bluuebunny/crossref_metadata_2025 huggingface dataset:
Soil Models Survey and Vehicle System Dynamics
Authors: Contreras Ulysses , Li Guangbu , Foster Craig D. , Shabana Ahmed A. , Jayakumar Paramsothy , Letherwood Michael D.
Published: September 2013

The mechanical behavior of soils may be approximated using different models that depend on particular soil characteristics and simplifying assumptions. For this reason, researchers have proposed and expounded upon a large number of constitutive models and approaches that describe various aspects of soil behavior. However, there are few material models capable of predicting the behavior of soils for engineering applications and are at the same time appropriate for implementation into finite element (FE) and multibody system (MBS) algorithms. This paper presents a survey of different commonly used terramechanics and continuum-based soil models. The aim is to provide a summary of soil models, compare them, and examine their suitability for integration with large-displacement FE absolute nodal coordinate formulation (ANCF) and MBS algorithms. Special emphasis is placed on the formulations of soils used in conjunction with vehicle dynamic models. A brief review of computer software used for soil modeling is provided and the implementation of these soil models in MBS algorithms used in the analysis of complex vehicle systems is discussed.
A Simple Analytical Tool for Legged Robot Design
Authors: Shen Zhuohua , Seipel Justin
Published: September 2013

Although legged locomotion is better at tackling complicated terrains compared with wheeled locomotion, legged robots are rare, in part, because of the lack of simple design tools. The dynamics governing legged locomotion are generally nonlinear and hybrid (piecewise-continuous) and so require numerical simulation for analysis and are not easily applied to robot designs. During the past decade, a few approximated analytical solutions of Spring-Loaded Inverted Pendulum (SLIP), a canonical model in legged locomotion, have been developed. However, SLIP is energy conserving and cannot predict the dynamical stability of real-world legged locomotion. To develop new analytical tools for legged robot designs, we first analytically solved SLIP in a new way. Then based on SLIP solution, we developed an analytical solution of a hip-actuated Spring-Loaded Inverted Pendulum (hip-actuated-SLIP) model, which is more biologically relevant and stable than the canonical energy conserving SLIP model. The analytical approximations offered here for SLIP and the hip actuated-SLIP solutions compare well with the numerical simulations of each. The analytical solutions presented here are simpler in form than those resulting from existing analytical approximations. The analytical solutions of SLIP and the hip actuated-SLIP can be used as tools for robot design or for generating biological hypotheses.
Direct Geometry Processing for Tele-Fabrication
Authors: Chen Yong , Li Kang , Qian Xiaoping
Published: September 2013

This paper presents a new approach for tele-fabrication where a physical object is scanned in one location and fabricated in another location. This approach integrates three-dimensional (3D) scanning, geometric processing of scanned data, and additive manufacturing technologies. In this paper, we focus on a set of direct geometric processing techniques that enable the tele-fabrication. In this approach, 3D scan data is directly sliced into layer-wise contours. Sacrificial supports are generated directly from the contours and digital mask images of the objects and the supports for Stereolithography Apparatus (SLA) processes are then automatically generated. The salient feature of this approach is that it does not involve any intermediate geometric models such as STL, polygons or non-uniform rational B-splines that are otherwise commonly used in prevalent approaches. The experimental results on a set of objects fabricated on several SLA machines confirms the effectiveness of the approach in faithfully tele-fabricating physical objects.
Automated Assembly Model Simplification for Finite Element Analysis
Authors: Russ Brian , Dabbeeru Madan M. , Chorney Andrew S. , Gupta Satyandra K.
Published: September 2013

Analyzing complex 3D assembly models using finite element analysis software requires suppressing parts that are not likely to influence the analysis results, but may significantly improve the computational performance during the analysis. The part suppression step often depends on many factors within the context and application of the model. Currently, most analysts perform this step manually. This step can take a long time to perform on a complex model and can be tedious in nature. In this paper, we present an approach to multi-part suppression based on the specified criteria. We have developed utilities in Pro/Engineer CAD system to identify parts that meet the specified criteria and suppress them. We present several examples to illustrate the value of the proposed approach.
A Compliant On/Off Connection Mechanism for Preloading Statically Balanced Compliant Mechanisms
Authors: Pluimers Pieter J. , Tolou Nima , Jensen Brian D. , Howell Larry L. , Herder Just L.
Published: September 2013

