opposing ears. In Experiment 2 tones were only slightly lateralized by a manipulation of interaural time disparities. Conjunction responses, reflecting the incorrect combination of features, frequently occurred, and were more common for slightly lateralized tones. To evaluate the perceptual event(s) responsible for conjunction responses, data were submitted to multinomial models that differed with respect to whether or not they allowed for illusory conjunctions, the misperception of features, or both errors. Across experiments, data fitting by models was improved by feature misperception, but was not further improved by illusory conjunctions. Implications for models of search performance and feature binding are discussed.
Dichotic pitch and the missing fundamental
Authors: Hall Joseph , Buss Emily , Grose John
Published: October 2013

A dichotic pitch can be heard by introducing interaural phase shifts in one or more low-frequency spectral regions of an otherwise diotic noise. The present study examined the perceived pitch associated with phase disparities in spectral regions corresponding to harmonics of a low-frequency fundamental. Of particular interest was whether the pitch of the complex was related to the frequency region of the harmonics or whether it was associated with the missing fundamental. Discrimination thresholds for this dichotic virtual pitch were estimated in a 3AFC paradigm, where listeners were asked to identify the interval with the lower virtual pitch. After modest training, listeners were able to perform this task well even when a randomized subset of harmonics above F0 were presented on each trial, a manipulation designed to make spectral region an unreliable cue. In another manipulation, frequency regions of the phase disparity were chosen such that although the frequency increased, the missing fundamental decreased (or vice versa). In these cases listeners reported that the perceived pitch shifted according to the change in F0, not according to the spectral region of the harmonics. Results were consistent with the interpretation that the perceived pitch correspond to the missing fundamental.
Estimation of vibrations due to walking on floors that support sensitive equipment
Authors: Ungar Eric E. , Zapfe Jeffrey A.
Published: October 2013

The development of the extensively used simple method for predicting footfall-induced vibrations of floors of buildings (American Institute of Steel Construction Design Guide 11) is reviewed. The empirical basis and underlying analytical assumptions of the method are delineated and critiqued. Its limitations are discussed and suggestions for its extension are presented. Results of some recent related measurements are summarized.
New pitch detection system for concurrent speech on a parallel processing system
Authors: Chisaki Yoshifumi , Nakagawa Akira , Nakashima Hidetoshi , Usagawa Tsuyoshi , Ebata Masanao
Published: October 2013

Pitch detection system based on the harmonic wavelet transform (HWT) algorithm for concurrent speech [Y. Chisaki, 6C.15, Proc. ICA2001] has been proposed. The HWT algorithm has two major advantages. One is to detect a pitch from a frame signal, which is a short duration, such as 20 ms. The other one is robustness against noise; namely, all pitches can be detected from concurrent speech in a short delay, simultaneously. However, processing time for the modified correlation method, as a conventional method is 8.6 times faster than that for the HWT based system. Due to the development of computers, processing time can be reduced easily by using PCs. This paper proposes a new pitch detection system for concurrent speech with a new parallel algorithm. The system is based on the HWT method, and implemented on a parallel processing system. Simulations are performed with some node arrangements. As a result, a processing speed for a parallelized block of the system is 6.3 times faster as that for the original one without being accompanied by degradation of pitch detection accuracy. [Part of this work is supported by The Sagawa Foundation for Promotion of Frontier Science, the Cooperative Research Project Program of the RIEC, Tohoku Univ., and the Ono Acoustics Research Fund (2001).]
Human factor cepstral coefficients
Authors: Skowronski Mark D. , Harris John G.
Published: October 2013

Automatic speech recognition (ASR) is an emerging field with the goal of creating a more natural man/machine interface. The single largest obstacle to widespread use of ASR technology is robustness to noise. Since human speech recognition greatly outperforms current ASR systems in noisy environments, ASR systems seek to improve noise robustness by drawing on biological inspiration. Most ASR front ends employ mel frequency cepstral coefficients (mfcc) which is a filter bank-based algorithm whose filters are spaced on a linear-log frequency scale. Although center frequency is based on a perceptually motivated frequency scale, filter bandwidth is set by filter spacing and not through biological motivation. The coupling of filter bandwidth to other filter bank parameters (frequency range, number of filters) has led to variations of the original algorithm with different filter bandwidths. In this work, a novel extension to mfcc is introduced which decouples filter bandwidth from the rest of the filter bank parameters by employing the relationship between filter center frequency and critical bandwidth of the human auditory system. The new algorithm, called human factor cepstral coefficients (hfcc), is shown to outperform the original mfcc and two popular variations in several ASR experiments and noise sources.
Vowel landmark detection
Authors: Howitt Andrew W.
Published: October 2013

