bluuebunny/crossref_metadata_2025 huggingface dataset:
Discrimination of mixed-directional whistles by a bottlenose dolphin (Tursiops truncatus)
Authors: Branstetter Brian K. , Black Amy , Bakhtiari Kimberly
Published: August 2013

Dolphins are hypothesized to deduce the swimming direction of group members by attending to the spectral pattern of whistle harmonics. This is known as the direction of movement cue hypothesis and may facilitate coordination of complex group behavior when visibility is poor. The direction of movement cue hypothesis hinges on the assumption that dolphins can discriminate between whistles with different harmonic patterns that are associated with signaler orientation. This assumption was tested with a bottlenose dolphin. Whistles were recorded from a dolphin at different azimuth positions (0° to 180° in 45° increments). Noise-free, synthetic whistles were created to mimic the direction-dependant spectral profiles of the recorded whistles. A dolphin was then tested in its ability to discriminate between the synthetic whistles using fixed level and roving level conditions. The dolphin's discrimination performance in both the fixed and roving level conditions was near 100% for whistles separated by angles greater than 45°, and near chance for 45° separations. Computer simulations of the task, along with the dolphin's performance, suggest that the dolphin's discrimination was level invariant and based on the spectral pattern of the whistles.
Real-time reporting of baleen whale passive acoustic detections from ocean gliders
Authors: Baumgartner Mark F. , Fratantoni David M. , Hurst Thomas P. , Brown Moira W. , Cole Tim V. N. , Van Parijs Sofie M. , Johnson Mark
Published: August 2013

In the past decade, much progress has been made in real-time passive acoustic monitoring of marine mammal occurrence and distribution from autonomous platforms (e.g., gliders, floats, buoys), but current systems focus primarily on a single call type produced by a single species, often from a single location. A hardware and software system was developed to detect, classify, and report 14 call types produced by 4 species of baleen whales in real time from ocean gliders. During a 3-week deployment in the central Gulf of Maine in late November and early December 2012, two gliders reported over 25 000 acoustic detections attributed to fin, humpback, sei, and right whales. The overall false detection rate for individual calls was 14%, and for right, humpback, and fin whales, false predictions of occurrence during 15-min reporting periods were 5% or less. Transmitted pitch tracks—compact representations of sounds—allowed unambiguous identification of both humpback and fin whale song. Of the ten cases when whales were sighted during aerial or shipboard surveys and a glider was within 20 km of the sighting location, nine were accompanied by real-time acoustic detections of the same species by the glider within ±12 h of the sighting time.
Reciprocity in the scattering coefficients of acoustic waveguide modes
Authors: Tong Yuhui , Pan Jie
Published: August 2013

In this Letter, a proof is provided for the reciprocity between modal scattering coefficients of the acoustic waveguides connected by a junction enclosure. The result holds for all waveguide modes and for junction enclosures with locally reactive boundary conditions away from the interfaces between the junction and waveguides. Also provided is a physical interpretation of the reciprocity of the modal scattering coefficients. The scattering of two-dimensional waveguide modes by a right-angled bend in a rectangular duct is used as an illustrating example.
Acoustical correlates of performance on a dynamic range compression discrimination task
Authors: Sabin Andrew T. , Gallun Frederick J. , Souza Pamela E.
Published: August 2013

Dynamic range compression is widely used to reduce the difference between the most and least intense portions of a signal. Such compression distorts the shape of the amplitude envelope of a signal, but it is unclear to what extent such distortions are actually perceivable by listeners. Here, the ability to distinguish between compressed and uncompressed versions of a noise vocoded sentence was initially measured in listeners with normal hearing while varying the threshold, ratio, attack, and release parameters. This narrow condition was selected in order to characterize perception under the most favorable listening conditions. The average behavioral sensitivity to compression was highly correlated to several acoustical indices of modulation depth. In particular, performance was highly correlated to the Euclidean distance between the modulation spectra of the uncompressed and compressed signals. Suggesting that this relationship is not restricted to the initial test conditions, the correlation remained largely unchanged both (1) when listeners with normal hearing were tested using a time-compressed version of the original signal, and (2) when listeners with impaired hearing were tested using the original signal. If this relationship generalizes to more ecologically valid conditions, it will provide a straightforward method for predicting the detectability of compression-induced distortions.
Theoretical analysis of signal-to-noise ratios for transient evoked otoacoustic emission recordings
Authors: Lineton Ben
Published: August 2013

Recordings of transient-evoked otoacoustic emissions (TEOAEs) suffer from two main sources of contamination: Random noise and the stimulus artifact. The stimulus artifact can be substantially reduced by using a derived non-linear recording paradigm. Three such paradigms are analyzed, called here the level derived non-linear (LDNL), the double-evoked (DE), and the rate derived non-linear (RDNL) paradigms. While these methods successfully reduce the stimulus artifact, they lead to an increase in contamination by random noise. In this study, the signal-to-noise ratio (SNR) achievable by these three paradigms is compared using a common theoretical framework. This analysis also allows the optimization of the parameters of the RDNL paradigm to achieve the maximum SNR. Calculations based on the analysis with typical parameters used in practice suggest that when ranked in terms of their SNR for a given averaging time, RDNL performs best followed by the LDNL and DE paradigms.
Modeling of wave propagation in drill strings using vibration transfer matrix methods
Authors: Han Je-Heon , Kim Yong-Joe , Karkoub Mansour
Published: August 2013

