bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluating urban soundscape quality with sound recording and reproduction.
Authors: Adams Tyler , Braasch Jonas
Published: October 2010

Sound recording is an obvious method when the sound quality of a soundscape needs to be assessed. The benefit of a recording, beyond archival purposes, is that the signal can be analyzed to obtain objective metrics of quality such as tonality, spectral composition, roughness, fluctuation strength, etc., and it may also be played back to listeners under controlled settings for the purpose of qualitative evaluation. The goal of the research reported here was to evaluate the advantages and disadvantages of different recording and reproduction methods and determine which method offered the greatest correlation between subjective evaluations made in a laboratory and those made \emph{in situ}. In addition, binaural and multichannel reproduction techniques were explored in tandem with photographs and videos to create different levels of immersion and determine the impact of visual cues on sound quality evaluation. Two parks in Manhattan were chosen as test environments for this study. All participants were given identical surveys which evaluated sound quality using descriptive content analysis techniques and semantic differential ratings.
Noise attenuation by phononic crystals made of recycled materials.
Authors: Sánchez-Dehesa J. , Garcia-Chocano V. M. , Torrent D. , Cervera F. , Cabrera S.
Published: October 2010

This paper reports recent advances on the topic of sound attenuation of airborne sound by noise barriers based on 2-D phononic crystals (PnCs). We consider here the case in which the PnC building units are made of rubber crumb, a porous absorptive material obtained by recycling used tires. The resulting sound attenuation is obtained by a combination of two effects: Bragg reflection by the periodic distribution of cylindrical scatterers and sound absorption by the rubber crumb. Several barrier samples consisting of three rows of scatterers have been fabricated and characterized. Their attenuation performance is compared with that of equivalent samples built with only rigid cylinders. Transmittance and reflectance spectra have been independently measured to obtain the absorption properties of each sample. The results indicate that samples made of rubber crumb show broadband sound attenuation in comparison with those fabricated with no absorptive material. Prototypes of actual size for traffic noise attenuation will also be reported and discussed. Numerical simulations based on the multiple scattering method are in agreement with the experimental data. [Work supported by ONR and by MICIIN of Spain.]
Resonant elements for sonic crystal barriers.
Authors: Attenborough Keith , Chong Alvin , Taherzadeh Shahram
Published: October 2010

Multiple scattering in periodically spaced, vertically orientated cylinder arrays produces band gaps, the (Bragg) frequencies of which are determined by the lattice constants. For rigid cylinders these band gaps tend to have azimuthal angle dependency. Additional relatively angle-independent band gaps at frequencies below the first Bragg frequency can be obtained by use of resonant array elements. The results of laboratory experiments investigating the acoustical performance of four types of resonant elements are reported. These include slotted cylinders, thin-walled cylindrical elastic shells, concentric arrangements of slotted cylinders and elastic cylindrical shells, and multiply resonant elements consisting of hard-backed cavities between thin cantilevered plates. [Work supported by EPSRC (UK) Grant no. EP/E062806/1.]
An effective medium model for sonic crystals with resonant elements.
Authors: Umnova Olga , Krynkin Anton
Published: October 2010

Periodic arrays of resonant scatterers can support low-frequency band gaps in addition to those associated with array periodicity. In the finite periodic arrays they correspond to frequency intervals of low transmission and lead to an improved attenuation below the first Bragg band gap. To describe low-frequency behavior, the effective medium model has been developed for the array of either thin elastic shells or composite scatterers. The latter consists of concentrically arranged hollow rigid cylinder with multiple slits (N-slit rigid cylinder) and thin elastic shell. The simplified description of the composite scatterer relies on the replacement of the N-slit cylinder by an equivalent fluid layer. Using coherent potential approximation, the analytical expressions are derived for the parameters of an effective medium. For the array of elastic shells it is demonstrated that complex density and complex compressibility become negative around n=1 resonance of the lossless shell and its axisymmetric (n=0) resonance frequencies, respectively. It is shown theoretically and confirmed in measurements that the presence of the concentric N-slit cylinder decreases the frequency of the axisymmetric resonance of the shell. The results are compared with the numerical solutions for infinite doubly periodic arrays and insertion loss data for finite arrays.
Sonic crystal barriers with absorbent and resonant scatterers.
Authors: Romero-García V. , Sánchez-Pérez J. V. , Garcia-Raffi L. M.
Published: October 2010

The ability of periodic distributions of absorbent and resonant scatterers embedded in air for attenuating a wide range of frequencies is studied. The scatterers consist of a rigid core with a resonant cavity, covered by a layer of absorbent material. A preliminary numerical analysis shows the resulting combination of the three main physical phenomena appearing in such a periodic system: scattering, absorptions, and resonance. The scattering reproduces the so-called band gaps, ranges of frequencies related with the periodicity of the crystal. In addition, resonant scatterers have been designed to present resonances in the range of frequencies below the band gap of the crystal, such that there appear attenuation peaks for the low frequencies. Finally, the resonant scatterers are covered by a layer of absorbent material, a fibrous woolen felt that produces an increase of the whole attenuation spectra without removing the multiple scattering and the resonance phenomena.
Analysis of the reflection properties of sonic crystal devices.
Authors: Snchez-Morcillo Victor , Picó Rubén , Garcia-Raffi Lluis M. , Sanchez-Perez Juan Vicente , Romero-García Vicente , Staliunas Kestutis
Published: October 2010

