bluuebunny/crossref_metadata_2025 huggingface dataset:
GABAB receptor‐mediated tonic inhibition regulates the spontaneous firing of locus coeruleus neurons in developing rats and in citalopram‐treated rats
Authors: Wang Han‐Ying , Kuo Zhao‐Chen , Fu Yu‐Show , Chen Ruei‐Feng , Min Ming‐Yuan , Yang Hsiu‐Wen
Published: October 2014

Key points

Noradrenaline (NA)‐releasing neurons in the locus coeruleus (LC) provide NA to the forebrain and play important roles in regulating many brain functions.

LC neurons are subject to tonic inhibition mediated by GABAB receptors (GABABRs) and that the extent of the effect varies with ambient GABA levels.

GABABR‐mediated tonic inhibition can effectively tune the spontaneous firing rate (SFR) of LC neurons; it is developmentally regulated and is responsible for maintaining a constant SFR of LC neurons during development.

In male, but not female rats, chronic perinatal treatment with citalopram, a selective serotonin reuptake inhibitor, results in downregulation of GABABR‐mediated tonic inhibition of LC neurons that partially accounts for increased SFR in male, but not female, rats receiving such treatment.

Our results show that GABABR‐mediated tonic inhibition could be an important player in the development of normal and abnormal behaviours/brain functions associated with the LC–NA system.

Noradrenaline (NA)‐releasing neurons in the locus coeruleus (LC) provide NA to the forebrain. Their activity is believed to be a key factor regulating the wakefulness/arousal level of the brain. In this study, we found that the activity of NA‐releasing neurons in the LC (LC neurons) was subject to γ‐aminobutyric acid (GABA) tonic inhibition through GABAB receptors (GABABRs), but not GABAA receptors. The intensity of GABABR tonic inhibition was found to depend on ambient GABA levels, as it was dramatically increased by blockade of GABA reuptake. It also varied with the function of GABABRs. The GABABR activity on LC neurons was found to increase with postnatal age up to postnatal days 8–10, resulting in increased tonic inhibition. Interestingly, there was no significant difference in the spontaneous activity of LC neurons at different postnatal ages unless GABABR tonic inhibition was blocked. These results show that, during postnatal development, there is a continuous increase in GABABR tonic inhibition that maintains the activity of LC neurons at a proper level. In male, but not female, rats, chronic perinatal treatment with citalopram, a selective serotonin reuptake inhibitor, reduced GABABR activity and tonic inhibition, which might result in the significantly higher spontaneous activity of LC neurons seen in these animals. In conclusion, our results show that GABABR‐mediated tonic inhibition has a direct impact on the spontaneous activity of LC neurons and that the extent of the effect varies with ambient GABA levels and functionality of GABABR signalling.
Effect of improved TLD dosimetry on the determination of dose rate constants for 125I and 103Pd brachytherapy seeds
Authors: Rodriguez M. , Rogers D. W. O.
Published: October 2014

Purpose:

To more accurately account for the relative intrinsic energy dependence and relative absorbed‐dose energy dependence of TLDs when used to measure dose rate constants (DRCs) for 125I and 103Pd brachytherapy seeds, to thereby establish revised “measured values” for all seeds and compare the revised values with Monte Carlo and consensus values.

Methods:

The relative absorbed‐dose energy dependence, frel, for TLDs and the phantom correction, Pphant, are calculated for 125I and 103Pd seeds using the EGSnrc BrachyDose and DOSXYZnrc codes. The original energy dependence and phantom corrections applied to DRC measurements are replaced by calculated (frel)−1 and Pphant values for 24 different seed models. By comparing the modified measured DRCs to the MC values, an appropriate relative intrinsic energy dependence, , is determined. The new Pphant values and relative absorbed‐dose sensitivities, , calculated as the product of (frel)−1 and , are used to individually revise the measured DRCs for comparison with Monte Carlo calculated values and TG‐43U1 or TG‐43U1S1 consensus values.

Results:

In general, frel is sensitive to the energy spectra and models of the brachytherapy seeds. Values may vary up to 8.4% among 125I and 103Pd seed models and common TLD shapes. Pphant values depend primarily on the isotope used. Deduced values are 1.074 ± 0.015 and 1.084 ± 0.026 for 125I and 103Pd seeds, respectively. For (1 mm)3 chips, this implies an overall absorbed‐dose sensitivity relative to 60Co or 6 MV calibrations of 1.51 ± 1% and 1.47 ± 2% for 125I and 103Pd seeds, respectively, as opposed to the widely used value of 1.41. Values of Pphant calculated here have much lower statistical uncertainties than literature values, but systematic uncertainties from density and composition uncertainties are significant. Using these revised values with the literature's DRC measurements, the average discrepancies between revised measured values and Monte Carlo values are 1.2% and 0.2% for 125I and 103Pd seeds, respectively, compared to average discrepancies for the original measured values of 4.8%. On average, the revised measured values are 4.3% and 5.9% lower than the original measured values for 103Pd and 125I seeds, respectively. The average of revised DRCs and Monte Carlo values is 3.8% and 2.8% lower for 125I and 103Pd seeds, respectively, than the consensus values in TG‐43U1 or TG‐43U1S1.

