bluuebunny/crossref_metadata_2025 huggingface dataset:
A multi-channel audio system based on the theory of integral equations.
Authors: Fazi Filippo M. , Nelson Philip A.
Published: October 2013

The basics of a multi-channel audio system, which attempts the reproduction of a desired sound field, are presented. The system’s hardware consists of a three-dimensional array of loudspeakers, and can be used in combination with a specially designed microphone array. The mathematical fundamentals on which this technique is grounded consist of the formulation of the problems as an integral equation. The loudspeaker signals are determined from the knowledge of the target sound field on the boundary of a given control volume. The solution to this inverse problem is computed performing a singular value decomposition of the integral operator involved. For some simple array geometries it is possible to calculate an analytical solution to the problem. A regularization method is applied, as required by the ill-posed nature of the inverse problem under consideration. Some insight into the physical meaning of the ill-posedness is given and some analogies to near-field acoustic holography are suggested. The effectiveness of the method proposed has been verified experimentally and some of the experimental results are presented. Finally, it is shown how this technique has been successfully applied to the design of a multi-channel auralization system for room acoustics.
Results and insights from operational acoustic monitoring networks.
Authors: Clark Christopher W. , Ellison William T. , Southall Brandon L. , Frankel Adam , Ponirakis Dimitri , Tremblay Christopher , Warde Ann , Spaulding Eric
Published: October 2013

Data from two acoustic monitoring networks operating off New England in an area frequented by whales reveal acoustic features of those habitats. These seafloor and moored systems continuously sample the acoustic environment, and resultant data provide mechanisms for mapping, quantifying, and describing the spatio-spectral-temporal variability of the acoustic habitat over ecologically meaningful scales. By focusing on species-specific frequency bands used by fin, humpback, and right whales for long-range communication, we are beginning to measure the acoustic dynamics of their primary communication channels. Results reveal the extent to which different sources of sound in the ocean, both natural and man-made, influence the probability of whale communication. In some habitats with high rates of vessel traffic and high levels of vessel noise, the predicted area over which animals can communicate is reduced to a small proportion of what it would be under quiet conditions. The dynamics of this masking effect are highly variable and vary by species. When considered from a large-scale and behavioral ecological perspective, this reduction in acoustic habitat, as measured in terms of the proportional loss of communication space, likely represents a significant loss for species in which acoustic communication is known to serve critical biological functions.
Habitat use of beluga whales revealed by acoustic loggers.
Authors: Castellote Manuel , Tregenza Nick , Leeney Ruth , Esteban José Antonio , O’Corry-Crowe Gregory , Lucey Bill , Stafford Kathleen M. , Kovacs Kit M. , Lydersen Christian L. , Lauhakangas Rauno , Krasnova Vera , Chernetsky Anton , Agafonov Alexandr , Bel’kovich Vsevolod
Published: October 2013

The detection of odontocete echolocation signals with acoustic loggers has proved to be a very effective way to monitor their distribution, seasonal patterns and habitat use. However, belugas (Delphinapterus leucas) have never been monitored using this methodology. In order to evaluate its viability, echolocation signals of captive belugas were analyzed and the performance of T-POD (Chelonia Ltd., UK) acoustic loggers in captivity and in the Arctic environment was tested. Results from captivity demonstrated the potential of beluga remote monitoring by T-PODs. Field tests were organized in different environmental conditions with different populations of belugas to ensure the validity and detection robustness of this method. T-PODs were deployed in Svalbard (Norway) in Spring 2007, in Yakutat (Alaska) in Spring 2008, and in Solovetsky (Russia) in Summer 2008. Instruments were deployed concurrently with visual observations and hydrophone recordings to compare presence/absence data from the three different methods. Results proved that T-PODs positively detected all the identified periods of beluga presence without false detections and revealed temporal distribution correlations with tide levels, feeding behaviors, and circadian rhythms in the echolocation activity. Results from this project indicate that beluga remote monitoring is feasible in the Arctic environment using acoustic loggers.
Passive acoustical counting of odontocetes using towed and stationed platforms.
Authors: Akamatsu Tomonari , Wang Ding , Wang Kexiong , Li Songhai , Dong Shouyue , Kimura Satoko
Published: October 2013

