bluuebunny/crossref_metadata_2025 huggingface dataset:
Four interpretations of temporal memory operators in the wave equation
Authors: Holm Sverre
Published: October 2015

Attenuation and dispersion in ultrasound and elastography may be modeled with convolution memory operators in the wave equation. When the attenuation follows an arbitrary frequency power law the memory is a time domain power law. Since that is also a fractional time derivative, a large body of literature on fractional derivatives then becomes available for analysis and simulation. It can also be shown that, e.g., an elementary grain shearing process in an unconsolidated saturated sediment results in fractional wave equations for both compressional and shear waves. Second, some of these wave equations can be derived from constitutive equations with memory operators, ensuring satisfaction of causality and the Kramers-Kronig relations. The fractional Kelvin-Voigt and Zener models and their resulting attenuation and dispersion will in particular be discussed. The fractional operators can also be interpreted as the result of an infinite number of basic processes. Therefore, third, a fractional wave equation can be shown to be the result of an infinite number of elementary relaxation processes. Fourth, the fractional constitutive equation can also be expressed as an infinite sum of integer order derivatives of higher order which is also equivalent to a wave equation with higher order derivative terms.
Modeling geometrically complex layered regions in ultrasound using a modified T Matrix approach
Authors: Clement Gregory T.
Published: October 2015

A penetrable finite region consisting of layers of arbitrary shape, density, and sound speed is considered. Solutions are formulated as a T-matrix operator that is independent of the incident field, thereby allowing scattering due to any external source field to be rapidly calculated in a single operation. In departure from standard methods, boundary terms are written in their Fourier integral forms in polar coordinates. It will be shown that the approach allows scattering terms to be reduced to a single integral equation, a set of which form a block tri-diagonal matrix; a well-studied matrix form with various methods available for efficiently solving the inverse problem. A numeric algorithm is developed around the approach and validated against a previously reported wave-vector approach. Several medically relevant examples will be shown and discussed along with the potential for such methods to aid in the development of diagnostic and therapeutic techniques. [Study funded under National Institutes of Health Grant R01EB014296.]
Ultrasonic interrogation of tissues and tissue-mimicking materials with the aid of wideband hydrophone-based transducer characterization
Authors: Wear Keith A.
Published: October 2015

Ultrasonic measurements can provide useful information to characterize biologic tissues and tissue-mimicking materials. Quantitative accuracy may be improved by first characterizing spatial and frequency dependence of ultrasound transducer beams, which may be measured with hydrophones in a water tank. Accuracy of estimates of acoustic output detected by hydrophones may be enhanced by deconvolving hydrophone sensitivity from hydrophone voltage output. Full deconvolution requires knowledge of magnitude and phase of hydrophone sensitivity, which may be measured over frequency bands of 1–40 MHz using time delay spectrometry. Time-delay spectrometry may also be used to provide wideband through-transmission measurements of attenuation and sound speed in tissues and tissue-mimicking materials. Much information regarding tissue composition and structure may be obtained from (1) through-transmission mode measurements of attenuation, sound speed, and dispersion, (2) pulse-echo mode measurements of backscatter, and (3) pulse-echo tracking of shear waves induced by acoustic radiation force push beams.
Acoustical characterization of nano-porous carbons
Authors: Horoshenkov Kirill , Pelegrinis Michael , Conte Marco , Venegas Rodolfo , Umnova Olga
Published: October 2015

The acoustical and related non-acoustical properties of activated carbon were studied to understand better the effect of added catalyst and acid treatment on the nano- and micro-structure of activated, porous nano-carbon. The acoustical impedance was measured in a 45 mm diameter impedance tube with a special adaptor to accommodate a very small material quantity available for this experiment. The presence of the adaptor was compensated using the procedure detailed in Dupont et al. [POMA 19, 065008 (2013); http://dx.doi.org/10.1121/1.4799701]. The acoustic impedance of activated carbon was predicted using the model proposed by Venegas [Section 6.1, Ph.D. thesis, University of Salford, 2011]. The micro- and nano-scale porosities and pore sizes were determined by fitting the model to the acoustic impedance data in the frequency range between 50 and 1000 Hz. It is shown that the acid treatment and addition of catalyst result in the reduced radius of nano-pores and reduced nano-porosity. These effects are small but measurable acoustically. These results are consistent with the results of the BET experiment. This work provides the foundation for the development of acoustical methods for nano-porous material characterization which are rapid and non-invasive.
Numerical and experimental analysis for the construction of an in situ measurement system of the acoustic impedance to be used as an academic tool
Authors: Lobato Lucas C. , Carneiro Eric B.
Published: October 2015