Conclusions:

This work shows that frel is TLD shape and seed model dependent suggesting a need to update the generalized energy response dependence, i.e., relative absorbed‐dose sensitivity, measured 25 years ago and applied often to DRC measurements of 125I and 103Pd brachytherapy seeds. The intrinsic energy dependence for LiF TLDs deduced here is consistent with previous dosimetry studies and emphasizes the need to revise the DRC consensus values reported by TG‐43U1 or TG‐43U1S1.
Benchmarking of a treatment planning system for spot scanning proton therapy: Comparison and analysis of robustness to setup errors of photon IMRT and proton SFUD treatment plans of base of skull meningioma
Authors: Harding R. , Trnková P. , Weston S. J. , Lilley J. , Thompson C. M. , Short S. C. , Loughrey C. , Cosgrove V. P. , Lomax A. J. , Thwaites D. I.
Published: October 2014

Purpose:

Base of skull meningioma can be treated with both intensity modulated radiation therapy (IMRT) and spot scanned proton therapy (PT). One of the main benefits of PT is better sparing of organs at risk, but due to the physical and dosimetric characteristics of protons, spot scanned PT can be more sensitive to the uncertainties encountered in the treatment process compared with photon treatment. Therefore, robustness analysis should be part of a comprehensive comparison between these two treatment methods in order to quantify and understand the sensitivity of the treatment techniques to uncertainties. The aim of this work was to benchmark a spot scanning treatment planning system for planning of base of skull meningioma and to compare the created plans and analyze their robustness to setup errors against the IMRT technique.

Methods:

Plans were produced for three base of skull meningioma cases: IMRT planned with a commercial TPS [Monaco (Elekta AB, Sweden)]; single field uniform dose (SFUD) spot scanning PT produced with an in‐house TPS (PSI‐plan); and SFUD spot scanning PT plan created with a commercial TPS [XiO (Elekta AB, Sweden)]. A tool for evaluating robustness to random setup errors was created and, for each plan, both a dosimetric evaluation and a robustness analysis to setup errors were performed.

Results:

It was possible to create clinically acceptable treatment plans for spot scanning proton therapy of meningioma with a commercially available TPS. However, since each treatment planning system uses different methods, this comparison showed different dosimetric results as well as different sensitivities to setup uncertainties. The results confirmed the necessity of an analysis tool for assessing plan robustness to provide a fair comparison of photon and proton plans.

Conclusions:

Robustness analysis is a critical part of plan evaluation when comparing IMRT plans with spot scanned proton therapy plans.
Asymmetric dose–volume optimization with smoothness control for rotating‐shield brachytherapy
Authors: Liu Yunlong , Flynn Ryan T. , Kim Yusung , Wu Xiaodong
Published: October 2014

Purpose:

It is important to reduce fluence map complexity in rotating‐shield brachytherapy (RSBT) inverse planning to improve delivery efficiency while maintaining plan quality. This study proposes an efficient and effective RSBT dose optimization method which enables to produce smooth fluence maps.

Methods:

Five cervical cancer patients each with a high‐risk clinical‐target‐volume (HR‐CTV) larger than 40 cm3 were considered as the test cases. The RSBT source was a partially shielded electronic brachytherapy source (Xoft Axxent™). The anchor RSBT plans generated by the asymmetric dose–volume optimization with smoothness control (ADOS) method were compared against those produced by the dose–surface optimization (DSO) method and inverse‐planning with simulated annealing (IPSA). Either L1‐norm or L2‐norm was used to measure the smoothness of a fluence map in the proposed ADOS method as one weighted term of the objective function. Uniform dwell‐time scaling was applied to all plans such that HR‐CTV D90 was maximized without violating the D2cc tolerances of the rectum, bladder, and sigmoid colon. The quality of the anchor plans was measured with HR‐CTV D90 of the anchor plans. Single‐shielded RSBT [(S‐RSBT), RSBT with single, fix sized delivery window] and dynamic‐sheilded RSBT [(D‐RSBT), RSBT with dynamically varying sized delivery window] delivery plans generated based on the anchor plans were also measured, with delivery time constraints of 10, 20, and 30 min/fraction (fx).

Results:

The average HR‐CTV D90 values of the anchor plans achieved by the ADOS, DSO, and IPSA methods were 111.5, 94.2, and 107.4 Gy, respectively, where the weighting parameter β used in ADOS with L2‐norm was set to be 100. By using S‐RSBT sequencing and 20 min/fx delivery time, the corresponding D90 values were 88.8, 81.9, and 83.4 Gy; while using D‐RSBT sequencing with 20 min/fx delivery time, the corresponding D90 values were 91.4, 88.3, and 78.9 Gy, respectively. The average optimization times for ADOS, DSO, and IPSA were, respectively, 77, 4, and 1800 s. By using L1‐norm instead of L2‐norm in the ADOS method, the optimization time was increased by 20 s, while the D90 was reduced by 6.8 Gy on average. ADOS‐L1 was found to be more sensitive to the weighting parameter than ADOS‐L2. If β was increased to 10 000, the D90 drop with ADOS‐L1 was 38 Gy, while the drop with ADOS‐L2 is 13 Gy.