Landmark based speech processing is a component of Lexical Access From Features (LAFF), a novel paradigm for feature based speech recognition. Detection and classification of landmarks is a crucial first step in a LAFF system. Vowel landmarks are detected using an existing syllabic segmentation algorithm with several novel extensions that incorporate durational information, absolute energy level, and F1 track information. The detector is scored against the TIMIT database, using a novel algorithm to convert the segmental transcriptions to a landmark representation for scoring. Previous experiments have validated the predictions of acoustic theory, specifically the presence of F1 peak in vowels, and demonstrated that amplitude peak in a fixed frequency band is practically as good as a formant tracker. Substantial improvements in performance are achieved by optimizing the fixed frequency band to the F1 range, and use of a trainable neural network to combine the multiple acoustic cues. The neural network can also be used to generate confidence scores for detected landmarks, which provide vital information for later stages of processing.
Evidence for single-mode propagation and its implications for range-dependent geoacoustic inversion in the SWAT experiment
Authors: Frisk George V. , Becker Kyle M.
Published: October 2013

During the Shallow Water Acoustic Technology (SWAT) experiments, which were conducted in October 2000 on the New Jersey Shelf, a 20 Hz pure tone was transmitted from a source in 73 m of water to two drifting receivers. The behavior of the pressure magnitude and phase out to ranges of about 8 km suggest that the field is dominated by a single normal mode. In particular, an adiabatic modal interpretation of the phase variation with range is consistent with an independent autoregressive spectral estimate of the wave number content of the field. It is then shown, within the context of an isovelocity bottom model with varying water depth, that the measured range-varying bathymetry does not account for the range dependence in the single modal eigenvalue. On the other hand, an alternative interpretation of the data in terms of a wave guide with constant depth and range-varying sound speed in the bottom yields reasonable estimates of the lateral seabed variability. [Work supported by ONR.]
Effects of measured bathymetry and subbottom variability on low-frequency shallow-water reverberation
Authors: Turgut Altan , Gauss Roger
Published: October 2013

A pseudo-spectral numerical method is used to study the effects of bathymetry and subbottom variability on shallow-water reverberation at low frequencies (less than 500 Hz). Bathymetry and subbottom variability at New Jersey Shelf Geoclutter and Boundary Characterization 2001 experimental sites were measured by using chirp sonar and sediment core data at different wavelength scales. A stochastic bottom simulator was incorporated with the measured deterministic bottom/subbottom features, including dipping layers, erosional channels, and buried river channels. Three-dimensional simulations were also performed to study the effects of anisotropic bottom/subbottom variability on the shallow-water reverberation. It has been shown that, for the Geoclutter and Boundary Characterization 2001 experimental sites, predicted anisotropy in the acoustic scattering field is mainly due to the deterministic features rather than due to anistropic small-scale variabilities in the sediment. [Work supported by ONR.]
Analysis of the effects of sea floor and sub-sea floor geology on underwater sound propagation estimation and performance prediction
Authors: Katz Richard , Sundvik Michael
Published: October 2013

In this study, we investigate shallow water sound propagation measurements and interactions with the seabed as a function of geologic composition and waveform characterization. We have analyzed sound transmission loss measurements in the shallow acoustic channel from the geoclutter experiments conducted in 2001 and 2002 and found them to be in good agreement with standard modeling results. The sound propagation through the acoustic channel and interactions with the boundaries lead to energy spreading losses, which make acoustic performance prediction and modeling uncertain. We quantify these losses to the extent possible based on the signals transmitted during the experiments. The contributions to and effects on sound propagation variability from sound speed profile (degree of downward refraction) are discussed with emphasis placed on interactions with the bottom and sub-bottom geology. Analysis is conducted for signals in the 400 Hz to 4 kHz range.
Geoacoustic measurements on the New Jersey shelf
Authors: Holland Charles
Published: October 2013