Static balancing is an important contribution to compliant mechanisms enabling low operating force, thus allowing high mechanical efficiency. Preloading is generally needed in statically balanced compliant mechanisms, which at smaller scales presents a significant challenge. Physical handling of zero-force structures without causing damage also becomes difficult. This paper presents a solution to both of these issues. A novel compliant connection mechanism based on bistable beams was used to precisely preload the system in the direction of motion without backlash. Once this bistable mechanism is engaged by loading beyond its threshold, the system is in operating condition, i.e. the ON position. When the connection mechanism is disengaged (OFF position), it is much stiffer than it is in the statically balanced state and therefore more robust for handling purposes. As a demonstrator, we present the first statically balanced gripper with a fully compliant ON/OFF-connection mechanism allowing pre-loading collinear with the direction of motion. The combination of a pre-loaded bistable mechanism (i.e. negative stiffness) and a voluntary closing gripper (i.e. positive stiffness) is used for static balancing (i.e. zero stiffness and zero actuation force). The results show that the actuation force is reduced by at least 91% when the preload is engaged. The proposed ON/OFF connection shows a promising method for pre-loading compliant mechanisms or related devices.
Evaluating the Directed Method for Bioinspired Design
Authors: Glier Michael W. , Tsenn Joanna , Linsey Julie S. , McAdams Daniel A.
Published: September 2013

Bioinspired design, the practice of looking to nature to find inspiration for engineering design, is becoming an increasingly desired approach to design. It allows designers to tap a wealth of time-tested solutions to difficult problems in a domain rarely considered by designers. Only recently have researchers developed organized, systematic methods for bioinspired design. These methods include BioTRIZ, an extension of functional modeling for bioinspired design, engineering-to-biology keyword translation tools, and specialized design tools like DANE and SAPPHIRE. These organized methods are currently active research efforts. Traditionally, however, bioinspired design has been conducted without the benefit of any organized method. Without the support of formal methods, designers have relied on the “directed method” of bioinspired design. The directed method approach simply directs designers to consider how nature might approach a problem in order to help designers find solutions. This paper presents an experiment to explore the impact upon idea generation of simply contemplating how nature would solve a design problem. This experiment is foundationally important to bioinspired engineering design method research. The results of this experiment serve as a fundamental baseline and benchmark for the comparison of more systematic, and often more involved, bioinspired design methods.

A group of 121 novice designers are given one of two design problems and instructed to either generate solutions using the “directed method,” considering how nature would solve the problem, or to generate solutions without being prompted to use any method. Based on the findings presented here, the directed method offers designers no advantage in the average number of non-redundant ideas the designers can produce, the average quality of their solutions, the average solution novelty, or the variety of solutions proposed. Overall, this investigation finds no significant difference in idea generation between the directed method and the control condition. In conclusion, systematic and organized methods for bioinspired design should instead be sought to effectively leverage nature’s design knowledge.
Free-Form Optimal Conjugation Design
Authors: Yu Bowen , Ting Kwun-lon
Published: September 2013

The paper presents the first optimal conjugation design methodology based on free-form conjugation modeling theory. The methodology is implemented for planar circular gearing and general for any planar gearing. According to the previous research of free-form conjugation, conjugate profiles are modeled by contact path geometries or cutter geometries which are represented by NURBS (non-uniform rational B-splines). The interchangeability between control points and interpolation points of NURBS are introduced in general to offer reasonable constraints of special interpolation conditions in conjugation design. To adapt to the flexibility brought by free-form techniques, the determination of an important conjugate property—contact ratio is carried out through geometric relationship. To make use of NURBS for optimal design, conjugate properties and their differentiations are represented by important parameters and then by control points and interpolation points of NURBS. The interested properties are relative curvature, specific sliding ratio and nominal Hertz contact stress, which are the main factors of gear efficiency and wear. The properties are well-known for their difficulties in optimization. The paper shows that with appropriate manipulations in mathematics and programming, it is feasible for gradient based optimization methods, which are accurate and fast in convergence. The methodology is consistent with the regular optimization of geometry design, and can be integrated into geometry design systems. The examples show the effectiveness of the proposed optimization framework.
Numerical Investigation and Experimental Lab Setting-Up for Analysis of Gas Turbine Combustor Dilution Process
Authors: Amano R. S. , Gupta Alka , Ibrahim Mohamed S. , Rux Andrew , Lang Mark , Moll Travis
Published: September 2013

A gas turbine combustor dilution process is modeled numerically using both 2-D and 3-D approaches, then an experimental set-up was designed and built for validation using standard air ducts. The combustor model is used to test various air cooling strategies with the goal of uniformly diluting combustion gas before it enters the turbine section. The high temperature combustion gas (simulated as hot air) is cooled by introducing a lower temperature secondary air flow through perforated plates. First a 2-D simulation was conducted to compare between introducing the dilution air from smaller but large number of holes or larger but smaller number of holes. It was found that the larger holes are more effective especially when pressure drop is taken into consideration. Then a 3-D simulation was run with larger holes for different configurations and the experimental set up was constructed accordingly. The temperature profile at the exit of the dilution section is considered the criteria for testing the uniformity of temperature after the dilution process, and it will be measured in the experimental work.