Conclusions:

The ADOS method had a reasonable optimization time cost, while achieving comparable RSBT dose plans as the IPSA method, which is of much higher time complexity. Compared to the DSO and IPSA methods, ADOS is able to generate anchor plans which are more suitable for RSBT delivery while preserving the high quality of the original plans. Compared to ADOS‐L1, ADOS‐L2 is able to achieve better quality of anchor plans more efficiently.
Visualization of the Invisible: The Qubit as Key to Quantum Physics
Authors: Dür Wolfgang , Heusler Stefan
Published: October 2014

Quantum mechanics is one of the pillars of modern physics, however rather difficult to teach at the introductory level due to the conceptual difficulties and the required advanced mathematics. Nevertheless, attempts to identify relevant features of quantum mechanics and to put forward concepts of how to teach it have been proposed.1–8 Here we present an approach to quantum physics based on the simplest quantum mechanical system—the quantum bit (qubit).1 Like its classical counterpart—the bit—a qubit corresponds to a two-level system, i.e., some system with a physical property that can admit two possible values. While typically a physical system has more than just one property or the property can admit more than just two values, in many situations most degrees of freedom can be considered to be fixed or frozen. Hence a variety of systems can be effectively described as a qubit. For instance, one may consider the spin of an electron or atom, with spin up and spin down as two possible values, and where other properties of the particle such as its mass or its position are fixed. Further examples include the polarization degree of freedom of a photon (horizontal and vertical polarization), two electronic degrees of freedom (i.e., two energy levels) of an atom, or the position of an atom in a double well potential (atom in left or right well). In all cases, only two states are relevant to describe the system.
From cookbooks to single sentences: The evolution of my labs
Authors: Morrison Andrew
Published: October 2014

Like many physics teachers, I love to have my students spend time working in the laboratory. There is often no better way to test an idea about how the physical world works than to actually set up an experiment and see if the idea can be ruled out or not. This process is an authentic representation of the scientific method, which can take a winding and unpredictable path rather than a clean step-by-step recipe that students want to believe science follows.
The acoustic characteristics of greater prairie-chicken vocalizations
Authors: Whalen Cara , Bomberger Brown Mary , McGee JoAnn , Powell Larkin A. , Smith Jennifer A. , Walsh Edward J.
Published: October 2014

Male Greater Prairie-Chickens (Tympanuchus cupido pinnatus) congregate in groups known as “leks” each spring to perform vocal and visual displays to attract females. Four widely recognized vocalization types produced by males occupying leks are referred to as “booms,” “cackles,” “whines,” and “whoops.” As part of a larger effort to determine the influence of wind turbine farm noise on lek vocal behavior, we studied the acoustic properties of vocalizations recorded between March and June in 2013 and 2014 at leks near Ainsworth, Nebraska. Although all four calls are produced by males occupying leks, the boom is generally regarded as the dominant call type associated with courtship behavior. Our findings suggest that the bulk of acoustic power carried by boom vocalizations is in a relatively narrow, low frequency band, approximately 100-Hz wide at 20 dB below the peak frequency centered on approximately 0.3 kHz. The boom vocalization is harmonic in character, has a fundamental frequency of approximately 0.30±0.01 kHz, and lasts approximately 1.81±0.18 s. Understanding Greater Prairie-Chicken vocal attributes is an essential element in the effort to understand the influence of environmental sound, prominently including anthropogenic sources like wind turbine farms, on vocal communication success.
Bioacoustics of Trachymyrmex fuscus, Trachymyrmex tucumanus, and Atta sexdens rubropilosa (Hymenoptera: Formicidae)
Authors: Carlos Amanda A. , Barbero Francesca , Cassaci Luca P. , Bonelli Simona , Bueno Odair C.
Published: October 2014

The capability to produce species-specific sounds is common among ants. Ants of the genus Trachymyrmex occur in an intermediate phylogenetic position within the Attini tribe, between the leafcutters, such as Atta sexdens rubropilosa, and more basal species. The study of stridulations would provide important cues on the evolution of the tribe’s diverse biological aspects. Therefore, in the present study, we described the stridulation signals produced by Trachymyrmex fuscus, Trachymyrmex tucumanus, and A. sexdens rubropilosa workers. Ant workers were recorded, and their stridulatory organs were measured. The following parameters were analyzed: chirp length [ms], inter-chirp (pause) [ms], cycle (chirp + inter-chirp) [ms], cycle repetition rate [Hz], and the peak frequency [Hz], as well as the number of ridges on the pars stridens. During the inter-chirp, there is no measurable signal for A. sexdens rubropilosa, whereas for Trachymyrmex fuscus and Trachymyrmex tucumanus, a low intensity signal was detected. In other words, the plectrum and the pars stridens of A. sexdens rubropilosa have no contact during the lowering of the gaster. Principal component analysis, to which mainly the duration of chirps contributed, showed that stridulation is an efficient tool to differentiate ant species at least in the case of the Attini tribe.
Atypical dynamic behavior of periodic frame structures with local resonance
Authors: Hans Stéphane , Boutin Claude , Chesnais Céline
Published: October 2014