Two key acoustic parameters for predicting shallow water reverberation are bottom reflection and bottom scattering strength. Historically, seabed reflection and scattering have been treated in a disconnected fashion both in measurement and analysis. A coupled approach to reflection and scattering was conducted during the GeoClutter and Boundary2001 Experiments. By coupled, it is meant that the reflection and scattering measurements are not only colocated, but sample commensurate spatial scales of the seabed. It is also meant that the processing and analyses employ commensurate assumptions and modeling. The coupled nature of the measurements provides the opportunity for determining the physical mechanisms responsible for the reflection and scattering. Deterministic and stochastic geoacoustic properties obtained from an analysis of these mechanisms show very high spatial variability across the measurement area. [Work supported by the NATO SACLANT Undersea Research Center and ONR.]
Statistical characterization of geologic clutter observed on the STRATAFORM
Authors: Preston John R. , Abraham Douglas A.
Published: October 2013

Together with SACLANTCEN, the authors recently participated in the 2001 Geoclutter Experiment to study shallow water bottom reverberation in the STRATAFORM off New Jersey. Sources were bistatic and monostatic coherent pulses near 400 Hz. The receivers were horizontal arrays. The STRATAFORM is known to have benign surface morphology but contains many buried river channels and other subsurface horizons. Some highlights of the reverberant returns are discussed that include the correlation of returns with the buried river channels and some other subbottom features. The main objective of this study is the statistical characterization of the geologic clutter. The K distribution has been shown to be useful in describing non-Rayleigh behavior. The clutter from STRATAFORM is described by its K-distribution parameters as a function of location and sediment type. [Work supported by ONR Code 32, Grant N00014-97-1-1034.]
Seafloor characterization from inversion of high-frequency backscatter
Authors: Bentrem Frank W. , Sample John , Avera Will
Published: October 2013

Geoacoustic inversion of high-frequency backscatter data is presented for characterization of the seafloor. The APL-UW (Applied Physics Laboratory at the University of Washington) backscattering model is used to model the grazing-angle dependence of the backscattering strength for a number of seafloor parameters. Backscattering strength versus grazing angle data sets (with frequencies 12–35 kHz) are provided for three sites along with sediment ground truth. Roughness measurements are also available for two of the sites. Inversion of these data sets is performed via simulated annealing, with some of the parameters constrained by empirical relationships with mean grain size. From the inversion, estimates are obtained for mean grain size, roughness, and volume interation. Inversion of data from a smooth, silty site in Arafura Sea yields estimates in good agreement with ground truth. Results also compare well with ground truth in a rough, sandy site (Quinault) and in Onslow Bay (sand). [Work supported by SPAWAR.]
Quetzal or not Quetzal, that is the question... . On the stairs of the Castillo monument in Chichen Itza
Authors: Elizondo-Garza Fernando J.
Published: October 2013

Some speculation will be presented about the hypothesis that states that the reflected sounds in the stairs of the Castillo building in Chichen Itza, Mexico, imitates the song of the quetzal bird. Some aspects of construction, both technical and social, are discussed as well as issues related with myth and fantasies.
Theoretical interpretation of a case study: Acoustic resonance in an archaeological site
Authors: Carrera Jorge , Beristain Sergio
Published: October 2013

It is well-known that the stairways of some Mexican archaeological sites, like Chichen-Itza or Teotihuacan, present an interesting sound reflection and resonance phenomenon which causes a special audible effect. In this paper, mathematical modeling of this situation is presented, and the practical phenomenon is discussed from a theoretical standpoint. More than an end in itself, the idea is, once this validated model is obtained, to use the results for the analysis of a more extensive architectural environment in order to establish whether this kind of phenomenon would have been purposely introduced in the design of the site. This will be presented in future publications.
Noise changes receptive fields of auditory neurons in A1
Authors: Blake David T. , Merzenich Michael M.
Published: October 2013