In order to understand critical vibration of a drill bit such as stick-slip and bit-bounce and their wave propagation characteristics through a drill string system, it is critical to model the torsional, longitudinal, and flexural waves generated by the drill bit vibration. Here, a modeling method based on a vibration transfer matrix between two sets of structural wave variables at the ends of a constant cross-sectional, hollow, circular pipe is proposed. For a drill string system with multiple pipe sections, the total vibration transfer matrix is calculated by multiplying all individual matrices, each is obtained for an individual pipe section. Since drill string systems are typically extremely long, conventional numerical analysis methods such as a finite element method (FEM) require a large number of meshes, which makes it computationally inefficient to analyze these drill string systems numerically. The proposed “analytical” vibration transfer matrix method requires significantly low computational resources. For the validation of the proposed method, experimental and numerical data are obtained from laboratory experiments and FEM analyses conducted by using a commercial FEM package, ANSYS. It is shown that the modeling results obtained by using the proposed method are well matched with the experimental and numerical results.
Imprecise vowel articulation as a potential early marker of Parkinson's disease: Effect of speaking task
Authors: Rusz Jan , Cmejla Roman , Tykalova Tereza , Ruzickova Hana , Klempir Jiri , Majerova Veronika , Picmausova Jana , Roth Jan , Ruzicka Evzen
Published: August 2013

The purpose of this study was to analyze vowel articulation across various speaking tasks in a group of 20 early Parkinson's disease (PD) individuals prior to pharmacotherapy. Vowels were extracted from sustained phonation, sentence repetition, reading passage, and monologue. Acoustic analysis was based upon measures of the first (F1) and second (F2) formant of the vowels /a/, /i/, and /u/, vowel space area (VSA), F2i/F2u and vowel articulation index (VAI). Parkinsonian speakers manifested abnormalities in vowel articulation across F2u, VSA, F2i/F2u, and VAI in all speaking tasks except sustained phonation, compared to 15 age-matched healthy control participants. Findings suggest that sustained phonation is an inappropriate task to investigate vowel articulation in early PD. In contrast, monologue was the most sensitive in differentiating between controls and PD patients, with classification accuracy up to 80%. Measurements of vowel articulation were able to capture even minor abnormalities in speech of PD patients with no perceptible dysarthria. In conclusion, impaired vowel articulation may be considered as a possible early marker of PD. A certain type of speaking task can exert significant influence on vowel articulation. Specifically, complex tasks such as monologue are more likely to elicit articulatory deficits in parkinsonian speech, compared to other speaking tasks.
Deconvolution for the localization of sound sources using a circular microphone array
Authors: Tiana-Roig Elisabet , Jacobsen Finn
Published: August 2013

During the last decade, the aeroacoustic community has examined various methods based on deconvolution to improve the visualization of acoustic fields scanned with planar sparse arrays of microphones. These methods assume that the beamforming map in an observation plane can be approximated by a convolution of the distribution of the actual sources and the beamformer's point-spread function, defined as the beamformer's response to a point source. By deconvolving the resulting map, the resolution is improved, and the side-lobes effect is reduced or even eliminated compared to conventional beamforming. Even though these methods were originally designed for planar sparse arrays, in the present study, they are adapted to uniform circular arrays for mapping the sound over 360°. This geometry has the advantage that the beamforming output is practically independent of the focusing direction, meaning that the beamformer's point-spread function is shift-invariant. This makes it possible to apply computationally efficient deconvolution algorithms that consist of spectral procedures in the entire region of interest, such as the deconvolution approach for the mapping of the acoustic sources 2, the Fourier-based non-negative least squares, and the Richardson–Lucy. This investigation examines the matter with computer simulations and measurements.
Effects of different analysis techniques and recording duty cycles on passive acoustic monitoring of killer whales
Authors: Riera Amalis , Ford John K. , Ross Chapman N.
Published: August 2013

Killer whales in British Columbia are at risk, and little is known about their winter distribution. Passive acoustic monitoring of their year-round habitat is a valuable supplemental method to traditional visual and photographic surveys. However, long-term acoustic studies of odontocetes have some limitations, including the generation of large amounts of data that require highly time-consuming processing. There is a need to develop tools and protocols to maximize the efficiency of such studies. Here, two types of analysis, real-time and long term spectral averages, were compared to assess their performance at detecting killer whale calls in long-term acoustic recordings. In addition, two different duty cycles, 1/3 and 2/3, were tested. Both the use of long term spectral averages and a lower duty cycle resulted in a decrease in call detection and positive pod identification, leading to underestimations of the amount of time the whales were present. The impact of these limitations should be considered in future killer whale acoustic surveys. A compromise between a lower resolution data processing method and a higher duty cycle is suggested for maximum methodological efficiency.
A practical weighting function for harbor porpoise underwater sound level measurements
Authors: Terhune John M.
Published: August 2013