This work investigates the dynamic behavior of periodic unbraced frame structures made up of interconnected beams or plates. Such structures can represent an idealization of numerous reticulated systems, as the microstructure of foams, plants, bones, the sandwich panels. As beams are much stiffer in tension-compression than in bending, the propagation of waves with wavelengths much greater than the cell size and the bending modes of the elements can occur in the same frequency range. Thus, frame structures can behave as metamaterials. Since the condition of scale separation is respected, the homogenization method of periodic discrete media is used to derive the macroscopic behavior. The main advantages of the method are the analytical formulation and the possibility to study the behavior of the elements at local scale. This provides a clear understanding of the mechanisms governing the dynamics of the material. In the presence of the local resonance, the form of the equations is unchanged but some macroscopic parameters depend on the frequency. In particular, this applies to the mass leading to a generalization of the Newtonian mechanics. As a result, there are frequency bandgaps. In that case, the same macroscopic modal shape is also associated with several resonant frequencies.
Tunable cylinders for sound control in water
Authors: Norris Andrew , Titovich Alexey
Published: October 2014

Long wavelength effective medium properties are achieved using arrays of closely spaced tunable cylinders. Thin metal shells provide the starting point: for a given shell thickness h and radius a, the effective bulk modulus and density are both proportional to h/a. Since the metal has large impedance relative to water it follows that there is a unique value of h/a at which the shell is effectively impedance matched to water. The effective sound speed cannot be matched by the thin shell alone (except for impractical metals like silver). However, simultaneous impedance and speed matching can be obtained by adding an internal mass, e.g., an acrylic core in aluminum cylindrical tubes. By varying the shell thickness and the internal mass, a range of effective properties is achievable. Practical considerations such as shell thickness, internal mass material, and fabrication will be discussed. Arrays made of a small number of different tuned shells will be described using numerical simulations: example applications include focusing, lensing, and wave steering. [Work supported by ONR.]
Sound waves over periodic and aperiodic arrays of cylinders on ground surfaces
Authors: Taherzadeh Shahram , Shin Ho-Chul , Attenborough Keith
Published: October 2014

Propagation of audio frequency sound waves over periodic arrays of cylinders placed on acoustically hard and soft surfaces has been studied through laboratory measurements and predictions using a point source. It is found that perturbation of the position of the cylinders from a regular array results in a higher insertion loss than completely periodic or random cylinder arrangements.
Ground effect due to rough and resonant surfaces
Authors: Attenborough Keith , Shin Ho-Chul , Taherzadeh Shahram
Published: October 2014

Particularly if the ground surface between noise source and receiver would otherwise be smooth and acoustically hard, structured low-rise ground roughness can be used as an alternative to conventional noise barriers. The techniques of periodic-spacing, absorptive covering, and local resonance can be used, as when broadening metamaterial stop bands, to achieve a broadband ground effect. This has been demonstrated both numerically and through laboratory experiments. Computations have employed multiple scattering theory, the Finite Element Method and the Boundary Element Method. The experiments have involved measurements over cylindrical and rectangular roughness elements and over their resonant counterparts created by incorporating slit-like openings. Resonant elements with slit openings have been found numerically and experimentally to add a destructive interference below the first roughness-induced destructive interference and thereby mitigate the adverse effects of the low-frequency surface waves generated by the presence of roughness elements. A nested configuration of slotted hollow roughness elements is predicted to produce multiple resonances and this idea has been validated through laboratory experiments.
Acoustic emissions from flyover measurements of F-35A and F-35B aircraft
Authors: McKinley Richard L. , Wall Alan T. , Gallagher Hilary L. , Hobbs Christopher M. , Page Juliet A. , Czech Joseph J.
Published: October 2014

Acoustic emissions of F-35A and F-35B aircraft flyovers were measured in September 2013, in a multi-organizational effort led by the Air Force Research Laboratory. These measurements followed American National Standards Institute/Acoustical Society of America S12.75-2012 guidance on aircraft flyover noise measurements. Measurements were made from locations directly under the flight path to 12,000 ft away with microphones on the ground, 5 ft, and 30 ft high. Vertical microphone arrays suspended from cranes measured noise from on the ground up to 300 ft above the ground. A linear ground-based microphone array measured noise directly along the flight path. In total, data were collected at more than 100 unique locations. Measurements were repeated six times for each flyover condition. Preliminary results are presented to demonstrate the repeatability of noise data over measurement repetitions, assess data quality, and quantify community noise exposure models.
Three-stream jet noise measurements and predictions
Authors: Henderson Brenda S. , Leib Stewart J.
Published: October 2014

An experimental and numerical investigation of the noise produced by high-subsonic three-stream jets was conducted. The exhaust system consisted of externally mixed-convergent nozzles and an external plug. Bypass- and tertiary-to-core area ratios between 1 and 1.75, and 0.4 and 1.0, respectively, were studied. Axisymmetric and offset tertiary nozzles were investigated for heated and unheated conditions. For axisymmetric configurations, the addition of the third stream was found to reduce mid- and high-frequency acoustic levels in the peak-jet-noise direction, with greater reductions at the lower bypass-to-core area ratios. The addition of the third stream also decreased peak acoustic levels in the peak-jet-noise direction for intermediate bypass-to-core area ratios. For the offset configurations, an s-duct was found to increase acoustic levels relative to those of the equivalent axisymmetric-three-stream jet while half-duct configurations produced acoustic levels similar to those for the axisymmetric jet for azimuthal observation locations of interest. Comparisons of noise predictions with acoustic data are presented for selected unheated configurations. The predictions are based on an acoustic analogy approach with mean flow interaction effects accounted for using a Green’s function, computed in terms of its coupled azimuthal modes, and a source model previously used for round and rectangular jets.
Comparison of upside-down microphone with flush mounted microphone configuration
Authors: Rasmussen Per
Published: October 2014