Due to the need for a non-destructive method to measure sound absorption of acoustic materials, in situ methods have achieved significance in research on acoustic. So, the goal of this work is to build and test a system of in situ measurement of acoustic impedance to be used as an academic tool for undergraduate students of Acoustical Engineering on the Federal University of Santa Maria, Brazil. At first, two measurement techniques are introduced in this article: PP system and PU probe. Then, numerical analyses through a FEM model for both techniques are presented. The choice of FEM to model the measurement system occurs as an alternative to the BEM model, widely used in the literature. Thus, through the numerical model, errors were observed due to the finite size of sample. So, a strategy based on techniques proposed by the literature was applied, obtaining better precision. All numerical analysis were referenced on the Johnson-Champoux-Allard model of porous material. At last, a prototype of the measurement system is presented, followed by experimental results, using two microphones (PP system). There results were compared to measurement performed with an Impedance Tube.
The Etiology of chatter in the Himalayan singing bowl
Authors: Keefer Chloe , Collin Samantha , Moore Thomas R.
Published: October 2015

The Himalayan singing bowl is a nearly symmetric idiophone played by rotating a wooden stick called a puja around the outer rim of the bowl. The vibrations of the bowl are excited by a stick-slip mechanism, which produces a radial motion of the bowl with a deflection shape similar to the (2,0) mode. We present experimental evidence that the position of the puja coincides with the point of minimum displacement on the bowl, indicating that it imposes a node in the deflection shape that rotates around the bowl with the puja. However, in many cases the puja is forced off of the bowl and an audible chatter is produced as the puja repeatedly strikes the bowl several times per second. This indicates that the position of the puja is not a node, but rather merely a point of minimum deflection. Examination of high-speed electronic speckle pattern interferograms and time-resolve acoustic spectra provide insight into the mechanics of the singing bowl and the origin of the chatter.
Loudness of temporally varying environmental sounds
Authors: Verhey Jesko L. , Hots Jan , Wächtler Moritz , Rennies Jan
Published: October 2015

Loudness of speech, speech-like signals, and other dynamic environmental sounds were measured and compared to predictions of current loudness models and predictions on the basis of the relevant standards. Loudness was assessed experimentally by using a loudness matching procedure and categorical loudness scaling. The scaling method used in our study is in agreement with the requirements of the international standard on categorical loudness scaling. Categorical scaling allows for a fast assessment of loudness over a large level range but has the disadvantage that loudness is not measured in sones, as commonly used in loudness models. The data of the two methods are compared by deriving levels at equal loudness from the categorical loudness data. In addition, the present study discusses to what extend the scaling data can be compared to loudness predictions by using recently proposed equations relating categorical units to sones. The comparison of the measured levels at equal loudness and simulations revealed that for speech and speech-like signals the long-term spectrum largely determines the loudness of the sound. Dynamic models with short time constants tend to overestimate loudness. In general, this is also true for the other environmental sounds although for some technical signals discrepancies remain.
Some factors affecting loudness measurement and prediction
Authors: Schlauch Robert S. , Carney Edward , Yu Tzu-Ling J. , Han Heekyung J.
Published: October 2015

The current ANSI standard (ANSI S3.4, 2007) estimates the loudness of sustained sound, but many naturally occurring sounds have time-varying levels. Glasberg and Moore (2002) published a model for the prediction of time-varying sounds and this aspect should be considered as part of a revision to the ANSI standard. To assess the predictions of the dynamic model, loudness magnitude estimation functions were obtained for 24 listeners using pure tones (0.5 and 1.0 kHz), vowels, spondees, and speech-shaped noise (SSN) presented at levels from 40 to 90 dB SPL. Inferred equal-loudness levels from the fitted loudness functions were compared to the model predictions. The loudness model was qualitatively consistent with the behavioral data. The model predicted SSN to be louder than vowels and spondees which would be louder than tones; however, the model over-predicted the loudness differences. Possible explanations for the over-prediction include biases in loudness judgments, cognitive factors regarding learned expectations for loudness, assumptions regarding the free-field-to-headphone transfer function, and the model’s over-prediction of spectral, loudness summation, a result found recently (Schlittenlacher et al., 2014) for the ANSI standard and DIN 45631.
Far-field acoustical measurements during a Space Launch System solid rocket motor static firing
Authors: Harker Blaine M. , Reichman Brent O. , Stout Trevor A. , Whiting Eric B. , Gee Kent L. , Neilsen Tracianne B.
Published: October 2015

Acoustical measurements were made in the very far field during a recent test firing of the five-segment QM-1 Space Launch System solid rocket motor at Orbital ATK. Data were taken using 6.35 mm and 12.7 mm type-1 microphones at three far-field locations to the sideline and aft of the nozzle at a range of 650–800 nozzle diameters. The experiment setup, including the appreciable terrain changes, is first discussed. Spectral and autocorrelation analyses highlight the variation of the noise with respect to observation angle. In addition, high-frequency spectral characteristics and waveform statistics are evidence of the significant nonlinear propagation over the propagation range. Effects of microphone size, terrain effects, and data stationarity during the firing are discussed. This dataset is compared to measurements of other solid rocket motors at closer and farther ranges, including the GEM-60 and the four-segment Shuttle Reusable Solid Rocket Motor.
Effects of age-related hearing loss on verbal processing and short-term memory
Authors: Janse Esther , Bree Elise D.
Published: October 2015