Primates engage in auditory behaviors under a broad range of signal to noise conditions. In this study, optimal linear receptive fields were measured in alert primate A1 in response to stimuli that vary in spectrotemporal density. As the random tone pip density increased, selective A1 excitatory receptive fields systematically changed. Receptive field sensitivity, expressed as the expected change in firing rate after a tone pip onset, decreased by an order of magnitude. Spectral selectivity more than doubled. Inhibitory subfields, which were rarely recorded at low sound densities, emerged at higher sound densities. The ratio of excitatory to inhibitory population strength changed from 14.4:1 to 1.4:1. At low sound densities, the sound associated with the evocation of an action potential from an A1 neuron was broad in spectrum and time. At high sound densities, a spike-evoking sound was more likely to be a spectral or temporal edge, and was narrower in both time and frequency range. Prediction experiments were performed to validate the assumption that linear receptive fields were representative of neural responses at high noise densities. The auditory context alters A1 responses across multiple parameter spaces; this presents a challenge for reconstructing neural codes.
FM signals produce a robust paradoxical latency shift that is important for coding of target range in the bat inferior colliculus
Authors: Feng Albert S. , Galazyuk Alexander
Published: October 2013

Echolocating bats utilize the time delay between an outgoing ultrasonic pulse and its echo to determine target range. Many neurons at the inferior colliculus (IC) and above are tuned to time delays between these sound pulses of unequal amplitudes. Sullivan previously proposed that paradoxical latency shift (PLS), characterized by a quantal increase in firing latency to loud sounds, is important for this attribute because PLS permits coincidence detection that is important for the creation of delay-tuned responses. In the IC of little brown bats, Galazyuk and Feng recently reported that, in response to tone pulses, the proportion of neurons showing PLS was low (<20%). This study was undertaken to determine whether PLS is a function of the acoustic stimulus. For this, the temporal discharge patterns of single IC neurons were investigated over a broad range of sound levels, using tone pulses at CF as well as FM sound pulses that mimicked bats’ ultrasonic cry as stimuli. For many IC neurons, tone pulses did not elicit PLS but FM sound pulses produced robust PLS. This result showed that PLS is stimulus dependent and that the bat’s auditory system is optimal for processing FM sounds employed during echolocation. [Work supported by NIH R01DC04998.]
Genesis of a space map in the owl’s brain
Authors: Pena Jose L.
Published: October 2013

In order to localize a sound source, the brain uses monaural and binaural cues that convey spatial information. In the owl, space-specific neurons of the inferior colliculus respond only to sounds coming from a particular direction and represent the results of this computation. The parallel pathways that process interaural time difference (ITD) and interaural level difference (ILD) merge in the external nucleus of the inferior colliculus where the space-specific neurons are selective to combinations of ITD and ILD. How is the combination selectivity to ITD–ILD pairs achieved? A multiplication of postsynaptic potentials tuned to ITD and ILD can account for the response of these neurons to ITD–ILD pairs. There are very few examples of multiplication by neurons or neural circuits; however, some computational models assume the existence of this basic arithmetic in sound localization. The owl’s auditory system uses such operation in creating a two-dimensional map of auditory space.
A new fragmentation mechanism in extracorporeal shock wave lithotripsy and a first clinical study in China
Authors: Eisenmenger Wolfgang
Published: October 2013

With ESWL-focus diameters of the order of the stone dimension or larger, fragmentation in planes perpendicular and parallel to the wave plane is observed. This is explained by circumferential pressure or ‘‘squeezing’’ of the stone by the wave propagating at the outside of the stone in the liquid or tissue. Since the pressure zone propagates with the sound velocity in the liquid which is below the propagation velocity in the stone, it causes an evanescent pressure zone in the stone resulting in tensile stress in planes perpendicular and parallel to the wave plane. A quantitative model predicting the ratio of pulses needed to fragment the stone to 2-mm particle size in relation to the number of pressure pulses needed for the first fragmentation is well in accord with experiments, supporting the ‘‘squeezing mechanism with binary fragmentation.’’ On the basis of these results it now appears possible to optimize the pressure pulse parameters measured using the fiber-optic probe hydrophone (FOPH). With correspondingly optimized shock wave generator systems, a clinical study of the concept ‘‘wide focus and low pressure’’ ESWL was performed in scientific cooperation between the Physical Institute of the University of Stuttgart and the Xixin Medical Instruments Co., Ltd. in Suzhou, China. [W. Eisenmenger, ‘‘The mechanism of stone fragmentation in ESWL,’’ Ultrasound Med. Biol. 27, 683–693 (2001); Eisenmenger, Du, Tang et al., ‘‘The first clinical results of wide focus and low pressure ESWL,’’ ibid. 8, 769–774 (2002) (in press).]
Comparison of the cavitation fields of an electromagnetic and electrohydraulic lithotripter
Authors: Chitnis Parag , Cleveland Robin
Published: October 2013