This paper presents a brief discussion on the importance of cooling combustion exit gas uniformly before it enters the turbine section. With this in mind, a testing concept is derived in order to gauge methods of improving this cooling. Detailed design specifications and initial conclusions are also outlined. Initial conclusions have yielded a desired primary airflow of 6 m/s (19.7 ft/s) and primary duct diameter of 0.4 m (16 in). With this information it was determined that the flow rate required by the fan is 1.727 m3/s (3660 CFM).
Assessment of impact of acoustic and nonacoustic parameters on performance and well-being
Authors: Mellert Volker , Weber Reinhard , Nocke Christian
Published: September 2013

It is of interest to estimate the influence of the environment in a specific work place area on the performance and well-being of people. Investigations have been carried out for the cabin environment of an airplane and for class rooms. Acoustics is only one issue of a variety of environmental factors, therefore the combined impact of temperature, humidity, air quality, lighting, vibration, etc. on human perception is the subject of psychophysical research. Methods for the objective assessment of subjective impressions have been developed for applications in acoustics for a long time, e.g., for concert hall acoustics, noise evaluation, and sound design. The methodology relies on questionnaires, measurement of acoustic parameters, ear-related signal processing and analysis, and on correlation of the physical input with subjective output. Methodology and results are presented from measurements of noise and vibration, temperature and humidity in aircraft simulators, and of reverberation, coloring, and lighting in a primary school, and of the environmental perception. [The work includes research with M. Klatte, A. Schick from the Psychology Department of Oldenburg University, and M. Meis from Hoerzentrum Oldenburg GmbH and with the European Project HEACE (for partners see www.heace.org).]
Ventilation noise and its effects on annoyance and performance
Authors: Landstrom Ulf
Published: September 2013

In almost every room environment, ventilation acts as a more or less prominent part of the noise exposure. The contribution to the overall sound environment is a question not only of the way in which the ventilation system itself functions, but also a question of the prominence of other contemporary sound sources such as speech, equipment, machines, and external noises. Hazardous effects due to ventilation noise are most prominent in offices, hospitals, control rooms, classrooms, conference rooms, and other types of silent areas. The effects evoked by ventilation noise have also been found to be related to the type of activity being conducted. Annoyance and performance thus not only seemed to be linked to the physical character of exposure, i.e., noise level, frequency characteristics, and length of exposure, but also mental and manual activity, complexity, and monotony of the work. The effects can be described in terms of annoyance, discomfort, and fatigue, with consequences on performance and increased mental load. The silent areas where ventilation noise may be most frequently experienced are often synonymous with areas and activities most sensitive to the exposure.
Variability of feeding buzzes in little brown bats (Myotis lucifigus)
Authors: Griffin Donald R. , Auger Gregory J.
Published: September 2013

When Myotis lucifigus are hunting actively in the early evening, search phase echolocation signals are easily detected by heterodyne bat detectors. Feeding or terminal buzzes are sometimes also detected, especially if the bat detector is tuned to 35 kHz. On other evenings when all conditions appeared comparable we detected no approach phase or buzz. Feeding bats and prey insects were observed and recorded with video and heterodyne and time expansion bat detectors during their early evening hunting at a small pond. Video was obtained with a Canon XL1 camcorder fitted with an ITT Pocketscope model 6010B light intensifier and near infra-red light from the side. Audio was captured with a Pettersson D-980 bat detector using both the heterodyne and the time expansion outputs. Signals were recorded on the left and right audio tracks of the camcorder. In addition to recording general insect feeding, bats were offered at times a small tethered fly-fishing lure with the hook removed. Microphone to lure and insect distance was 0.5 to 2.0 m. Observations have shown variability in the length, presence, and loudness of search, approach, and terminal phases. Examples of video records of insect catching will be shown.
Performance constraints and the production of birdsong
Authors: Suthers Roderick A. , Vallet Eric , Zollinger Sue Anne
Published: September 2013

The role of physical and physiological constraints in determining the performance limits on the tempo and frequency bandwidth of birdsong was investigated. One series of experiments examined the mechanism by which a vocal mimic, the northern mockingbird (Mimus polygottos), copied the songs of other species with which it was tutored as a juvenile. Other experiments analyzed the motor basis of special canary (Serinus canaria) syllables eliciting sexual responses from females. In each case, the mechanism of vocalization was determined by measuring the respiratory dynamics and sound produced on each side of the songbirds duplex vocal organ, the syrinx. When mockingbirds copied the songs of other species the accuracy of their copy depended on the accuracy with which they reproduced the motor pattern used by the tutor species. Motor difficulty of various acoustic features was assessed by the accuracy of its copy. The high repetition rate, broadband canary syllables preferred by females required especially demanding bilateral motor skills. The results indicate that constraints on the rate of respiratory ventilation and bilateral syringeal coordination can set an upper limit on syllable repetition rate and frequency bandwidth. [Work supported by NIH and NSF.]
Echolocation click rates and behavior of foraging Hawaiian spinner dolphins
Authors: Benoit-Bird Kelly J. , Au Whitlow W. L.
Published: September 2013