Adult aging is frequently accompanied by hearing loss, as well as by cognitive decline. Both play a role in listeners' understanding of noisy, foreign-accented speech and fast conversational speech. Hearing loss leads to increased perceptual effort during listening, which affects memory encoding of the spoken message. Furthermore, some studies have suggested that acquired hearing loss also has long-term effects by degrading the quality or accessibility of phonological representations in long-term memory. This was investigated further by looking into non-word reading, thus bypassing immediate effects of hearing loss. A sample of 29 older adults, varying in degree of high-frequency hearing loss and visual digit span performance, saw 72 multisyllabic nonwords varying in phonotactic frequency (i.e., the phoneme-co-occurrence statistics of the language). They saw the nonwords for 5 seconds and were prompted to produce them from memory after another 3 seconds. As expected, response accuracy was influenced by phonotactic frequency of the nonword and digit span performance. Crucially, response accuracy was also higher if the participant had better hearing, supporting the claim that hearing loss degrades phonological representations in long-term memory. These results emphasize the broad consequences hearing loss has on language processing beyond its immediate effect on speech audibility.
Forward and back scattering in a shallow inhomogeneous environment
Authors: Stotts Steven A. , Knobles David P. , Koch Robert A.
Published: October 2015

An experiment in 20 m of water off Panama City, FL, motivates the simulation with several propagation models of the time series produced from rough seabed scattering. Both the forward and backward scattered time series are simulated on vertical line arrays in the 2–4 kHz band to ranges out to 5 km. Results from several Born approximation approaches are compared to the results of a full numerical two-way coupled-mode solution to analyze the measured data. The results from a method of separating the forward and backward scattered amplitudes are also presented. Competing effects, such as the interplay between modal attenuation and the scattering of the higher order modes, are examined within the context of both the full coupled-mode and Born approximation solutions.
Model-data comparisons of range-dependent shallow-water reverberation including both boundary and volume scattering
Authors: Ellis Dale D. , Pecknold Sean
Published: October 2015

A range-dependent shallow-water reverberation model using adiabatic normal modes has been previously developed [Ellis et al., ISURC Conference, La Spezia, 2008] to handle bottom scattering and clutter echoes in a range-dependent environment. It has now been extended to handle volume scattering from the water column and volume scattering from the sub-bottom. Beam time series similar to that from a horizontal line array can be produced. Comparisons can then be made directly with data, and area scattering maps created. Of particular interest will be data obtained on the triplet line array during the 2013 TREX experiment in the Gulf of Mexico off Panama City, Florida. Predictions will be compared with data for average reverberation from a number of pings, as well as ping-to-ping variability on a particular run. [Work supported in part by U.S. Office of Naval Research, Code 32.]
Acoustic comfort in living environment
Authors: Wiratha Made Samantha , Tsaih Lucky
Published: October 2015

As population of aging people growing fast, the need of long-term care facility is also increased. In the living environment of elder people, acoustic comfort has the same importance as thermal comfort and visual comfort. This research is to study the preference of acoustic comfort through the listening evaluation with normal hearing people. The listening evaluation is based on 20 live recorded sound samples from two Taiwanese long term care facilities and a university dormitory. The listening evaluation was participated by 66 architecture students. A semantic differential scale questionnaire with 11 pairs of sound qualities for each sound sample were used. The results shown that normal hearing people have negative impression for the current acoustic comfort condition of these Taiwanese long term care facilities. All of the respondents gave negative impression to water pump machine sound due to the “noisy” and “harsh” sound qualities. A live percussive music rehearsed event was associated with “noisy” and “agitating” impression by 97% of the respondents. Speech, TV, telephone ringing, snoring, and footsteps were also identified as discomfort sound quality. Bird chirping and quite dormitory room were recognized by 91% of the respondents as the most comfortable sound with the “natural” and “quiet” impression.
Effects of noise flanking paths on ceiling attenuation class ratings of ceiling systems and inter-room speech privacy
Authors: Madaras Gary , Heuer Andrew E.
Published: October 2015

Continuous plenums above suspended, modular ceilings and partial-height walls in buildings can result in inter-room speech privacy and annoyance problems, especially when noise flanking paths via air diffusers, grilles, and lights exist. However, testing of the effects of ceiling system noise flanking paths is limited in the industry. Multiple ceiling systems comprised of various noise flanking paths through air diffusers, grilles, and lights were tested in an independent, accredited, acoustics laboratory according to ASTM International (ASTM) E-1414 and E-413. Additionally, recorded speech was played back in the test chamber source room and binaurally recorded in the test chamber receiver room. The results show that wideband ceiling attenuation class (CAC) decreases by 10 decibels (dB) and 1/3 octave band normalized ceiling attenuation (Dn,c) decreases by 15 to 22 dB in the higher frequency bands when common noise flanking paths are introduced into a ceiling system with CAC-37 ceiling panels. Subjective listening during the course of these tests shows that a ceiling system comprised of CAC-37 panels and typical noise flanking paths (that drop the system rating down to CAC-27) did not provide speech privacy. Intelligibility of recorded speech transmitting into the receiver room was high.
The status of classroom acoustics in Colombia
Authors: Jaramillo Ana M. , Olson Bruce C. , Salcedo Milton A.
Published: October 2015

