bluuebunny/crossref_metadata_2025 huggingface dataset:
The national opera theatre in Bucharest—Update of the room-acoustical properties
Authors: Ahnert Wolfgang , Behrens Tobias , Pana Radu
Published: October 2015

After the destruction of the old opera house in WWII, the new edifice was designed in 1952–1953. The hall and the pit was almost not changed over the time, so based on the original design the hall acoustics was like in classic opera house not very lively, i.e., very dry. Also, the mutual hearing of the musicians in the pit and between the singers on stage and the musicians was not good. The facelift of the hall involved significant changes of the orchestra pit. A new lift has been built, and the cover of the musicians in the pit has been reduced. Also, the secondary structure of all wall and ceiling parts in the pit has been modified. The same has been done in hall, the carpet in the stalls, and the galleries has been substituted by a parquet floor, the absorbing materials in the boxes, and other wall parts was exchanged by wood panels and the completely absorbing chairs have been changed to less absorbing ones. Acoustic measurements have been done before and after the refurbishment. The paper will describe all changes and the achieved results.
Source qualification environments and their impact on speech privacy measurements in open offices
Authors: Browne Sean , Good Kenneth
Published: October 2015

The ASTM standards for measuring speech privacy in an open office call for specific loudspeaker dimensions and performance attributes. The standards also details specific testing environments required to qualify those attributes and set measurement reference levels. Often times, these environments are not accessible or practical during the course of a field measurement. Several additional test environments were explored in addition to the preferred and alternate test environments defined in ASTM E1179. The reference levels from these alternate environments were used, and the resulting speech privacy measurements were compared.
Extreme vocal plasticity in adult budgerigars: Analytical challenges, social significance, and underlying neurogenetic mechanisms
Authors: Wright Timothy F. , Hara Erina , Young Anna M. , Araya Salas Marcelo , Dahlin Christine R. , Whitney Osceola , Lucero Esteban , Smith Vidaurre Grace
Published: October 2015

Vocal learning is a complex trait that is expressed differently across different taxa. While many of the best-studied species exhibit close-ended learning, in which vocal signals are learned from adult tutors during juvenile critical learning periods, other species have open-ended learning in which new signals are learned throughout life. Budgerigars (Melopsittacus undulatus) are an extreme example of an open-ended learner, in which both sexes have a repertoire of multiple contact calls types that continually change through adulthood to match the call types of social associates. We discuss the analytical challenges posed by the rapid plasticity of the budgerigar vocal repertoire and compare results from several different approaches to characterizing call variation. We then consider the social implications and benefits of contact call matching in fission–fusion groups. Finally, we examine the mechanisms underlying this plasticity, with a special focus on the role of the gene FoxP2. We find downregulation of FoxP2 mRNA and protein in the primary parrot vocal learning center, MMSt, across a variety of social conditions in which birds also show vocal plasticity. The results support the hypothesis that FoxP2 is a key gene regulating the neural plasticity that underlies the persistent vocal plasticity exhibited by budgerigars.
Next generation full-wave ultrasound simulation: Exploiting parallelism in the move toward exascale
Authors: Treeby Bradley , Jaros Jiri , Cox Ben
Published: October 2015

In recent years, the capability of performing 3D full-wave nonlinear ultrasound simulations in tissue-realistic media has been demonstrated by a number of groups. These models have since underpinned a range of interesting studies into the interaction of ultrasound fields with the human body. However, simulations have thus far been limited to domain sizes on the order of 1 billion grid points. This limitation usually means either the spatial area or highest frequency of interest is truncated. Looking toward the exascale era, where supercomputers integrating over 1M cores are predicted to appear before 2020, there is a significant opportunity to use models to gain new insight into ultrasound-tissue interaction with unprecedented detail. The challenge is to develop suitable numerical methods that map to these massively parallel architectures, in particular, that minimize data movement, allow the exploitation of co-processors, and minimize the accumulation of numerical errors. Here, we show a novel domain decomposition approach for the Fourier collocation spectral method that allows ultrasound simulations to be distributed across up to 32k CPU cores or hundreds of accelerators with reasonable efficiency. Using this model, we demonstrate for the first time the possibility of ultrasound simulations exceeding 70 billion grid points.
Acoustic characterization of flexural metamaterial elements using an impedance tube
Authors: Guild Matthew D. , Calvo David , Orris Gregory
Published: October 2015