The phenomenon of band-gaps typical of wave propagation in periodic materials has been a subject of extensive investigations. In acoustics, the interest is mainly related with the ability of such structures, the so-called sonic crystals, of blocking the propagation of sound at certain frequencies, acting as filters. Recently, there is an increasing interest in the use of sonic crystals to control the beam propagation, and a number of interesting features as focusing and collimation have been predicted and observed. At the root of these phenomena is the angle-dependent dispersion introduced by the crystal. In propagating regimes, for frequencies outside the gap, the particular form of the dispersion relations in the wavenumber (reciprocal) space allows us to determine the spatial characteristics of the transmitted field. In this work, we merge the two ideas above, and investigate the spatial characteristics of the reflected acoustic field when its frequency belongs to a band-gap. In a band-gap, the propagating modes are substituted by evanescent ones, defined by complex wavenumbers. We evaluate the complex dispersion relation, and relate the particular form of the isofrequency contours in k-space with the numerically evaluated spatial distribution of the reflected field. Different reflection regimes are presented and discussed.
Spatial filtering and beam forming with sonic crystals.
Authors: Sanchez-Morcillo Victor J. , Picó Rubén , Prez-Arjona Isabel , Staliunas Kestutis
Published: October 2010

Sonic crystals are known to act as temporal filters for a broadband incident radiation, the part of the temporal spectrum belonging to a band-gap being removed or filtered-out from the transmitted field. In this work we examine the role of sonic crystals as spatial filters, i.e., the selective removal of a part of the spatial spectrum of a sound beam. A sound beam can be considered as a collection of plane waves propagating at different angles, the width of the beam being inversely proportional to the width of its spatial spectrum. We show the existence of two different mechanisms leading to spatial filtering, depending on whether there is an angular gap at particular propagating angles or not. In the former case, the filtered radiation is reflected backwards; in the latter, it is strongly deflected from its trajectory. As a result, by removing the higher spatial frequencies of the spectrum (those mostly related to inhomogeneities in the beam profile), the crystal can form a beam with improved spatial quality, presenting a smooth profile. The effect can be used also to broaden a narrow beam by reducing its spatial spectrum. The combined action of focusing and filtering is also demonstrated and discussed.
Shear wave scattering generated by the interaction of a circular half-cylinder with a wavefield originated by a line source.
Authors: Pech Andrés , Jiménez Carlos , Vzquez Alejandro , Cortés Eduardo
Published: October 2010

The problem of shear wave diffraction caused by a circular half-cylinder was considered. In this case, the incident field was assumed to be generated by a line source, which was set to be parallel to the axis of the cylinder. The solution of this eigenvalue problem was obtained through the application of the superposition principle. In this case, the wavefield outside of the half-cylinder was expressed in terms of the free field and the diffracted field. On the other hand, the wavefield inside of the cylinder was defined in terms of refracted fields. Since the scatterer and the source possess cylindrical symmetry, all the wavefields could be expressed in terms of series of Bessel and Hankel functions. The unknown coefficients of these series were obtained by evaluating boundary conditions. With the solution of this problem, the seismic response of a semi-circular alluvial valley was studied.
Modal analysis of acoustic structural coupled system by finite element method.
Authors: Merodio V. Hector , Mollinedo P. Helvio , Rabadan M. Itzala , Ortega H. Jose Angel
Published: October 2010

In this work the development of an analytic study and of simulation by the finite element method(FEM) is presented to calculate the modal response (eigenvalues and eigenvectors) of coupled structural acoustic systems. An important application of this methodology is to include models that permit to predict the interior noise in the vehicles. The results of a simulation are presented, using a small acoustics enclosure made of steel plates by FEM. In the case of the uncoupled systems, the acoustic and structural, its solution using an implementation in MATLAB is also shown. The results of uncoupled fields are very similar in both cases.
Long-term formant distribution as a forensic-phonetic feature.
Authors: Jessen Michael , Becker Timo
Published: October 2010