With the lack of standards to regulate classrooms in Colombia, we decided to find out what the current status was in terms of acoustical comfort. Due to the mild weather, classrooms usually do not have mechanical heating or cooling. For this reason, noise levels are mandated by proximity to busy roads or other noise sources. Their construction is typically done using heavy materials such as brick and concrete, which results in very low noise transmission, but Reverberation Times tend to be higher than recommended due to the little use of absorptive materials. Measurements and visual inspections were performed in several schools to evaluate these parameters against the current S12.60 ANSI standard.
Acoustical characterization of touristic caves in Portugal
Authors: Carvalho Antonio P. , Sousa Joana I.
Published: October 2015

Since the Palaeolithic, Mankind has been taking advantage of the acoustical characteristics of natural caves to perform its rituals. Nowadays, many of these spaces are used as touristic attractions or even as stages for musical performances. This study characterizes three touristic caves in Portugal where in situ measurements were done, of background noise sound pressure levels, RASTI, and Reverberation Time. The average RT values were 1.3 s to 1.7 s, and the RASTI average values revealed good intelligibility (from 0.50 to 0.57). The sound absorption coefficient of the stone that constitutes the interior of those caves was also measured in a standing wave apparatus.
A study on the analysis of hanok (the Korean traditional houses) acoustic characteristics
Authors: Lee Won-Hee , Kim Myung-Sook , Bae Myung-Jin
Published: October 2015

Hanok is a type of Korean traditional houses, which is built based on science. In order to build Hanok, necessary materials are wood, rock, and clay, which can be easily acquired in nature. Due to the natural building materials, it is known that hanok is efficient to keep it warm and cool. Its heating system, Ondol, uses thermal conduction and convection of heat from the fireplace. Doors and windows are located on south and east sides because cold wind comes from northwest side in winter and cool breeze blows from southeast side in summer. On the other hand, the genre of music that goes well with the Hanok is the unique melody of Gukak (Korean classic music). The floors and walls of the Hanok, the rafters, highlights Gukak's uniqueness and plays the role of a sound box. This study was conducted to analyze the harmony between Hanok features and Gukak's acoustic characteristics.
Transmission properties of vocalizations in a year-round territorial bird
Authors: Sandoval Luis
Published: October 2015

Acoustic Adaptation Hypothesis (AAH) predicts that acoustic signals using in long-distance communication should be optimized for transmission through its natural environment. To test if White-eared Ground-sparrows (Melozone leucotis) vocalizations are adapted to transmit long distances, I conducted two sound transmission experiments where I broadcast and re-recorded different calls, songs, and duets. This ground-sparrows use vocal communication year round for territory defense and mate attraction. I conducted the experiments inside ground-sparrows territories in Costa Rica, broadcasting natural vocalizations at different combination of distances, speaker and microphone heights to quantified the signal-to-noise ratio, tail-to-signal ratio, blur ratio, and excess attenuation. Songs and duets of White-eared Ground-sparrows showed similar patterns of degradation with distance and with proximity to the ground, suggesting that vocalizations facilitate communication with receivers at similar shorter distances (in less than a typical territory’s diameter). Chip calls showed higher degradation in comparison to tseet calls with the distance, suggesting that tseet calls are design for longer distance communication. To my surprise, chip calls, songs, and duets has not experienced strong selection for long distance communication, because results do not support the AHH, and probably these vocalization characteristics are under other selective forces as sexual selection or phylogenetic constrain.
Cetacean acoustic survey using towed array in the western South Atlantic shelf break
Authors: Andriolo Artur , Castro Franciele R. , Amorim Thiago , Secchi Eduardo R. , Di Tulio Juliana , Moron Juliana , Ramos Gabriela , Ribeiro Bruna , Zerbini Alexandre N. , Dalla Rosa Luciano , Mendes Raíssa R. , Palácio Fábio B.
Published: October 2015