Measurement of fly-over aircraft noise is often performed using the microphones mounted in an upside-down configuration, with the microphone placed 7 mm above a hard reflecting surface. This method assumes that most of the sound is coming from the back of the microphone within an angle of + -60 degrees. The same microphone configuration is proposed for installed and un-installed jet-engine test in which case, however, the incidence angle for the microphone may be in the range of 60–85 degrees. The response of the upside-down microphone configuration is compared with flush mounted microphones as reference. The influence of microphone diameter (ranging from 1/8 in. to ½ in.) is compared in the different configurations and the effect of windscreens is investigated.
Active control of noise from hot, supersonic turbulent jets
Authors: Colonius Tim , Towne Aaron , Schlinker Robert H. , Reba Ramons A. , Shannon Dan
Published: October 2014

We report on an experimental and reduced-order modeling study aimed at reducing mixing noise in hot supersonic jets relevant to military aircraft. A spinning valve is used to modulate four injection nozzles near the main jet nozzle lip over a range of frequencies and mass flow rates. Diagnostics include near-, mid-, and far-field microphone arrays aimed at measuring the effect of actuation on the near-field turbulent wavepacket structures and their correlation with mixing noise. The actuators provide more than 4 dB noise reduction at peak frequencies in the aft arc, and up to 2 dB reduction in OASPL. Experiments are performed to contrast the performance of steady and unsteady blowing with different amplitudes. The results to date suggest that the noise reduction is primarily associated with attenuated wave packet activity associated with the rapidly thickened shear layers that occur with both steady and unsteady blowing. Mean flow surveys are also preformed and serve as inputs to reduced-order models for the wave packets based on parabolized stability equations. These models are in turn used to corroborate the experimental evidence suggesting mechanisms of noise suppression in the actuated flow.
Three transformations of a crackling jet noise waveform and their potential implications for quantifying the “crackle” percept
Authors: Swift S. Hales , Gee Kent L. , Neilsen Tracianne B.
Published: October 2014

In the 1975 paper by Ffowcs-Williams et al. on jet “crackle,” there are several potentially competing descriptors—including a qualitative description of the sound quality or percept, a statistical measure, and commentary on the relation of the presence of shocks to the sound’s quality. These descriptors have led to disparate conclusions about what constitutes a crackling jet, waveform, or sound quality. This presentation considers three modifications of a jet noise waveform that exhibits a crackling sound quality and initially satisfies all three definitions. These modifications alter the statistical distributions of primarily the pressure waveform or its first time difference in order to demonstrate how these modifications do or do not correspond to changes in the sound quality of the waveform. The result, although preliminary, demonstrates that the crackle percept is tied to the statistics of the pressure difference waveform instead of the pressure waveform itself.
Usability of SpeechMark® landmark analysis system for teaching speech acoustics
Authors: Speights Marisha , Boyce Suzanne E.
Published: October 2014

Learning about the intersection of articulation and acoustics, and particularly acoustic measurement techniques, is challenging for students in Linguistics, Psychology and Communication Sciences and Disorders curricula. There is a steep learning curve before students can apply the material to an interesting research question; for those in more applied programs such as Communication Disorders or ESL, there is an additional challenge in envisioning how the knowledge can be applied in changing behavior. The availability of software tools such as Wavesurfer, Praat, Audacity, TF32, the University College of London software suite, among others, has made it possible for instructors to design laboratory experiences in visualization, manipulation, and measurement of speech acoustics. Many students have found them complex for their first exposure to taking scientific measurements. The SpeechMark® acoustic landmark analysis system has been developed to automate the detection of specific acoustic events important for speech, such as voicing offset and onset, stop bursts, fricative noise, and vowel midpoints, and to provide automated formant frequency measurement used for vowel space analysis. This paper describes a qualitative multiple case study in which seven teachers of speech acoustics were interviewed to explore whether such pre-analysis of the acoustic signal could be useful for teaching.
Impact of mismatch conditions between mobile phone recordings on forensic voice comparison
Authors: B T Nair Balamurali , Alzqhoul Esam A. , Guillemin Bernard J.
Published: October 2014

Mismatched conditions between the recordings of suspect, offender and relevant background population represent a typical scenario in real forensic casework. In this paper, we investigate the impact of mismatch conditions associated with mobile phone speech recordings on forensic voice comparison (FVC). The two major mobile phone technologies currently in use today are the Global System for Mobile Communications (GSM) and Code Division Multiple Access (CDMA). These are fundamentally different in the way in which they handle the speech signal, which in turn will lead to significant mismatch between speech recordings. Our results suggest that the resulting degradation on the accuracy of a FVC analysis can be very significant (as high as 150%). Surprisingly, though, our results also suggest that the reliability of a FVC analysis may actually improve. We propose a strategy for lessening this impact by passing the suspect speech data through the GSM or CDMA codecs, depending on the network origin of the offender data, prior to the FVC analysis. Though this goes a long way to mitigating the impact (a reduction in loss of accuracy from 150% to 80%), it is still not as good as analysis under matched conditions.
99.8 percent accuracy achieved on Peterson and Barney (1952) acoustic measurements
Authors: Stokes Michael A.
Published: October 2014