Acoustic metamaterials have been a topic of interest in recent years and have enabled exotic effective fluid properties to be achieved, including those with negative or near-zero dynamic values. These extreme properties arise through the particular design of the microstructure, which make use of simple microscale acoustic elements to create the desired macroscopic characteristics. While many of these acoustic elements utilize the quasistatic motion of the surrounding fluid, recently thin elastic plates have been receiving more attention in the use of transmission-line acoustic metamaterials. Due to the high acoustic impedance and flexural coupling of the elastic material, the acoustic characterization of these elastic structures using traditional techniques such as an air-filled impedance tube presents a significant challenge. In this work, flexural elastic elements are examined in an acoustic impedance tube. Using theoretical formulations for elastic plates in conjunction with acoustic impedance tube measurements, information about both the effective and intrinsic material properties of the flexural metamaterial elements can be obtained. The results of this analysis and its implications on acoustic metamaterial design will be discussed. [Work supported by the Office of Naval Research and the National Research Council.]
Multimode nonlinear resonant ultrasound spectroscopy (NRUS): From one-dimensional to three-dimensional characterization of the hysteretic elastic nonlinearity
Authors: Ulrich Timothy J. , Remillieux Marcel , Le Bas Pierre-Yves , Payan Cedric
Published: October 2015

Nonlinear Resonant Ultrasound Spectroscopy (NRUS) has been used extensively over the last two decades to quantify, through the nonlinear parameter α, the hysteretic nonlinearity of materials for geophysical, biomedical, and civil engineering applications. This technique relies on the variations of the damping and frequency of a resonance mode with the amplitude of this mode. A typical NRUS experiment is conducted on a long bar using its first longitudinal mode. In some experiments, higher order modes have been used because the nonlinearity was more pronounced but the type of motion involved has not been characterized. The parameter α measured from these experiments is then used to calibrate a 1D model of the non-classical nonlinearity. As a first step toward extending this model from 1D to 3D, experiments were conducted on long bar samples (assumed to be macroscopically isotropic) where modes are excited selectively and the type of motion involved in each mode is well characterized. In this simple isotropic case, longitudinal and torsional motions are decoupled in order to find the α11 and α44 parameters that correspond to the compression (C11) and shear (C44) moduli, respectively.
Modified resonator method for laboratory measurement of the low frequency compressional wave speed in granular sediments
Authors: Venegas Gabriel R. , Wilson Preston S.
Published: October 2015

Several models have been developed to describe dispersion in granular sediments. There is an abundance of measurements confirming these models above 10 kHz, obtained via time-of-flight measurements, but there is far less data for accurate model verification under 10 kHz. The present work focuses on laboratory compressional wave speed measurements of water-saturated glass beads in the frequency range 1 kHz to 10 kHz using a resonance tube technique that, in future work, will be scaled in size to attain results below 1 kHz. In previous versions of this technique, the granular sediment completely filled the resonator; however, grain interaction with the resonator walls and the development of grain-to-grain force chains yielded undesirable results. The present method isolates a cylindrical volume of sediment from the resonator wall by a tulle net membrane and a layer of water. The effective sediment wave speed is inferred through the measured system resonance frequencies and a finite-element model that relates the system resonance frequencies to the intrinsic sound speed of the sediment. Sound speed measurements in a model sediment composed of 1-mm-diameter glass beads and distilled water agreed with the Effective Density Fluid Model (EDFM). [Work supported by ONR.]
Exploring the bowed string dynamical behavior using a linearized model approach
Authors: Debut Vincent , Inácio Octávio , Antunes José
Published: October 2015

For several decades bowed-strings have captured the attention of many researchers aiming for a thorough understanding of this system. Different approaches have been adopted particularly in the time-domain numerical simulations of the self-excited nonlinear regimes. Recently, the authors have been exploring the advantages of using a linearized approach to this problem, with or without the body coupling influence. Despite the highly non-linear bow/string friction force, the problem can be linearized about the average sliding velocity, as usually done in break-squeal noise, and an eigenvalue analysis can offer interesting information. For example, this approach allowed exploring the modal dynamics of bowed-string/body coupled system, studying the prediction of modes instabilities and the possible emergence of a strongly coupled mode responsible for the wolf-note, among other features. Here, using the linearized modal dynamics of bowed-strings we look in detail to the behavior of the string modes as a function of the bowing parameters. We start from a modal formulation of the string acted by the nonlinear bowing forces and develop the corresponding linearized formulation, which enables computation of the complex eigenvalues and eigenvectors as a function of the bowing velocity and normal force as well as location of the bow on the string.
Bifurcations in cello bowing using bow force below or above the Helmholtz regime
Authors: Bader Rolf , Mores Mobert
Published: October 2015

Two bifurcation regimes with bowing forces above and below the thresholds for regular Helmholtz or sawtooth motion are investigated on a cello. During operation, string acceleration is measured at the bridge while bow force and speed are defined and measured on a bowing machine. High bow force causes subharmonics where the pitch depends on bowing pressure and velocity. Here sudden pitch changes were recorded at playing parameter thresholds while with slightly different parameters quasi-random scratchy sounds occurred. At very low bow forces, bifurcations appeared in the higher harmonics with two- and four-fold subdivision of periodicity, while the fundamental pitch remained stable. The reason for these bifurcations are bistable periodicities of the time series. To account for this, the sounds were analyzed using a Finite-Difference cochlea model which results in Interspike Intervals (ISI) with precise temporal resolution of these periodicities.
Some factors influencing loudness asymmetries between rising and falling-intensity stimuli
Authors: Ponsot Emmanuel , Meunier Sabine , Susini Patrick
Published: October 2015

