bluuebunny/crossref_metadata_2025 huggingface dataset:
The relevance of low-frequency sound properties for performance and pleasantness
Authors: Persson Waye Kerstin , Bengtsson Johanna
Published: September 2013

The sound environment in the workplace has been found to influence performance, stress, mood, and well-being after work. However few studies can provide dose-response relationships and little is known of the importance of sound-quality aspects for adverse effects on critical tasks or task requirements. We have, during the last 8 years, been engaged in studies investigating the critical performance effects due to the presence of low frequencies (20–200 Hz) in sounds. The main hypotheses on critical effects derived from studies in the general environment were that low-frequency noise induced great annoyance, concentration difficulties, and was difficult to filter out or habituate to. On the other hand, results from truck drivers indicated that low-frequency sounds may lead to reduced alertness and increased sleepiness. In total, three studies were designed with regard to these hypotheses, all of them with the intention to be applicable to office and control room environment, using equivalent A-weighted sound-pressure levels of 40 and 45 dB. The fourth study investigated the importance of sound properties in low-frequency sounds for the perception of pleasantness. The results will be presented and discussed in relation to noise assessment aspects. [Work supported by Swedish Council for Working Life and Social Research.]
Relating human productivity and annoyance to indoor noise criteria systems
Authors: Bowden Erica E. , Wang Lily M.
Published: September 2013

The goal of this research is to determine a noise criteria system which best relates the effects of background noise to human productivity and annoyance. A number of indoor noise criteria systems are currently used to rate the background noise in built environments, including noise criteria (NC), balanced noise criteria (NCB), room criteria (RC), room criteria Mark II (RC-Mark II), and others. Many questions still remain about the accuracy of these predictors in assessing human response to background noise under the variety of ambient noise situations encountered. To support the use of any individual criterion, subjective testing was performed under a range of background noise situations and statistically related to the various noise criteria predictors listed above. Subjects completed an annoyance survey and performed typing and proofreading tasks in an acoustically controlled environment under 12 simulated background noise settings. These settings varied across three sound levels and four spectral qualities. Subjective testing methodology and results are presented. [Work supported by INCE and ASHRAE.]
Environmental impact on workplace performance
Authors: Knight Derrick P. , Orfield Steven J. , Smith Thomas J.
Published: September 2013

Since 1998, Orfield Laboratories has led research efforts into the effects of the office environment on worker performance through the Open Plan Working Group. This collaboration of researchers, designers, and facility managers works with OPWG in gathering environmental data (including noise, lighting, and thermal measurements) and subjective occupant ranking data. The OPWG then employs statistical analysis to correlate the environmental measurements, occupant performance, and occupant preference measurements. Through efficient measurement stations and Web-based surveys, Orfield Laboratories has helped many companies to begin to view their employees as their greatest operational profit center. This presentation will discuss the effect that noise as well as other environmental factors has on work performance.
Human annoyance and reactions to hotel room specific noises
Authors: Everhard Ian L.
Published: September 2013

A new formula is presented where multiple annoyance sources and transmission loss values of any partition are combined to produce a new single number rating of annoyance. The explanation of the formula is based on theoretical psychoacoustics and survey testing used to create variables used to weight the results. An imaginary hotel room is processed through the new formula and is rated based on theoretical survey results that would be taken by guests of the hotel. The new single number rating compares the multiple sources of annoyance to a single imaginary unbiased source where absolute level is the only factor in stimulating a linear rise in annoyance [Fidell et al., J. Acoust. Soc. Am. 66, 1427 (1979); D. M. Jones and D. E. Broadbent, ‘‘Human performance and noise,’’ in Handbook of Noise Control, 3rd ed., edited by C. M. Harris (ASA, New York, 1998), Chap. 24; J. P. Conroy and J. S. Roland, ‘‘STC Field Testing and Results,’’ in Sound and Vibration Magazine, Acoustical Publications, pp. 10–15 (July 2003)].
Array measurement of echolocation signals on the melon of harbor porpoises (Phocoena phocoena)
Authors: Au Whitlow , Benoit-Bird Kelly , Kastelein Ronald , Cranford Ted
Published: September 2013

The melon of odontocetes has been hypothesized to be a focusing body that channels echolocation signals produced within the nasal region of the animal’s head into the water. The acoustic field of two echolocating harbor porpoises (Phocoena phocoena) was measured at the melon’s surface with an array of four broadband hydrophones embedded in suction cups. The clicks detected by each hydrophone were simultaneously digitized at a sampling rate of 500 kHz and stored on a PC. Digital still photographs of the array were taken before each echolocation trial to measure the hydrophone’s position. The shape and dimensions of the melon were measured with a flexible shape-retaining measuring device. The axis of the echolocation beam was found to be approximately 5.6–6.1 cm from the edge of the animal’s upper lip along the midline of the melon, which coincides with the axis of the low-density lipid core of the melon. Click amplitudes dropped off rapidly (12–14 dB) from the maximum at hydrophones 3.5 cm apart, providing support for the melon-focusing hypothesis. Changes in the waveform on consecutive hydrophones suggest that the porpoises can manipulate either the shape of the melon or the output of the sources within 0.086 s.
Optoacoustics for high-frequency ultrasonic imaging and manipulation
Authors: O’Donnell Matthew , Buma Takashi
Published: September 2013