In 2012, a paper was presented (Reetz, 2012) discussing the lack of working phonemic models, which was an acknowledgment to an earlier presentation (Ladefoged, 2004) discussing 50 + years of phonetics and phonology. These presentations highlighted the successes in phonological research over the last 60 and 50 years, respectively, but both concluded that there is still no recognized working model of phoneme identification. This presentation will discuss the Waveform Model of Vowel Perception (Stokes, 2009) achieving 99.8% accuracy on the Peterson and Barney (1952) dataset using 30 conditional statements across all ten vowels produced by the 33 males (509/510 for the vowels identified by humans at 100%). These results replicate and improve on the 99.2% achieved across the vowels produced by the males in the Hillenbrand (1995) dataset (Stokes, 2011). As a logical progression, ELBOW was developed in 2013 using the algorithm developed for static data to identify streaming vowel productions achieving over 91% before introducing improvements. Beyond ELBOW, it was essential to replicate earlier results on the most cited dataset in the literature. The Waveform Model has now replicated human performance across multiple datasets and is being successfully introduced into automatic speech recognition applications.
Lombard effect based speech analysis across noisy environments for voice communications with cochlear implant subjects
Authors: Lee Jaewook , Ali Hussnain , Ziaei Ali , Hansen Jonh H.
Published: October 2014

Changes in speech production including vocal effort based on auditory feedback are an important research domain for improved human communication. For example, in the presence of environmental noise, a speaker experiences the well-known phenomenon known as Lombard effect. Lombard effect has been studied for normal hearing listeners as well as for automatic speech/speaker recognition systems, but not for cochlear implant (CI) recipients. The objective of this study is to analyze the speech production of CI users with respect to environmental change. We observe and study this effect using mobile personal audio recordings from continuous single-session audio streams collected over an individual's daily life. Prior advancements in this domain include the “Prof-Life-Log” longitudinal study at UTDallas. Four CI speakers participated by producing read and spontaneous speech in six naturalistic noisy environments (e.g., office, car, outdoor, cafeteria, etc.). A number of speech production parameters (e.g., short-time log-energy, fundamental frequency, etc.) known to be sensitive to Lombard speech were measured for both communicative and non-communicative speech as a function of environment. Results indicate that variability in the speech production parameters were found in the upward direction with an increase in background noise level. Overall higher values in acoustic variables were observed in the inter-personal conversations related to the non-conversational speech.
Bayesian sampling for practical design of multilayer microperforated panel absorbers
Authors: Fackler Cameron J. , Xiang Ning
Published: October 2014

Bayesian sampling is applied to produce practical designs for microperforated panel acoustic absorbers. Microperforated panels have the capability to produce acoustic absorbers with very high absorption coefficients, without the use of porous materials. However, the absorption produced by a single panel is limited to a narrow frequency range, particularly at high absorption coefficient values. To provide broadband absorption, multiple microperforated panel layers may be combined into a multilayer absorber. To design such an absorber, the necessary number of layers must be determined and four design parameters must be specified for each layer. Using Bayesian model selection and parameter estimation, this work presents a practical method for designing multilayer microperforated panel absorbers. Particular attention is paid to aspects of the underlying sampling method that enable automatic handling of design constraints such as limitations of the manufacturing process and availability of raw materials.
Model selection using Bayesian samples: An introduction to the deviance information criterion
Authors: Steininger Gavin , Dosso Stan E. , Dettmer Jan , Holland Charles W.
Published: October 2014

This paper presents the deviance information criterion (DIC) as a metric for model selection based on Bayesian sampling approaches, with examples from seabed geoacoustic and/or scattering inversion. The DIC uses all samples of a distribution to approximate Bayesian evidence, unlike more common measures such as the Bayesian information criterion, which only use point estimates. The DIC uses distribution samples to approximate Bayesian evidence, unlike more common measures such as the Bayesian information criterion based on point estimates. Hence the DIC is more appropriate for non-linear Bayesian inversions utilizing posterior sampling. Two examples are considered: determining the dominant seabed scattering mechanism (interface and/or volume scattering), and choosing between seabed profile parameterizations based on smooth gradients (polynomial splines) or discontinuous homogeneous layers. In both cases, the DIC is applied to trans-dimensional inversions of simulated and measured data, utilizing reversible jump Markov chain Monte Carlo sampling. For the first case, the DIC is found to correctly select the true scattering mechanism for simulations, and its choice for the measured data inversion is consistent with sediment cores extracted at the experimental site. For the second case, the DIC selects the polynomial spline parameterization for soft seabeds with smooth gradients. [Work supported by ONR.]
Acoustic ray model for the scattering from an object on the sea floor
Authors: Kargl Steven G. , Espana Aubrey L. , Williams Kevin L.
Published: October 2014