Previous research demonstrated that the loudness asymmetry between 1-kHz rising and falling-intensity tones is a robust phenomenon, whose origins still remain unclear. In the present study, this phenomenon was further examined as a function of two stimuli characteristics: the spectral content and the intensity-region. In a first experiment, the global loudness of rising and falling-intensity sounds with various spectral contents (pure tones from 250 Hz to 8 kHz and broadband noises) presented in different intensity-regions (from [50–65 dB SPL] to [70–85 dB SPL]) was assessed in an absolute magnitude estimation task. Significant asymmetries were found for tones at all frequencies, but not for broadband noises. In addition, a significant interaction between the stimulus direction and the intensity-region was observed for both tones and noises. This interaction was further examined in a second experiment using an adaptive loudness-matching procedure. Although greater asymmetries were again observed for tones, significant asymmetries were found for noises as well. Furthermore, the size of the asymmetries was significantly decreased with the intensity-region when the pairs were composed of rising followed by falling stimuli. These results are discussed in the light of recent physiological and neuroscience studies conducted with this type of stimuli.
Sound source localization for filtered noises when listeners rotate
Authors: Yost William
Published: October 2015

Yost and Zhong (2015, JASA, 137, 2200) recently showed that sound source localization when listeners rotate depends on both spatial cues and information about the world-centric location of the listener. In these experiments, the sound was a broad-band (0.125—15 kHz), 200-ms noise burst. This stimulus does not allow for an estimation of the role of interaural time (ITD) and/or level (ILD) differences in sound source localization when listeners rotate. The present experiment used the following stimuli: low-pass noise (0.125–0.5 kHz) implicating ITD cues, high-pass noise (2–8 kHz) implicating ILD cues, broad-band noise (0.125–8 kHz) implicating both ITD and ILD cues, and mid-frequency noise (1–4 kHz) for which neither an ITD nor an ILD cue provides good information about sound source location. Listeners rotated at constant velocity (45o/sec) in the azimuth plane, while sounds changed position around a 24-loudspeaker array in the same azimuth plane. Listeners responded in an eyes-open condition in which they would receive information about their world-centric location and in an eyes-closed condition in which they would not. The task was to decide if two successive noise bursts were presented from the same or different loudspeakers as listeners rotated. [Research funded by an AFOSR grant.]
Managing property distribution errors in arrays of coupled resonators
Authors: Vignola Joseph F. , Kurdila Andrew J. , Sterling John , Judge John A. , Glean Aldo A. , Ryan Teresa J.
Published: October 2015

Arrays of small attachments can be designed to draw mechanical energy from a primary structure in a manner far in excess of their proportional size. Earlier work has shown that slight variations or errors in the property distributions of arrays of coupled resonators can have a dramatic effect on the response of primary structure to an external force. This work investigates the use of an electro-mechanical approach to making small adjustments in the stiffness of the individual elements of the array to alter the response of the primary. The electro-mechanical coupling is achieved by way of laminated thin piezoactuators mounted on a fraction of the subordinate elements. The piezoactuators are electrically coupled to a switching network that changes the effective stiffness of the subordinate elements. This ability to adjust the stiffness distribution facilitates real time control of the rate at which the energy is transferred into the coupled array. This apparent damping can then be adjusted to draw or reject energy from specific frequency bands. The presentation will describe the underling theory, present numerical results, and some preliminary experimental results.
Removable damping treatments for use in sheet metal fabrication
Authors: Cunefare Kenneth A.
Published: October 2015

Many industrial fabrication processes on metallic structures generate a great deal of work place noise. For example, riveting and chiseling on light-weight, stiff aerospace structures such as fusalage components and flight surfaces subject the workpiece to repeated impacts and consequent noise generation. Many such structures may be lightly damped. Many damping treatments are targeted toward permanent installation on a structure, but if the treatments are considered to be removable, one has design freedoms including placement on a structure, as well as mass and damping means, that might not otherwise exist if the treatment had to remain in place. A shot-mass or particle-impact damper configured in an elastic, cellular array is shown to provide high loss factors and mass loading, which, along with ease of placement and removal, may provide significant reduction in component vibration during fabrication and consequent reduction in noise in the work place. The concept applied to an example aircraft panel when subjected to riveting operations yields more than 10 dB of noise reduction.
Reconceptualizing the vowel space in analyzing regional variation
Authors: Fox Robert A. , Jacewicz Ewa
Published: October 2015