Harbor porpoise (Phocoena phocoena) are subject to underwater noise disturbance from anthropogenic sources, especially shipping. The underwater audiograms of harbor porpoise were used to create a frequency weighting function, dBht(Phocoena phocoena), to permit estimation of the broadband perceived amplitudes of ambient and shipping noise. An equation was fit to the 0.02–20 kHz range of unmasked detection thresholds and normalizing to 0 dB at 20 kHz; dB = 46.4–35.6 log(kHz). The weighting function de-emphasizes the low frequency components of noise. Harbor porpoise hearing is less sensitive to low frequency shipping noise and, except at high amplitudes, estimating potential noise impacts using linear measurements will be misleading.
Determining the detection thresholds for harbor porpoise clicks of autonomous data loggers, the Timing Porpoise Detectors
Authors: Verfuß Ursula K. , Dähne Michael , Gallus Anja , Jabbusch Martin , Benke Harald
Published: August 2013

Timing Porpoise Detectors (T-PODs, Chelonia Ltd.) are autonomous passive acoustic devices for monitoring odontocetes. They register the time of occurrence and duration of high frequency pulsed sounds as possible odontocetes echolocation clicks. Because of evolution, five T-POD versions exist. Although the manufacturer replaced those by a digital successor, the C-POD, T-PODs are still used, and data from many field studies exist. Characterizing the acoustic properties of T-PODs enables the interpretation of data obtained with different devices. Here, the detection thresholds of different T-POD versions for harbor porpoise clicks were determined. While thresholds among devices were quite variable in the first T-POD generations, they became more standardized in newer versions. Furthermore, the influence of user-controlled settings on the threshold was investigated. From version 3 on, the detection threshold was found to be easily adjustable with version-dependent setting options “minimum intensity” and “sensitivity,” enabling the presetting of standard thresholds. In version 4, the setting “click bandwidth” had a strong influence on the detection threshold, while “selectivity” in version 3 and “noise adaptation = ON” or “OFF” in version 4 hardly influenced thresholds obtained in the tank tests. Nevertheless, the latter setting may influence thresholds in a complex acoustic environment like the sea.
An automatic detection algorithm for extracting the representative frequency of cetacean tonal sounds
Authors: Lin Tzu-Hao , Chou Lien-Siang , Akamatsu Tomonari , Chan Hsiang-Chih , Chen Chi-Fang
Published: August 2013

Most studies on tonal sounds extract contour parameters from fundamental frequencies. The presence of harmonics and the frequency distribution of multiple tonal sounds have not been well researched. To investigate the occurrence and frequency modulation of cetacean tonal sounds, the procedure of detecting the instantaneous frequency bandwidth of tonal spectral peaks was integrated within the local-max detector to extract adopted frequencies. The adopted frequencies, considered the representative frequencies of tonal sounds, are used to find the presence of harmonics and overlapping tonal sounds. The utility and detection performance are demonstrated on acoustic recordings of five species from two databases. The recordings of humpback dolphins showed a 75% detection rate with a 5% false detection rate, and recordings from the MobySound archive showed an 85% detection rate with a 5% false detection rate. These detections were achieved in signal-to-noise ratios of −12 to 21 dB. The parameters that measured the distribution of adopted frequency, as well as the prominence of harmonics and overlaps, indicate that the modulation of tonal sounds varied among different species and behaviors. This algorithm can be applied to studies on cetacean communication signals and long-term passive acoustic monitoring.
Source levels of dugong (Dugong dugon) vocalizations recorded in Shark Bay
Authors: Parsons Miles J. G. , Holley Dave , McCauley Robert D.
Published: August 2013

Dugongs (Dugong dugon) spend significant time in shallow, turbid waters and are often active at night, conditions which are not conducive to visual cues. In part, as a result, dugongs vocalize to gain or pass information. Passive acoustic recording is a useful tool for remote detection of vocal marine animals, but its application to dugongs has been little explored compared with other mammals. Aerial surveys, often used to monitor dugong distribution and abundance, are not always financially or logistically viable and involve inherent availability and perception bias considerations. Passive acoustic monitoring is also subject to sampling biases and a first step to identifying these biases and understanding the detection or communication range of animal calls is to determine call source level. In March 2012, four dugongs were fitted with satellite tags in Shark Bay, Western Australia by the Department of Environment and Conservation. During this, acoustic recordings were taken at 5.1 m range. Source levels for each of five call types (two types of chirp, bark, squeak, and quack) were estimated, assuming spherical spreading as the transmission loss. Mean source levels for these call types were 139 (n = 19), 135 (12), 142 (2), 158 (1), and 136 (9) dB re 1 μPa at 1 m, respectively.
Acoustic detection probability of bottlenose dolphins, Tursiops truncatus, with static acoustic dataloggers in Cardigan Bay, Wales
Authors: Nuuttila Hanna K. , Thomas Len , Hiddink Jan G. , Meier Rhiannon , Turner John R. , Bennell James D. , Tregenza Nick J. C. , Evans Peter G. H.
Published: August 2013