Groups of spinner dolphins work together to actively aggregate small animals in the deep-scattering layer that serve as their prey. Detailed information on dolphin foraging behavior, obtained with a 200-kHz multibeam sonar (Simrad MS2000), made it possible to correlate echolocation and foraging. Fifty-six groups of spinner dolphins foraging at night within a midwater micronekton sound-scattering layer were observed with the sonar. During sonar surveys, the rates of whistles and echolocation clicks were measured using four hydrophones at 6-m depth intervals. Significant differences in click rates were found between depths and between the different stages of foraging. Groups of foraging dolphins ranged in size from 16 to 28 dolphins. Click rates were not significantly affected by the number of dolphins in a foraging group. Contrary to initial predictions, click rates were relatively low when sonar data indicated that pairs of dolphins were actively feeding. Highest echolocation rates occurred within the scattering layer, during transitions between foraging states. Whistles were only detected when dolphins were not in a foraging formation and when animals were surfacing. This suggests clicks may be used directly or indirectly to cue group movement during foraging.
Scattering and statistical models for very-high-frequency ultrasonic monitoring of tumor therapy
Authors: Lizzi Frederic L.
Published: September 2013

Our laboratories examined spectral changes in ultrasonic backscatter from tumors undergoing various forms of treatment, with the goal of developing noninvasive treatment monitoring. Human tumor explants in athymic mice were treated in vivo with ultrasonic hyperthermia, high-intensity focused ultrasound, and chemical agents. Pre- and posttreatment spectral examinations were conducted using very-high frequency ultrasound (40-MHz center frequencies). Physical scatterer properties were estimated from measured spectral data. Spatially averaged spectra showed that successful treatment progressively increased acoustic concentration by about 3 dB. It also produced average changes of 2 μm in scatter sizes of cell-sized (10 μm) structures; these perturbations may be associated with apoptosis, vacuole formation, and frank cellular disruption. These findings are consistent with clinical observations (40 MHz) following radiotherapy of ocular tumors. Theoretical scattering and statistical models were applied to specify transducer and processing schemes that will permit these changes to be mapped in high resolution images, rather than evaluated as spatially averaged values. This requires improved estimator precision for spectral assays of small scatterers near the Rayleigh size limit. Results showed that this goal can be achieved with 50-MHz annular arrays combined with adaptation of spectral calibration and processing procedures; these are now being implemented for clinical application.
In vitro measurements of acoustic properties using a high-frequency scanning acoustic microscope (SAM)
Authors: Farny Caleb H. , Szabo T. L. , Roy Ronald A. , Cleveland Robin O.
Published: September 2013

A scanning acoustic microscope (SAM) is described that can measure attenuation, sound speed, impedance, and backscatter coefficient of a sample. The SAM consists of a spherically focused transducer (10–40 MHz) which operates in pulse-echo mode and is scanned in a 2D raster pattern over a sample. A plane wave analysis is presented which allows the impedance, attenuation, and phase velocity of a sample to be recovered from the front and back echoes. A causality model is used to validate the attenuation, and phase velocity measurements. The analysis of Chen et al. [UFFC, 445, 515] is used to obtain the backscatter coefficient based on the echoes generated by subwavelength scatterers within the sample. The results for the impedance, attenuation and phase velocity were validated for high- and low-density polyethylene against published results. The SAM was used to measure the impedance, attenuation, phase velocity, and backscatter coefficient for the medial and adventitial layers of an in vitro human femoral artery. The theory was extended to account for propagation through multiple layers. The SAM measurements of acoustic properties were in good agreement with previously published results. [Work supported by the NSF through the Center for Subsurface Sensing and Imaging Systems.]
DeltaEZ: A visual interpreter for DeltaE
Authors: Smith Gordon P.
Published: September 2013

Thermoacoustic devices typically begin their development utilizing DeltaE, a numerical simulator developed by researchers at the Los Alamos National Laboratories. The program is highly popular amongst the thermoacoustics community for its ability to successfully describe the physical parameters and geometries that a thermoacoustic device requires to operate. However, the program is text-based, and can be somewhat counterintuitive to the novice user. Alternate, graphically based, programs have been developed for the thermoacoustic community, meeting with mixed reactions. This approach differs from earlier efforts in that no attempt is made to replace DeltaE itself. A front-end interface possessing the intuitive benefits of graphical programs has been created, which then runs DeltaE. Details of the beta version of the program will be presented in the hopes of gathering volunteers for further development.
The influence of gravity on Rayleigh streaming in thermoacoustic systems
Authors: Matveev Konstantin , Backhaus Scott , Swift Gregory W.
Published: September 2013