With the long-term formant distribution (LTF) method [F. Nolan and C. Grigoras, Int. J. Speech, Lang. Law 12, 143–173 (2005)], manually corrected LPC-based formant tracks are extracted over all vocalic portions of the recording of a speaker in which the formants F2 and F3 are sufficiently well-structured. LTF analysis has been successfully added to the inventory of phonetic features that are used in voice comparison casework. Current research has highlighted a number of advantages of the LTF method, including high inter-expert reliability (different phoneticians arrive at highly consistent results), anatomical motivation (long-term F2 and F3 are negatively correlated with speaker height), and language independence (LTF patterns in different languages—so far, German, Russian, and Albanian—do not differ significantly). Presently, quantitative measures of inter-individual variation in case data are investigated, including equal error rates and calibrated likelihood ratios based on Gaussian mixture modeling of the formant tracking raw data [Becker et al., Proc. Interspeech, 1505–1508, 2008]. The final inter-individual variation results will be presented, along with results on how the LTF method compares to automatic speaker recognition, which is applied to the same data.
High-performance session variability compensation in forensic automatic speaker recognition.
Authors: Ramos Daniel , Gonzalez-Dominguez Javier , Gonzalez-Rodriguez Joaquin
Published: October 2010

Recently, the main performance improvement in automatic speaker recognition technology has been due to session variability compensation techniques, mainly based on factor analysis (FA), which have reduced the equal error rate (EER) of state-of-the-art systems by a factor of 10 in less than five years (e.g., EER<2% for NIST SRE 2008 telephone speech). Moreover, such systems are able to compute millions of comparisons a thousand times faster than real time after speech features are extracted. However, some challenges remain, because if there is a mismatch between the conditions of the FA training database and the speech used for comparison, the effectiveness of the compensation significantly decreases. This problem is especially relevant in forensic voice comparison, where the availability of speech matching operational conditions is usually sparse. In this presentation we show the impact of this effect in realistic simulated case studies. We use the Baeza–Ahumada IV database, which contains speech acquired with the Spanish Guardia Civil facilities, used in their daily work. We also present algorithms to handle sparsity in the data used for training FA models. Finally, we outline future research plans in order to improve session variability compensation performance in forensically realistic conditions.
Measuring reliability in forensic voice comparison.
Authors: Morrison Geoffrey Stewart , Epps Julien , Rose Philp , Thiruvaran Tharmarajah , Zhang Cuiling
Published: October 2010

Recently there has been a great deal of concern in forensic science about validity and reliability (accuracy and precision). The log-likelihood-ratio cost (Cllr), developed for automatic speaker recognition, is increasingly applied as a standard measure of accuracy in forensic voice comparison, but so far there has been little work on developing a metric of precision within this field. Because voice data can have a large amount of intrinsic variation at the source, and likelihood ratios are typically calculated using a single suspect recording and a single offender recording, assessing the precision of a forensic-voice-comparison system is extremely important. This presentation discusses the importance of measuring precision and describes two procedures, one parametric and one non-parametric, for calculating 95% credible intervals for the likelihood ratios resulting from running tests of forensic-voice-comparison systems (in which some comparisons are known to be same-speaker comparisons and others are known to be different-speaker comparisons). Examples are drawn from both acoustic-phonetic and automatic forensic-voice-comparison systems.
Bearing estimation using compressive sensing.
Authors: Edelmann Geoffrey F. , Gaumond Charles F.
Published: October 2010

The performance of compressive sensing for determining bearing angle on a horizontal array is presented. The sampling requirements for infinite signal-to-noise ratio (SNR) is shown first. Detection capabilities are determined using a suboptimal array which is degraded both in length and number of elements. Using a detection threshold based on additive noise, the number of samples needed per tonal is shown as a function of SNR. The effects of anisotropic noise and array element location uncertainty in an oceanic waveguide are discussed. [Work supported by the Office of Naval Research.]
Use of unidirectional microphones for the localization of sound sources.
Authors: Tajari Mahdi , Rizzo Piervincenzo
Published: October 2010

Targeting peoples or object’s sound by passive acoustic sensors is of relevant interest in several military and civil applications. To date, methods are based on beam-forming algorithms or time-delay-estimate applied to sound detected by using sparsely deployed omnidirectional microphones (OMs). In this paper an approach for the localization of acoustic sources based on the use of unidirectional microphones (UMs) and amplitude-based signals’ features to extract information about the direction of the incoming sound is proposed. As the method relies on the accurate knowledge of the microphones’ directivity, analytical expressions of the acoustic sensors’ polar pattern were derived by testing them in an anechoic chamber. Then an experiment was conducted in a classroom-type environment by using an array of three UMs. The novelty of the method presented here consists on the use of UMs rather than OMs and on the ability to extract the sound direction by considering features such as pulse amplitudes rather than pulse arrival times.
Application-specific integrated circuits based on reconfigurable logic.
Authors: Jiménez Flores Armando , Peña Guerrero Maximino , Negrete Redondo Jose J.
Published: October 2010

A problem for developers of measuring and control instruments for medical equipment consists of building systems with higher degrees of sophistication, automation, and programmability, at the same time that it must limit the necessary space for the increasing number of components involved in his designs. In this context, it is attractive to develop application-specific integrated circuits (ASICs) for technologies of Field Programmable Logic Array (FPGA) devices because they allow circuit architecture and they are reconfigurable. This paper presents an analysis of the advantages of the FPGA technology in the development of specific applications to capture and to process signal with high performance. The tools used are Integrated Software Environment, ISE 10.1, based on language Very High Speed Integrated Circuits Hardware Description Language (VHDL) and a development system, Virtex-5 ML501, both of Xilinx. The results presented describe some basic logic functions that contain ASICs on FPGAs, oriented to the capture and signal processing.
Deep water fossil fuel extraction and production technologies: A developing source of ocean noise pollution.
Authors: Stocker Michael
Published: October 2010