We contrast the cavitation of two lithotripters of different shock wave (SW) generation: electrohydraulic (EHL) and electromagnetic (EML). The cavitation field induced by the SWs was measured using a dual passive cavitation detector consisting of two 1 MHz focused transducers. The characteristic time (tc) was obtained from the time difference of the arrival of the SW and the inertial collapse of the cavitating bubble. The tc increased significantly with energy level for both lithotripters. At the highest energy level, tc=332 μs±65 μs for the EML and tc=277 μs±43 μs for the EHL. Increasing the pulse rate frequency from 1 Hz to 2 Hz led to a significant increase in tc for the EHL but no significant change for the EML. The region of strong cavitation activity corresponded with the focal region of the lithotripters. Based on a 6 dB decrease in the amplitude of the inertial collapse signal, the region of strong cavitation was 7 mm wide for the EHL and 2 mm wide for the EML. Measurements of the acoustic pressure indicate that the −6 dB width of the focal spots were 12 mm and 4 mm, respectively. [Work supported by the NIH P01-DK43881.]
Measuring acoustic impedances using a semi-infinite waveguide reference: Applications to wind instruments and vocal tracts
Authors: Wolfe Joe , Smith John , Tann John , France Ryan
Published: October 2013

Acoustic pressures may generally be measured with much greater sensitivity, dynamic range, and frequency response than acoustic currents. Consequently, most measurements of acoustic impedance consist of comparison with standard impedances. The method reported here uses a semi-infinite waveguide as the reference because its impedance is purely resistive, frequency independent and accurately known, independent of theories of the boundary layer. Waveguides are effectively infinite for pulses shorter than the echo return time, or if the attenuation due to wall losses (typically 80 dB) exceeds the dynamic range of the experiment. The measurement signal from a high output impedance source is calibrated to have Fourier components proportional to fn, where n may be 1 for convenience or chosen to improve the signal:noise ratio. The method has been used on diverse systems over the range 50 Hz to 13 kHz. When applied to systems with simple geometries, the technique yields results with a little higher wall losses than those expected from the calculations of Rayleigh and Benade. Discontinuities introduce further losses as well as the expected departures from simple one-dimensional models. Measurements on musical wind instruments and on the human vocal tract are reported. [Work supported by the Australian Research Council.]
Diffusion of ultrasonic waves in porous glass bead sinters
Authors: Page John H. , Beck James , Holmes Russel , Bobowski Jake
Published: October 2013

Sintered networks of glass beads form an interesting example of a porous medium, analogous to a very porous rock, in which very strong multiple scattering of elastic waves is observed when the ultrasonic wavelength is comparable with the size of the pores. To investigate the diffusive transport of energy by multiply scattered waves, the transmission of the diffuse energy flux through finite slabs of this material has been measured. From these data, the diffusion coefficient D, as well as the absorption time, was determined by fitting the predictions of the diffusion approximation to the experimental time-of-flight profiles. To accurately measure D, the internal reflection of diffuse waves at the sample boundaries was taken into account by extending the method used previously for acoustic waves [J. H. Page et al., Phys. Rev. E 52, 3106 (1995)]. The frequency dependence of the diffusion coefficient was measured over an extended range of frequencies, and compared with estimates of D from ballistic measurements of the scattering mean free path and group velocity. Because of its relatively simple structure, this material may be an ideal system for probing the diffusion of elastic waves, where diffuse waves have mixed character consisting of both longitudinal and transverse polarizations.
Competition between two different resonance acoustic modes in a thermoacoustic prime mover
Authors: Canul-Vargas W. R. , Vera-Manrique I. , Miranda R. , Nahmad-Molinari Y. , Ruiz-Suárez J. C. , Huelsz G.
Published: October 2013

