bluuebunny/crossref_metadata_2025 huggingface dataset:
Active acoustics for music rehearsal rooms
Authors: Freiheit Ronald R.
Published: October 2013

The use of virtual acoustics has the ability to provide a new level of rehearsal experience for the musician. By integrating the signal processing of an active acoustic system (with time variant-gain before feedback) into a relatively small rehearsal room, musicians can now benefit from the experience of rehearsing in multiple acoustic environments including those of the actual performance venue in which they will perform. To effectively communicate the various acoustics environments, the musicians must be immersed in the sound field of the active acoustics without being able to discern source locations of the speakers. The system must also be cable of supporting the dynamic range of the musicians without presenting artifacts of its own such as system noise or audible distortion. An installation of such a system will be provided as a case study describing the challenges that were overcome for a successful implementation including areas such as adequate sound isolation, background noise levels and system security. The paper will also briefly discuss programming methodologies for the system. Anecdotal responses from musicians who have used the active acoustic rehearsal room and some unexpected issues will also be covered.
Optimally resolving Lambertian surface orientation
Authors: Bertsatos Ioannis , Makris Nicholas C.
Published: October 2013

Sonar images of remote surfaces are typically corrupted by signal-dependent noise known as speckle. Relative motion between source, surface, and receiver causes the received field to fluctuate over time with circular complex Gaussian random (CCGR) statistics. In many cases of practical importance, Lambert’s law is appropriate to model radiant intensity from the surface. In a previous paper, maximum likelihood estimators (MLE) for Lambertian surface orientation have been derived based on CCGR measurements [N. C. Makris, SACLANT Conference Proceedings Series CP-45, 1997, pp. 339–346]. A Lambertian surface needs to be observed from more than one illumination direction for its orientation to be properly constrained. It is found, however, that MLE performance varies significantly with illumination direction due to the inherently nonlinear nature of this problem. It is shown that a large number of samples is often required to optimally resolve surface orientation using the optimality criteria of the MLE derived in Naftali and Makris [J. Acoust. Soc. Am. 110, 1917–1930 (2001)].
Geocorrection and filtering of 3D bottom images from multi-beam sonar records
Authors: Demkowicz Jerzy , Bikonis Krzysztof , Stepnowski Andrzej , Moszynski Marek
Published: October 2013

For the last decade multibeam sonars have been increasingly used for mapping and visualization of the seafloor to provide the ‘‘physical bases’’ for environmental studies. Increasing amount of digital (raster) echo records of high resolution from a multibeam sonar have enhanced the potential of computer modeling of the marine environment to improve our understanding of the bottom processes. However, the 3D bottom images as the result of merging different sonar transects do not comply exact geographical positions and should be corrected. Additionally, the raw sonar records are subject to systematic errors, random noise and outliers. In this paper, Kalman filtering techinque to generating optimal estimates of bottom surface from a noisy raw sonar records is proposed. The experiment on the surface indicates that after applying the Kalman filtering the outliers of raw records can be efficiently removed. Moreover, the two-step Kalman filtering method enables 3D seabed visualization in real time. The paper proposes the geographical corrections applied to the merged mutibeam sonar transects records. The 3D bottom relief before, and after the filtering method are presented.
An inward striking free reed coupled to a cylindrical pipe
Authors: Vines Justin , Paquette Ammon , Cottingham James P.
Published: October 2013

A number of acoustical measurements have made on a reed-pipe combination consisting of a harmonium-type reed from an American reed organ installed at the closed end of a cylindrical pipe. This configuration, which somewhat resembles the configuration of free-reed organ pipes, differs from the reed-pipe combination occurring in the mouth organs of Asia, which use symmetric (outward striking) free reeds and normally operate on both possible directions of airflow. Measurements have been made of the sounding frequency, amplitude of vibration of the reed tongue, and the sound spectrum. Of particular interest is the degree to which the reed frequency can be altered by altering the pipe length, and hence the pipe resonance frequency. In this case the sounding frequency can be pulled considerably below the natural frequency of the reed. These results can be compared with the results of similar measurements on free-reed organ pipes [J. Braasch, C. Ahrens, J. P. Cottingham, and T. D. Rossing, Fortschr. Akust., DAGA (2000)]. In addition, some interesting ‘‘special effects’’ have been studied, which can be obtained using unusual pipe lengths and blowing in the ‘‘wrong’’ direction. [Work supported by the NSF from REU Grant No. 0139096.]
Airflow patterns in the vicinity of an air-driven free reed
Authors: Jensen Jesse T. , Cottingham James P.
Published: October 2013