The era of easy oil is rapidly closing and more challenging reservoirs are being developed offshore on outer continental shelves using a suite of developing technologies. Deep water (1000–10 000 ft) development occurs under ambient pressures of 30–300 atm (400–4000 psi) and wellhead differential pressures of up to 20 000 psi. Active processing equipment is mounted on the sea floor to diminish the risks and costs of the multiple pipe runs that would be required for above sea-level processing. The equipment includes separators, multi-phase and multi-stage pumps, injectors, and metering equipment. Given the potential for extreme pressure differentials and the multi-phase nature of the product (liquids, gas, and solids) it is likely that some of these processes generate substantial noise. This paper is a review of the deep water extraction and production technologies and an overview of the physical conditions found in global deep water fossil fuel extraction and production.
Projections on acoustic techniques and strategies in the Deepwater Horizon response and beyond.
Authors: Caruthers Jerald W. , Sidorovskaia Natalia A. , Hansen Kurt
Published: October 2010

The subject of non-floating oil, in the context of oil spills such as the Deepwater Horizon spill (DwHS), refers to both shallow, approximately neutrally buoyant, sub-surface oil and heavier oil that has sunk to a shallow-water seafloor. For the DwHS, in neither case is there firm evidence of the existence of such wayward oil. For the case of sub-surface oil there is only anecdotal evidence and a video clip of such oil observed in the scuba diving of Philippe Cousteau. Initial reports from the NOAA ship Thomas Jefferson on the DwHS response indicated no conclusive evidence to shallow-subsurface oil as of June 11, 2010 using multibeam sonars. To our knowledge, there has been no reported work on oil on the shallow seafloor in the DwHS response area. This paper summarizes recent work on acoustic techniques for use in detecting non-floating oil and discusses new techniques and strategies.
Acoustic propagation and ambient noise in the Philippine Sea: The 2009 and 2010-2011 Philippine Sea experiments.
Authors: Worcester Peter F. , Andrew Rex K. , Baggeroer Arthur B. , Colosi John A. , D'Spain Gerald , Dzieciuch Matthew A. , Heaney Kevin D. , Howe Bruce M. , Kemp John N. , Mercer James A.
Published: October 2010

The 2010–2011 North Pacific Acoustic Laboratory Philippine Sea experiment (PhilSea10) combines measurements of acoustic propagation and ambient noise with the use of acoustic remote sensing to characterize the oceanographically complex Philippine Sea. The goals are to (i) understand the impacts of fronts, eddies, and internal tides on acoustic propagation; (ii) determine whether acoustic methods, together with other measurements and ocean modeling, can yield estimates of the time-evolving ocean state useful for making improved acoustic predictions and for understanding the local ocean dynamics; (iii) improve our understanding of the physics of scattering by small-scale oceanographic variability; and (iv) characterize the depth dependence and temporal variability of the ambient noise field. The PhilSea10 experiment was preceded by a pilot study/engineering test in April–May 2009 (PhilSea09) to obtain an initial look at propagation and ambient noise in the Philippine Sea, study short-term variability using long-duration transmissions, and test equipment to be used in 2010–2011. In both experiments, a combination of moored and ship-suspended low-frequency acoustic sources transmit to a newly developed distributed vertical line array receiver capable of spanning the water column in deep water. In 2009, the towed five octave research array also recorded the transmissions. [Work supported by ONR.]
The University of Washington’s Applied Physics Laboratory’s participation in the Philippine Sea 2009 and Philippine Sea 2010 experiments: A summary.
Authors: Mercer James , Andrew Rex , Ganse Andy , White Andrew , D’Spain Gerald
Published: October 2010

The Office of Naval Research’s (ONR) program in Ocean Acoustics maintains a thrust in deep-water acoustics and has recently funded two major efforts in the Philippine Sea known as PhilSea09 and PhilSea10. PhilSea09 was planned as a pilot study and an engineering test in preparation for the more extensive PhilSea10 experiment. However, PhilSea09 was also partially supported by ONR’s program in undersea signal processing. This paper will summarize the Applied Physics Laboratory’s involvement in PhilSea09, its support to the undersea signal processing program, and the Laboratory’s efforts in PhilSea10.
Reliable acoustic path and convergence zone bottom interaction in the Philippine Sea 09 Experiment.
Authors: Baggeroer Arthur B. , Scheer Edward K. , Heaney Kevin , D’Spain Gerald , Worcester Peter , Dzieciuch Matthew
Published: October 2010