Counting the number of animals is essential for monitoring and management of marine mammals. Autonomous stereo acoustic event recorder (A-tag) to identify each sound source enabled to count phonating odontocetes in the wild. Finless porpoises were surveyed by towed A-tags in 1100 km stretch of Yangtze River from Wuhan to Shanghai. The calculated detection probability using acoustic method was approximately twice that for visual detection. The difference in detection probabilities between the two methods was caused by the large number of single individuals that were missed by visual observers. However, acoustics tended to underestimate group size due to the limited resolution of sound source bearing angles. The detection performance regarding stationary acoustic monitoring of this species was also examined. Three stereo acoustic data loggers were placed at different locations near the confluence of Poyang Lake and the Yangtze River. Acoustic monitoring confirmed the low density bottle neck of the population between the lake and the river that was consistent with visual observations. The passive pulse event monitoring was proved to be a practical and useful alternative to visual observations, especially for long-term and range-wide monitoring.
A real-time detection system for odontocete echolocation clicks in the low-energy processing environment of an acoustic glider.
Authors: Klinck Holger , Mellinger David K.
Published: October 2013

This presentation will introduce a real-time system, the energy ratio mapping algorithm (ERMA), for detection of odontocete echolocation clicks. The system has been developed to run continuously over extended periods of time in low-energy processing environments such as acoustic gliders. The detector operates in the time domain and takes advantage of the species-specific differences in the power spectra and interclick interval of echolocation clicks to minimize the number of false positive detections. We will demonstrate the operation of ERMA using the clicks of beaked whales, family Ziphiidae, as example target species. To get information on the performance of ERMA, a comparison with more sophisticated and already established detection systems was conducted. Preliminary results indicate that the developed method is a promising tool to reliably detect echolocation clicks emitted by beaked whales in real time. On-going work is focused on implementation of the detector in the acoustic seaglider developed by the Applied Physics Laboratory of the University of Washington (APL-UW) and the use of this platform for autonomous passive acoustic monitoring and mitigation of beaked whales and other odontocete species.
Passive acoustic survey of bowhead whales in the Chukchi Sea.
Authors: Delarue Julien , Laurinolli Marjo , Martin Bruce
Published: October 2013

Western Arctic bowhead whales (Balaena mysticetus) transit through the Chukchi Sea in spring and fall during their seasonal migration between their winter grounds in the Bering Sea and their summer feeding grounds in the Beaufort Sea, where their presence is well documented. Comparatively little is known about their use of the Chukchi Sea in summer and winter. Here results are presented from a long-term passive acoustic monitoring program using a multi-recorder array deployed from late July 2007 through July 2008 in this area. Bowhead calls were recorded intermittently between August 2007 and January 1, 2008 and again from May 27, 2008 until the end of the study. Of particular interest is the detection of songs in late fall–early winter, which had previously only been recorded during the northward spring migration. They were compared to songs recorded off West Greenland during the previous mating season and found to be different. This is the first evidence of geographic variation of bowhead songs. Overall these detections provide new information on bowheads’ spatiotemporal use of the Chukchi Sea. The successes of the study also highlight the effectiveness of autonomous underwater acoustic recorders for marine mammal surveys in remote locations.
Atlantic herring low frequency target strength estimation from ocean acoustics wageguide remote sensing (OAWRS) data in the Gulf of Maine over 10 days of observation.
Authors: Tran Duong Duy , Gong Zheng , Srikanth Nikhila , Andrews Mark , Ratilal Purnima , Makris Nicholas
Published: October 2013

During the Gulf of Maine acoustic experiment in the fall of 2006, massive shoals of Atlantic herring were instantaneously imaged over wide areas using an ocean acoustics waveguide remote sensing (OAWRS) system during evening to midnight hours over a period of 10 days from Sept. 26 to Oct. 5. The low frequency target strength (TS) and abundances of the herring population have been estimated by correlating the OAWRS data with localized measurements from a conventional fish finding sonar (CFFS) for 3 days from Oct. 1–3 [Gong et al., J. Acoust. Soc. Am. 124, 2586 (2008)]. Here we provide an analysis of the low frequency TS of the herring population in the frequency range from 300 to 1500 Hz and abundances for the remaining 7 days of the experiment. The acoustic scattering from herring populations is highly frequency dependent and is well modeled using a resonant scattering model for swimbladder bearing fish. Here we compare the TS estimates and the neutral buoyancy depth for herring over the observation period of 10 days.
Broadband acoustic backscattering from live squid: Experiment and analysis.
Authors: Lee Wu-Jung , Stanton Timothy K. , Lavery Andone C.
Published: October 2013