Pulsed lasers can generate ultrasound through thermoelastic expansion of a thin optical absorber. By carefully designing the optical absorbing structure, efficient transduction is possible for a number of biomedical applications including high-frequency imaging, microfluidics, and sensing. The major key for efficient optoacoustic transduction in biomedical applications is to engineer a nearly perfect optical absorber possessing a large coefficient of thermal expansion with acoustic properties well matched to a water medium. We have obtained an optoacoustic efficiency increase of over 20 dB compared to conventional approaches using a thin, optically absorbing layer consisting of polydimethylsiloxane (PDMS) and carbon black spin coated onto a clear PDMS substrate. This structure has been extensively analyzed both experimentally and analytically and seems to provide opportunities for a wide range of optoacoustic devices. In this talk we show how PDMS-based optoacoustic transduction can be used for high-frequency imaging using longitudinal waves and acoustic tweezing using Lamb waves. The basic mechanism of optoacoustic transduction will be described, and specific devices will be presented.
Robust diffraction correction method for high-frequency ultrasonic tissue characterization
Authors: Raju Balasundar
Published: September 2013

The computation of quantitative ultrasonic parameters such as the attenuation or backscatter coefficient requires compensation for diffraction effects. In this work a simple and accurate diffraction correction method for skin characterization requiring only a single focal zone is developed. The advantage of this method is that the transducer need not be mechanically repositioned to collect data from several focal zones, thereby reducing the time of imaging and preventing motion artifacts. Data were first collected under controlled conditions from skin of volunteers using a high-frequency system (center frequency=33 MHz, BW=28 MHz) at 19 focal zones through axial translation. Using these data, mean backscatter power spectra were computed as a function of the distance between the transducer and the tissue, which then served as empirical diffraction correction curves for subsequent data. The method was demonstrated on patients patch-tested for contact dermatitis. The computed attenuation coefficient slope was significantly (p<0.05) lower at the affected site (0.13±0.02 dB/mm/MHz) compared to nearby normal skin (0.2±0.05 dB/mm/MHz). The mean backscatter level was also significantly lower at the affected site (6.7±2.1 in arbitrary units) compared to normal skin (11.3±3.2). These results show diffraction corrected ultrasonic parameters can differentiate normal from affected skin tissues.
High frequency nonlinear imaging
Authors: Poulsen Jens K.
Published: September 2013

Nonlinear imaging has already shown improved image resolution compared to fundamental imaging at lower frequencies (2–4 MHz). The required steps to obtain nonlinear images at high frequencies are presented here. The transmit frequency was from 20 to 60 MHz and on receive, pulse-inversion, the first, second, and the third harmonic were used for imaging. Experiments were conducted using a wire phantom and in vitro from a human femoral artery. PVDF transducer (6 mm diameter, 10 mm focal length, central frequency 42 MHz, −6 dB bandwidth 38 MHz) was used with a filtered amplifier (46.0 and 50.6 dBm output). The pulse-inversion experiment at 40 and 60 MHz had lateral resolution (−6 dB contours) 64 and 52 μm and axial 43 and 31 μm. The fundamental experiments at 20, 30, 40, and 60 MHz had lateral resolutions 104, 89, 74, 57 μm and axial 72, 86, 46, 35 μm. The second harmonic at 40 and 60 MHz had lateral resolution 62 and 47 μm and axial 52 and 38 μm. The third harmonic at 60 MHz had lateral resolution 48 μm and axial 42 μm. Nonlinear tissue images had improved resolution compared to fundamental imaging, though the improvement was small for the second harmonic experiment.
40–50-MHz lithium niobate (LiNbO3) transducers for pulsed Doppler measurements in mouse embryos
Authors: Aristizábal Orlando , Turnbull Daniel H. , Ji Ruiping , Phoon Colin
Published: September 2013

An ultrasound biomicroscopy (UBM) system operating between 40 and 50 MHz has been developed for imaging and detecting blood flow in normal and genetically modified mouse embryos, which has contributed to the understanding of the functional consequences of specific genetic defects affecting cardiovascular development. In this scanner, UBM images and Doppler blood velocity waveforms are acquired simultaneously with separate transducers, enabling independent optimization of either the imaging or Doppler transducer. Air backed, 1.5-mm-diameter, unfocused 44-MHz LiNbO3 Doppler transducers designed for the 40- to 50-MHz pulsed Doppler ultrasound system have been developed. The fabrication and characterization of the electromechanical and ultrasonic beam properties of these transducers will be described. The two-way insertion loss at 44 MHz was measured to be −16 dB before tuning, a 60% improvement over the piezo-polymer transducers typically used for UBM-Doppler. Beam-plot data demonstrate the expected collimated near-field pattern to a depth of 13 mm, providing reasonable lateral resolution (1.0–1.5 mm) over a wide depth of field. The utility of these Doppler transducers for interrogating blood vessels such as the dorsal aorta in normal and mutant mouse embryos with defects in cardiac valve formation has been demonstrated.
The development of noise-induced hearing loss in military trades
Authors: Abel Sharon M. , Jewell Stephanie
Published: September 2013