Free reed instruments are characterized by high-volume airflow rates through the oscillating reeds. Measurements have been made of the average volume flow rate through a single American organ reed as a function of blowing pressure. In addition, measurements of average air velocity have been made at a grid of points close to the vibrating air-driven reed, mounted on the surface of a laboratory wind chest. These measurements supplement earlier investigations, which explored relations among the reed motion, airflow, and acoustic pressure associated with the vibration of free reeds. [M. Busha and J. P. Cottingham, J. Acoust. Soc. Am. 111, 2376 (2002)]. An attempt has been made to determine whether the left–right asymmetry due to the asymmetric shape (twist) of the reed is reflected in the airflow pattern. A graphing program has been developed so that the airflow pattern can be visualized in two or three dimensions.
Sound radiation and phase mapping of Caribbean steelpans
Authors: Morrison Andrew
Published: October 2013

At the 145th ASA meeting [J. Acoust. Soc. Am. 113, 2315 (2003)] modal analysis and sound intensity plots of two Caribbean steelpans were presented. Since that meeting the relationship of pan dimension to radiated sound has been examined. Sound radiation was explored using a two-microphone probe to gather sound intensity measurements. Preliminary phase maps of vibrating note areas have also been obtained using holographic interferometry with phase imaging.
Future evolution of structure in an accelerating universe
Authors: Busha Michael T.
Published: October 2013

Current cosmological data have confirmed the big bang and dark matter hypothesies, and indicate that our universe contains a substantial component of dark vacuum energy that is driving the cosmos to accelerate. We examine the immediate and long-term consequences of this dark energy on large scale structures formed in the universe. Using spherical model solutions and realistic 3D clustering simulations, we present criteria for test bodies to remain bound to existing structures. We show that collapsed halos become spatially isolated and dynamically relax to a particular kinematic profile. From this state, the asymptotic form of the space-time metric is well specified.
Speech intelligibility index predictions for young and old listeners in automobile noise: Can the index be improved by incorporating factors other than absolute threshold?
Authors: Saweikis Meghan , Surprenant Aimée M. , Davies Patricia , Gallant Don
Published: October 2013

While young and old subjects with comparable audiograms tend to perform comparably on speech recognition tasks in quiet environments, the older subjects have more difficulty than the younger subjects with recognition tasks in degraded listening conditions. This suggests that factors other than an absolute threshold may account for some of the difficulty older listeners have on recognition tasks in noisy environments. Many metrics, including the Speech Intelligibility Index (SII), used to measure speech intelligibility, only consider an absolute threshold when accounting for age related hearing loss. Therefore these metrics tend to overestimate the performance for elderly listeners in noisy environments [Tobias et al., J. Acoust. Soc. Am. 83, 859–895 (1988)]. The present studies examine the predictive capabilities of the SII in an environment with automobile noise present. This is of interest because people’s evaluation of the automobile interior sound is closely linked to their ability to carry on conversations with their fellow passengers. The four studies examine whether, for subjects with age related hearing loss, the accuracy of the SII can be improved by incorporating factors other than an absolute threshold into the model. [Work supported by Ford Motor Company.]
(Re-)constructed reality and context—When sound quality becomes soundscape
Authors: Schulte-Fortkamp Brigitte
Published: October 2013

In the interior of a vehicle sound quality is a brandname. Bi-aurale measurement and analysis technology is more or less standard, but there are still no general standards and parameters for sound quality. Evaluation of noises is highly sensitive to context, but testing procedures that can include this realization are exceedingly rare. Soundscapes are specific constellations of a general noise volume in clearly defined ambiences; they even can characterize those ambiences and combine the daily recurrent patterns of sound multi-factorial in the process of analysis. The evaluation of noise situations gets interactively modified by their significance for the general residential space. It is contingent upon the respective ponderation of acoustic and nonacoustic modifiers which in turn constitute the soundscape.
Compressor noise control with a two-dimensional enclosure
Authors: George Ballard W.
Published: October 2013

This paper is concerned with the use of a two-dimensional enclosure with masonry block wall to mitigate compressor noise in a northern California location for consistency with city standards. Sensitive receptors consist of a duplex and single residences across the street from the source. Background sound is provided primarily by a nearby highway that is elevated. Noise reduction is accomplished by the barrier effect of the wall along with sound absorption realized from a pegboard wall surface in the vicinity of the compressor, unpainted concrete block surface and acoustic treatment on the doors. Design considerations for the pegboard are discussed with the intention of balancing the overall low- and high-frequency noise reduction from the absorption and from the barrier effect and with the intention of reasonably reducing the number of pegboard holes required. Some considerations from the standpoint of ray acoustics are discussed. A complicating factor for the interior acoustics consists of three full height tanks in a row that serve as sound diffusers. Comments on vibration isolation for equipment and pipes are offered.
Some comparisons of binaural measurements made with different dummy heads and stereo microphone techniques
Authors: Mapp Peter A.
Published: October 2013