Target scattering within a waveguide is recast into a ray model, where time-of-flight wave packets are tracked. The waveguide is replaced by an equivalent set of image sources and receivers, where rays are associated with these images and interactions with the waveguide's boundaries are taken into account. By transforming wave packets into the frequency domain, scattering becomes a multiplication of a wave packet's spectrum at the target location and the target's free-field scattering amplitude. Data- and model-model comparisons for an aluminum replica of a 100-mm unexploded ordnance will be discussed. For the data-model comparisons, synthetic aperture sonar (SAS) data were collect during Pond Experiment 2010 from this replica, where it was placed on a water-sand sediment boundary. The model-model comparisons use the results from a hybrid 2-D/3-D model. The hybrid model combines a 2D finite-element model to predict the scattered pressure and its derivatives in the near-field of the target, and then a 3D Helmholtz integral to propagate the pressure to the far field. The data- and model-model comparisons demonstrate the viability of using the ray model to quickly generate realistic pings suitable for both SAS and acoustic color template processing. [Research supported by SERDP and ONR.]
Orientation dependence for backscattering from a solid cylinder near an interface: Imaging and spectral properties
Authors: Plotnick Daniel , Marston Philip L. , Espana Aubrey , Williams Kevin L.
Published: October 2014

When a solid cylinder lies proud on horizontal sand sediment significant contributions to backscattering, specular and elastic, involve multipath reflections from the cylinder and interface. The scattering structure and resulting spectrum versus azimuthal angle, the “acoustic template,” may be understood using a geometric model [K. L. Williams et al., J. Acoust. Soc. Am. 127, 3356–3371 (2010)]. If the cylinder is tilted such that the cylinder axis is no longer parallel to the interface the multipath structure is modified. Some changes in the acoustic template can be approximately modeled using a combination of geometric and physical acoustics. For near broadside scattering the analysis gives a simple expression relating certain changes in the template to the orientation of the cylinder and the source geometry. These changes are useful for inferring the cylinder orientation from the scattering. Changes to the template at end-on and intermediate angles are also examined. The resulting acoustic images show strong dependence on the cylinder orientation in agreement with this model. A similar model applies to a metallic cylinder adjacent to a flat free surface and was confirmed in tank experiments. The effect of vertical tilt on the acoustic image was also investigated. [Work supported by ONR.]
Acoustic scattering enhancements for partially exposed cylinders in sand and at a free surface caused by Franz waves and other processes
Authors: Smith Anthony R. , Gunderson Aaron M. , Plotnick Daniel S. , Marston Philip L. , Eastland Grant C.
Published: October 2014

Creeping waves on solid cylinders having slightly subsonic phase velocities and large radiation damping are described as Franz waves because of association with complex poles investigated by Franz. For free-field high frequency broadside backscattering in water, the associated echoes are weak due to radiation damping. It was recently demonstrated, however, that for partially exposed solid metal cylinders at a free surface viewed at grazing incidence, the Franz wave echo can be large relative to the specular echo when the grazing angle is sufficiently small [G. C. Eastland and P. L. Marston, J. Acoust. Soc. Am. 135, 2489–2492 (2014)]. The Fresnel zone associated with the specular echo is occluded making it weak while the Franz wave is partially reflected at the interface behind the cylinder. This hypothesis is also supported by calculating the exact backscattering by half-exposed infinitely long rigid cylinders viewed over a range of grazing angles. Additional experiments concern the high frequency backscattering by cylinders partially buried in sand viewed at small grazing angles. From the time evolution of the associated backscattering by short tone bursts, situations have been identified for which partially reflected Franz wave contributions become significant. Franz waves may contribute to sonar clutter from rocks. [Work supported by ONR.]
The construction and implementation of a multichannel loudspeaker array for accurate spatial reproduction of sound fields
Authors: Neal Matthew T. , Snell Colton D. , Vigeant Michelle C.
Published: October 2014

The spatial distribution of sound has a strong impact upon a listener’s overall impression of a room and must be reproduced accurately for auralization. In concert hall acoustics, directionally independent metrics such as reverberation time and clarity index simply do not predict this impression. Late lateral energy level, lateral energy fraction, and the interaural correlation coefficient are measures of spatial impression, but more work is needed before we fully understand how the directional distribution of sound should influence architectural design decisions. A three-dimensional array of 28 loudspeakers and two subwoofers has been constructed in a hemi-anechoic chamber at PSU, allowing for accurate reproduction of sound fields. For the array, closed-box loudspeakers were built and digitally equalized to ensure a flat frequency response. With this facility, subjective studies investigating spatial sound in concert halls can be conducted using measured sound fields and perceptually motivated auralizations, not tied to a physical room. Such a facility is instrumental in understanding and communicating subtle differences in sound fields to listeners, whether they be musicians, architects, or clients. The flexibility and versatility of this system will facilitate room acoustics research at Penn State for years to come. [Work supported by NSF Award 1302741.]
Arrayvolution—An overview of array systems to study bats and toothed whales
Authors: Koblitz Jens C. , Wahlberg Magnus , Stilz Peter , MacAulay Jamie , Götze Simone , Seibert Anna-Maria , Laidre Kristin , Schnitzler Hans-Ulrich , Benke Harald
Published: October 2014