An investigation is in progress to determine risk factors for the development of noise-induced hearing loss in Canadian Forces personnel. A total of 1057 individuals representing a wide range of military trades have contributed their current audiogram, first audiogram on record, and responses to a 56-item questionnaire. The protocol for the hearing test was standardized and conformed to current audiological practice. The items included in the questionnaire related to demographics, occupational and nonoccupational noise exposure history, training in and utilization of personal hearing protectors, and factors other than noise which might affect hearing (e.g., head injury, ear disease, exposure to solvents, and the use of medications). Analyses are underway to determine the average current hearing thresholds as a function of frequency and change relative to baseline values at recruitment for groups defined by trade, rated noise hazard, and years of service. Preliminary results suggest ways to improve the training of personnel with respect to the effects of both occupational and nonoccupational noise exposure and methods of implementing hearing conservation strategies. The role of head injury, history of ear disease, and the use of medications appear to be small. [Work supported by Veterans Affairs Canada.]
Attenuation of high-level acoustic impulses by earplugs
Authors: Zera Jan , Mlynski Rafal
Published: September 2013

Attenuation of acoustic impulses by various models of foam, premolded, formable and semi-insert earplugs was measured. The impulses were generated by a loudspeaker system in the 115–130 range of levels, and by a blast of air expanding from a cylinder in the 150–170 level range. Transmission loss method was used to determine the difference between the peak level under the earplug and outside the earplug. The earplugs were inserted into in-house designed cylindrical or conical couplers attached to an artificial test fixture. The measurements showed that attenuation of high-level impulses depends on the type of coupler and the depth of earplug insertion. Attenuation measured using a conical coupler was consistently about 5 dB lower than for cylindrical coupler. Decreasing the depth of earplug insertion from 75% to 50% was especially critical at high level impulses and lowered attenuation by about 6 dB. For various models of foam and premolded earplugs, attenuation of high-level impulses varies by more than 20 dB. Particularly high attenuation was obtained for formable earplug made of modified wax. [Work supported by the State Committee for Scientific Research Grant No. III-7.03, III-6.07.]
Evidence for training effects of the acoustical environment on hearing
Authors: Fleischer Gerald , Mueller Reinhard
Published: September 2013

A database of roughly 10000 adult persons—from 18 years to 70 years—was analyzed with a procedure that accounts for normal aging of the ear. Auditory performance of good-hearing persons of various groups was determined: office personnel, construction workers, university students, airline pilots, dentists, orchestra musicians, fans of discotheques, avoiders of discotheques, Tibetian nomads, Chinese peasants living without technical noise, etc. Pure-tone auditory threshold—based on pulsed signals—was analyzed from 125 Hz to 10 kHz. The Leq of the long-term acoustic environment was estimated, using acoustic measurements. Results confirm the well-known fact that excessive noise levels damage the ear. However, at lower levels, sound can apparently improve the sense of hearing, as measured by the auditory threshold. Ranking the various groups according to their hearing performance reveals that the best-hearing groups are all living and working in a loud acoustic environment. In these groups aging of the ear is reduced. Groups living in an environment with very low sound levels do not hear well. Apparently the auditory system needs training, in order to develop its full potential, and to keep functioning well.
Vulnerability of the ear in men and women
Authors: Fleischer Gerald , Mueller Reinhard
Published: September 2013

A special procedure was developed to separate ears with auditory damage from those without damage. It was applied to a database of roughly 10000 persons, containing pure-tone audiograms and other information. Persons with medical problems of the ear were excluded. For analysis, groups of persons with similar ways of life were examined: college students, orchestra musicians, dentists, Tibetian nomads, Chinese city dwellers, etc. Looking specifically at ears that suffered noise-induced auditory damage, the damages are different in men and women. At frequencies below about 2 kHz men typically have less hearing loss than women. However, above 2 kHz, men have more hearing loss than women. This effect is quite strong and highly significant. It could be found in every group that is large enough. It is present in persons going regularly to discotheques, as well as in Tibetian nomads, who live without any technical noise, but use fire crackers now and then. This effect appears not related to the acoustic environment, but can be the result of differences in vulenerability between men and women. It can also be found in youngsters and, to some extent, in children.
Thermoacoustic boundary layers near the liquid–vapor critical point
Authors: Gillis Keith A. , Shinder Iosif I. , Moldover Michael R.
Published: September 2013