Acoustic dataloggers are used for monitoring the occurrence of cetaceans and can aid in fulfilling statutory monitoring requirements of protected species. Although useful for long-term monitoring, their spatial coverage is restricted, and for many devices the effective detection distance is not specified. A generalized additive mixed model (GAMM) was used to investigate the effects of (1) distance from datalogger, (2) animal behavior (feeding and traveling), and (3) group size on the detection probability of bottlenose dolphins (Tursiops truncatus) with autonomous dataloggers (C-PODs) validated with visual observations. The average probability of acoustic detection for minutes with a sighting was 0.59 and the maximum detection distance ranged from 1343–1779 m. Minutes with feeding activity had higher acoustic detection rates and longer average effective detection radius (EDR) than traveling ones. The detection probability for single dolphins was significantly higher than for groups, indicating that their acoustic behavior may differ from those of larger groups in the area, making them more detectable. The C-POD is effective at detecting dolphin presence but the effects of behavior and group size on detectability create challenges for estimating density from detections as higher detection rate of feeding dolphins could yield erroneously high density estimates in feeding areas.
Seabed roughness parameters from joint backscatter and reflection inversion at the Malta Plateau
Authors: Steininger Gavin , Holland Charles W. , Dosso Stan E. , Dettmer Jan
Published: August 2013

This paper presents estimates of seabed roughness and geoacoustic parameters and uncertainties on the Malta Plateau, Mediterranean Sea, by joint Bayesian inversion of mono-static backscatter and spherical wave reflection-coefficient data. The data are modeled using homogeneous fluid sediment layers overlying an elastic basement. The scattering model assumes a randomly rough water-sediment interface with a von Karman roughness power spectrum. Scattering and reflection data are inverted simultaneously using a population of interacting Markov chains to sample roughness and geoacoustic parameters as well as residual error parameters. Trans-dimensional sampling is applied to treat the number of sediment layers and the order (zeroth or first) of an autoregressive error model (to represent potential residual correlation) as unknowns. Results are considered in terms of marginal posterior probability profiles and distributions, which quantify the effective data information content to resolve scattering/geoacoustic structure. Results indicate well-defined scattering (roughness) parameters in good agreement with existing measurements, and a multi-layer sediment profile over a high-speed (elastic) basement, consistent with independent knowledge of sand layers over limestone.
ACOUSTICAL STANDARDS NEWS
Authors: Blaeser Susan B. , Schomer Paul D.
Published: August 2013

American National Standards (ANSI Standards) developed by Accredited Standards Committees S1, S2, S3, and S12 in the areas of acoustics, mechanical vibration and shock, bioacoustics, and noise, respectively, are published by the Acoustical Society of America (ASA). In addition to these standards, ASA publishes catalogs of Acoustical Standards, both National and International. To receive copies of the latest Standards Catalogs, please contact Susan B. Blaeser.

Comments are welcomed on all material in Acoustical Standards News.

This Acoustical Standards News section in JASA, as well as the National and International Catalogs of Acoustical Standards, and other information on the Standards Program of the Acoustical Society of America, are available via the ASA home page: http://acousticalsociety.org.
Hearing thresholds of a harbor porpoise (Phocoena phocoena) for playbacks of multiple pile driving strike sounds
Authors: Kastelein Ronald A. , Hoek Lean , Gransier Robin , de Jong Christ A. F.
Published: August 2013

Pile driving is presently the most common method used to attach wind turbines to the sea bed. To assess the impact of pile driving sounds on harbor porpoises, it is important to know at what distance these sounds can be detected. Using a psychophysical technique, a male porpoise's hearing thresholds were obtained for series of five pile driving sounds (inter-pulse interval 1.2–1.3 s) recorded at 100 and 800 m from the pile driving site, and played back in a pool. The 50% detection threshold sound exposure levels (SELs) for the first sound of the series (no masking) were 72 (100 m) and 74 (800 m) dB re 1 μPa2s. Multiple sounds in succession (series) caused a ∼5 dB decrease in hearing threshold; the mean 50% detection threshold SELs for any sound in the series were 68 (100 m) and 69 (800 m) dB re 1 μPa2s. Depending on the actual propagation conditions and background noise levels, the results suggest that pile driving sounds are audible to porpoises at least at tens of kilometers from pile driving sites.
Preparation of stimuli for timbre perception studies
Authors: Labuschagne Ilse B. , Hanekom Johan J.
Published: August 2013

Stimuli used in timbre perception studies must be controlled carefully in order to yield meaningful results. During psychoacoustic testing of individual timbre properties, (1) it must be ensured that timbre properties do not co-vary, as timbre properties are often not independent from one another, and (2) the potential influence of loudness, pitch, and perceived duration must be eliminated. A mathematical additive synthesis method is proposed which allows complete control over two spectral parameters, the spectral centroid (corresponding to brightness) and irregularity, and two temporal parameters, log rise-time (LRT) and a parameter characterizing the sustain/decay segment, while controlling for covariation in the spectral centroid and irregularity. Thirteen musical instrument sounds were synthesized. Perceptual data from six listeners indicate that variation in the four timbre properties mainly influences loudness and that perceived duration and pitch are not influenced significantly for the stimuli of longer duration (2 s) used here. Trends across instruments were found to be similar.
Antisymmetric feature-guided ultrasonic waves in thin plates with small radius transverse bends from low-frequency symmetric axial excitation
Authors: Ramdhas Abilasha , Pattanayak Roson Kumar , Balasubramaniam Krishnan , Rajagopal Prabhu
Published: August 2013