Vowel space area calculated on the basis of the corner vowels has emerged as a metric for the study of regional variation, speech intelligibility, and speech development. We verify the basic assumptions underlying both the concept of the vowel space and the utility of the vowel space area in making speaker, dialect, or language comparisons. Undeniably, the traditional vowel triangle and vowel quadrilateral both fail as a metric in the context of dialect variation because substantial parts of the actual working space are excluded from analysis. Utilizing the formant values at a number of different locations for a wider range of individual vowels has significant implications for the size and shape of the resulting vowel space. Indeed, dialectal variations in vowel production can best be characterized in terms of formant density regions in the formant space and not as locations of individual vowel categories. The formant density approach is based on the assumption that vowel sounds are dynamically changing multidimensional units, which naturally overlap in the acoustic space. The formant density approach is able to minimize the amount of empty space within the overall shape while still respecting the outer boundary of the dataset.
United States accents compared: The relation of acoustic distances and perceptual tasks
Authors: LaMonica Clelia R.
Published: October 2015

This project investigates correlations between accent production and perception by comparing two sets of data: acoustic distances of American dialectal speech samples, measured using Euclidean distances of each vocalic stimuli's first three formants across a trajectory, and perceptual data in the form of online survey material and EEG tests which judge the differences between the same varieties. The speech samples used consist of six sentences from eight regions of the United States; each sentence containing phonological features that may be marked as perceptually relevant for dialect classification. Here, we examine the preliminary outcomes from such perceptual tests performed by naïve listeners, which include free classification, identification, perceived difference and ranking similarity, as well as attitude judgment tasks. Additionally, EEG tests were carried out to evaluate the relation between acoustic distance of accents and ERPs. Of special interest here is the relation between a non-regionally specified American accent and others. This “standardized” variety is judged in comparison with each of the regional accents in order to investigate listeners’ perceptions of non-regional vs. regional accents, and in turn the correlation between measured accent (dis)similarity and perception.
Working memory problems of the elderly arise in the central processor, not the phonological loop
Authors: Nittrouer Susan , Lowenstein Joanna H.
Published: October 2015

Declines in cognitive and communicative capacities can negatively impact quality of life for even healthy aging individuals. One such capacity involves working memory, which is modeled as consisting of a phonological loop that recovers phonological structure for storage and a central executive that processes that structure. In this study, working memory was investigated to evaluate which component is responsible for age-related declines. Two groups of listeners with good hearing participated: 20 young adults (18 to 32 years) and 25 elderly adults (60 to 80 years). Accuracy and speed of recall were measured for forward and backward digits, and for three sets of CVC words: nonrhyming nouns, rhyming nouns, and nonrhyming adjectives. Phonological awareness was also assessed. Results showed no differences in digit span, but significant age-related differences in accuracy of word recall and in speed of recall for both digits and words. Phonological awareness did not differ across groups. When speed of recall was used as a covariate, effect size of age on word recall diminished. It was concluded that the problems observed in cognitive and communicative functioning of the elderly can be attributed to a slowing of processing, not to a diminishment in sensitivity to phonological structure. [NIH R01-DC000633.]
Speech production in the later years: Changes in fundamental frequency and speech breathing
Authors: Hunter Eric J. , Graetzer Simone , Hunter Ethan J.
Published: October 2015

With age, vocal quality can be affected by changes in articulatory, velo-pharyngeal, laryngeal, and breathing function. For example, past studies have shown that the voice is sensitive to hormonal changes. Other studies have indicated that there is atrophy of the vocal folds and a hardening of the laryngeal cartilages in old age. In the current study, recordings of three female adults (spanning 18 to 30 years) and three male adults (spanning 38 to 48 years, with one individual being 98 years old at the latest recording) were acquired and analyzed for changes in speech production. For a representative segment of each recording, the temporal boundaries of speech breath groups were identified by raters so that the durations of groups could be calculated. Additionally, the effect of age on speech fundamental frequency was considered. Finally, how fundamental frequency changes during a long speech task was examined, to track vocal fatigue. Results suggested a decrease in breath group duration for most subjects as age increased. Importantly, the effect of age on fundamental frequency seemed to change more than is commonly discussed (based on cross-sectional studies). Finally, there was a gender difference in how both breathing and fundamental frequency changed with age.
Frequency-sum beamforming in a random scattering environment
Authors: Abadi Shima H. , Leckta David C. , Mercado Karla , Haworth Kevin J. , Dowling David R.
Published: October 2015

In a uniform environment, sound propagation direction(s) or the location of a sound source may be determined from array-recorded signals by beamforming. However, the beamforming results may be degraded when there is random scattering between the source and the receivers. Such sensitivity to mild scattering may be altered through use of an unconventional beamforming technique that manufactures higher frequency information from lower-frequency signal components via a quadratic product of complex signal amplitudes. This presentation will describe frequency-sum beamforming, and then illustrate it with simulation results and near-field acoustic experiments. The simulations suggest that frequency-sum beamforming may be beneficial when there is one loud source and the environment provides one primary propagation path. The experiments were conducted in either a 1.0-m-deep 1.07-m-diameter cylindrical water tank using 50 kHz and 100 kHz signals broadcast from a single source to an array of 16 hydrophones when discrete scatterers are present and absent from the tank or in a tissue-mimicking phantom with a dominant scatterer embedded and insonified at 2 MHz and the scatter received by a 128-element array. The results from frequency-sum beamforming are compared to the output of conventional delay-and-sum beamforming and minimum variance beamforming. [Work supported by NAVSEA through the NEEC.]
Algorithms for measuring periodicity in F0 tracking
Authors: Chen Xiao , Zhang Hao , Zahorian Stephen A.
Published: October 2015