The sound attenuation in resonators filled with xenon at its critical density ρc was calculated and measured as a function of the reduced temperature τ≡(T−Tc)/Tc. (Tc is the critical temperature.) Over the temperature and frequency ranges of the measurements [10−3<τ<10−1, 0.1 kHz<f<7.5 kHz], the attenuation was dominated by the thermal boundary layer. The model predicts that the attenuation at the boundary first increases as τ decreases and then saturates when the effusivity of the xenon exceeds that of the solid. [The effusivity is ε≡√ρCPλT, where CP is the isobaric specific heat and λT is the thermal conductivity.] The model correctly predicts (±1.0%) the quality factors Q of resonances measured in a steel resonator (εss=6400 kg⋅K−1⋅s−5/2); it also predicts the observed increase of the Q, by up to a factor of 8, when the resonator is coated with a polymer (εpr=370 kg⋅K−1⋅s−5/2). The thickness δT of the thermal boundary layer in the xenon decreases as τ decreases until 2πfγζ/(ρc2)≊1. (ζ is the bulk viscosity, γ is the heat capacity ratio, and c is the speed of sound.) For smaller τ, δT is predicted to become complex and increase. [Work supported by NASA.]
Maximum in the damping of shape oscillations of foam drops near the critical void fraction
Authors: Wang Hai , Liu Li , McDaniel Gregory J. , Holt Glynn R.
Published: September 2013

Small spheroidal samples of aqueous foam (‘‘foam drops’’) of varying gas volume fraction are acoustically levitated in an ultrasonic field. The normalized natural frequency and damping ratio are determined by treating a foam drop as a damped linear oscillator and measuring shape mode frequency response. The observed natural frequencies are compared to a wet foam model without any fitting parameters. Good agreement is found for gas volume fractions ranging from 0.01 to 0.87. The observed damping ratio of a foam drop exhibits a maximum for gas volume fractions 0.5 to 0.7. The data are inverted to infer the shear elastic modulus and its dependence on gas volume fraction for dry foams. [Work supported by NASA.]
BUSS: Final results from an experiment to determine the effect of gravity on sonoluminescence
Authors: Thomas Charles , Roy Ronald , Holt R. Glynn
Published: September 2013

The goal of the Boston University Sonoluminescence in Space (BUSS) project was to investigate the dependence of SBSL on ambient acceleration by performing experiments both on the KC-135 and in a land-based lab at Boston University. In this talk the final results of the KC-135 portion of the project will be discussed. Measurements of the maximum bubble Radius, bubble position, and peak light intensity emitted (Rmax, z, and Ipeak, respectively) were made during parabolic flight while keeping the acoustic pressure constant. Trends in Rmax, z, and Ipeak are studied by picking out their extrema from the data for each parabola. Additionally, the measured time-dependent Rmax, z, and Ipeak are compared to a quasi-static model which was developed to predict changes in these variables as a function of the changing acceleration and cabin pressure of the KC-135 during flight. Given the relatively good agreement of the model with measured data, it is concluded that the changes in Rmax, z, and Ipeak can be explained simply by considering the change in hydrostatic pressure caused by the variable acceleration. [Work supported by NASA.]
Chemical oscillations in bubbles: Resolving the mystery of chaotic sonoluminescence
Authors: Thomas Charles , Roy Ronald , Holt R. Glynn , Holzfuss Joachim
Published: September 2013

One aspect of the Boston University Sonoluminescence in Space project included 1 g experiments to map the position of stable bubbles in (Pa,Rmax) space, in water for a range of dissolved gas concentrations. While performing these experiments a regime was found in which Rmax and the position of the bubble oscillate periodically on a slow timescale despite a constant acoustic pressure. Histograms of the phase of light emission from a bubble in such an oscillatory state reveal a broadband distribution. These measurements partially explain previous measurements of quasiperiodic and chaotic sonoluminescence. We hypothesize that the oscillations are caused by the competing mass transfer mechanisms of rectified diffusion (growth) and chemical reaction (shrinkage). [Work supported by NASA.]
Modeling of the bulk acoustic wave effects of electrode thin films in piezoelectric resonators
Authors: Srivastava Sonal , Yong Yook-Kong
Published: September 2013

The modeling of very high frequency piezoelectric resonators such as the thickness shear mode resonators is computationally and memorywise very intensive. The finite element mesh must be sufficiently fine so as to prevent the mesh impedance from interfering with the wave acoustics of the vibrating modes. The thin film of electrodes introduces additional complexity to the finite element models, hence an efficient method for treating the acoustic effects of such films are needed. Since the films on the resonator surfaces are stress-free, the film stiffness is small and negligible, and only the inertial effects need be modeled. Finite elements models are used to demonstrate the effects of electrode film stiffness and mass on the bulk acoustic wave characteristics of the piezoelectric plate. Results are presented to show the upper limits of the electrode film thickness upon which only the inertial effects are predominant. Results are also shown to demonstrate the efficiency of modeling only the inertial effects and neglecting the stiffness effects of thin electrode films.
Nonlinear acoustic experiments involving landmine detection: A connection between mesoscopic/nanoscale effects in geomaterials
Authors: Korman Murray S.
Published: September 2013