Passive acoustic towed array during ship surveys has being applied to increase the knowledge about cetacean. From 2012 to 2015, towed arrays were used to investigate cetacean distribution along the western South Atlantic shelf break. Research cruises were performed between 26°S and 38°S over the continental shelf break and slope. Acoustic tracklines comprised an average of 780 nm of effort per survey. Hydrophone arrays (Auset®) were towed 150 and 300 m behind the vessel. The system was configured to give a variable frequency response from 1592 (High Pass Filter) to 100,000 Hz. Acoustic data were recorded as .wav files. Concurrent environmental and GPS data were logged automatically using WinCruz software. Visual positive identifications were associated to the acoustic recordings. The .wav files were analyzed using partially automated detections tools complemented with visual and acoustical searched for species confirmation whenever possible. A total of nine cetacean species were acoustically detected. The most frequently species were Physeter macrocephalus, Delphinus delphis, Stenella longirostris, Orcinus orca, and Globicephala sp.. Additional studies are needed to describe acoustic parameters of the various species present in this region in order to improve automated detection systems. [This study was supported by Instituto Aqualie and was funded by BG Group and Chevron Brasil Upstream Frade LTDA.]
Enhanced feature extraction using the Morlet transform on 1 MHz recordings reveals the complex nature of Amazon River dolphin (Inia geoffrensis) clicks
Authors: Trone Marie , Glotin Hervé , Balestriero Randall , Bonnett David E.
Published: October 2015

The Amazon River dolphin lives exclusively in freshwater throughout the Amazon River watershed, a dynamic and acoustically complex habitat. Although generally considered a relatively non-vocal species, recent evidence suggests that these animals are acoustically active, producing tremendous quantities of high-frequency, pulsed signals. Moreover, these pulsed signals appear to be considerably more complex than previously believed. This study explored the high-frequency pulsed emanations produced by Amazon River dolphins in Peru. Audio recordings were made using a two hydrophone array, one of which was sampled at 1 MHz, in August of 2015. Digitized recordings were analyzed using FFT and Morlet wavelets. Subsequently, unsupervised machine learning attempted to delineate various click categories based upon inter-click intervals, the frequency bandwidth of each click, and the formants contained within each click. Although the Morlet transform is much more robust and accurate for higher frequencies than the FFT, its performance was not constant for all frequencies. Thus, the Morlet transform and the FFT produced different click categories. Thus, formant results above 230 kHz most likely were skewed. These results are the first to clearly demonstrate the heterogeneity of the high-frequency pulsed emanations of the Amazon River dolphin.
Preliminary evidence for signature and copied whistles among spinner dolphins in the Southwest Atlantic Ocean: Beacon purpose?
Authors: Moron Juliana R. , Andriolo Artur
Published: October 2015

In order to evaluate strategies of cohesion in a fission-fusion society, the occurrence of signature and copied whistles were investigated in free-ranging spinner dolphins, Stenella longirostris. Through an one-element hydrophone array towed over the Brazilian continental shelf break, a group of approximate 400 dolphins were recorded at 96 kHz/24 bits while navigating. The preliminary results demonstrated 218 similar signals that fit into previous definitions of signature or copied whistles. These whistles were produced in bouts with an inter-whistle interval of 0.066—11.56 s (mean ± SD: 2.66 ± 2.72) that varied from 2 to 32 repetitions comprising six different contour shapes. Thus, these data support previous hypothesis that these signals are important units in the dolphin’s repertoire. It may also suggests a potential use on individual direction and localization, where repeated contours could be acting as a beacon to direct and locate the animals within the group. Additional research to ascertain the natural function of these vocalizations may clarify the basis for acoustic badges of membership and group organization of this cosmopolitan species.
Acoustic description and synchronization of the duetting species Pezopetes capitalis, Costa Rica
Authors: Trejos Carla V. , Barrantes Gilbert
Published: October 2015

Duetting has been widely studied, and its function vary across species, though in all cases temporal synchrony of the elements sang by each sex in the duet seems to play an important role. My goals in this study were to describe the structure of the duet of Pezopetes capitalis, and the degree of temporal synchronization of each individual of the pair during duetting. Duets of P. capitalis consist of overlapping elements between both members of a mated pair and can be initiated by either sex. Synchronization was similar between both individuals. For 11 pairs, both, females and males, reduce their silence intervals before singing a new element as a response to an increase in the duration of its partner's elements. Furthermore, both mates lower the high frequency of their elements of the second section, as the duet continues. Birds showed this pattern even in those cases where the female joins the male after he had began to sing its duet's part. This suggests a temporal coordination in frequencies (high frequency decreases with time). Indirect evidence suggest that duets in P. capitalis serve as a joint defense of territory and as a way to recognized mates when a pair reunited.
Frequency dependence of thresholds for lethal cardiomyocyte injury in myocardial contrast echocardiography
Authors: Miller Douglas L. , Lu Xiaofang , Dou Chunyan
Published: October 2015