One of the objectives of the Philippine Sea 09 (PhilSea09) was to examine the multipath structure of RAP propagation at the seafloor. For a source near the surface, a receiver at the seafloor, and ranges approaching one-half a CZ, one expects a direct path, seafloor reflected and refracted paths plus water column multiples. These were measured using the bottom elements of the SIO deep vertical line array. Similarly, for both a source and a receiver at the surface and at CZ ranges, these same paths propagate back to the surface. These were also measured with the PSU FORA (five octave research array). The experiment was part of an NPAL Group effort. [Work supported by ONR Ocean Acoustics.]
Towed CTD (conductivity, temperature, and depth) chain measurements in the 2010 Philippine Sea experiment.
Authors: Ganse Andrew A. , Mercer James A.
Published: October 2010

The 2010 Philippine Sea Experiment cruise included two tows of the “towed CTD chain”, an 800-m-long, ship-towed cable with 88 CTD sensor fins distributed along its length. The goal of this instrument’s use in the experiment was to obtain high-resolution (in space and time) measurements of ocean conductivity and temperature in the upper 500–700 m of the deep-ocean water column, in order to characterize the horizontal spatial statistics of internal waves and “spice” (density-compensated sound-speed fluctuations). The effects of such ocean variability upon acoustic variability in long-range ocean acoustic propagation is an active area of current research. Despite technical difficulties with the system, measurements at 3–5 s sampling periods were obtained on one to three dozen sensors distributed over 700 m depth. The first tow was 93 km for about 39 h and the second tow was 124 km for about 30 h. These datasets will be validated and/or augmented by measurements from a Microcat CTD mounted on the bottom of the cable on each tow and a second mounted at mid-cable during the second tow. A summary of the dataset and initial findings will be shown. [Work supported by ONR.]
Hot topics in engineering acoustics: Acoustic metamaterials.
Authors: Howarth Thomas R.
Published: October 2010

The emerging field of acoustic metamaterials is an outgrowth of the field of electromagnetic metamaterials. Acoustic metamaterials are engineered materials and/or fluids designed to control the behavior of propagating sound. The control includes the focusing of sound as well as the redirection of sound around objects in order to avoid interactions. This presentation begins with an introduction of leading theoretical efforts followed by an overview of recent engineering developments including an acoustic superlens for high-resolution clinical imaging and an acoustic metamaterials panel for sound attenuation. Challenges and opportunities for future developments will be discussed.
A comprehensive approach to high performance hearing protection.
Authors: Svean Jarle , Holter Trym , Ottesen Georg Esa , Henriksen Viggo , Kvaloy Olav
Published: October 2010

The ideal hearing protection device (HPD) should ensure a safe level of noise exposure while at the same time providing a high degree of situational awareness. This paper describes the core elements of a digital signal processing based HPD representing such a comprehensive approach to hearing protection. A set of features has been designed to offer optimal protection. First, a built-in automatic sealing control warns the user if the appropriate passive attenuation is not achieved. Second, the hear-through functionality ensures that the user is not overprotected such that situational awareness is compromised, while at the same time the level of the reproduced sound is kept within safe limits. This functionality is combined with instantaneous impulse compression. Further adding to the HPD scheme, digital active noise reduction is used for the attenuation of low-frequency sound. Based on the performance characteristics of any given HPD, traditional approaches to noise exposure control use some highly uncertain estimates of the HPD attenuation, often including de-rating schemes. The HPD described here, on the other hand, offers the option to monitor in-ear noise exposure. This offers an additional barrier against noise induced hearing loss by warning the user in situations where he is approaching over-exposure from noise.
Improving the speech intelligibility of forensic audio recordings through adaptive filtering with non-synchronous interference signals.
Authors: Boyczuk Jeff , Luknowsky David , Gover Bradford , Ding Heping
Published: October 2010

Forensic audio recordings are frequently made in uncontrollable acoustic environments where background sound emanating from television, radio, and video or music playback may interfere with the intelligibility of the intended “target” speech on a recording. In such cases, adaptive filtering techniques have proven highly effective in eliminating the interfering sound sources and improving intelligibility, provided that the interfering reference signal was acquired simultaneously with the target speech. However, in cases where interfering signals are acquired through a post hoc retrieval of broadcast, music, or video recordings, non-linear time base differences between the original and the secondarily acquired reference may significantly lessen the effectiveness of conventional adaptive filtering techniques in improving speech intelligibility. The current paper describes the results in applying a commercially available, adaptive filtering tool as well as a newly developed tool, drift-compensated adaptive filtering (DCAF), for improving the intelligibility of recorded speech when utilizing a non-synchronously acquired reference signal. Listening tests show an overall improvement in speech intelligibility through the application of adaptive filtering with non-synchronous reference signals, with greater intelligibility for DCAF-processed audio recordings as compared to recordings processed with conventional adaptive filtering techniques.
The effects of Lombard speech on vowel formant measurements.
Authors: Kirchhuebel Christin
Published: October 2010