When a stack of plates is placed near the closed end of an open tube, and a temperature gradient is applied to the stack (the hotter part next to the sealed tube end), a sound wave is produced. The greater the temperature gradient beyond a critical value, the stronger the sound wave produced. Inversely, to switch off the sound wave one has to decrease the temperature gradient applied to the stack. In the present work we report a new method to turn off and on this thermoacoustic prime mover almost instantaneously, without modifying the temperature gradient. A second resonator of different length and much smaller cross section (a tube with both ends open) is introduced into the first tube until contact with the stack is made. When this new resonator is left in place there is no change in the sound wave, but as soon as the end of the small tube outside the main resonator is closed, the sound wave disappears completely. Under this condition,the system goes rapidly from an acoustic thermodynamic cycle in which heat is transported by the wave, to a simple heat diffusion through the stack. We study the physics of this intriguing phenomenon.
Analysis and minimization of power flow in a mechanical vibration isolation system using a hybrid (active/passive) approach
Authors: Herdic Peter C. , Houston Brian H. , Corsaro Robert D. , Judge John A.
Published: October 2013

Implementation of active control techniques in mechanical vibration isolation systems has been a challenging problem for a number of years where numerous physical control laws have been explored. An energy-based approach to the problem involving the energy transfer or power flow through the mount into the base structure is a first-principles approach to developing control laws and evaluating the system performance. A lumped-parameter model of a passive–active hybrid isolation mount has been developed and validated with experimental data. The mount device has a conventional passive compliant spring, embedded force and velocity sensors, and a piezoceramic actuation layer. This study investigates a complete set of possible layer configurations, that is, the optimal placement of sensors and actuator relative to the passive compliant isolator element. A number of different local physical control laws are examined and the level of power flow through the mount is used to evaluate the performance for the matrix of possible implementations. These results will be discussed with particular emphasis placed on the optimal control configuration and laws, and the related physics. a)Also with SFA, Inc., Largo, MD 20774.
Combining statistical energy analysis and finite element analysis in RESOUND mid frequency vibroacoustic analysis
Authors: Gardner Bryce K. , Shorter Philip J. , Bremner Paul G.
Published: October 2013

At low frequencies, vibroacoustic systems exhibit a dynamic response characterized by spatially correlated motion with low modal density. These systems are typically modeled with deterministic methods. While at high frequencies, the dynamic response is characterized by weak spatial correlation and a large number of modes with high modal overlap. These systems are typically modeled with statistical methods. However many vibroacoustic systems have some regions with high modal density and some regions with low modal density. Such systems require a midfrequency solution technique. One such method has been developed based on a hybrid approach combining finite element analysis (FE) in the low modal density regions and statistical energy analysis (SEA) in the high modal density regions. This method is called RESOUND [Langley and Bremner, J. Acoust. Soc. Am. 105, 1657–1671 (1999)]. Recent developments of RESOUND have focused on predicting the appropriate dynamic interactions and mechanisms for energy flow between the FE and the SEA regions. By including these effects, RESOUND can predict the dynamic response of systems having regions with low modal densities and regions with high modal densities. This paper will provide an overview of recent developments.
Technical considerations in the design of a wearable voice dosimeter
Authors: Popolo Peter S. , Rogge-Miller Karen , Svec Jan G. , Titze Ingo R.
Published: October 2013