The vibration interaction between the top-plate interface of a buried plastic landmine and the soil above it appears to exhibit many characteristics of the mesoscopic/nanoscale nonlinear effects that are observed in geomaterials like rocks (sandstone) or granular materials. Experiments are performed with an inert VS 1.6 anti-tank mine that is buried 3.6 cm deep in dry sifted loess soil. Airborne sound at two primary frequencies f1=120 Hz and f2=130 Hz undergo acoustic-to-seismic coupling. Interactions with the compliant mine and soil generate combination frequencies that, through scattering, can affect the vibration velocity at the surface. Profiles of the soil surface particle velocity at f1 and f2 and the nonlinearly generated f1−(f2−f1) component are characterized by a single peak. Doubly peaked profiles at 2f1+f2 and 2f2+f1 are attributed to the familiar mode shape of a timpani drum. Near resonance, the bending (a softening) of a family of tuning curves for the soil surface vibration over a landmine exhibits a linear relationship between the peak frequency and the corresponding peak particle velocity, which also exhibit hysteresis effects. [Work supported by U.S. Army Communications-Electronics Command RDEC, NVESD, Fort Belvoir, VA.]
Laser-induced acoustic landmine detection
Authors: DiMarzio Charles A. , Shi Tianchen , Blonigen Florian J. , McKnight Stephen W.
Published: September 2013

Laser-induced acoustic (LIA) imaging is a new approach for underground object detection, especially for shallow buried landmine detection. This noncontact detection technique is based on a pulsed laser initiating photo-acoustic interaction in the ground. If sufficient photon energy couples into the ground, generating acoustic signals larger than seismic noise, a high enough mismatch of acoustic impedance between background media and target could provide a clear acoustic image revealing both the target’s position and the 3-D shape information to reduce false alarms. In this paper, we present a model for laser-induced acoustic wave generation, including models of photo-acoustic sources and propagation of sound waves in media, to obtain a better understanding of basic physics behind the process. A photon-induced thermoelastic source and a photon-induced plasma source are investigated. Also, an investigation was performed in terms of attenuation, angular distribution, and phase velocities, and experimental results are reported and compared with theoretical analysis.
Land mine detection by time reversal acousto-seismic method
Authors: Sutin Alexander , Sarvazyan Armen , Johnson Paul , TenCate James
Published: September 2013

We present a concept and results of a pilot study on land mine detection based on the use of time reversal acoustics (TRA). TRA provides a possibility of highly effective concentrating of seismic wave energy in time and space in complex heterogeneous media. TRA focusing of seismic waves on a land mine increases the detection abilities of conventional linear and nonlinear acousto-seismic methods. Such factors as medium inhomogeneities, presence of reflecting boundaries, which could critically limit conventional acoustic approaches, do not affect TRA based method. The TRA mine detection system comprises several air borne or seismic sources and a noncontact (laser vibrometer) device for remote measurements of the surface vibration. The TRA system focuses a seismic wave at a surface point where the vibration is measured. The focusing point is scanned across the search area. The amplitude and frequency dependence of the signal from the seismic wave focusing point and nonlinear acoustic effects are analyzed to assess probability of the mine presence. Preliminary experiments confirmed high focusing ability of the TRA seismo-acoustic system in complex conditions (a laboratory tank with sand) and demonstrated a significant increase in the surface vibration in the presence of mine imitator. [Work supported by DoD grant.]
Dissonance perception by listeners with sensorineural hearing loss
Authors: Tufts Jennifer B. , Leek Marjorie R. , Molis Michelle R.
Published: September 2013

The perceived dissonance of two simultaneous tones (a dyad) depends upon their frequency separation (in the case of two pure tones) or their fundamental frequency ratio (in the case of two harmonic complex tones). The purpose of this study was to determine whether the perceived dissonance of puretone and harmonic complex dyads is altered in the presence of sensorineural hearing (SNHL), and, if so, whether this can be explained by the reduced frequency selectivity typically associated with SNHL. Four normal-hearing and four hearing-impaired listeners evaluated the dissonance of puretone and harmonic complex dyads centered at 500 and 2000 Hz. Frequency selectivity was estimated at 500 and 2000 Hz for each listener. People with SNHL rated the dissonance of puretone dyads similarly to the normal-hearing listeners, although auditory sensitivity and frequency selectivity differed considerably between the groups. However, their ratings of harmonic complex dyads did not show the pronounced differences in dissonance as a function of fundamental frequency ratio that were observed in the normal-hearing group. The poorer frequency selectivity of these listeners may have allowed more extensive interactions to occur among harmonic components, resulting in a less clear separation of dissonance and consonance. [Work supported by NIH-NIDCD.]
Place-pitch and excitation patterns in cochlear implant listeners
Authors: Galvin John J. , Fu Qian-Jie
Published: September 2013