This study analyzes the effects of Lombard speech on vowel formant frequencies. Ten male native German speakers were selected from the “Pool 2010” corpus, which was recorded at the Bundeskriminalamt, Germany. Spontaneous speech produced in a neutral setting and Lombard setting, where 80 dB of noise was played through headphones, was analyzed. Measurements of F1, F2, and F3 were collected from 10 vowel categories for every speaker in both conditions. The results agree with previous findings in that F1 is consistently higher in the Lombard condition. The effect on F2 is very variable and complex. F3 was less affected than F1 and F2, but changes were present, especially for speakers with low F3’s in modal speech. Differences could be observed among vowel categories. Inter-speaker variability was found to be large with respect to the size of increase in F1 and the direction and size of change in F2. The findings are discussed in light of the articulatory changes that have been associated with Lombard speech, and the implications for forensic speaker comparison are spelled out.
Bathymetric scattering and seafloor interface waves in long-range ocean acoustic propagation.
Authors: Stephen Ralph A. , Bolmer S. Thompson , Dzieciuch Matthew A. , Worcester Peter F. , Andrew Rex K. , Mercer James A. , Colosi John A. , Howe Bruce M.
Published: October 2010

Ocean bottom seismometer observations during a long-range ocean acoustic propagation experiment in the North Pacific in 2004 showed robust, coherent, late arrivals that were not observed on hydrophones suspended 750 m and more above the seafloor and that were not readily explained by ocean acoustic propagation models. These deep seafloor arrivals were the largest amplitude arrivals on the vertical velocity channel for ranges from 500 to 3200 km. They appear to correspond to energy converted from ocean acoustic waves into seafloor interface (Scholte) waves at a small bathymetric high about 18 km from the receivers. Some problems with this model are the following: (a) It is rare to observe discrete Scholte waves propagating 18 km or so on the seafloor. It is usually assumed that Scholte and shear waves decay rapidly in and along the seafloor because of strong scattering and intrinsic attenuation. (b) There is apparently insignificant scattering back into the water column because this would have been observed on the DVLA. (c) Why is there no sign of this scattering process for ranges less than 500 km? (d) Although this model accurately predicts arrival times of the deep seafloor arrivals, the amplitudes are not consistent. [Work supported by ONR.]
Parameter-based mathematical optimization using MATLAB and CATT-A software.
Authors: Rife Dave
Published: October 2010

Mathematical optimization techniques have been applied to room acoustic modeling within CATT-A. Stochastic optimization methods such as genetic algorithms, pattern search, and ant colony optimization are used via software integration between MATLAB and CATT-A, allowing for acoustic parameter specific optimization of variable room geometry. The optimization routines rely on results from geometrical ray tracing, which informs the designer on aspects of room acoustics that empirical formulas cannot take into account. An example is presented showing an algorithm that optimizes placement of sound absorbing treatment to obtain a fixed speech transmission index using minimal sound absorbing material in a classroom setting.
Sound energy decay analysis in multiple coupled volume systems.
Authors: Xiang Ning , Robinson Philip , Jing Yun
Published: October 2010

There has been an increasing need in analyzing sound energy decays consisting of more than one decay slope, so-called non-single-exponential decays. It has been considered very challenging to estimate parameters associated with double-slope decay characteristics, even more challenging when the coupled-volume systems contain more than two decay processes. To meet the need of characterizing energy decays of multiple decay processes, this work reports investigations using both acoustical scale-models and numerical models of three coupled volumes. Two levels of Bayesian inference: model selection and parameter estimation, have been applied to detection and characterization of sound energy decays. Experimental results measured in acoustical scale models and numerical results from diffusion-equation-based models are used to validate the Bayesian analysis methods. The analysis methods are then applied to geometric-acoustics simulations of a conceptual concert hall. This work demonstrates that the analysis method within the Bayesian framework is capable of determining more than two decay slopes and estimating the corresponding decay parameters and parameter uncertainties.
Noisy neighbors: A role for masking interference in the evolution of communication systems in neotropical dendrobatid frogs.
Authors: Amézquita Adolfo , Pimentel Lima Albertina , Hdl Walter
Published: October 2010

Signal detection and signal recognition are necessary for effective communication and, thus, vulnerable to the selective effects of interference by heterospecific signals. Previously, we showed correlative evidence that the frequency response curve of territorial frogs Allobates femoralis is narrower at places where it co-occurs with the frog Ameerega trivittata, which utters a spectrally overlapping call. Here we (1) conducted manipulative experiments to test the underlying assumption that A. trivittata calls affect the behavioral and reproductive performance of unexperienced A. femoralis males. The addition of A. trivittata calls led to larger territories and lower opportunities for mating and breeding in A. femoralis males. Thus, heterospecific masking reduces breeding opportunities through its effects on territorial but not calling behavior. We also (2) tested at a species-rich acoustic community whether the recognition space of five frog species was shaped in a way that minimizes overlap with the heterospecific signal spaces. The recognition space was modeled from the all-or-none phonotactic reactions of territorial males. Our data supported the initial hypothesis for three out of five species. Both data sets suggest that masking interference may shape the receiver portion of the communication systems without concomitant changes in the call.
Monitoring frog species recovery in secondary tropical forests using automated species identification.
Authors: Hilje B. , Aide T. M. , Corrada-Bravo C.
Published: October 2010