Measuring periodicity is an important measurement in speech processing. It can be used in many areas, especially for tracking fundamental frequency (F0), typically referred to as pitch. This seemingly easy measurement is made difficult since even voiced sections of speech are only semi-periodic or periodic over short intervals. In this paper, four functions for measuring periodicity are compared for both time domain and frequency domain processing. They are autocorrelation, normalized cross correlation function, spectral harmonics correlation, and normalized spectral harmonics correlation. In some cases, these four functions behave very similarly to each other; however, there are advantages and disadvantages, depending on conditions. The functions were experimentally evaluated in an F0 tracking experiment based on the Keele database, which has “ground truth” for pitch.
Interpretations of the frequency difference autoproduct in multipath environments
Authors: Worthmann Brian M. , Dowling David R.
Published: October 2015

When locating remote acoustic sources in a shallow ocean sound channel, the established array signal processing technique known as matched field processing (MFP) has shown much success. However, MFP is sensitive to mismatch between the modeled and actual environments, and may fail to localize acoustic sources in the presence of such mismatch, particularly at high frequencies. A recent nonlinear array signal processing technique, frequency difference MFP (Abadi et. al. 2012, Worthmann, et. al., under review), has shown some success in localizing high frequency sources by moving the replica calculations to a lower, out-of-band, difference frequency where the detrimental effects of environmental mismatch are less severe. To extract the requisite out-of-band difference frequency information from the measured signals, a quadratic product, termed the autoproduct, is formed from complex signal amplitudes separated by the difference frequency but still lying within the signal bandwidth. Through the use of simple multipath propagation environments, the nature of this autoproduct is explored, and the reasons that it provides out-of-band field information are presented. More complex propagation environments are simulated as well to demonstrate some of the expected and unexpected behaviors of the autoproduct. [Sponsored by the Office of Naval Research and the National Science Foundation.]
Robust source-range estimation using a vertical array and the array invariant
Authors: CHO Chomgun , Song Hee-Chun , Hodgkiss William S.
Published: October 2015

The array invariant based on beam-time migration has been proposed for instantaneous source-range estimation in acoustic waveguides using a horizontal or vertical array. With minimal knowledge of the environment, the approach has been demonstrated successfully with experimental data in shallow water using a horizontal array. Moreover, it was determined recently that the array invariant can be derived from waveguide invariant theory based on the dependence of group speed on phase speed. In this paper, the array/waveguide invariant approach to source-range estimation is applied to a vertical array in a fluctuating ocean environment over a one-day period. Specifically, the range estimates using a 12-m long vertical array in ∼100 m deep water are within 9–16% relative error for a 2–3 kHz source at 6-km range, demonstrating the robustness of this approach.
Acoustic propagation in the Strait of Georgia
Authors: Pelavas Nicos , Pecknold Sean , Coffin Matthew , Dunphy Kevin , Thomson Dugald
Published: October 2015

In recent years, there has been a proliferation of Ocean Observing Systems (OOS) along with a wide distribution of their associated data products. The collected data support scientific research, industry, and government organizations by providing long term measurements of biological, chemical, and physical properties of the ocean environment. However, the collection and distribution of underwater acoustic data poses a potential security risk for naval vessels operating in the vicinity of OOS. The Canadian Forces Maritime Experimental and Test Ranges (CFMETR) provide an underwater tracking facility for naval tests, and are approximately 50 km from hydrophones of the Victoria Experimental Network Under the Sea (VENUS) observatory. Under an existing CFMETR-VENUS agreement, data are diverted during certain naval tests. In order to minimize the frequency of these data diversions, a study is being conducted to investigate acoustic propagation in the Strait of Georgia. The results of acoustic modeling and measurement of transmission loss from CFMETR to VENUS will be presented. A software application called CAVEAT is also presented. The application was developed to integrate the transmission loss results along with other sonar parameters to enable operators at CFMETR to determine the risk of acoustic exposure.
Temporal variation of transmission loss by internal tide in the southern sea of Jeju island in summer
Authors: Kim Juho , Kim Hansoo , Paeng Dong-Guk , Pang Ig-Chan
Published: October 2015