Binaural measurements have been made in a number of acoustic environments, and the results from different binaural heads and stereo microphones are compared. The object of the study was not only to establish what practical differences occurred between the various head formats, but also to see if a stereo microphone or pseudohead could be used for making auditorium binaural measurements. Five measurement platforms were employed. These included two binaural dummy heads, binaural in-ear probe microphones, an SAAS pseudohead stereo microphone and a M-S (midside) stereo microphone. In the latter case, three different midside ratios were employed and compared. The measurements were made in a reverberant recital hall (2.5-s RT) and small acoustically treated listening room (RT 0.2 s). Whereas relatively minor differences were found to occur between the heads, significant differences were found to occur with the stereo microphones. It is concluded that while useful information can be obtained from a stereo microphone, it is far from being the same as binaural.
Visualization of sound fields by three-dimensional representations
Authors: Tokita Yasuhiro , Yamasaki Yoshio
Published: October 2013

In this study, three-dimensional sound fields can be visualized by measured data in an addition to transient numerical solutions. Concretely, the results of measurements by the four-point microphone method are used in the visualization of three-dimensional sound fields. By the results, distribution of virtual sources and hedgehog pattern are visualized as the receiving point is located on the center point in three-dimensional sound fields. The analyses of the transient sound fields are performed by the discretization of the wave equation. As the technique of numerical calculation, the finite difference method (FDM) is used. Transient sound fields are visualized by numerical solutions of sound pressure, instantaneous sound intensity, sound energy and particle displacement in three-dimensional space in addition to two-dimensional space. It has been verified that the numerical solutions have high accuracy by comparison with the corresponding analytical solutions. VRML97 is used as the viewer of three-dimensional sound fields. In this study, several trials of three-dimensional animation are going to be shown by VRML97 in order to visualize the transient sound fields.
Binaural signal analysis of diffuse sound fields
Authors: Novo Pedro A.
Published: October 2013

The simulation and the binaural recording of sounds produced by large crowds and rain impact sounds has produced an unexpected result. The listeners have reported that the auditory events were mainly concentrated to the left and to right, although the sound sources were equally distributed around the listeners. A similar result was reported with binaural recordings of applause. The results of a binaural signal analysis suggest that the key aspect regarding the lateral position dominance of the auditory events is connected to the sections where the cross-correlation coefficient assumes negative values. A comparison between normalized and non-normalized cross-correlation function predictions indicates that the latter is a better predictor for the cases studied. An adaptation period of several seconds was reported by several listeners. It is suggested that this adaptation period is related to the variations of the cross-correlation, which only average out after, approximately 2 s. The binaural impulse responses of a concert hall at two different listener positions have been analyzed in the light of the previous findings. In particular the diffuse sound field buildup will be analyzed in detail. Implications for the auditory source width and listener envelopment will be discussed.
Ultrasonic wave propagation and scattering in cancellous bone
Authors: Wear Keith A.
Published: October 2013

Theoretical models and experimental data describing the interaction between ultrasound and cancellous bone will be discussed. Ultrasonic attenuation in cancellous bone is much greater than that for soft tissues and varies approximately linearly with frequency between 400 kHz and 1.7 MHz. Speed of sound in cancellous bone is slightly higher than that for soft tissues and decreases gradually with frequency at diagnostic frequencies (between 300 and 700 kHz). The dependence of phase velocity on porosity may be predicted from theory of acoustic propagation in fluid-filled porous solids. The negative dispersion can be explained using a stratified two-component model. At diagnostic frequencies, scattering varies approximately as frequency to the nth power where 3<n<3.5. This may be explained either by a continuous or discrete scattering model. The latter represents trabeculae as small finite-length cylindrical scatterers. The frequency dependence of scattering, along with the anisotropy of scattering and attenuation, implies that absorption is a greater source of attenuation than scattering. [Funding from the FDA Office of Women’s Health is gratefully acknowledged.]
Some aspects of the atypical acoustic behavior of cancellous bone
Authors: Nicholson Patrick H.
Published: October 2013

Cancellous bone, consisting of a porous framework of solid trabeculae saturated in marrow fluid, is a challenging material in terms of ultrasonic characterization. This study considers some unusual aspects of the ultrasonic behavior of cancellous bone. These anomalies highlight the boundaries of our knowledge and, arguably, point us towards promising directions for future progress. Profoundly different wave propagation regimes can exist along different anatomical axes. Along the main axis of trabecular orientation, two longitudinal waves are observed, but only one wave is observed for propagation transversely across the trabeculae. In the latter case, a positive attenuation slope and negative velocity dispersion are seen, in apparent violation of the Kramers–Kronig relations. The properties of the saturating fluid have major effects on acoustic properties, and temperature studies also point towards the importance of the fluid. In some clinical studies, velocity and attenuation in the heel show opposite changes, which is difficult to explain without considering the possibility of changes in the marrow as well as the bone. Shear wave propagation in fluid-filled cancellous bone has received little attention. Measurements in whale bone suggest that shear waves propagate in dry bone, but are rapidly attenuated in the presence of saturating fluid.
Numerical simulation of wave propagation in cancellous bone
Authors: Bossy Emmanuel , Padilla Frederic , Jenson Frederic , Haiat Guillaume , Laugier Pascal
Published: October 2013