Contrast enhanced diagnostic ultrasound employs microbubble activation for microvascular imaging; however, the on-screen Mechanical Index is a poor parameter for safety guidance. More research is needed on microvascular bioeffects, particularly their variation with frequency. A GE Vivid 7 with an S3 probe operated at 1.6 MHz, and an S5 probe operated at 2.5 and 3.5 MHz was used for myocardial contrast echocardiography of rats mounted in a water bath. Power settings were varied in 2 dB steps for determination of the thresholds for cardiomyocyte injury. The contrast agent was made to duplicate the properties of the clinical agent Definity. The scans were intermittently triggered each 4 heartbeats from the ECG signal. The cardiomyocyte death was assessed using Evans blue vital staining. Thresholds were defined as the mean of the lowest exposure with a statistically significant cardiomyocyte death and the next lower exposure level. Thresholds were 1.2 MPa, 1.7 MPa, and 2.7 MPa peak rarefactional pressure amplitude (derated for 1 dB/cm/MHz attenuation) for 1.6, 2.5, and 3.5 MHz, respectively. Linear regression showed that the thresholds were essentially proportional to frequency (0.72 f1.02, r2 = 0.97). Theoretical analysis is under development to explain this dependence and develop a contrast-specific safety parameter.
Imaging a barely visible impact damage in a laminated composite without contact using air-coupled nonlinear elastic wave spectroscopy
Authors: Remillieux Marcel C. , Pieczonka Łukasz , Le Bas Pierre-Yves , Anderson Brian E. , Ulrich TJ
Published: October 2015

We present the first set of experiments in which air-coupled ultrasonic emission is used for exhaustive and rapid imaging of a Barely Visible Impact Damage (BVID) introduced by an impact test on a laminated composite. Such experiments have been limited thus far by the impedance mismatch of nearly five orders of magnitude between the air and an elastic solid. This limitation was overcome by designing an ultrasonic source capable of generating a focused elastic wave field in the sample with an amplitude sufficiently large to allow the use of nonlinear elastic wave spectroscopy. The images of the damaged area obtained with the proposed apparatus and signal processing technique reveal the same features, namely a delamination and a crack, as with vibro-thermography and more features than with a C-scan, but remove the need to be in direct contact with the composite, thus reducing the test time by orders of magnitude. [This work was supported by the U.S. Department of Energy through the LANL/LDRD Program and the Fuel Cycle R&D, Used Fuel Disposition (Storage) campaign. The visit of Dr. Pieczonka at LANL was supported by the Foundation for Polish Science (FNP) within the scope of the WELCOME Program—project no. 2010-3/2.]
Seismic surface wave method for subsurface layered soil exploration
Authors: Lu Zhiqu
Published: October 2015

Subsurface soils in the vadose zone are layered structures. Typically, there are three distinctive layers at the depths of a few meters, featuring as a top rigid layer (due to surface crusting and sealing), a middle soft zone (due to soil moisture), and a region with stiffness increasing with depth (due to increased overburden pressure). The properties of subsurface soils in the vadose zone are often altered by natural events (weather and chemical reactions) or cultural activities (compaction). The exploration of the subsurface soils is required for agricultural, environmental, civil engineering, and military applications. In this talk, a seismic surface wave technique is developed, a so-called high frequency multi-channel analysis of surface wave method (HF-MASW). In the method, an electromagnetic shaker is placed on the ground and serves as a seismic source, a vibration sensor (either a laser Doppler vibrometer or an accelerometer) is used to record surface vibrations at multiple locations alone a straight line. Rayleigh waves propagation theory, layered structural modeling, and spectral analysis are applied for processing received signals and conducting inversion. A soil profile in terms of shear wave velocity is determined from the method. In this talk, several applications using MASW method will be reported, including layering delineation with cross-section imaging, weather effects monitoring, fragipan detection, and surface crusting and sealing evaluation.
Acoustical innovations in nineteenth-century violinmaking
Authors: Gilbert Sarah
Published: October 2015

Tensions between innovation and tradition in violinmaking have impeded the acceptance of most attempts to improve or alter the structure of the instrument. The nineteenth century, however, saw a proliferation of innovative violins as luthiers responded to musical developments and changing social and economic environments during the Industrial Revolution. As nineteenth-century composers called for greater range and diversity in timbre, chromaticism, dynamics, range, and key, instruments were developed to accommodate these demands. But perhaps more important than the purely musical considerations was the interdisciplinary collaboration between musicians and scientists in the pursuit of acoustic perfection. Many luthiers, such as François Chanot and Jean-Baptiste Vuillaume, viewed themselves as scientists and engineers, experimenting with acoustic properties and new materials in order to improve upon the existing form of the violin. In a reciprocal relationship, acousticians recognized musical instruments as rich sources for the study of acoustic principles, and luthiers consulted with acousticians and engineers about the technical construction of experimental forms. In this paper, I examine the technical construction of several of these instruments for insight into their novel construction techniques and acoustical properties, relating this experimental trend to the alliance of the sciences and arts during the Industrial Revolution.
Early history of the European free reed instruments
Authors: Cottingham James P.
Published: October 2015

Free reed instruments have been known in Asia for thousands of years, but the Western free reed instruments such as the harmonica, accordion, and reed organ were only invented and developed during the last two centuries. In 1780, Kratzenstein published a paper in St. Petersburg describing a speaking machine, which produced vowel sounds using free reeds with resonators of various shapes. This event marks a convenient, if arbitrary, starting point for the history of the free reed musical instruments of European origin. These instruments developed rapidly, and by 1850, the accordion, concertina, harmonica, reed organ, and harmonium all had been invented and developed into more or less final form. This paper presents some episodes in the development of these instruments. Also addressed is the question of the influence of the Asian free reed mouth organs on the origin and development of the European free reeds.
The acoustic complexity of keyboard percussion instruments. Part I: (What we know and what we wish we knew) Leigh Howard Stevens
Authors: Stevens Leigh H.
Published: October 2015