Squid are important organisms both ecologically and commercially. Acoustic scattering techniques can provide synoptic data on their distribution and abundance, and have the advantage of being efficient compared with traditional net sampling methods. However, knowledge of the scattering properties of squid is required to accurately convert the acoustic data into meaningful biological information. To better understand the scattering of sound by squid, and to facilitate future model development, a controlled laboratory backscattering experiment was conducted on live squid (Loligo pealeii) using broadband linear chirp signals (45–105 kHz) with data collected over the full 360 deg of orientation in the lateral plane, in 1-deg increments. The scattered spectra often showed significant structure over the frequency band available at different angles of orientation, in addition to high levels of ping-to-ping variability. Pulse compression signal processing techniques were also used, revealing the following dominant scattering features: (1) at normal incidence, the front and back interface of the animal were resolved and (2) at off-normal incidence, the anatomical features in the head region were found to dominate the scattering. This information can serve as the basis for an accurate acoustic scattering model for squid.
Temporal patterns of fish and mesozooplankton near the Columbia River plume.
Authors: Kaltenberg Amanda M. , Benoit-Bird Kelly J. , Emmett Robert L.
Published: October 2013

The distribution of the dominant fish species in the California Current System is seasonal, with the timing and variability of these distributions having significant ecological consequences. The objective of this study was to observe the seasonal timing of fish school presence and to characterize the temporal patterns their abundance. Fish and mesozooplankton were observed near the Columbia River plume using 200-kHz bioacoustic moorings deployed throughout the transition period from winter conditions to summer upwelling conditions in 2008. Sea surface temperature, sea surface salinity, and ocean current data were used to characterize the oceanographic habitat. Acoustic mooring data revealed that the seasonal timing of schools of Pacific sardine and northern anchovy were linked with temperature and persisted after a rapid increase in temperature occurred near the end of May. The abundance of fish schools and mesozooplankton at two mooring stations was highly variable with dramatic fluctuations occurring over a period of hours to days that were linked with ocean conditions. The use of stationary acoustic moorings in this study provided an effective tool to monitor fish abundance at high temporal resolution and provides insight into the timing and variability of fish populations that will improve ecosystem-based management decisions.
Acoustic radiation force on a gas bubble in tissue.
Authors: Ilinskii Yurii A. , Zabolotskaya Evgenia A. , Hamilton Mark F.
Published: October 2013

The motion of a gas bubble subjected to acoustic excitation in a soft elastic medium such as tissue was analyzed previously assuming the radiation force acting on the bubble is the same as in liquid [Ilinskii et al., J. Acoust. Soc. Am. 117, 2338 (2005)]. In the present work we discuss corrections to the acoustic radiation force for finite values of the shear modulus. The analysis is based on the Piola-Kirchhoff equation in Lagrangian coordinates, in which only the stress tensor is nonlinear, and the equation is solved by perturbation. In the linear approximation an analytical solution is obtained for the scattered acoustic wave. The nonlinear stress and full radiation force is calculated at the next order of approximation. For negligible shear modulus the result for a liquid is recovered. For small but finite shear modulus the resulting force differs from that for a liquid by a factor that depends on ktR, where R is bubble radius, kt=ω/ct the wavenumber, ω the angular frequency, and ct the shear wave propagation speed. For ktR>10 the radiation force is practically the same as in liquid, but for ktR<10 its value can be significantly different. [Work supported by NIH DK070618.]
Optimization of ultrasound radiation force source for shear wave dispersion measurements.
Authors: Urban Matthew W. , Greenleaf James F.
Published: October 2013

The objective of this study was to analyze and optimize the ultrasound radiation force source for creating shear waves for quantitative elasticity and viscosity measurements. A simulation model based on work by Bercoff et al., [IEEE Trans. Ultrason. Ferroelectr. Freq. Contr. 51(11), 1523–34 (2004)] was utilized to examine the shear wave propagation from a spatiotemporal impulsive force and the simulated radiation force generated from a linear array transducer. Parameters such as aperture size, F-number of the transducer, and medium shear elasticity and viscosity were varied to analyze how the shear wave amplitude and shape changes. The wave attenuation and group and phase velocities were evaluated. The aperture size and the F-number of the transducer affected the spatial distribution of the propagating shear wave significantly. The influence of the coupling term between the bulk and shear waves was analyzed spatially and temporally by evaluating parameters such as shear wave amplitude, wave attenuation, and the group and phase velocities. This simulation model provides insight for making shear wave propagation measurements from the perspective of optimizing the spatial and temporal characteristics of induced shear wave motion from an applied radiation force. [This work was supported in part by Grant EB002167 from NIH.]
Acousto-magnetometry: A new vibrometery based on acoustic radiation force and magnetic measurement.
Authors: Carneiro Antonio Adilton O. , Baffa Oswaldo , Silva Glauber T. , Fatemi Mostafa
Published: October 2013