Physical mechanisms implied in the propagation of ultrasound waves in trabecular bones are not yet clearly understood. The relative role of scattering and absorption in the attenuation process is unknown. To dissociate these two effects, a simulation of wave propagation in 3D volumes of trabecular bone is performed, and compared to experimental results. The simulation algorithm accounts for scattering and volumetric absorption into both the saturating fluid and bone. The simulation software uses a finite difference approach based on the Virieux numerical scheme. An incident plane wave is propagated on a volume of bone of approximately 5×5×8 mm3. These volumes were reconstructed from high resolution micro-CT experiments. Several types of simulations are computed: bone described as a fluid matrix saturated by fluid (i.e., neglecting the shear wave propagation into the matrix) and bone described as a solid matrix saturated by fluid, with or without absorption. From the transmitted signals, attenuation and speed of sound through the specimens are calculated and compared to experimental values obtained on the same specimens. Finally, the contribution of scattering to the total attenuation is estimated, and the importance of mode conversions as well as absorption.
Systematic speaker variation and within-speaker center of gravity correlations in the TIMIT database
Authors: Javkin Hector R. , Christie Carol , Cangiano Gaston R. , Drom Elaine , McClain Katia
Published: October 2013

The systematicity of speaker variation in consonants was examined by measuring the noise component of consonants in the TIMIT database. Fricatives and stops were compared by measuring at the temporal middle of fricatives and at the release of stops. There is a high correlation between many of the center of gravity measures. For example, if a speaker has a particularly high center of gravity in the sound /t/, she or he will also have a high center of gravity in /d/, /s/, /p/, /k/, and other consonants. The full set of correlations will be described in the paper. The correlations appear to stem from individual differences and not from dialect variations. The implications of the results for rapid speaker adaptation in speech recognition will be explored. [Work supported by San Jose State University Faculty Grant.]
Separation of formants from glottal impulses in high-resolution spectrograms using higher-order short-time Fourier transform (STFT) phase derivatives
Authors: Fulop Sean A.
Published: October 2013

The channelized instantaneous frequency of a signal x(T) is CIFx(ω,T)=(∂/∂T)arg(Fh(ω,T)), where Fh is the short-time Fourier transform of x(T) using window function h. The local group delay of a signal is LGDx(ω,T)=−(∂/∂ω)arg(Fh(ω,T)). For each point Fh(ω0,T0) in the STFT, the f−t coordinates [CIF(ω0,T0),t−LGD(ω0,T0)] pinpoint the local mean of the Rihacek distribution of complex signal energy, and this reassignment of the STFT magnitude yields a high-resolution spectrogram without blurriness [Auger and Flandrin, ‘‘Improving the readability of time-frequency and time-scale representations by the reassignment method,’’ IEEE Trans. Signal Process 43(5), 1068–1089 (1995)]. Nelson [‘‘Instantaneous higher order phase derivatives,’’ Digital Signal Process 12, 416–428 (2002)] demonstrated that the significant AM/FM components of a signal x(T) have (∂/∂ω)CIFx(ω,T)≊0. By plotting just those STFT points meeting this condition to within a threshold, a spectrogram showing only speech resonances can be drawn using short analysis frames. By moving to a long-frame analysis, the resonance tracker becomes an effective pitch and harmonic tracker. Nelson further demonstrated that the impulses in a signal x(T) have (∂/∂T)LGDx(ω,T)≊1. By plotting just those points meeting this condition to within a threshold, a spectrogram of speech impulses can alternatively be drawn.
Capturing the acoustic response of historical spaces for interactive music performance and recording
Authors: Woszczyk Wieslaw , Martens William
Published: October 2013

Performers engaged in musical recording while they are located in relatively dry recording studios generally find their musical performance facilitated when they are provided with synthetic reverberation. This well established practice is extended in the project described here to include highly realistic virtual acoustic recreation of original rooms in which Haydn taught his students to play pianoforte. The project has two primary components, the first of which is to capture for posterity the acoustic response of such historical rooms that may no longer be available or functional for performance. The project’s second component is to reproduce as accurately as possible the virtual acoustic interactions between a performer and the re-created acoustic space, as performers, during their performance, move relative to their instrument and the boundaries of surrounding enclosure. In the first of two presentations on this ongoing project, the method for measurement of broadband impulse responses for these historical rooms is described. The test signal is radiated by a group of omnidirectional loudspeakers approximating the layout and the complex directional radiation pattern of the pianoforte, and the room response is sampled by a spaced microphone array. The companion presentation will describe the method employed for virtual acoustic reproduction for the performer.
Mapping the sound field of the Lyric Theater
Authors: Ermann Michael , Kidner Michael , McCoy Joe , Mennitt Dan , Tawney Adam , Yoder Bill
Published: October 2013