Although the most important causes of the current amphibian decline and species extinction are habitat degradation and habitat loss, in some regions, forests are recovering where agriculture has been abandoned. After 30–40 years of recovery ,vegetation characteristics are often similar to those of mature forests, but little is known about the recovery of the fauna. In this study we evaluated the recovery of amphibian species in a chronosequence of secondary forests (10–30 years old) and mature forest. Each site was sampled in March, April, and May 2010 for 10 days using automated recorders which produce 2000 1 min recordings per site. Species specific algorithms were developed for 20 species of frogs and an automated species identification software was used to process the recordings. A total of 11 species were identified, and most were leaf-litter frogs. Species Oophaga pumilio and Diasporus diastema were identified in all sites. The highest species richness was observed in the 22–30-year-old forest, where there was a mix of species from both young and mature forests. These results suggest that similar to the vegetation, the majority of the original frog community has been able to recolonize these secondary forests.
Flexibility in the advertisement call of Hypsiboas pulchellus (Anura: Hylidae) in response to microhabitat characteristics.
Authors: Ziegler Lucia , Arim Matías , Narins Peter M.
Published: October 2010

The structure of the environment determines patterns of signal degradation and attenuation, potentially affecting communication. The expected adjustment in call structure improving signal transmission in an environment was formalized in the acoustic adaptation hypothesis. Within this framework, most studies considered anuran calls as fixed attributes determined by local adaptations. However, intra-individual variability in vocalizations has also been reported. Evidence is presented here for phenotypic flexibility in the advertisement call of Hypsiboas pulchellus in response to induced changes in microhabitat structure. Males were recorded in free-field conditions. Microhabitat was then modified, placing a styrofoam enclosure around each calling male, re-recording calls therein. Student tests for independent samples (intra-individual variation) and paired samples (inter-individual variation) rendered similar results. All temporal variables were significantly longer when individuals were broadcasting inside the enclosure. Spectral attributes were also subject to modulation, although the magnitude and direction of these adjustments were inconsistent among males. Playback experiments within the enclosure yielded results which rule out treatment-induced variation, highlighting the potential rôle of call flexibility on detected call patterns. This study questions the view of fixed adaptations as the sole determinant of the match between call and environment, positing phenotypic flexibility as a main determinant of this interplay.
Communication through the substrate as a solution for small plant-dwelling insects.
Authors: Cokl Andrej , Virant-Doberlet Meta
Published: October 2010

High-frequency airborne sound is quickly absorbed in vegetation, and outside the plant shelter such signals attract predators. Furthermore, small insects cannot emit efficiently low-frequency airborne sound when their diameter is smaller than a third of the radiated wavelength. For plant-dwelling insects, substrate-borne sound signaling remains the best solution for communication in dense vegetation typical for the tropics. Communication range in such an environment depends on tuning of vibratory signal properties with mechanical characteristics of plants and sensory abilities to extract the information from the environmental noise. Nezara viridula and other until now investigated species of the stink bug family Pentatomidae represent the model for solutions optimizing long-range communication through green plants. They communicate with vibratory signals of the dominant frequency around 100 Hz, which travel through plants with low attenuation, creating standing wave conditions in the plant’s rod-like structures. Green plants act as low-pass filter and their resonant peaks fit well with the spectral peaks of stink bug vibratory emissions. The species’ leg sensory organs with the underlying neural network are sensitive enough to enable communication through a plant on a distance of several meters. Comparative data on substrate-borne sound communication in burrower (Cydnidae) and predatory (Asopinae) bugs will be discussed.
Visualization of a focused ultrasound beam to guide radiation force-induced clearance of kidney stones.
Authors: Owen Neil R. , Cunitz Bryan W. , Shah Anup , Curra Francesco P. , Bailey Michael R. , Crum Lawrence A.
Published: October 2010

The incidence of kidney stones within the US population is now 10%, and rising. Many patients present with small stones, primary or recurrent, do not indicate interventional stone removal. We previously described a new stone removal method employing selective application of acoustic radiation force, at diagnostic output levels, to reposition stones for passive clearance. In this method, an imaging array transducer transmits pulses for image guidance and focused pulses to reposition the stone. Here we propose a new flash imaging modality to visualize the focused pulse to confirm targeting on the stone. To visualize the focused beam, short pulses were phase-delayed across the transducer aperture to transmit a focused wave, from which echo data were collected, beamformed, and overlaid on a B-mode image. The beam profile is visible because echo amplitude is higher within the convergent, focal, and divergent regions. During experiment, a stone was placed within a tissue phantom simulating the kidney lower pole and ureter. Once identified with B-mode imaging, focal delays were calculated, targeting was confirmed by the beam visualization modality, and the stone was repositioned. Flash imaging visualization of the focused beam could be similarly applied to high-intensity focused ultrasound therapy. [Work supported by NIH DK43881 NSBRI-SMST01601.]
Acoustic stone localization during lithotripsy.
Authors: Kracht Jonathan M. , Manzi Nicholas J. , Feijo’o Gonzalo R. , Barbone Paul E. , Cleveland Robin O.
Published: October 2010