The thermal buffer tube is the component of thermoacoustic systems intended to transmit sound and to provide a thermal barrier between the hot and cold heat exchangers located at the opposite ends of the tube. In high-power operating regimes of thermoacoustic devices, the sound amplitude is high enough to cause significant mass (Rayleigh) streaming in the thermal buffer tube. The streaming flow convects heat, which can degrade the overall performance of a thermoacoustic system by thermally short-circuiting the hot and cold heat exchangers. This leads to increased heat consumption by prime movers and to reduced cooling capacity in refrigerators. The thermal buffer tube is characterized by a significant axial variation of temperature, so effects of gravity on the streaming should be important. A simple analytical model allows quantitative estimation of gravity effects, showing that gravity may significantly suppress the streaming under certain conditions. The important parameters of the system and operating conditions that affect the streaming in the presence of gravity are identified. [Work supported by DOE’s Office of Science.]
Modulated single-bubble sonoluminescence: Dependence of phase of flashes, their intensity and rise/decay times on viscosity, the modulation strength, and frequency
Authors: Mastikhin Igor , Djurkovic Borko
Published: September 2013

The single-bubble sonoluminescence (SBSL) signal was studied for the case of driving frequency modulated by lower frequency with an offset. In our work, the driving frequency of 28 kHz and the modulation frequencies of 25–1000 Hz were used. The modulation strength of 0.2, 0.5, and 0.8 was defined as the difference of highest and lowest pressures over modulation period. The measurements were performed for water–glycerol mixtures of various viscosities. The measured SBSL signal appeared as a train of flashes for modulation frequencies below 250 Hz, and as a continuous modulated signal for higher frequencies. At the same frequency, the flashes covered similar phase intervals for different modulation strengths and, accordingly, pressure ranges. At higher glycerol concentrations (up to 24%) both the intensity and the stability of flashes increased, due to damped shape instabilities and reduced dancing; however, the phase interval of flashes remained about the same. Such phase-locked behavior can be explained by translational movements of the bubble due to modulated Bjerknes force and changes in the symmetry of the bubble collapse. The changes in intensities and rise/decay times can serve as a measure of the gas exchange between the bubble and its surroundings during silent and luminescent intervals.
Combining magnitude and phase features in acoustic landmine detection
Authors: Wang Tsaipei , Keller James M. , Gader Paul D.
Published: September 2013

The utility of acoustic-to-seismic coupling systems for landmine detection has been clearly established. They have been shown to be able to detect very low metal content landmines that are difficult to detect for ground-penetrating radars. This technique measures the difference in ground vibration velocity of regions with and without buried landmines when subject to acoustic excitation. For most applications, only the magnitude of the surface velocity is used to construct recognition algorithms. We recently introduced phase-based features in the classification scheme, significantly reducing false alarms at given detection probabilities. Here the focus is on the analysis of ground velocity data collected in the time domain with a moving array of laser Doppler vibrometers. The processing techniques used to extract the magnitude and phase information are described, as well as examples to demonstrate how combined magnitude and phase features help improve the detection of buried mines with weak signatures and reduce false alarms. Simple mass-and-spring models are shown to be useful in understanding the observed features. Also analyzed are the phase signatures of a number of ground regions with buried man-made clutter objects and how they can be useful in separating these clutters from actual landmine regions.
Channel interaction in cochlear implants as a function of phase duration and pulse rate
Authors: Başkent Deniz , Shannon Robert V.
Published: September 2013

Multichannel cochlear implants stimulate auditory nerves at different locations along the cochlea. It is widely assumed that good speech recognition requires independent activation of distinct tonotopic regions with no interactions between electrodes; interactions between electrodes can produce a result similar to spectral smearing. The electrical pulses produced by multiple electrodes can interact both spatially and temporally. However, little is known about the effect of basic electrical stimulation parameters on the degree of electrode interaction. It is possible that high stimulation pulse rates could improve the temporal representation of the signal but reduce the spatial (tonotopic) resolution due to increased electrode interaction. Differences in electrode stimulation configuration (monopolar or bipolar), pulse phase duration, pulse amplitude, and stimulation rate could change the level of electrode interaction. The present study used forward masking to measure electrode interaction patterns as a function of the stimulating pulse phase duration and the stimulation rate. A masker was placed on one electrode and the threshold elevation of a following signal was measured as a function of cochlear location. Forward-masked electrode interaction patterns will be presented for the different stimulation configurations and parameters for several masker levels. [Work supported by NIDCD Grant R01-DC-01526.]
ZEST as a tool for rapid assessment of frequency discrimination
Authors: Stahl Michael , Buus So/ren , Florentine Mary
Published: September 2013