Impulse response measurements were taken in each of the 235 orchestra-level house-left seats of the Lyric Theater in order to explore spatial differences in the sound field of the room. These measurements produced graphic mappings depicting gradients of sound decay time and loudness. Significant interseat variations appeared when mapping the decay times for the 63- and 125-Hz octave bands; these variations largely disappeared when mapping the decay times for octave bands greater than 250 Hz. A scaled physical model and a CATT-Acoustics software model of the space were built to explore the veracity and usefulness of modeling to determine intraroom spatial differences in sound fields.
Quantitative benthic habitat characterization at Heceta Bank, Oregon
Authors: Whitmire Curt E. , Wakefield W. Waldo , Embley Robert W. , Merle Susan G. , Tissot Brian N. , Puniwai Noelani
Published: October 2013

Recent studies have highlighted the shortcomings of regional trawl surveys for quantifying abundance of demersal fishes in rugged habitats. Many species show strong affinities to areas of high topographic relief and rugosity, therefore precluding sampling by bottom trawl gears. Consequently, advanced survey technologies such as submersibles and camera sleds have been utilized to survey demersal fishes in situ. One prerequisite in extrapolating densities of demersal fishes observed in situ is the mapping of benthic habitats beyond the observational extent of submersibles. Habitat characteristics observed from submersible and ROV dives in the late 1980s, 2000, and 2001 were used to establish habitat classes that have been statistically shown to correlate with demersal fish distributions. Those habitat characteristics were then extrapolated over the extent of a multibeam sonar survey conducted in 1998 using quantitative parameters derived from high-resolution bathymetric and acoustic backscatter data. The resultant map predicts the coverage of four lithologic habitat classes: mud (unconsolidated), sand (unconsolidated), boulder/cobble (high acoustic reflectivity), and rock outcrop (high vertical relief). Those four habitat classes will facilitate the extrapolation of fish densities to the larger spatial scales at which resident fish populations and physiographic provinces occur.
Relationships between seafloor substrates, benthic epifauna, and spatial properties of multibeam echosounder bathymetry and backscatter data
Authors: Cutter George R. , Mayer Larry A. , Ward Larry G.
Published: October 2013

The seafloor in the mouth of the Piscataqua River Estuary, near Portsmouth, New Hampshire, contains several geomorphological regions that are evident in bathymetric data from multibeam sonar soundings. Those morphological regions generally are associated with surficial sediment type classes previously identified from sediment samples. We demonstrate that the morphologies are distinguishable using parameters from models of spatial variation for gridded depth soundings and backscatter values. Ground-truth seafloor-video transects data suggest that apparent facies and morphological regions are associated with different surficial sediment classes and rates of facies transitions. We show that the spatial variability of depth and backscatter is associated with the substrate transition rate, the number of microhabitats (microfacies), and distribution of certain epifauna identified using video. We show that, in some cases, a single region defined based upon spatial morphological attributes from depth data and apparent sedimentological attributes from backscatter data represented several benthic habitats. The results suggest that although we can use spatial variability of depth or backscatter to segment the seafloor into apparent facies or habitat class regions, some of the regions will have unpredicted associated microhabitats and organisms. The results have implications for habitat-specific assessment of organisms.
Effects of fish with swim bladders on absorption and scintillation
Authors: Diachok Orest
Published: October 2013

Bioacoustic absorption spectroscopy (BAS) experiments, which were conducted in the Santa Barbara Channel in 2001 and 2002, were designed to investigate the effects of fish with swim bladders on absorption and scintillation. These experiments included a broadband source, which transmitted a sequence of 65-s-long tones between 0.25 and 10 kHz, and a vertical array which spanned most of the water column. The range was fixed. A fisheries echo sounder and trawls provided bio-acoustic parameters. Strongest absorption lines and highest values of the scintillation index were observed at night at about 1.1 kHz, the resonance frequency of 15 cm long sardines, when they were dispersed at an average depth of 13 m. Smaller absorption lines were correlated with other species. During the day sardines occupied a depth of about 50 m, where their extinction cross sections were diminished; some were dispersed and resonated at the frequency of individuals; others formed schools and resonated at collective frequencies. As a result of these phenomena, absorption lines due to sardines were much weaker, and the effect of this species on the scintillation index was not evident. [Work was supported by ONR.]
Acoustical monitoring of fish behavior in a tank
Authors: Conti Stephan G. , Maurer Benjamin D. , Roux Philippe , Fauvel Christian , Demer David A. , Waters Kendall R.
Published: October 2013