The influence of bends constituting annular polygonal structures on ultrasonic guided waves propagating along their axis is investigated. Considering a single bend as a bent plate connects this problem to the better-understood physics of guided waves in straight plates. Using a three-dimensional finite element simulation validated with experiments, bends in plates are shown to act as features that can concentrate and guide ultrasonic energy along their length. Two interesting feature-guided modes are identified when the bent plate is subjected to “in-plane” or axial excitation applied uniformly along a through-thickness line bisecting the bent edge. Of these, the faster traveling mode has properties similar to, but travels at group velocities lower than, the S0 (fundamental symmetric) Lamb mode in flat plates. This paper however focuses on the slower bend-guided mode that is similar to the A0 (fundamental anti-symmetric) Lamb mode in flat plates. This mode is shown to be more strongly generated in smaller angle bends where it has a low attenuation. The results are discussed in light of simple modal studies performed using the Semi-Analytical Finite Element method.
Neural network predictions of acoustical parameters in multi-purpose performance halls
Authors: Cheung L. Y. , Tang S. K.
Published: August 2013

A detailed binaural sound measurement was carried out in two multi-purpose performance halls of different seating capacities and designs in Hong Kong in the present study. The effectiveness of using neural network in the predictions of the acoustical properties using a limited number of measurement points was examined. The root-mean-square deviation from measurements, statistical parameter distribution matching, and the results of a t-test for vanishing mean difference between simulations and measurements were adopted as the evaluation criteria for the neural network performance. The audience locations relative to the sound source were used as the inputs to the neural network. Results show that the neural network training scheme using nine uniformly located measurement points in each specific hall area is the best choice regardless of the hall setting and design. It is also found that the neural network prediction of hall spaciousness does not require a large amount of training data, but the accuracy of the reverberance related parameter predictions increases with increasing volume of training data.
Parametric head-related transfer function modeling and interpolation for cost-efficient binaural sound applications
Authors: Ramos German , Cobos Maximo
Published: August 2013

Parametric methods for modeling the perceptually relevant features of head-related transfer functions (HRTFs) are very important for the development of low-cost immersive sound applications. This letter describes an efficient method based on a low-order infinite impulse response filter implemented by a chain of second order sections of conventional shelving and peak audio filters. The parameters (central frequency, gain, and quality factor) are numerically adjusted by iteratively fitting the frequency response of the filter to the desired HRTF. Besides allowing for low-order binaural models, the proposed approach provides an efficient way to synthesize HRTFs for non-measured angles by applying a simple interpolation between the parameters from neighboring responses. Additionally, the HRTF database size is significantly reduced.
Range estimation of cetaceans with compact volumetric arrays
Authors: Zimmer Walter M. X.
Published: August 2013

Passive acoustic monitoring is the method of choice to detect whales and dolphins that are acoustically active and to monitor their underwater behavior. The NATO Science and Technology Organization Centre for Maritime Research and Experimentation has recently implemented a compact passive acoustic monitor (CPAM), consisting of three arrays of two hydrophones each that are combined in a fixed three-dimensional arrangement and that may be towed at depths of more than 100 m. With its volumetric configuration, the CPAM is capable of estimating the three-dimensional direction vector of arriving sounds and under certain conditions on relative geometry between the whale and hydrophone array, the CPAM may also estimate the range to echolocating animals. Basic ranging methods assume constant sound speed and apply straightforward geometry to obtain depth and distance to the sound source. Alternatively, ray-tracing based methods may be employed to integrate the information provided by real sound speed profiles. Both ranging methods combine measurements of sound arrival angles and surface reflection delays and are easily implemented in real-time applications, whereby one could promote the ray-tracing approach as the preferred method because it may integrate real sound speed profiles.
Methods for reverberation suppression utilizing dual frequency band imaging
Authors: Rau Jochen M. , Måsøy Svein-Erik , Hansen Rune , Angelsen Bjørn , Tangen Thor Andreas
Published: August 2013

Reverberations impair the contrast resolution of diagnostic ultrasound images. Tissue harmonic imaging is a common method to reduce these artifacts, but does not remove all reverberations. Dual frequency band imaging (DBI), utilizing a low frequency pulse which manipulates propagation of the high frequency imaging pulse, has been proposed earlier for reverberation suppression. This article adds two different methods for reverberation suppression with DBI: the delay corrected subtraction (DCS) and the first order content weighting (FOCW) method. Both methods utilize the propagation delay of the imaging pulse of two transmissions with alternating manipulation pressure to extract information about its depth of first scattering. FOCW further utilizes this information to estimate the content of first order scattering in the received signal. Initial evaluation is presented where both methods are applied to simulated and in vivo data. Both methods yield visual and measurable substantial improvement in image contrast. Comparing DCS with FOCW, DCS produces sharper images and retains more details while FOCW achieves best suppression levels and, thus, highest image contrast. The measured improvement in contrast ranges from 8 to 27 dB for DCS and from 4 dB up to the dynamic range for FOCW.
Realization of an omnidirectional source of sound using parametric loudspeakers
Authors: Sayin Umut , Artís Pere , Guasch Oriol
Published: August 2013