It is desirable to mitigate damage to kidney tissue induced by shock waves administered during lithotripsy. Stone movement due to patient respiration causes a fraction of the shock waves to miss the stone. The goal here is to ensure that shock waves are delivered to the kidney only when the kidney stone is in the focal region of the lithotripter. We present the design of a collar with an array of ultrasound transducers that can be retrofitted to a clinical lithotripter. The transducers are used in a pulse-echo mode and a hybrid technique combining numeric time-reversal and MUSIC (MUltiple-SIgnal-Classification) is employed to determine the location of a kidney stone relative to the focus of the lithotripter. A model of the acoustic collar was used to select system parameters including the transducer count, center frequency, and transducer placement. The performance of the collar was assessed by translating artificial kidney stones in water and using porcine body wall as an aberrating layer. Performance will be reported of the system including resolution limit, ability to target multiple stone fragments, and the effect of an aberrating layer. [Work supported by NIH.]
Exploitation of cavitation-enhanced heating for release of doxorubicin from thermosensitve liposomes by therapeutic ultrasound.
Authors: Mylonopoulou Eleonora , Bazan-Peregrino Miriam , Arvanitis Costas D. , Coussios Constantin C.
Published: October 2010

The systemic toxicity of current chemotherapeutic treatments motivates the investigation of targeted delivery techniques to restrict the action of drugs to the tumor region. ThermoDox© copyright (Celsion Corporation) consists of doxorubicin, a common anticancer agent, encapsulated within thermally sensitive liposomes designed to release their contents above 39 °C. Activation of such an agent with the use of HIFU, which can generate localized heating non-invasively, potentially combines the benefits of targeted chemotherapy and hyperthermia while minimizing undesirable systemic side-effects. ThermoDox© release was investigated and optimized in a novel cell-embedding, tissue-mimicking material. The material was exposed to 1.1 MHz HIFU using a range of clinically relevant pressure amplitudes, duty cycles, and exposure durations to identify optimal insonation conditions for complete doxorubicin release, resulting in cell death that is solely due to drug activity. The corresponding temperature profiles were mapped throughout the focal region using embedded needle thermocouples. Drug release and cell viability were quantified using fluorescent microscopy and cell luminescence, respectively. Optimal conditions for drug release only due to the thermal effects of HIFU, with and without cavitation, were identified and cell death only due to drug release was achieved, demonstrating the potential for safe and effective targeted drug release by HIFU-induced hyperthermia.
Bamboo pipe wall vibrations in Asian free reed instruments.
Authors: Cottingham James P.
Published: October 2010

Wall vibrations in the bamboo pipes of the Asian free reed mouth organs have been investigated. The pipes studied include quasi-cylindrical examples from a khaen built in northeastern Thailand and some pipes from a Southeast Asian free reed gourd pipe. Modal frequencies and mode shapes of a number of the pipes were measured using mechanical excitation. The modes of vibration of these pipes were also simulated using measured physical properties of the bamboo, which has a relatively low density and elastic modulus, and a significant difference between the elastic moduli parallel and perpendicular to the grain. Vibration of the pipe walls was also studied for the mechanically blown reed-pipe combination. Measurements of pipe input impedance have been made, showing changes occurring as a result of damping the pipe vibrations. Possible effects of wall vibrations on the radiated sound have also been explored.
Regulatory protocol for Colombia’s national regulations on environmental noise and noise emission Act 0627.
Authors: Echeverri Londoño Carlos , González Alice Elizabeth , Acosta Alejandro , Lenis Juan Fernando
Published: October 2010

Act 0627 of April 7, 2006, was an important progress regarding national regulations on environmental noise and noise emissions. However, during the first years of its validity, doubts about its interpretation and application have been raised. In response to this issue, the Ministry of Environment, Housing and Territorial Development has signed a contract with the University of Medellin for the development of a detailed protocol that would allow the unambiguous and rigorous implementation of the Act. The protocol was submitted to the Ministry in January 2010. It includes detailed guidelines for organizing and carrying out measurements of noise levels (including the selection of points to consider), processing and interpretation of measurement results, minimum content of the reports delivered as a result of the measurements, performing acoustic maps, and guidelines for the preparation of plans for noise abatement.
Environmental noise culture.
Authors: Lizana Pablo
Published: October 2010

Noise generation and perception are highly related to given societies, so in order to improve the acoustic quality of life for communities, it is necessary to include noise items in formal education. The American States Organization is doing research on the relation of science, technology, society, and values to help implement programs to set these principles for the new generation. Some of these relationships are discussed.