In recent publications, it has been demonstrated that the total scattering cross section of fish moving in a tank can be estimated from ensembles of reverberation time series. However, the reproducibility of these measurements is influenced by parameters such as the motion or the behavior of the fish. In this work, we propose to observe acoustically the behavior of fish in a tank, and to measure their average speed. The total scattering cross section of live fish (sardines, sea bass and bocaccio) in a tank was measured repeatedly over multiple days. The species used in this study have different behaviors, which are reflected in the acoustical measurements. Depending on the behavior of the fish, such as the average displacement between two acoustic pings or the aggregation type, the total scattering cross section is different. Correlation between the acoustical measurements and the day and night behavior of the fish is demonstrated. Interpretation of such measurements can lead to monitoring acoustically and nonintrusively the behavior of fish in tanks.
Scanning acoustic microscopy on bone—status and perspectives
Authors: Raum Kay
Published: October 2013

High-frequency ultrasound has become one of the most powerful tools for the elastic characterization of hard materials since its invention in 1974. Many of the imaging and measurement techniques developed for NDE were also applied for the characterization of bone. However, the heterogeneous structure at several levels of organization implies multifold problems, e.g., tissue preparation, validity and applicability of the measurement techniques, resolution limitations, interpretation of results, etc. Furthermore, the technical development of commercially available high-resolution SAM lacks far behind other quantitative imaging modalities. The talk will describe the acoustic microscopes developed in our group, concepts for acoustic impedance mapping with frequencies up to 1 GHz, and techniques for determining longitudinal, shear, and surface wave velocities. The relations of acoustic to elastic parameters, either directly derived from the acoustic measurement or obtained from micromechanical tests, are presented. Combinations with other experimental and clinical techniques (US, SR-CT, nanoindentation, Raman) demonstrate the potential of SAM for an improved diagnosis, both in experimental and in clinical studies. In vitro results demonstrate the feasibility for assessing the elastic anisotropy and microstructural parameters of cortical bone, compositional variations within alternating osteon lamellae, structural and elastic changes in arthrotic cartilage and subchondral bone, respectively.
Assessment of trabecular bone quality in human cadaver calcaneus using scanning confocal ultrasound and dual x-ray absorptiometry (DEXA) measurements
Authors: Qin Yixian , Xia Yi , Lin Wei , Rubin Clinton , Gruber Barry
Published: October 2013

Microgravity and aging induced bone loss is a critical skeleton complication, occurring particularly in the weight-supporting skeleton, which leads to osteoporosis and fracture. Advents in quantitative ultrasound (QUS) provide a unique method for evaluating bone strength and density. Using a newly developed scanning confocal acoustic diagnostic (SCAD) system, QUS assessment for bone quality in the real body region was evaluated. A total of 19 human cadaver calcanei, age 66 to 97 years old, were tested by both SCAD and nonscan mode. The scanning region covered an approximate 40×40 mm2 with 0.5 mm resolution. Broadband ultrasound attenuation (BUA, dB/MHz), energy attenuation (ATT, dB), and ultrasound velocity (UV, m/s) were measured. The QUS properties were then correlated to the bone mineral density (BMD) measured by DEXA. Correlations between BMD and QUS parameters were significantly improved by using SCAD as compared to nonscan mode, yielding correlations between BMD and SCAD QUS parameters as R=0.82 (BUA), and R=0.86 (est. BMD). It is suggested that SCAD is feasible for in vivo bone quality mapping. It can be potentially used for monitoring instant changes of bone strength and density. [Work supported by the National Space Biomedical Research Institute (TD00207), and New York Center for Biotechnology.]
Ultrasonic assessment of bone: Comparison with other characterization modalities
Authors: Nicholson Patrick H.
Published: October 2013

Compared to other techniques, quantitative ultrasound of bone (QUS) has a unique potential arising from the mechanical nature of the wave phenomena involved, the ability to use wavelengths spanning the dimensions of key structural features of bone, and the absence of ionizing radiation. However, QUS suffers from fundamental problems of interpretation when compared to most other bone assessment modalities. For example, dual energy x-ray absorptiometry gives a direct estimate of a well-understood physical parameter: bone mineral density. In contrast, QUS yields acoustic properties that cannot be so easily interpreted, and whose clinical value is derived largely from empirical relationships with physical properties of interest, such as bone density, or with other factors such as risk of fracture. Hence for QUS we cannot trace a clear causal path connecting an ultrasonic measurement to specific bone properties and on, in turn, to clinical outcomes and decisions. Without developing the theoretical framework required to achieve this, QUS will not achieve its full potential and is likely to remain sidelined and mistrusted in comparison to the x-ray-based modalities which are its principal competitors.
Propagation of interface waves in a clay soil
Authors: Muir Thomas G. , Burgett Richard , O’Neill Robert M.
Published: October 2013