Temporal variations of acoustic transmission loss (TL) affected by internal tide are simulated using oceanic data measured at two sites in the southern sea of Jeju island. Temperature and salinity were measured every hour for 25 hours during July 27th and 28th 2009. The periodic fluctuation of temperature due to the internal tide was observed and its vertical displacement was more than 10m. In order to investigate the variation of TL, acoustic propagation between two measurement sites (3.8 km distance) was computed at a source depth of 10 m. Acoustic propagation model RAM was used for the simulation. Standard deviations of TL variation were 4.2 dB and 3.7 dB for center frequencies of 100 Hz and 1 kHz with 1/3 octave band, respectively. The lower frequency was more correlated with the tidal period than the higher one. Detection range was also varied by the internal tidal, up to 1 km for the 60 dB detection level. These results imply that tidal variation of TL should be considered for acoustic researches at the southern sea of Jeju island. [This work was supported by UD130007DD and IITP-2015-H8601-15-1004.]
Signature calls predict foraging success in big brown bats (Eptesicus fuscus)
Authors: Wright Genevieve S. , Chiu Chen , Xian Wei , Wilkinson Gerald S. , Moss Cynthia F.
Published: October 2015

Animals foraging in the dark must simultaneously pursue prey, avoid collisions, and interact with conspecifics, making efficient non-visual communication essential. A variety of birds and mammals emit food-associated calls that inform, attract, or repel conspecifics. While echolocation by the insectivorous, aerial-hawking big brown bat (Eptesicus fuscus) has been studied extensively, communicative calls used by this species have received comparatively little research attention. We report on a rich repertoire of vocalizations produced by big brown bats in a large flight room equipped with synchronized high-speed stereo video and audio recording equipment. We also provide evidence that a specific social call, the “frequency-modulated bout” (FMB), which is emitted only by males, exclusively in a foraging context, and only when conspecifics are present, predicts the caller’s foraging success and is individually distinct. Bats were studied individually and in pairs, while sex and experience with a foraging task were experimentally manipulated. Individuals emitting a higher number of FMBs showed greater prey capture success. Following FMB emission, inter-bat distance, diverging flight, and the other bat’s distance to the prey increased. These findings highlight the importance of vocal communication for nocturnal animals mediating interactions in a fast-paced foraging setting.
Probabilistic strategies for dynamic coordination of biosonar emissions in social groups
Authors: Smotherman Michael
Published: October 2015

Echolocating bats are social animals and must be able to use their biosonar capabilities in a wide range of social contexts. Bats roosting or flying in groups routinely adapt their pulse emissions to accommodate sharing the acoustic space with potentially many bats. In this regard, echolocation may be bound by the same rules and constraints governing social communication. Bats can alter pulse acoustics, temporal patterns, projections patterns, and locomotor trajectories to minimize acoustic interference across individuals. Here, we present evidence that the highly gregarious free-tailed bat, Tadarida brasiliensis, primarily relies upon probabilistic strategies for mitigating acoustic interference rather than trying to predict or extract information from the pulses of other bats. When free-tailed bats hear the pulses of another bat they shift the timing of subsequent pulse emissions following a randomized back-off algorithm similar to those that have evolved in artificial wireless communications systems. Importantly, this behavior is only effective if all bats strictly follow the same strategy. I will present the results of recent measurements of this back-off algorithm and use computational modeling to illustrate how and when it improves sonar imaging in social settings.
Vocal flexibility and regional variation in free-tailed bat songs
Authors: Salazar Israel , Bohn Kirsten
Published: October 2015

Male Brazilian free tailed bats (Tadarida brasiliensis), sing to attract females and defend territories during the mating season. These songs are unusual among mammalian vocalizations in that they are highly complex and hierarchically structured. Songs are composed of multiple syllables which are combined into three phrases that vary in number and order across renditions. While much work has been done on regional vocal variation in birds, relatively a few studies have found similar evidence in mammals. This study aimed to determine if T. brasiliensis songs vary across agographical regions. To accomplish this, we compared spectro-temporal characteristics, and phrase composition of songs recorded from wild colonies in various locations throughout Florida, Georgia, and Texas. Although we found considerable inter-individual and within-individual variation, there are salient regional differences in song structure. These findings combined with a high level of within-individual flexibility, and the lack of local adaptation in foraging echolocation pulses, support a possible role of vocal learning in song production in this species.
Bats as new models for social communication
Authors: Bohn Kirsten M.
Published: October 2015

Bat echolocation has been the focus of extensive acoustic research for over 50 years. However, our knowledge of bat social communication is in its infancy, having really only begun to develop over the last decade. This is because only recently have ultrasonic recording and playback become affordable, rugged, and portable—making field research highly expedient. These advances have in essence opened up an entirely new frontier in acoustic research. Indeed a very large frontier with over 1000 diverse species, nearly all of which are highly social. Here, I review the types of vocalizations bats produce, from echolocation calls, to simple calls to complex songs. For example, simple infant isolation calls are produced by the majority of mammals with little to no specialization in bats. In contrast, our work on Molossid bats shows that they embed “echolocation” calls into complex song phrases while roosting and in flight. In this case, social communication is likely an exaptation of the highly specialized echolocation system. Finally, I discuss where bats fit into our current models—birds, anurans, cetaceans, and rodents—and how using a comparative approach can greatly expand our understanding of acoustic communication.
Improved ear simulator for extended application range
Authors: Rasmussen Per , Soendergaard Jacob , Wille Morten
Published: October 2015