This paper deals with the technical issues involved in the design of a voice dosimeter, a wearable device to be used by teachers to measure vocal dose on the job, at home and elsewhere during the total waking hours of each day. The concept of vocal dose is introduced and definitions of various dose measures are presented. Practical issues of the design are discussed, including software development, selection of an external transducer, and devising a comfortable, reliable and repeatable means of attaching the transducer to the subject. The dosimeter software was designed to calculate SPL (sound pressure level), F0 (fundamental frequency) and voicing time. In addition, an interactive portion was developed that prompts the user to verify the validity of the stored data every two hours, and to perform a rating of vocal effort and quality of soft phonation. The SAL (surface acceleration level) to SPL relation for the prototype dosimeter was determined. The prototype has been field-tested, and SPL, F0, and voicing time data have been analyzed. A sensitivity analysis shows that small errors in SPL have a large effect on the accuracy of dose calculations, while F0 errors have less of an effect.
Invariance of lognormal distribution parameters in speech segment durations
Authors: Rosen Kristin , Kent Raymond
Published: October 2013

This study re-examines speech segment duration using lognormal distributions and presents a basis for the unification of many previous measurements in connected speech. Distributions of speech segment length in previous studies (Pols, Wang, and ten Bosch, 1996; Crystal and House, 1982, 1988; Duez–Goldman–Eislinger, 1968) were replotted onto lognormal cumulative plots. Speech segments were consistently symmetric on the logarithmic scale and well characterized by the lognormal distribution, with the exception of fricatives. Analysis with respect to the logarithmic scale reveals surprising consistencies within categories. Specifically, geometric standard deviation appears to be essentially preserved across phonemic categories. The nature of the distributions themselves suggests possible clues to the understanding or modeling of the underlying timing mechanisms, and provides a foundation for meaningful comparisons in connected speech. Possible advantages of logarithmic-based measures (i.e., geometric mean, geometric standard deviation) over linear measures (e.g., coefficient of variability) are presented.
Model-based acoustic characterization and classification of irregular-shaped targets: Application to fisheries and zooplankton acoustics
Authors: Chu Dezhang , Stanton Timothy K. , Wiebe Peter H.
Published: October 2013

Acoustic scattering by fish and zooplankton is a complicated function of the geometrical and physical properties of the targets, as well as the environmental and sonar system parameters. The shape and anatomy of zooplankton vary significantly from taxa to taxa and their dominant scattering mechanisms can be completely different. As a result, the acoustic classification of such targets is extremely difficult and often nonunique. To reduce the ambiguity and nonuniqueness, a number of model-based methods are presented. These methods use the temporal, spatial, spectral, and statistical signatures of acoustical scattering signals and can be applied to a variety of acoustic systems, including narrow-band, broadband, and multifrequency systems. The methods also depend strongly on whether or not the targets are resolved. Individual targets with different shapes and material properties have their unique characteristics and can be classified acoustically in terms of their size, orientation, scattering mechanisms, as well as their material properties. Results of applying these methods to the laboratory and field data will be presented and analyzed. [Work supported by ONR, NSF, and the Comer Science and Education Foundation.]
Coupled electrokinetic-Biot theory and measurement techniques in sediment acoustics
Authors: Block Gareth , Chotiros Nicholas
Published: October 2013

Biot theory will no doubt play an important role in modeling wave propagation in ocean sediments. One prediction of Biot theory is the existence of the Biot slow wave, described by out-of-phase motion of the pore fluid and porous grain structure. Unfortunately, slow wave motion has been extremely difficult to verify using acoustical transducers. Electrokinetic (EK) transduction techniques shed new light on this effort. EK parameters, such as the surface chemistry of the grains and pore fluid salinity, are coupled to Biot theory at the microscopic level, and therefore provide another method of determining the microstructural properties of sediments. One application of this is the electrokinetic transmission of acoustic pressure waves. This occurs when an applied voltage drives ionic (and thus fluidic) currents in electrolyte-saturated porous media. Experimental and theoretical results for electrokinetic motion in sediments will be reported. [Work supported by ONR, Ocean Acoustics.]
Environmental influences on the frequency dependence of effective bottom attenuation
Authors: Nickila James D. , Smith Kevin B.
Published: October 2013