Part I Introduction to tuned bars and resonators Keyboard Percussion Instruments include innumerable variations of marimbas, xylophones, vibraphones, and glockenspiels. The tone bars, made of wood, metal, or other materials, are often incapable of producing sufficient volume without the amplifying assistance of a resonating tube or chamber. Unfortunately, these two vibrating systems (bar and resonator) react in opposite directions to changes in temperature, decoupling from their ideal relationship with any rise or fall in temperature. Also, unlike string, brass, or woodwind instruments, where the overtones are produced “naturally” and “are what they are,” the overtones of the bars of keyboard percussion instruments can be manipulated and controlled in the design and manufacturing process. For example, while both instruments have tone bars made of rosewood, the xylophone has the second partial tuned to an octave and a perfect fifth above the fundamental, while a marimba has the second partial tuned to a frequency two octaves above the fundamental. While we can identify and lower the frequency of many of the prominent partials contained in tone bars, their interdependence within the bar, and their coupling with a resonator provides a level of complexity for the designer and manufacturer, perhaps unrivaled in musical instrument manufacturing.
A short acoustical history of flutes from the Paleolithic period to nowadays
Authors: FABRE Benoit , Vauthrin Camille
Published: October 2015

Flutes appear at different time periods and places over the world. The instrument making adapts to the cultural and musical context. Studying the instruments from the acoustical point of view allows to understand some evolutions in instrument making, focusing on different aspects such as the geometry of the bore of the instrument and its consequences on the passive resonances, the playing conditions and aeroacoustical consequences, the sound characteristics such as intonation, spectral content, and sound intensity. The talk will focus on a few instruments and periods in order to illustrate some evolutions and relations between these different aspects.
Development of hearing protection device calculators for the F-35A and F-35B tactical aircraft
Authors: Pilon Anthony R.
Published: October 2015

Simple spreadsheet-based near field noise prediction tools for the F-35A (conventional takeoff and landing) and F-35B (short takeoff and vertical landing) aircraft have been developed recently. Near field noise predictions are based on empirical data collected during static engine runs conducted at Edwards AFB, and during hover/vertical landing operations at MCAS Yuma in September, 2013. The tools are programmed to calculate near field one-third octave band sound pressure levels as a function of engine power setting and listener location. The calculated near field levels can be used to determine the Total Daily Exposure (TDE) of personnel required to work in the vicinity of powered aircraft. Alternatively, the calculators can be used to determine the amount of hearing protection required so that the personnel TDEs remain below 1.0. The calculators are adjustable so that they can be employed for differing domestic and international noise exposure regulations. [Work supported by the Air Force Research Laboratory and Ball Aerospace.]
Comparison of holography, beamforming, and intensity-based inverse measurements on full-scale jet noise sources. Part I: Numerical investigations
Authors: Wall Alan T. , Harker Blaine M. , Stout Trevor A. , Neilsen Tracianne B. , Gee Kent L.
Published: October 2015

The reduction of high-performance fighter aircraft noise, which is of particular concern due to its potential negative impact on communities near air bases and damage to military personnel hearing, is facilitated by improved understanding of the jet noise sources. To this end, near-field acoustical holography, beamforming, and acoustic vector intensity methods have been investigated for the source imaging of full-scale jets. In the first of a two-part investigation, a numerical experiment is performed to test the accuracy of each of these methods, using a simulated measurement array similar to a physical array from an actual full-scale measurement. Extended, partially correlated sources are generated over a range of frequencies using a wavepacket ansatz, and array measurements are simulated in the geometric near field. Source reconstructions are obtained using each of the methods. These equivalent sources are then propagated to the mid and far field. The various reconstructions are compared to simulated benchmarks in order to highlight the advantages and disadvantages of each method, and to evaluate the frequency ranges over which they provide accurate results at the source and in the mid and far fields. [Work supported by USAFRL through ORISE.]
Comparison of holography, beamforming, and intensity-based inverse measurements on full-scale jet noise sources. Part II: Experimental results
Authors: Harker Blaine M. , Wall Alan T. , Stout Trevor A. , Neilsen Tracianne B. , Gee Kent L. , James Michael M.
Published: October 2015