The international standard IEC 60318-4 specifies an occluded ear simulator for testing headphones, earphones, hearing protectors, hearing aids etc. The standard specifies a specific microphone type which limits the dynamic range of the coupler, such that it is not possible to measure very low levels or very high levels. Additionally, the standard 711 coupler is often interfaced to a pinna simulator incorporated in a Head and Torso simulator as per IEC 60318-7. This interface has traditionally been implemented as a cylindrical, straight ear canal simulator. This makes the fit of many modern in-ear headphones and hearing protectors problematic and unrealistic. By using low noise microphones instead of the standard microphones, the coupler can be used for measuring extremely low sound pressure levels such as noise floor, low level distortion or microphonics. Conversely, by using low sensitivity microphones, the coupler can be used for extremely high level measurements—useful for testing active and passive attenuation ratings of hearing protectors. Moreover, using a vast database of 3D human ear canal scans, a new pinna and ear canal simulator is proposed that will greatly improve measurement accuracy and repeatability on products going on or in the ear.
Measurement of tortuosity and viscous characteristic length of double-layered porous absorbing materials with rigid frames via transmitted ultrasonic wave
Authors: Sadouki Mustapha , Berbiche Amine , fellah Mohamed , fellah Zine El Abidine , Depollier Claude
Published: October 2015

In this work, an indirect method is proposed for measuring simultaneously acoustic parameters describing the ultrasonic propagation in double-layered porous medium. The porous media consist of two slabs of homogeneous isotropic porous materials with a rigid frame. Each porous slab is described by equivalent fluid model, in which the acoustic wave propagates only in the fluid saturating the material. The inverse problem is solved numerically using experimental transmitted waves in time domain. Four parameters are inverted: tortuosity and viscous characteristic lengths of the two layers. Tests are performed using industrial plastic foams. Experimental and numerical validation results of this method are presented.
Durational characteristics of sentence-medial and sentence-final pauses in the production of a paragraph
Authors: Kakita Kuniko , Hiki Shizuo
Published: October 2015

The present study investigated the durational characteristics of sentence-medial and sentence-final pauses in the production of a paragraph, with an aim to elucidate the factors that determine the durational organization of connected speech. A phonetically trained native speaker of Japanese read a paragraph consisting of eight sentences at a moderate speaking rate. Three recordings varying slightly in total duration — roughly 55 s, 52 s (−5%), and 49s (−10%) — were analyzed acoustically. Results showed that approximately 30% of the paragraph duration was pause duration, of which about 80% was sentence-final and 20% sentence-medial. Pause duration affected paragraph duration more significantly than speech duration, e.g., 10% shortening in paragraph duration resulted from 25% shortening in pause duration but only 5% shortening in speech duration. The duration of sentence-medial pauses was positively correlated to the duration of preceding speech, while the duration of sentence-final pauses reflected the internal structure of the paragraph, i.e., paragraph-internal topic transitions were accompanied by longer pauses, possibly providing opportunities, too, for physiological adjustments such as breathing and swallowing. The ratio of accumulated pause duration to accumulated speech duration increased in an asymptotic manner, approaching the final ratio value near the end of paragraph production.
The effect of background speech variation on perceived foreign accent
Authors: Pearson Dylan , Sankhagowit Amara , Park Hanyong
Published: October 2015

We investigate what effect the presence of differing degrees of accented babble speech has on the perceived foreign accent of the target utterances. We presented various degrees of foreign accented English sentences in multi-talker babble conditions to native speakers of English to rate the accentedness on a 1−9 Likert scale. Male and female native speakers of English and native Korean speakers having light to heavy foreign accent produced the target stimuli. We overlapped babble recorded from two talkers (1 male and 1 female) to generate the multi-talker babbles, where the talkers were speaking in native English, native Korean, heavy accented English, and light accented English. Our results show a tendency for listeners to rate the stimuli presented in more native-rated babble as sounding more native-like than the same utterance presented with less native babble. The data also points to native target speech being more sensitive to a change in the degree of accent in babble than non-native target speech. All taken together, the results suggest a “bleedthrough effect” as a result of pieces of the background babble appearing to be processed along with the target speech, thus affecting the perceived accent.
Acoustical Society of America Distinguished Service Citation: Paul D. Schomer
Authors: Schulte-Fortkamp Brigitte , Daigle Gilles A. , Nelson Peggy B. , Hellweg Robert D. , Blaeser Susan
Published: October 2015

The Distinguished Service Citation is awarded to a present or former member of the Society in recognition of outstanding service to the Society.
Hiding in Plain Sight: The Embedded Nature of Sexism in Sport
Authors: Fink Janet S.
Published: October 2015