Parametric loudspeakers are often used in beam forming applications where a high directivity is required. Withal, in this paper it is proposed to use such devices to build an omnidirectional source of sound. An initial prototype, the omnidirectional parametric loudspeaker (OPL), consisting of a sphere with hundreds of ultrasonic transducers placed on it has been constructed. The OPL emits audible sound thanks to the parametric acoustic array phenomenon, and the close proximity and the large number of transducers results in the generation of a highly omnidirectional sound field. Comparisons with conventional dodecahedron loudspeakers have been made in terms of directivity, frequency response, and in applications such as the generation of diffuse acoustic fields in reverberant chambers. The OPL prototype has performed better than the conventional loudspeaker especially for frequencies higher than 500 Hz, its main drawback being the difficulty to generate intense pressure levels at low frequencies.
On-road and wind-tunnel measurement of motorcycle helmet noise
Authors: Kennedy J. , Carley M. , Walker I. , Holt N.
Published: August 2013

The noise source mechanisms involved in motorcycling include various aerodynamic sources and engine noise. The problem of noise source identification requires extensive data acquisition of a type and level that have not previously been applied. Data acquisition on track and on road are problematic due to rider safety constraints and the portability of appropriate instrumentation. One way to address this problem is the use of data from wind tunnel tests. The validity of these measurements for noise source identification must first be demonstrated. In order to achieve this extensive wind tunnel tests have been conducted and compared with the results from on-track measurements. Sound pressure levels as a function of speed were compared between on track and wind tunnel tests and were found to be comparable. Spectral conditioning techniques were applied to separate engine and wind tunnel noise from aerodynamic noise and showed that the aerodynamic components were equivalent in both cases. The spectral conditioning of on-track data showed that the contribution of engine noise to the overall noise is a function of speed and is more significant than had previously been thought. These procedures form a basis for accurate experimental measurements of motorcycle noise.
Enhanced awakening probability of repetitive impulse sounds
Authors: Vos Joos , Houben Mark M. J.
Published: August 2013

In the present study relations between the level of impulse sounds and the observed proportion of behaviorally confirmed awakening reactions were determined. The sounds (shooting sounds, bangs produced by door slamming or by container transshipment, aircraft landings) were presented by means of loudspeakers in the bedrooms of 50 volunteers. The fragments for the impulse sounds consisted of single or multiple events. The sounds were presented during a 6-h period that started 75 min after the subjects wanted to sleep. In order to take account of habituation, each subject participated during 18 nights. At equal indoor A-weighted sound exposure levels, the proportion of awakening for the single impulse sounds was equal to that for the aircraft sounds. The proportion of awakening induced by the multiple impulse sounds, however, was significantly higher. For obtaining the same rate of awakening, the sound level of each of the successive impulses in a fragment had to be about 15–25 dB lower than the level of one single impulse. This level difference was largely independent of the degree of habituation. Various explanations for the enhanced awakening probability are discussed.
Orangutan (Pongo spp.) whistling and implications for the emergence of an open-ended call repertoire: A replication and extension
Authors: Lameira Adriano R. , Hardus Madeleine E. , Kowalsky Bernd , de Vries Han , Spruijt Berry M. , Sterck Elisabeth H. M. , Shumaker Robert W. , Wich Serge A.
Published: August 2013

One of the most apparent discontinuities between non-human primate (primate) call communication and human speech concerns repertoire size. The former is essentially fixed to a limited number of innate calls, while the latter essentially consists of numerous learned components. Consequently, primates are thought to lack laryngeal control required to produce learned voiced calls. However, whether they may produce learned voiceless calls awaits investigation. Here, a case of voiceless call learning in primates is investigated—orangutan (Pongo spp.) whistling. In this study, all known whistling orangutans are inventoried, whistling-matching tests (previously conducted with one individual) are replicated with another individual using original test paradigms, and articulatory and acoustic whistle characteristics are compared between three orangutans. Results show that whistling has been reported for ten captive orangutans. The test orangutan correctly matched human whistles with significantly high levels of performance. Whistle variation between individuals indicated voluntary control over the upper lip, lower lip, and respiratory musculature, allowing individuals to produce learned voiceless calls. Results are consistent with inter- and intra-specific social transmission in whistling orangutans. Voiceless call learning in orangutans implies that some important components of human speech learning and control were in place before the homininae-ponginae evolutionary split.
Lysobacter enzymogenes Uses Two Distinct Cell-Cell Signaling Systems for Differential Regulation of Secondary-Metabolite Biosynthesis and Colony Morphology
Authors: Qian Guoliang , Wang Yulan , Liu Yiru , Xu Feifei , He Ya-Wen , Du Liangcheng , Venturi Vittorio , Fan Jiaqin , Hu Baishi , Liu Fengquan
Published: August 2013