Targeted reduction of high-amplitude jet noise is facilitated by accurate source imaging and sound field prediction models. To provide guidance for future jet noise reduction efforts, near-field acoustical holography, beamforming, and acoustic vector intensity-based inverse methods (AVIBIM) have been implemented in efforts to measure and predict full-scale high-performance aircraft noise sources. Patch-and-scan array measurements were taken in the near-field of a tethered tactical aircraft. From these data, equivalent source reconstructions are calculated using each method at multiple frequencies, and the source results are then propagated outward and compared with benchmark locations in the mid and far fields. The frequency ranges where each method’s reconstructions predict the measured sound pressure levels are identified and guidelines are provided for the design of measurements to optimize source reconstructions. These results are compared to those obtained in the numerical study (Part I) of this two-part investigation. [Work supported by USAFRL through ORISE.]
Singing away from home: Song is used to create and defend foraging territories in the African megadermatid bat, Cardioderma cor
Authors: Smarsh Grace C.
Published: October 2015

The diversity of song repertoires and functions of singing in mammals are not well known. In bats, singing in the roost to court and defend mates has been studied; however, the concept of territorial behaviors and the role of singing outside of the roost is poorly understood. The heart-nosed bat, Cardioderma cor, roosts in mixed-sex and age groups in the hollows of baobab trees, but disperses to exclusive areas whereupon they move about foraging and singing. We investigated singing in this species by mist-netting, pit-tagging, and tracking 12 singing individuals during which we recorded songs and collected singing and movement behavioral data. We conducted song playbacks to further test song function. Male C. cor individuals return to same foraging area nightly, which are often over 100 m across, and favor perches where they sing back and forth with neighbors. Low-frequency, repetitive syllables are likely adapted for song transmission across the cluttered bush habitat. Songs vary within and across individuals both spectrally and temporally. Song playbacks elicited aggressive responses, confirming that these bats use song as part of their territorial defense strategy, similar to the way song is used by many songbirds.
Investigation of low-frequency broadband dipole transducer driving by PMN-PT transverse shear mode
Authors: Dai Yuyu , Zhou Yinqiu , Wang Xiuming , He Hongbin , Wang Zhengbo
Published: October 2015

A low-frequency broadband dipole transducer with a standard dipole directivity pattern is a crucial factor in the research and development of a sonic logging tool. A new dipole transducer design based on cylindrical shell oscillating is proposed in this paper, in which transverse shear polarization PMN-PT crystal stacks are used to provide a driving force to excite a cylindrical-shell oscillation to generate dipole acoustic field. The resonant frequency of the transducer is decided by the dimensions of crystal stacks. Piezoelectric coefficient d15 of the PMN-PT crystals can reached 7000 pC/N, which means there is enormous potential in high power transducer design; Several ceramic plates are connected in a series to reduce the resonant frequency of the exciting source and increase the driving amplitude at the same time so as to enhance the radiation power further; several stacks of different sizes are connected in a parallel to broaden the bandwidth. Finite element method is adopted to optimize the structure of transducer. According to the optimized results, a prototype is produced and then tested in anechoic tank. Test results show that the transmitting response is larger than traditional dipole transducer and the directivity pattern is better in the operating frequency range.
On frequency dependences of material damping and dynamic elastic properties
Authors: Pritz Tamás
Published: October 2015

The various solid materials may exhibit diverse damping and dynamic elastic behavior as a function of frequency over a wide range extending from zero hertz up to the meaningful high frequencies. Nevertheless, some general characters in the dynamic behavior of materials can be experienced, especially if a limited frequency range is concerned. The aim of this paper is to establish and classify the general characters of frequency dependence of linear damping and elastic properties with special emphasize to the sonic range and the materials used for sound and vibration control. Based on simple physical views, the frequency dependences of damping properties (loss modulus and loss factor) are established as a first step. It is shown that basically two types of damping behavior can be distinguished, namely, (a) damping increasing with frequency and (b) damping exhibiting a peak. All other types of damping (e.g., the decreasing and the hysteretic damping) can be interpreted through the above mentioned ones. The dynamic elastic properties (shear or bulk modulus, etc.) as a function of frequency are determined from the damping by considering causality principle. The frequency dependences predicted for the dynamic moduli are discussed.
Perception and production abilities of question vs. statement intonation patterns in young deaf children with early cochlear implantation
Authors: Choi Sangsook , Barbu Ioana , Core Cynthia , Mahshie James
Published: October 2015

Little research exists studying production and perception of prosody in early-implanted children with cochlear implants (CIs). Because of limited F0 information conveyed by CIs, there is particular interest in the impact of CIs on intonation perception and production. The aim of the present study was to describe and compare the ability of hearing (HC) and implanted (IC) children to perceive and produce distinctions between question vs. statement intonation patterns. Nine HC and 9 IC between 38 and 58 months of age participated in the study. All IC received their first implant prior to 15 months and had no other identified medical or developmental problems besides hearing loss. To determine the children’s ability to perceive rising and falling intonation, an imitation task was used. Results showed no significant difference in perception between the groups (p = .09). Intonation production was examined by eliciting yes–no questions and statements during a play-based task. Production measures included mean, range, and slope of F0. While F0 range was significantly greater for IC than for HC (p = .015), no other measure was found to be significantly different between the two groups. Overall, early-implanted deaf children with CIs appear to develop intonation comparable to their hearing peers.