The purpose of this study is to develop a rapid and reliable procedure for obtaining discrimination thresholds. ZEST [King-Smith et al., Vision Res. 34, 885–912 (1994)] has been found to be a promising candidate for this purpose. The present study used ZEST to obtain frequency-discrimination thresholds in 30 trials with a 2AFC paradigm. Subsequent analysis allowed calculation of thresholds for any number of trials up to 30. The stimuli were 600-ms tones at seven frequencies, ranging from 250 to 7000 Hz. Data for six normal listeners obtained with three different slopes (beta) of the assumed psychometric function indicate that reliable thresholds can be obtained in 10 to 15 trials. Simulations indicate that threshold estimates have only slight bias ranging from 15% with 9 trials to under 5% with 30 trials. Interestingly, these simulations also show that this bias can be reduced with only a small increase in the variability if the assumed psychometric function used by ZEST is made steeper than the listener’s psychometric function (i.e., if beta is increased from 1.23 to 6). Altogether these results suggest ZEST combined with a 2AFC paradigm is a promising candidate for rapid and reliable assessment of listeners’ discrimination thresholds.
Thresholds for inattentive listeners obtained with adaptive forced-choice procedures
Authors: Schlauch Robert , Carney Edward
Published: September 2013

Forced-choice adaptive procedures enjoy widespread use for measurement of detection and discrimination thresholds. Using computer simulations and behavioral data, this paper examines the effect of step size (2 and 4 dB), decision rule (targets =70.7%, 75%, and 79.4% correct) and initial starting level on thresholds obtained under conditions of inattention and complete attention. Simulations of two-alternative forced-choice (AFC) and three-AFC procedures demonstrate that the best general strategy for measuring thresholds under conditions of inattention is to employ a low percentage (e.g., 70.7%) as a target on the psychometric function combined with a large step size. When a track for an inattentive listener is begun far above threshold, we found that using a large step size for the first two turnarounds (reversals in stimulus level direction) and then switching to a step size that is 1/2 the initial step size was less effective than using the large step size for the entire threshold estimation run. Behavioral data obtained in a tonal detection-in-noise task with a 2-AFC procedure support the validity of the simulations.
Acute effects of nicotine on processing of complex stimuli in smokers and nonsmokers
Authors: Harkrider Ashley , Hedrick Mark
Published: September 2013

Effects of nicotine in the auditory system of normal-hearing smokers and nonsmokers were investigated both behaviorally and physiologically. Discrimination of consonant–vowel speech in quiet and noise was assessed in the presence and absence of a transdermal nicotine patch by measuring categorical boundaries and mismatch negativity (MMN). Data indicate that the effects of nicotine on both behavioral and physiological measures increased with an increase in severity of nicotine-induced symptoms. Smokers showed improved CV discrimination in quiet and noise with nicotine. Additionally, smokers exhibited more measurable and significantly sharper boundaries as well as larger MMN areas than nonsmokers in quiet and noise for both placebo and nicotine sessions. MMN data acquired for both quiet and noise, and behavioral data acquired in quiet, indicate that smokers show the greatest improvements in discrimination during nicotine exposure, followed by symptomatic nonsmokers. Asymptomatic nonsmokers show little improvement with nicotine and, on occasion, show decrements in performance. These data may contribute to our understanding of the role of nAChRs in the auditory system, the neural mechanisms that underlie the recognition of sound in quiet and noise, and mechanisms mediating improved information processing and enhanced cognitive performance that serve as reinforcement for continued tobacco use by smokers.
Low-frequency sounds and psychological tests at 7, 18, and 40 Hz
Authors: Damijan Zbigniew , Kasprzak Cezary , Panuszka Ryszard
Published: September 2013

Research included the results of tests aimed to determine how LFN (low-frequency noise) with the dominating frequency (7 Hz at 120 dB, 18 Hz at 120 dB, and 40 Hz at 110 dB) influences human brain potentials and understanding the dependency of results achieved in psychological questionnaires. The psychological questionnaires (EPQ-R Eysencks and SSS-5 Zuckermans) were analyzed. Presented issue existences difference, relative influence LFN on human biopotentials, dependence from acquired results in ranges EPQ-R Eysencks and SSS-5 Zuckermans. The test included 96 experiments. Standard EEG potentials, ECG potentials, and EDP (dermal) were recorded before, during and after subject’s 35-min exposures to LFN. Evident differences in changed bio-signals especially in EEG subject’s dispersion, were easily determined and correlated to questionnaire reports.
Sound fields in biosphere of the mountain streams and their influence on the human EEG
Authors: Kasprzak Cezary , Damijan Zbigniew , Panuszka Ryszard
Published: September 2013

Low-frequency acoustics fields in the biosphere of the headwater regions in Poland (Bieszczady Mountains and Tatry Mountains) were researched and the the influence of observed low-frequency acoustics field on changes of human EEG signals was analyzed. Several places were found with specific distribution of sound fields where low frequencies dominated. Interesting parameters of distribution of the riverbeds and physical characterization of flows were determined. Standard EEG signal was recorded from subjects until exposure for 20 min. It was ascertained that spectra of sound-pressure levels were with specific shape, very similar for a group of rivers. The influences of SPL on level of power spectrum of EEG signal were analyzed. Changes in the brain waves were observed with increases in delta and decreases in alpha. Tested subjects reported behavior specific for relaxation.
Fundamental frequency discriminability and utility in normal-hearing listeners using noise-excited vocoders
Authors: Qin Michael , Oxenham Andrew
Published: September 2013