Some echolocation signal parameters can be studied using a single receiver. However, studying parameters such as source level, directionality, and direction of signal emission require the use of multi-receiver arrays. Acoustic localization allows for determination of the position of echolocators at the time of signal emission, and when multiple animals are present, calls can be assigned to individuals based on their location. This combination makes large multi-receiver arrays a powerful tool. Here we present an overview of different array configurations used to study both toothed whales and bats, using a suite of systems ranging from semi-3D-minimum receiver number-number-arrays (3D-MINNAs), linear-2-D-over determined arrays (2D-ODAs), to 3-D-over-determined-arrays (3D-ODAs). We discuss approaches to process and summarize the usually large amounts of data. In some studies, the absolute position of an echolocator and not only relative to the array is crucial. Combining acoustic localizations from a source with geo-referenced receivers allows for determining geo-referenced movements of an echolocator. Combining these animal tracks with other geo-referenced data such as hydrographic parameters will allow new insights into habitat use.
Tracking Cuvier’s beaked whales using small aperture arrays
Authors: Gassmann Martin , Wiggins Sean M. , Hildebrand John
Published: October 2014

Cuvier beaked whales are deep-diving animals that produce strongly directional sounds using high frequencies (>30 kHz) at which attenuation due to absorption and scattering is high (>8 dB/km). This makes it difficult to track beaked whales in three dimensions with standard large-aperture hydrophone arrays. By embedding two volumetric small-aperture (~1 m element spacing) arrays into a large-aperture (~1 km element spacing) array of five nodes, individuals and even groups of Cuvier beaked whales were tracked in three dimensions continuously up to one hour within an area of 10 km2 in the Southern California Bight. This passive acoustic tracking technique provides a tool to study the characteristics of beaked whale echolocation, and their behavior during deep-diving.
Applications of an adaptive back-propagation method for passive acoustic localizations of marine mammal sounds
Authors: Lin Ying-Tsong , Newhall Arthur E. , Lynch James F.
Published: October 2014

An adaptive back-propagation localization method utilizing the dispersion relation of the acoustic modes of low-frequency sound signals is reviewed in this talk. This method employs an adaptive array processing technique (the maximum a posteriori mode filter) to extract the acoustic modes of sound signals, and it is capable of separating signals from noisy data. The concept of the localization algorithm is to back-propagate modes to a location where the modes align with each other. Gauss-Markov inverse theory is applied to make the normal mode back-propagator adaptive to the signal-to-noise ratio (SNR). When the SNR is high, the localization procedure will push the algorithm to achieve high resolution. On the other hand, when the SNR is low, the procedure will try to retain its robustness and reduce the noise effects. Examples will be shown in the talk to demonstrate the localization performance with comparisons to other methods. Applications to baleen whale sounds collected in Cape Cod Bay, Massachusetts, will also be presented. Lastly, population density estimation using this passive acoustic localization method will be discussed.
Sei whale localization and tracking using a moored, combined horizontal and vertical line array near the New Jersey continental shelf
Authors: Newhall Arthur E. , Lin Ying-Tsong , Lynch James F. , Baumgartner Mark F.
Published: October 2014

In 2006, a multidisciplinary experiment was conducted in the Mid-Atlantic continental shelf off the New Jersey coast. During a 2 day period in mid-September 2006, more than 200, unconfirmed but identifiable, sei whale (Balaenoptera borealis) calls were collected on a moored, combined horizontal and vertical line hydrophone array. Sei whale movements were tracked over long distances (up to tens of kilometers) using a normal mode back propagation method. This approach uses low-frequency, broadband passive sei whale call receptions from a single-station, two-dimensional hydrophone array to perform long distance localization and tracking by exploiting the dispersive nature of propagating acoustic modes in a shallow water environment. Source depth information and the source signal can also be determined from the localization application. This passive whale tracking, combined with the intensive oceanography measurements performed during the experiment, was also used to examine sei whale movements in relation to oceanographic features observed in this region.
Investigation of fabricated 1 MHz lithium niobate transfer standard ultrasonic transducer
Authors: Petchpong Patchariya , Kim Yong Tae
Published: October 2014

The fabrication of a single element transducer made from Lithium Niobate (LiNbO3) operating at 1 MHz is focused on this paper. The air-backed LiNbO3 transducer is developed to be used as the standard transfer ultrasonic transducer to calibrate the ultrasound power-meter, which is measured the total emitted acoustic power radiated from the medical equipment. To clarify the precision of the acoustic power, the primary standard calibration measurement (radiation force balance, RFB) based on IEC 61161 is used to investigate the fabricated transducer. The geometry of the piezoelectric active element was first designed by the prediction of Krimholtz, Leedom, and Matthaei (KLM) simulation technique. The electrical impedance measurements of the LiNbO3 element, before and after assembling into the transducer, were checked and compared. The results of electrical impedance show that the operating frequency is in the range from 1 MHz to 10 MHz by forming harmonics. The evaluations of total emitted power and radiation conductance of fabricated transducer were also revealed. Results of acoustic power have been responding up to 2.1 W, which can be assessed within 6% of expanded uncertainty (k = 2).