Lysobacter enzymogenes
is a ubiquitous environmental bacterium that is emerging as a potentially novel biological control agent and a new source of bioactive secondary metabolites, such as the heat-stable antifungal factor (HSAF) and photoprotective polyene pigments. Thus far, the regulatory mechanism(s) for biosynthesis of these bioactive secondary metabolites remains largely unknown in
L. enzymogenes
. In the present study, the diffusible signal factor (DSF) and diffusible factor (DF)-mediated cell-cell signaling systems were identified for the first time from
L. enzymogenes
. The results show that both Rpf/DSF and DF signaling systems played critical roles in modulating HSAF biosynthesis in
L. enzymogenes
. Rpf/DSF signaling and DF signaling played negative and positive effects in polyene pigment production, respectively, with DF playing a more important role in regulating this phenotype. Interestingly, only Rpf/DSF, but not the DF signaling system, regulated colony morphology of
L. enzymgenes
. Both Rpf/DSF and DF signaling systems were involved in the modulation of expression of genes with diverse functions in
L. enzymogenes
, and their own regulons exhibited only a few loci that were regulated by both systems. These findings unveil for the first time new roles of the Rpf/DSF and DF signaling systems in secondary metabolite biosynthesis of
L. enzymogenes
.
Moderate Prevalence of Antimicrobial Resistance in Escherichia coli Isolates from Lettuce, Irrigation Water, and Soil
Authors: Holvoet Kevin , Sampers Imca , Callens Benedicte , Dewulf Jeroen , Uyttendaele Mieke
Published: August 2013

Fresh produce is known to carry nonpathogenic epiphytic microorganisms. During agricultural production and harvesting, leafy greens can become contaminated with antibiotic-resistant pathogens or commensals from animal and human sources. As lettuce does not undergo any inactivation or preservation treatment during processing, consumers may be exposed directly to all of the (resistant) bacteria present. In this study, we investigated whether lettuce or its production environment (irrigation water, soil) is able to act as a vector or reservoir of antimicrobial-resistant
Escherichia coli
. Over a 1-year period, eight lettuce farms were visited multiple times and 738 samples, including lettuce seedlings (leaves and soil), soil, irrigation water, and lettuce leaves were collected. From these samples, 473 isolates of
Escherichia coli
were obtained and tested for resistance to 14 antimicrobials. Fifty-four isolates (11.4%) were resistant to one or more antimicrobials. The highest resistance rate was observed for ampicillin (7%), followed by cephalothin, amoxicillin-clavulanic acid, tetracycline, trimethoprim, and streptomycin, with resistance rates between 4.4 and 3.6%. No resistance to amikacin, ciprofloxacin, gentamicin, or kanamycin was observed. One isolate was resistant to cefotaxime. Among the multiresistant isolates (
n
= 37), ampicillin and cephalothin showed the highest resistance rates, at 76 and 52%, respectively.
E. coli
isolates from lettuce showed higher resistance rates than
E. coli
isolates obtained from soil or irrigation water samples. When the presence of resistance in
E. coli
isolates from lettuce production sites and their resistance patterns were compared with the profiles of animal-derived
E. coli
strains, they were found to be the most comparable with what is found in the cattle reservoir. This may suggest that cattle are a potential reservoir of antimicrobial-resistant
E. coli
strains in plant primary production.
Insertion of Endocellulase Catalytic Domains into Thermostable Consensus Ankyrin Scaffolds: Effects on Stability and Cellulolytic Activity
Authors: Cunha Eva S. , Hatem Christine L. , Barrick Doug
Published: August 2013

Degradation of cellulose for biofuels production holds promise in solving important environmental and economic problems. However, the low activities (and thus high enzyme-to-substrate ratios needed) of hydrolytic cellulase enzymes, which convert cellulose into simple sugars, remain a major barrier. As a potential strategy to stabilize cellulases and enhance their activities, we have embedded cellulases of extremophiles into hyperstable α-helical consensus ankyrin domain scaffolds. We found the catalytic domains CelA (CA, GH8;
Clostridium thermocellum
) and Cel12A (C12A, GH12;
Thermotoga maritima
) to be stable in the context of the ankyrin scaffold and to be active against both soluble and insoluble substrates. The ankyrin repeats in each fusion are folded, although it appears that for the C12A
c
atalytic
d
omain (CD; where the N and C termini are distant in the crystal structure), the two flanking ankyrin domains are independent, whereas for CA (where termini are close), the flanking ankyrin domains stabilize each other. Although the activity of CA is unchanged in the context of the ankyrin scaffold, the activity of C12A is increased between 2- and 6-fold (for regenerated amorphous cellulose and carboxymethyl cellulose substrates) at high temperatures. For C12A, activity increases with the number of flanking ankyrin repeats. These results showed ankyrin arrays to be a promising scaffold for constructing designer cellulosomes, preserving or enhancing enzymatic activity and retaining thermostability. This modular architecture will make it possible to arrange multiple cellulase domains at a precise spacing within a single polypeptide, allowing us to search for spacings that may optimize reactivity toward the repetitive cellulose lattice.
bZIP Transcription Factors in the Oomycete Phytophthora infestans with Novel DNA-Binding Domains Are Involved in Defense against Oxidative Stress
Authors: Gamboa-Meléndez Heber , Huerta Apolonio I. , Judelson Howard S.
Published: August 2013