Measurements and analyses on the propagation of interface waves, previously conducted on a sandy beach in Monterey, CA, are extended to a clay soil in Oxford, MS, in support of research on seismic sonar. Data are presented on attenuation versus lateral range and frequency, which may result from attenuation and scattering, as well as refraction and modal effects. Data are also presented on spatial coherence and group velocity, as a function of angle, along semi-circular arcs, also as a function of lateral range. The interface waves were generated in pulses, with both moving coil and moving mass sources (shakers), and were measured with three axis seismometers, at frequencies ranging from a few tens of Hz to several hundred Hz, at lateral ranges from a few meters to a few tens of meters. The sources excited numerous seismo-acoustic wave types; but the analysis focused on (1) Rayleigh waves having radial and vertical components in the vertical plane, and (2) transverse waves in the horizontal plane, thought to be Love waves. The data are interpreted with respect to environmental ‘‘ground truth’’ measurements. [Work supported by the U.S. Marine Corps Systems Command.]
Fifty years of progress in speech waveform coding
Authors: Atal Bishnu S.
Published: October 2013

Over the past 50 years, sustained research in speech coding has made it possible to encode speech with high speech quality at rates as low as 4 kb/s. The technology is now used in many applications, such as digital cellular phones, personal computers, and packet telephony. The early research in speech coding was aimed at reproducing speech spectra using a small number of slowly varying parameters. The focus of research shifted later to accurate reproduction of speech waveforms at low bit rates. The introduction of linear predictive coding (LPC) led to the development of new algorithms, such as adaptive predictive coding, multipulse and code-excited LPC. Code-excited LPC has become the method of choice for low bit rate speech coding and is used in most voice transmission standards. Digital speech communication is rapidly moving away from traditional circuit-switched to packet-switched networks based on IP protocols (VoIP). The focus of speech coding research is now on providing to low cost, reliable, and secure transmission of high-quality speech on IP networks.
Fifty years of progress in speaker verification
Authors: Rosenberg Aaron E.
Published: October 2013

The modern era in speaker recognition started about 50 years ago at Bell Laboratories with the controversial invention of the voiceprint technique for speaker identification based on expert analysis of speech spectrograms. Early speaker recognition research concentrated on finding acoustic-phonetic features effective in discriminating speakers. The first truly automatic text dependent speaker verification systems were based on time contours or templates of speaker specific acoustic features. An important element of these systems was the ability to time warp sample templates with model templates in order to provide useful comparisons. Most modern text dependent speaker verification systems are based on statistical representations of acoustic features analyzed as a function of time over specified utterances, most particularly the hidden markov model (HMM) representation. Modern text independent systems are based on vector quantization representations and, more recently, on Gaussian mixture model (GMM) representations. An important ingredient of statistically based systems is likelihood ratio decision techniques making use of speaker background models. Some recent research has shown how to extract higher level features based on speaking behavior and combine it with lower level, acoustic features for improved performance. The talk will present these topics in historical order showing the evolution of techniques.
Fifty years of progress in speech recognition
Authors: Reddy Raj
Published: October 2013

Human level speech recognition has proved to be an elusive goal because of the many sources of variability that affect speech: from stationary and dynamic noise, microphone variability, and speaker variability to variability at phonetic, prosodic, and grammatical levels. Over the past 50 years, Jim Flanagan has been a continuous source of encouragement and inspiration to the speech recognition community. While early isolated word systems primarily used acoustic knowledge, systems in the 1970s found mechanisms to represent and utilize syntactic (e.g., information retrieval) and semantic knowledge (e.g., Chess) in speech recognition systems. As vocabularies became larger, leading to greater ambiguity and perplexity, we had to explore the use task specific and context specific knowledge to reduce the branching factors. As the need arose for systems that can be used by open populations using telephone quality speech, we developed learning techniques that use very large data sets and noise adaptation methods. We still have a long way to go before we can satisfactorily handle unrehearsed spontaneous speech, speech from non-native speakers, and dynamic learning of new words, phrases, and grammatical forms.
Measured effects of diffusers and absorbers on the low-frequency modal structures in two reverberation chambers
Authors: Nutter David , Shepherd Micah , Leishman Timothy , Shafer Benjamin
Published: October 2013

The Brigham Young University Acoustics Research Group has recently constructed two rectangular reverberation chambers for its research efforts. Steps have been taken to qualify the chambers for a variety of applications. Stationary diffusers and low-frequency absorbers were designed and installed as part of this process. This paper presents measurements taken at various stages of the installation to assess the impact of the diffusers and absorbers on the modal structure of the low-frequency fields.
Acoustic3D Teaching Program
Authors: Barnett Norman E. , Turner James A.
Published: October 2013