Although enormous progress has been made in the development of cochlear implants, the speech reception of implant users is still not comparable to that of normal-hearing listeners. The difference in performance is especially pronounced in complex auditory situations, such as in the presence of competing talkers. The poorer speech reception performance of implant users in complex environments may, at least in part, be due to the poorer fundamental frequency (F0) representation. The present study examined the effects of implant-like processing (i.e., noise-excited vocoding) on F0 discriminability and utility in normal-hearing listeners. F0 difference limens (F0DLs) were measured as a function of the number of vocoder channels. In addition, vowel identification was measured as a function of F0 difference between competing vowels in a double-vowel paradigm, with number of vocoder channels as a parameter. Our findings show that despite the reasonable F0DLs (less than one semitone) with 24- and 8-channel vocoder processing, listeners were unable to benefit from F0 differences between the competing vowels in a double-vowel paradigm. The implications of the findings for pitch theories and cochlear implant design will be discussed. [Work supported by NIDCD Grant R01 DC05216.]
Effects of speaking rate on the perception of phonemic length contrast in Japanese
Authors: Kato Hiroaki , Tajima Keiichi
Published: September 2013

Segment length is distinctive in Japanese, for example, /kaite/ (buyer) versus /kaite:/ (seabed). Such length contrasts are not necessarily categorical for non-native speakers. To study this property precisely, a series of perception experiments was conducted. A professionally trained native-Japanese speaker produced the nonsense word /erete/ at slow, normal, and fast rates with or without a carrier sentence. Either the second vowel or second consonant of each word was gradually lengthened until reaching its longer counterpart, i.e., /ete:te/ or /eret:e/, in all rate and carrier conditions using STRAIGHT, a high-fidelity speech analysis, synthesis, and manipulation system [Kawahara et al., Speech Commun. 27, 187–207 (1999)], resulting in 12 stimulus continua. Seven native-Japanese listeners participated in a single-stimulus, two-alternative forced-choice identification task with the method of constant stimuli. The speaking rate of the presented stimuli within a session was either fixed or randomized trial by trial. Results suggest that native listeners’ identification boundaries systematically altered due to changes in speaking rate, whereas their boundaries became unstable in the randomized-rate condition, especially for no-carrier stimuli. These results will be discussed from the viewpoint of second-language phoneme perception and acquisition through comparisons with results from non-native listeners. [Work supported by TAO, Japan.]
Perceiving non-native speech: Word segmentation
Authors: Mondini Michèle , Miller Joanne L.
Published: September 2013

One important source of information listeners use to segment speech into discrete words is allophonic variation at word junctures. Previous research has shown that non-native speakers impose their native-language phonetic norms on their second language; as a consequence, non-native speech may (in some cases) exhibit altered patterns of allophonic variation at word junctures. We investigated the perceptual consequences of this for word segmentation by presenting native-English listeners with English word pairs produced either by six native-English speakers or six highly fluent, native-French speakers of English. The target word pairs had contrastive word juncture involving voiceless stop consonants (e.g., why pink/wipe ink; gray ties/great eyes; we cash/weak ash). The task was to identify randomized instances of each individual target word pair (as well as control pairs) by selecting one of four possible choices (e.g., why pink, wipe ink, why ink, wipe pink). Overall, listeners were more accurate in identifying target word pairs produced by the native-English speakers than by the non-native English speakers. These findings suggest that one contribution to the processing cost associated with listening to non-native speech may be the presence of altered allophonic information important for word segmentation. [Work supported by NIH/NIDCD.]
The role of low-frequency hearing in speakers sensitivity to delayed auditory feedback
Authors: Barac-Cikoja Dragana , Johnson Cara
Published: September 2013

Sensitivity to delayed auditory feedback (DAF) during speech production was assessed in six normal-hearing, fluent speakers using a two-interval, forced-choice (2IFC) adaptive procedure. Subjects repeated a syllable (either PA, TA, or KA) for approximately 2 s in two successive intervals and listened through headphones for a delay in the speech feedback. Subjects were required to identify which of the two utterances was delayed relative to the production onset. The length of the delay was changed stepwise depending on the accuracy of the subjects response. The estimates of the minimal delay yielding a 71% correct performance were obtained under three experimental conditions. The conditions varied in how the delay affected the low frequency (300 Hz) band (LFB) of the speech feedback signal: (a) LFB was delayed along with the rest of the speech spectrum; (b) LFB was separated from the rest of the spectrum by band-pass filtering, remained present in the feedback, but was never subjected to a delay; and (c) it was eliminated from the feedback by filtering and noise masking. Obtained estimates varied between 3 and 5 ms, but were not systematically related to the experimental manipulation.
Implicit learning of nonadjacent phonotactic dependencies in the perception of spoken language
Authors: McLennan Conor T. , Luce Paul A.
Published: September 2013