In cochlear implants (CIs), an electrode’s pitch is largely determined by the excitation pattern produced by stimulation. For CI users, is pitch perception most strongly influenced by the peak, edge or some intermediate location within the excitation pattern? By varying the stimulation mode at four evenly spaced electrode locations, four spectral profiles were hypothesized: single-peaked, apically weighted, basally weighted or multi-peaked (with an intermediate pitch). Forward-masked excitation patterns and pitch judgments were obtained for the four electrode locations, for all experimental stimulation modes, relative to a standard set of BP1 electrodes. Results showed individual differences in CI users’ excitation patterns and pitch judgments produced by the different stimulation modes. Most subjects’ pitch judgments were sensitive to single, sharp peaks in the excitation pattern; however, subjects differed in their sensitivity to broader, multi-peaked patterns. For widely spaced electrode configurations, some subjects consistently judged pitch according to the apical edge of stimulation, some to the basal edge and others to an intermediate location. For some electrode locations, varying the stimulation mode produced significantly different pitches and excitation patterns. Future speech processing strategies may wish to combine stimulation modes to improve the spectral resolution available with a fixed number of implanted electrodes.
Different learning patterns for tone detection in three simultaneous-masking conditions with different temporal characteristics
Authors: Huyck Julia L. , Wright Beverly A.
Published: September 2013

Can the processes underlying performance on basic masking tasks be modified with practice? To address this question, 17 listeners completed pre- and posttests in which detection thresholds for a 20-ms 1-kHz tonal signal were measured in three notched-noise simultaneous-masking conditions that differed in the masker duration and relative onset times of the signal and masker, and three forward-masking conditions that differed in the tonal frequencies of the maskers. For the ∼8 days between tests, eight of these listeners practiced 240 trials/day on each simultaneous-masking condition. Learning differed across conditions. When the signal and a 20-ms masker began and ended together, both trained and untrained listeners improved, but trained listeners improved more, learning gradually. When the signal began 400 ms after a 500-ms masker, only the trained group improved, learning quickly. When the signal and the 500-ms masker began together, both groups improved equally. Both groups also improved equally on each of the three forward-masking conditions. These results suggest that processes underlying performance on simultaneous- and forward-masking tasks are modifiable, training affects different mechanisms in simultaneous-masking conditions with different temporal characteristics, and the simultaneous-masking mechanisms affected by multi-hour training are not involved in forward masking. [Work supported by NIH.]
Fundamental frequency discrimination for resolved and unresolved harmonics with the same pitch in the same spectral region
Authors: Watkinson Rebecca K. , Plack Christopher J. , Carlyon Robert P.
Published: September 2013

To investigate the hypothesis that fundamental frequency (F0) is encoded via different mechanisms for resolved and unresolved harmonics, F0 discrimination was measured for harmonics that had the same pitch and were in the same spectral region, but which differed in resolvability. Summing unresolved harmonics in alternating phase increases their pitch by an octave relative to sine-phase summation; this is not found for resolved harmonics. An alternating-phase, 100-Hz F0 complex tone and a sine-phase, 200-Hz F0 complex tone, both filtered between 1000 and 2000 Hz, have the same pitch. However, the first complex tone contains unresolved harmonics and the second contains resolved harmonics. The experiment measured sequential F0DLs and d’s for two such groups of harmonics that were both resolved, both unresolved, or for which one group was resolved and the other unresolved. Performance was worse for unresolved versus unresolved comparisons than for resolved versus resolved comparisons. More importantly, performance was worse still when the harmonic groups differed in resolvability (resolved versus unresolved). This provides some evidence for the hypothesis that resolved versus unresolved comparisons are impaired by the need to compare the outputs of separate pitch mechanisms. [Work supported by an EPSRC doctoral training grant.]
Establishing a hierarchy among octave equivalent forms of a 12-tone row
Authors: Ho Hubert C.
Published: September 2013

The perceptability of tone hierachies in dodecaphonic rows has been well documented in the literature. This study investigates similarity among octave-equivalent variants of a given dodecaphonic row. The aggregate pitch proximity of a given row is represented by a 12-dimensional ‘‘contour vector,’’ the elements of which consist of the intervals (in semitones) of successive members of the row. Participants were asked to perform a series of probe-tone rating tasks in a variety of given contexts according to techniques used by Krumhansl et al. (1987). Test rows varied with respect to the contour vector. Control rows consisted of randomly generated tone rows. It was found that the similarity between contour vectors of a given row is positively correlated with their respective probe tone ratings.
Production and perception of a temporal contrast by native and non-native speakers
Authors: Bent Tessa , Bradlow Ann R. , Smith Bruce
Published: September 2013

In previous work, we found that both native and Chinese-accented talkers of English varied considerably in the extent to which they realized the duration contrast for vowels before voiced versus before voiceless consonants. The current study explored the perceptual consequences of this individual variability in production. Twenty native and 35 non-native listeners participated in a minimal pair identification task using stimuli from two native and two non-native talkers who differed substantially in the extent to which they realized the temporal contrast. Stimuli were consonant-vowel-consonant words that differed only in the voicing of the final consonant. Both native and non-native listeners exhibited sensitivity to variation in the production of this temporal contrast: greater identification accuracy was observed for relatively large duration differences. There was also a talker-listener interaction such that non-native listeners identified words produced by the non-native talkers more accurately than those produced by the native talkers. In a follow-up experiment, we investigated the perception-production relationship for this temporal contrast in the non-native listeners. Generally, non-native listeners who were more sensitive to this duration contrast in native-accented English showed a greater duration contrast in English production than non-native listeners who were less sensitive to this contrast. [Work supported by NIH-NIDCD.]
Effects of audio-visual presentation of target words in word translation training
Authors: Akahane-Yamada Reiko , Komaki Ryo , Kubo Rieko
Published: September 2013