Over the past several years, concern has grown over the appropriateness of bottom attenuation models that assume a linear frequency dependence. Empirical analyses of experimental data have suggested power-law dependence with frequency exponents as high as 1.7 and above, but with large variability between geographic regions [Zhou et al., J. Acoust. Soc. Am. 82, 287–292 (1987)]. The fundamental cause of this dependence is unknown. In this analysis, the influence of the propagation and interaction with environmental variability is investigated. Specifically, a propagation model that assumes linear frequency dependence is employed which incorporates such environmental variability as range-dependent water column sound-speed profiles, bottom sound-speed gradients, bottom sound-speed and density fluctuations, and rough water/bottom interfaces. These data are then correlated with results from similar calculations without environmental variability but with attenuation as a free parameter used to maximize the correlation. By performing such comparisons over a band of frequencies, the effective frequency dependence of the bottom attenuation can be determined. The dominant environmental influences will then be identified and quantified.
Subjective evaluation of a concert hall’s acoustics using a free-format-type questionnaire and comparison with objective measurements
Authors: Okano Toshiyuki , Beranek Leo L.
Published: October 2013

A free-format type of audiences’ judgment of the acoustical properties of a hall and music critics’ writings were used as the basis for this study. These subjective responses are related to the Dai-Ichi Seimei Hall in Tokyo. This hall is an oval-shaped, one-balcony space, seating 767 persons. Its primary use is for various types of chamber music and solo-instrument performances. Eight acoustical attributes were investigated, ‘‘reverberation,’’ ‘‘clarity,’’ ‘‘loudness,’’ ‘‘intimacy,’’ ‘‘spaciousness,’’ ‘‘balance,’’ ‘‘localization,’’ and ‘‘timbre,’’ plus ‘‘general impression.’’ Subjective comments about these attributes were obtained. Objective measurements were made in the hall and are compared with those made in several similar-sized halls of two shapes. In the rear seats of two oval-shaped halls the strength factor GE (determined in the first 80 ms of the impulse response) was greater than the GE found in the rear seats of similar-sized rectangular halls. The subjective results and the objective measurements were closely correlated, especially for reverberation, clarity, and warmth (a subcomponent of timbre). It was suggested that the greater strength GE in the rear seats made the hall seem smaller and thus more intimate. The subjective comments also confirmed the hall’s wide applicability, indicating that the acoustical characteristics used for its design were well chosen.
Predicted and measured structural intensity in a plate excited by a diffuse acoustic field
Authors: Daley Michael , Hambric Stephen
Published: October 2013

Structural intensity (S-I) fields indicate energy source and sink regions in structures as well as energy flow paths through structures. Various S-I-based studies have been performed for structures excited at a point or group of points. Little attention, however, has been paid to S-I fields in structures under distributed random loads, such as those due to turbulent boundary layer pressure fields and diffuse acoustic fields. Such excitations occur in common engineering problems. This study presents experimental S-I results for a thin, simply supported, rectangular plate with an attached damper excited by a diffuse acoustic field. The plates velocity response to the excitation is measured using a scanning laser Doppler vibrometer. Finite differencing techniques are applied to the measured velocity field to yield S-I vectors. The experiments results are shown to be similar to predicted S-I fields. [Work supported by ARL Penn State.]
Cues for question intonation in Arabic: Disambiguation techniques for use in automatic speech recognizer systems
Authors: Barrett Leslie , Hata Kazue
Published: October 2013

The focus of this study is to determine the extent to which prosodic characteristics can contribute to the improvement of speech recognition in Arabic. F0 rising rate was chosen to disambiguate yes–no question from declarative sentences. In Arabic, as in English, a rising intonation indicates a yes–no question whether the question takes lexical question markers or uses an inverted word order or whether the sentence takes just a declarative form. We conducted a production study with 55 yes–no question sentences uttered by a female native speaker of Arabic. Two types of measurements were taken for F0 rise rate. First, we visually obtained the best-fit rise in sentence-final position. Second, we computed the rate based on minimum and maximum F0 values within the sentence-final 500 ms. The results show that although the rise obtained from the final 500 ms (0.41 Hz/ms) is different from the best-fit rise rate (0.49 Hz/ms) (p<0.05), when examining two different F0 rising shapes and considering JND for the rising rate (Nabelek and Hirsh, 1962), a threshold of 0.4 Hz/ms can be considered a threshold indicator of a yes–no question intonation for this speaker. Thus, a sufficient rise rate was extracted automatically from a fixed sentence-final duration.