In this article, from the 2015 Earle F. Zeigler Lecture Award presented in Ottawa, Canada, I hope to create greater awareness of how sexism remains uncontested in sport. I highlight the persistence of sexism in sport and note the form of sexism is different from that found in other industries. I also argue that sexism is treated quite differently than other types of discrimination in sport and provide examples of its impact. I suggest that adapting Shaw and Frisby’s (2006) alternative frame of gender equity is necessary for real change to occur and call on all NASSM members as researchers, teachers, or participants to take action to eradicate sexism in sport.
Comet Siding Spring, up close and personal
Authors: Lisse Carey
Published: October 2015

Observations during a close flyby of Mars shed light on a little-understood group of comets
Cruel and unuseful punishment
Why Torture Doesn't Work The Neuroscience of Interrogation
Shane O'Mara
Harvard University Press, 2015. 330 pp.
Authors: McNally Richard J.
Published: October 2015

Psychological studies call into question the efficacy of enhanced interrogation techniques.
Chromatin complex, crystal clear
Authors: Schapira Matthieu
Published: October 2015

The long-sought structure of an active polycomb repressive complex is solved

[Also see Research Article by
Jiao and Liu
]
Polyploid Titan Cells Produce Haploid and Aneuploid Progeny To Promote Stress Adaptation
Authors: Gerstein Aleeza C. , Fu Man Shun , Mukaremera Liliane , Li Zhongming , Ormerod Kate L. , Fraser James A. , Berman Judith , Nielsen Kirsten
Published: October 2015

Cryptococcus neoformans
is a major life-threatening fungal pathogen. In response to the stress of the host environment,
C. neoformans
produces large polyploid titan cells. Titan cell production enhances the virulence of
C. neoformans
, yet whether the polyploid aspect of titan cells is specifically influential remains unknown. We show that titan cells were more likely to survive and produce offspring under multiple stress conditions than typical cells and that even their normally sized daughters maintained an advantage over typical cells in continued exposure to stress. Although polyploid titan cells generated haploid daughter cell progeny upon
in vitro
replication under nutrient-replete conditions, titan cells treated with the antifungal drug fluconazole produced fluconazole-resistant diploid and aneuploid daughter cells. Interestingly, a single titan mother cell was capable of generating multiple types of aneuploid daughter cells. The increased survival and genomic diversity of titan cell progeny promote rapid adaptation to new or high-stress conditions.

IMPORTANCE
The ability to adapt to stress is a key element for survival of pathogenic microbes in the host and thus plays an important role in pathogenesis. Here we investigated the predominantly haploid human fungal pathogen
Cryptococcus neoformans
, which is capable of ploidy and cell size increases during infection through production of titan cells. The enlarged polyploid titan cells are then able to rapidly undergo ploidy reduction to generate progeny with reduced ploidy and/or aneuploidy. Under stressful conditions, titan cell progeny have a growth and survival advantage over typical cell progeny. Understanding how titan cells enhance the rate of cryptococcal adaptation under stress conditions may assist in the development of novel drugs aimed at blocking ploidy transitions.
Factors that predict a poor outcome 5–8 years after the diagnosis of patellofemoral pain: a multicentre observational analysis
Authors: Lankhorst N E , van Middelkoop M , Crossley K M , Bierma-Zeinstra S M A , Oei E H G , Vicenzino B , Collins N J
Published: October 2015

Background

Patellofemoral pain (PFP) has traditionally been viewed as self-limiting, but recent studies show that a large proportion of patients report chronic knee pain at long-term follow-up. We identified those patients with an unfavourable recovery (‘moderate improvement’ to ‘worse than ever’ measured on a Likert scale) and examined whether there is an association between PFP and osteoarthritis (OA) at 5–8-year follow-up.

Methods

Long-term follow-up data were derived from 2 randomised controlled trials (n=179, n=131). Patient-reported measures were obtained at baseline. Pain severity (100 mm visual analogue scale (VAS)), function (Anterior Knee Pain Scale (AKPS)) and self-reported recovery were measured 5–8 years later, along with knee radiographs. Multivariate backward stepwise linear regression analyses were used to evaluate the prognostic ability of baseline pain duration, pain VAS and AKPS on outcomes of pain VAS and AKPS at 5–8 years.

Results

60 (19.3%) participants completed the questionnaires at 5–8-year follow-up (45 women, mean age at baseline 26 years) and 50 underwent knee radiographs. No differences were observed between responders and non-responders regarding baseline demographics, and 3-month and 12-month pain severity and recovery. 34 (57%) reported unfavourable recovery at 5–8 years. 48 out of 50 participants (98%) had no signs of radiographic knee OA. Multivariate models revealed that baseline PFP duration (>12 months; R2=0.22) and lower AKPS (R2=0.196) were significant predictors of poor prognosis at 5–8 years on measures of worst pain VAS and AKPS, respectively.

Summary and conclusion

More than half of participants with PFP reported an unfavourable recovery 5–8 years after recruitment, but did not have radiographic knee OA. Longer PFP duration and worse AKPS score at baseline predict poor PFP prognosis. Education of health practitioners and the general public will provide patients with more realistic expectations regarding prognosis.