A computer program has been under development for several years to assist the teaching of architectural acoustics to architecture students. This program is an outgrowth of a 2D program used routinely by the students since 1999. Emphasis is on where, when and how much sound distributes within a geometrical envelope. The initial geometry of a space is drawn or modeled with commercial programs that students typically would use to represent a design. That geometry is exported in the dxf file format and imported into the acoustic program. There it is combined with at least one sound source and initial sound reflection characteristics representing the room surfaces. As such, an acoustical simulation is produced that can be manipulated to reveal the implicit acoustical behavior of the representation. A description is given about how the program is organized and how it functions. Two brief examples are provided. The first is for a simple rectangular schoolroom such as might be used to develop some introductory learning about architectural acoustics. The second is for a more complicated geometry more appropriate for students who are reasonably well grounded in acoustics. They are presumably ready to undertake some acoustical investigation at a design development level.
Dr. Ronald Schusterman’s contributions to national acoustic policy
Authors: Gentry Roger L.
Published: October 2013

When the effects of underwater noise on marine mammals became a national issue in the 1990’s, the federal government needed people trained in those fields to manage programs. No trained managers with that background existed, so a few scientists took on management roles. Of today’s five Washington, DC managers in this issue, three received advanced degrees under Ron Schusterman. One started ONR’s comprehensive research program on this topic, and two run NMFS’s regulatory policy program on acoustics. Dr. Schusterman intended his students to work in basic science, specifically cognition, learning, sensory perception, and social behavior of marine mammals. Ironically, and despite his aversion to bureaucracy, this background equipped his students to become government decision makers. Such are the twists of history. He also taught his students to rigorously apply the scientific method and to assume nothing. If his science castaways in Washington, DC are worthy of his training, the national noise issue will be the better for it.
How acoustic signals become meaningful to listeners: An experimental approach
Authors: Reichmuth Kastak Colleen , Lindemann Kristy , Schusterman Ronald
Published: October 2013

Most models of animal acoustic communication describe how vocal cues produced by a signaler influence the behavior of a listener. The response made by a listener depends in large part on the perceived meaning of the signal. But, how do signals become meaningful to listeners? In some cases, such as imprinting, signal meaning can be attributed to structural cues that are perceived and acted upon through an innate releasing mechanism. In other instances, signals may be arbitrarily related to objects, individuals, or species. Equivalence theory provides a model describing how some arbitrary signals may acquire meaning. Here, we describe theory and experimental evidence in the form of cross-modal matching-to-sample tasks showing how acoustic signals can become referents for visual stimuli. The subject of these behavioral experiments is a California sea lion with extensive experience in performing associative learning tasks. The aim of the experiments is to establish multiple auditory-visual discriminations and then test for the emergence of untrained relationships between disparate visual stimuli linked by a common auditory signal. Preliminary data show successful emergent matching across visual and auditory modalities. These findings suggest that acoustic signals become meaningful to listeners when learned associations lead to the formation of equivalence classes.
Hearing loss and echolocation signal change in dolphins
Authors: Moore Patrick W. , Finneran James , Houser Dorian S.
Published: October 2013

Recent studies and ongoing research have shown that echolocating dolphins can change the structure of their emitted echolocation signals during active echo-investigation of targets. The presumption has been that the animal adjusts various parameters (source level, peak frequency, etc.) of the emitted signal to maximize the information return in the target echo as a function of task or environmental constraints and requirements. Other work has suggested that the frequency range over which this dynamic control is exerted may change due changes in the animals hearing ability. Specifically, dolphins that develop high frequency hearing loss, for example from age, noise exposure or ototoxic drugs, shift the center frequency of the emitted echolocation click to lower frequency ranges. Observations of several Navy Marine Mammal Program animals with known high frequency hearing loss have demonstrated these frequency shifts. In this paper we will elaborate and extend ongoing analysis of emitted echolocation signals of several dolphins that show hearing loss associated changes in emitted signal structure, discuss the implications of these measures and suggest approaches that may prove useful for evaluating basic hearing capabilities from collected echolocation signals.
Transmission loss and signal coherence statistics in the northeastern South China Sea shelf edge
Authors: Chiu Ching-Sang , Miller Christopher
Published: October 2013

Observations from the Northeastern South China Sea shelf edge in May 2001 showed spectacular changes in the sound-speed profile, transmission loss, and signal coherence at low frequency. These significant acoustical fluctuations were induced by the passage of large-amplitude, nonlinear internal waves that depressed the shallow isotherms to the ocean bottom along the transmission path. In this talk, the measured statistics of transmission loss, temporal coherence, and horizontal coherence of a 400-Hz signal transmitted upslope from a moored sound source to an L-shaped hydrophone array are presented and discussed. Specifically, the discussion is focused on both the inter- and intradaily variability of these observed statistics of the sound field and their dependence on the strength and timing of the nonlinear internal waves. [The research is sponsored by ONR.]