We investigated the learning of nonadjacent phonotactic dependencies in adults. Following previous research examining learning of dependencies at a grammatical level (Gomez, 2002), we manipulated the co-occurrence of nonadjacent phonological segments within a spoken syllable. Each listener was exposed to consonant-vowel-consonant nonword stimuli produced by one of two phonological grammars. Both languages contained the same adjacent dependencies between the initial consonant-vowel and final vowel-consonant sequences but differed on the co-occurrences of initial and final consonants. The number of possible types of vowels that intervened between the initial and final consonants was also manipulated. Listeners learning of nonadjacent segmental dependencies were evaluated in a speeded recognition task in which they heard (1) old nonwords on which they had been trained, (2) new nonwords generated by the grammar on which they had been trained, and (3) new nonwords generated by the grammar on which they had not been trained. The results provide evidence for listener’s sensitivity to nonadjacent dependencies. However, this sensitivity is manifested as an inhibitory competition effect rather than a facilitative effect on pattern processing. [Research supported by Research Grant No. R01 DC 0265802 from the National Institute on Deafness and Other Communication Disorders, National Institutes of Health.]
Auditory phonological priming in children and adults during word repetition
Authors: Cleary Miranda , Schwartz Richard G.
Published: September 2013

Short-term auditory phonological priming effects involve changes in the speed with which words are processed by a listener as a function of recent exposure to other similar-sounding words. Activation of phonological/lexical representations appears to persist beyond the immediate offset of a word, influencing subsequent processing. Priming effects are commonly cited as demonstrating concurrent activation of word/phonological candidates during word identification. Phonological priming is controversial, the direction of effects (facilitating versus slowing) varying with the prime-target relationship. In adults, it has repeatedly been demonstrated, however, that hearing a prime word that rhymes with the following target word (ISI=50 ms) decreases the time necessary to initiate repetition of the target, relative to when the prime and target have no phonemic overlap. Activation of phonological representations in children has not typically been studied using this paradigm, auditory-word + picture-naming tasks being used instead. The present study employed an auditory phonological priming paradigm being developed for use with normal-hearing and hearing-impaired children. Initial results from normal-hearing adults replicate previous reports of faster naming times for targets following a rhyming prime word than for targets following a prime having no phonemes in common. Results from normal-hearing children will also be reported. [Work supported by NIH-NIDCD T32DC000039.]
F0 peaks aligned with nonprominent syllables in American English
Authors: Shattuck-Hufnagel Stefanie , Veilleux Nanette , Brugos Alejna , Speer Robert
Published: September 2013

The occurrence of F0 peaks on nonprominent syllables in American English (e.g., -ing or a- in reading again) raises the question of how to label these inflection points. This pattern is not infrequent, as shown by samples from two prosodically labeled corpora of natural speech (ToBI labeled MIT Maptask and BU FM Radio News). The Maptask sample from a single speaker (235 seconds, 520 words) contained 46 H* !H* sequences; 19 had an F0 peak on a weak syllable between the two accented syllables. Individual speakers vary in their use of this pattern: for 3 Radio News speakers reading the same paragraph, each speaker produced 11 H* !H* sequences of which 6, 1, and 5, respectively, showed the non-accent-aligned peak. Informal listening as well as experiments described by Dilley (2004) suggest that alignment of the F0 peak with different nonprominent syllables between the two accents can change the perceived relative prominences of the accents, but current ToBI labels do not specify this alignment. Because F0 inflection points unaligned with the syllables perceived as prominent are common, and their location influences perceived prominence patterns, it is important to specify this aspect of an intonational contour. [Work supported by NIH Grants DC0075, DC02978, DC02125.]
Environmental influences on the frequency dependence of effective bottom attenuation
Authors: Nickila James D. , Smith Kevin B. , Potty Gopu
Published: September 2013

Over the past several years, concern has grown over the appropriateness of bottom-attenuation models that assume a linear frequency dependence. Empirical analyses of experimental data have suggested power-law dependence with frequency exponents as high as 1.7 and above, but with large variability between geographic regions [Zhou et al., J. Acoust. Soc. Am. 82, 287–292 (1987)]. The fundamental cause of this dependence is unknown. In this analysis, the influence of the propagation and interaction with environmental variability is investigated. Specifically, a propagation model that assumes linear frequency dependence is employed which incorporates such environmental variability as range-dependent water column sound-speed profiles, bottom sound-speed gradients, bottom sound-speed and density fluctuations, and rough water/bottom interfaces. These data are then decomposed into normal-mode amplitudes at various ranges. Based on an approach similar to Potty et al. [J. Acoust. Soc. Am. 114, 1874–1887 (2003)], estimates of average bottom attenuation may be inverted directly. By computing such estimates over a band of frequencies, the effective frequency dependence of the bottom attenuation can be determined as a function of range. The dominant environmental influences will also be identified and quantified.