Transcription factors of the basic leucine zipper (bZIP) family control development and stress responses in eukaryotes. To date, only one bZIP has been described in any oomycete; oomycetes are members of the stramenopile kingdom. In this study, we describe the identification of 38 bZIPs from the
Phytophthora infestans
genome. Half contain novel substitutions in the DNA-binding domain at a site that in other eukaryotes is reported to always be Asn. Interspecific comparisons indicated that the novel substitutions (usually Cys, but also Val and Tyr) arose after oomycetes diverged from other stramenopiles. About two-thirds of
P. infestans
bZIPs show dynamic changes in mRNA levels during the life cycle, with many of the genes being upregulated in sporangia, zoospores, or germinated zoospore cysts. One bZIP with the novel Cys substitution was shown to reside in the nucleus throughout growth and development. Using stable gene silencing, the functions of eight bZIPs with the Cys substitution were tested. All but one were found to play roles in protecting
P. infestans
from hydrogen peroxide-induced injury, and it is proposed that the novel Cys substitution serves as a redox sensor. A ninth bZIP lacking the novel Asn-to-Cys substitution, but having Cys nearby, was also shown through silencing to contribute to defense against peroxide. Little effect on asexual development, plant pathogenesis, or resistance to osmotic stress was observed in transformants silenced for any of the nine bZIPs.
Novel Feature of Mycobacterium avium subsp. paratuberculosis, Highlighted by Characterization of the Heparin-Binding Hemagglutinin Adhesin
Authors: Lefrancois Louise H. , Bodier Christelle C. , Cochard Thierry , Canepa Sylvie , Raze Dominique , Lanotte Philippe , Sevilla Iker A. , Stevenson Karen , Behr Marcel A. , Locht Camille , Biet Franck
Published: August 2013

Mycobacterium avium
subsp.
paratuberculosis
comprises two genotypically defined groups, known as the cattle (C) and sheep (S) groups. Recent studies have reported phenotypic differences between
M. avium
subsp.
paratuberculosis
groups C and S, including growth rates, infectivity for macrophages, and iron metabolism. In this study, we investigated the genotypes and biological properties of the virulence factor heparin-binding hemagglutinin adhesin (HBHA) for both groups. In
Mycobacterium tuberculosis
, HBHA is a major adhesin involved in mycobacterium-host interactions and extrapulmonary dissemination of infection. To investigate HBHA in
M. avium
subsp.
paratuberculosis
, we studied
hbhA
polymorphisms by fragment analysis using the GeneMapper technology across a large collection of isolates genotyped by mycobacterial interspersed repetitive-unit–variable-number tandem-repeat (MIRU-VNTR) and IS
900
restriction fragment length polymorphism (RFLP-IS
900
) analyses. Furthermore, we analyzed the structure-function relationships of recombinant HBHA proteins of types C and S by heparin-Sepharose chromatography and surface plasmon resonance (SPR) analyses.
In silico
analysis revealed two forms of HBHA, corresponding to the prototype genomes for the C and S types of
M. avium
subsp.
paratuberculosis
. This observation was confirmed using GeneMapper on 85
M. avium
subsp.
paratuberculosis
strains, including 67 strains of type C and 18 strains of type S. We found that HBHAs from all type C strains contain a short C-terminal domain, while those of type S present a long C-terminal domain, similar to that produced by
Mycobacterium avium
subsp.
avium
. The purification of recombinant HBHA from
M. avium
subsp.
paratuberculosis
of both types by heparin-Sepharose chromatography highlighted a correlation between their affinities for heparin and the lengths of their C-terminal domains, which was confirmed by SPR analysis. Thus, types C and S of
M. avium
subsp.
paratuberculosis
may be distinguished by the types of HBHA they produce, which differ in size and adherence properties, thereby providing new evidence that strengthens the genotypic differences between the C and S types of
M. avium
subsp.
paratuberculosis
.
Persistent left superior vena cava draining into the left atrium
Authors: Tobbia Patrick , Norris Leslie A , Lane Timothy
Published: August 2013

A 40-year-old man was admitted with necrotising fasciitis of the right thigh. Further workup to evaluate for an infectious source revealed an incidental finding of persistent left superior vena cava via transesophageal echocardiography. This finding was confirmed by cardiac MRI. During his hospitalisation, he also developed altered mental status which was found to be secondary to systemic emboli by a head MRI. The primary source of infection was likely his dental abscesses. He underwent intravenous antibiotic therapy for a total of 6 weeks and was then referred to a specialised vascular centre for further management of his congenital anomaly.
Unusual aetiology of isolated lower motor neuron facial palsy: systemic lupus erythematosus presenting with cranial nerve palsy and nephritis
Authors: Kazzaz Nayef Mohammed , El-Rifai Rasha
Published: August 2013

A 20-year-old woman presented with common cold symptoms was found to have a left-sided facial droop. On examination, peripheral facial nerve palsy was confirmed. Subsequent testing showed nephrotic range proteinuria and positive serologies including antinuclear antibody and anti-smith antibody. Kidney biopsy showed stage III lupus nephritis. Treatment with pulse steroids along with mycophenolate mofetil for her lupus nephritis resulted in concomitant improvement of her facial palsy.