Komaki and Akahane-Yamada (Proc. ICA2004) used 2AFC translation task in vocabulary training, in which the target word is presented visually in orthographic form of one language, and the appropriate meaning in another language has to be chosen between two choices. Present paper examined the effect of audio-visual presentation of target word when native speakers of Japanese learn to translate English words into Japanese. Pairs of English words contrasted in several phonemic distinctions (e.g., /r/–/l/, /b/–/v/, etc.) were used as word materials, and presented in three conditions; visual-only (V), audio-only (A), and audio-visual (AV) presentations. Identification accuracy of those words produced by two talkers was also assessed. During pretest, the accuracy for A stimuli was lowest, implying that insufficient translation ability and listening ability interact with each other when aurally presented word has to be translated. However, there was no difference in accuracy between V and AV stimuli, suggesting that participants translate the words depending on visual information only. The effect of translation training using AV stimuli did not transfer to identification ability, showing that additional audio information during translation does not help improve speech perception. Further examination is necessary to determine the effective L2 training method. [Work supported by TAO, Japan.]
Temporal patterns of native Mandarin Chinese speakers’ productions of English stop-vowel syllable
Authors: Wang Yue , Behne Dawn M.
Published: September 2013

Second language (L2) production can be a kind of interlanguage, a relatively stable system bearing the nature of both the native language (L1) and L2. Within such a system sound components of a syllable may bear their own interlanguage characteristics and yet interact with the other component sounds. The present study investigates temporal patterns of L1–L2 interaction at the syllable level. Audio recordings were made of English stop-vowel syllables produced by native speakers of Mandarin who were fluent in English (ChE). Native English productions (AmE) of these syllables and native productions of Mandarin (ChM) stop-vowel syllables were acquired as native norms. Temporal measures included stop closure duration, voice-onset time (VOT), vowel duration, and syllable duration. Results show that the internal timing components of ChE often deviate from AmE, with the closure duration, VOT, and vowel duration being intermediate to AmE and ChM. However, at the syllable level, ChE productions tend to follow the overall patterns of AmE. Temporal deviations were often compensated by temporal compensation of other components in the syllable, maintaining a balanced consonant/vowel distribution. These findings have implications for a broader understanding of L2 productions.
Intelligibility of non-native Lombard speech for non-native listeners
Authors: Li Chi-Nin
Published: September 2013

Previous study [C-N. Li, J. Acoust. Soc. Am. 114, 2364 (2003)] has shown that foreign-accented Lombard speech is more intelligible than normal speech when presented in noise to native English listeners. This research extends that work and examines the intelligibility of non-native English speakers’ Lombard speech perceived by listeners from the same L1 background. Twelve Cantonese speakers and a comparison group of English speakers read 48 simple true and false English sentences in quiet and in 70 dB of cafeteria noise. Normal and Lombard sentences were masked with noise at a constant signal-to-noise ratio, and presented along with noise-free stimuli to eight native Cantonese speakers who assessed intelligibility by transcribing the sentences in standard English orthography. Analyses indicated that for both groups of speakers, sentences presented in noise were less well perceived than those presented without noise. The Cantonese speakers’ utterances were more intelligible than were the native English productions. However, in noisy conditions, the Lombard speech of the Cantonese speakers was correctly transcribed less often than their normal utterances, and the English speakers’ Lombard speech was not more intelligible than their normal speech.
Compensation for phonological assimilation can be triggered by nonspeech sounds
Authors: Mitterer Holger
Published: September 2013

Several previous experiments have shown that phonological assimilations are compensated for perceptually by a context-sensitive mechanism. For instance, the Hungarian assimilated form ‘‘bar’’ of the word ‘‘bal’’ (‘‘left’’) is recognized as such only if it occurs in a context that allows assimilation (i.e., ‘‘balrol’’ assimilated to ‘‘barrol,’’ ‘‘from the left’’), but not in other contexts (*‘‘barnal’’). This ‘‘compensation for assimilation’’ is independent of language experience: Similar results were found with Hungarian and Dutch listeners [Mitterer et al., Proceedings of the 15th International Congress of Phonetic Sciences (2003)]. This suggests that an auditory mechanism underlies compensation. Nonspeech analogs of the phonetic contexts ‘‘nal’’ and ‘‘rol’’ should therefore trigger similar context effects as speech sounds: Three pairs of nonspeech analogs were played after syllables from a ‘‘bal’’-to-‘‘bar’’ continuum: First, a broadband noise was used with-analog to the trill in ‘‘rol’’—or without-analog to the nasal in ‘‘nal’’—amplitude modulation (AM) at the onset. Second, the same AM manipulation was applied to a 400-Hz tone. Third, frequency modulation replaced the AM of the 400-Hz tone. In each case, the nonspeech sounds had the same effect on identification and discrimination performance as the speech sounds.
Frequency effects in phoneme processing
Authors: Moates Danny , Stockmal Verna , Bond Zinny
Published: September 2013

This study tested the hypothesis that phonological segments are activated during word recognition in proportion to their frequency of use, analogous to frequency effects in whole word recognition. Preliminary evidence for the hypothesis was given by Moates, Bond, and Stockmal [LabPhon 7 (2002)] using a word reconstruction task. The present study used a gating task in which progressively longer fragments of a word are presented to listeners who must identify the word after as few gates as possible. High- and low-frequency segments were contrasted by presenting them in word pairs that differed in two segments, e.g., collision–collusion, where /I/ is more frequent than /u/. We constructed 15 words pairs contrasting vowels and 16 pairs contrasting consonants (e.g., relief–release, where /s/ is more frequent than /f/). Identification judgments were gathered from 125 participants. An ANOVA showed high-frequency consonants to be identified at significantly earlier gates than their matched low-frequency consonants with both subjects and items as random factors. No such effect appeared for vowels. Also, whole words containing the high-frequency segments were not identified significantly earlier than those containing low-frequency segments. If the phoneme frequency effect is reliable, then spoken word recognition models should address it.
The ‘‘listener’’ in the modeling of speech prosody
Authors: Kohler Klaus J.
Published: September 2013

Autosegmental-metrical modeling of speech prosody is principally speaker-oriented. The production of pitch patterns, in systematic lab speech experiments as well as in spontaneous speech corpora, is analyzed in f0 tracings, from which sequences of H(igh) and L(ow) are abstracted. The perceptual relevance of these pitch categories in the transmission from speakers to listeners is largely not conceptualized; thus their modeling in speech communication lacks an essential component. In the metalinguistic task of labeling speech data with the annotation system ToBI, the ‘‘listener’’ plays a subordinate role as well: H and L, being suggestive of signal values, are allocated with reference to f0 curves and little or no concern for perceptual classification by the trained labeler. The seriousness of this theoretical gap in the modeling of speech prosody is demonstrated by experimental data concerning f0-peak alignment. A number of papers in JASA have dealt with this topic from the point of synchronizing f0 with the vocal tract time course in acoustic output. However, perceptual experiments within the Kiel intonation model show that ‘‘early,’’ ‘‘medial’’ and ‘‘late’’ peak alignments need to be defined perceptually and that in doing so microprosodic variation has to be filtered out from the surface signal.
Prosodic complexity and phrase length as factors in pause duration
Authors: Krivokapic Jelena
Published: September 2013

Research on pauses has mainly focused on predicting the likelihood of pause occurrence and on the effect of syntactic structure on pause duration within an utterance. Very little is known about what factors, apart from syntactic and discourse factors, influence the length of pauses between utterances or phrases. This experiment examines the effect of prosodic structure and phrase length on pause duration. Subjects read 24 English sentences varying along the following parameters: (a) the length in syllables of the intonational phrase preceding and following the pause and (b) the prosodic structure of the intonational phrase preceding and following the pause, specifically whether or not the intonational phrase branches into smaller phrases. In order to minimize variability due to speech rate and individual differences, speakers read sentences synchronously in dyads (Cummins, 2002; Zvonik and Cummins, 2002). The results show that length has a significant effect on pause duration both pre- and postboundary for all dyads, and that prosodic complexity has a significant postboundary effect for some dyads. The possible reasons for the observed pause duration effects and the implications of these results on the question of incrementality in speech production are discussed. [Work supported by NIH DC03172.]
Prosodic effects on glide-vowel sequences in three Romance languages
Authors: Chitoran Ioana
Published: September 2013

Glide-vowel sequences occur in many Romance languages. In some they can vary in production, ranging from diphthongal pronunciation [ja,je] to hiatus [ia,ie]. According to native speakers’ impressionistic perceptions, Spanish and Romanian both exhibit this variation, but to different degrees. Spanish favors glide-vowel sequences, while Romanian favors hiatus, occasionally resulting in different pronunciations of the same items: Spanish (b[j]ela, ind[j]ana), Romanian (b[i]ela, ind[i]ana). The third language, French, has glide-vowel sequences consistently (b[j]elle). This study tests the effect of position in the word on the acoustic duration of the sequences. Shorter duration indicates diphthong production [jV], while longer duration, hiatus [iV]. Eleven speakers (4 Spanish, 4 Romanian, 3 French), were recorded. Spanish and Romanian showed a word position effect. Word-initial sequences were significantly longer than word-medial ones (p<0.001), consistent with native speakers more frequent description of hiatus word-initially than medially. The effect was not found in French (p>0.05). In the Spanish and Romanian sentences, V in the sequence bears pitch accent, but not in French. It is therefore possible that duration is sensitive not to the presence/absence of the word boundary, but to its position relative to pitch accent. The results suggest that the word position effect is crucially enhanced by pitch accent on V.