This work introduces a new method based on acoustic radiation force and magnetic measurement for interrogating the mechanical properties of fluid and biological tissues. In this method, ultrasound radiation is used to exert a low-frequency (in kHz range) force on a rigid magnetized target immersed in a viscoelastic medium. In response, the target vibrates in a pattern determined by viscoelastic properties of medium. We report the relation between the magnetic field signal and the incident ultrasonic pressure field in terms of the mechanical parameters of the medium. Simulations were conducted to demonstrate a simple approach based on using amplitude-modulated ultrasound to generate a dynamic acoustic radiation force on a magnetic target. The magnetic field generated by vibration of this target is then obtained and used to estimate the radiation-force-induced displacement as a function of time. It was observed that the intensity of the dynamic component of the magnetic field caused by the acoustic excitation is high enough to be registered by a conventional magnetic sensor. This proposed methodology presents a powerful tool for evaluation of acoustic radiation force as well as the mechanical properties of soft material.
Targeted ultrasound contrast agents for the imaging of biofilm infections.
Authors: Anastasiadis Pavlos , Mojica Kristina , Matter Michelle L. , Allen John S.
Published: October 2013

Targeted ultrasound contrast agents (UCA) offer a novel, potential method for diagnostic imaging of biofilm infections. Currently, there is no established method for molecular imaging of in vitro biofilm infections with any type of modality. For infective endocarditis, the case of biofilm formation on damaged or diseased heart valves, an early diagnostic method might greatly reduce the associated high mortality rate. Fluorescently labeled lectins were used with targeted ultrasound contrast agents in conjunction with epifluorescence microscopy and time-resolved scanning acoustic microscopy for visualization and characterization of the extracellular polymeric substances (EPS) of two types of infectious biofilms (Staphylococcus aureus and Pseudomonas aeruginosa). Noninvasive acoustic measurements of the biofilms were conducted at high-frequency (100 MHz) with a time-resolved scanning acoustic microscope. Measurements of the reflection and transmission coefficients, over a broad frequency spectrum for a range of biofilm growth stages in both, the presence and absence of targeted UCA were obtained. The biofilm morphology and structure were also investigated with acoustic microscopy as a function of growth. [This work was supported by the National Institutes of Health Grants NIH 2 P20 RR016453-05A1 and NIH 2 G12 RR0030161-21.]
On continuous-line acoustic array behavior in a laser Doppler sound pressure measurement system.
Authors: McBeth Michael S. , Hu Yongxiang
Published: October 2013

Continuous-line acoustic array behavior in a laser doppler anemometry (LDA) based sound pressure measurement system is considered. Traditional LDA ultrasound measurement systems intentionally minimize the laser beam intersection or interference fringe volume to better achieve point measurements of the sound field. The large laser beam diameters due to beam spreading in remote sensing applications from space or airborne platforms make this approach impractical. Since the sound pressure signal is integrated over the interference fringe volume, continuous-line acoustic array behavior is expected to be observed proportional to the length of the laser light path through the interference fringe volume. This behavior is analyzed from a theoretical perspective and an experimental setup to test for continuous-line acoustic array behavior in a LDA sound pressure measurement system is presented.
A laser-based method of detecting underwater sound through an ice layer.
Authors: Antonelli Lynn T. , Blackmon Fletcher A.
Published: October 2013

An aerial, remote sensor has been devised to detect underwater sound through an ice layer by optically measuring the resulting vibration velocity on the ice surface, using a laser Doppler vibrometer. The laser was focused on an ice block approximately 8 in. wide by 12 in. long and 3.5 in. thick floating in a tank of water 16 in. deep. A submerged transducer was used to generate underwater acoustic signals to provide ice surface vibrations for the sensor to detect. Although acoustic attenuation through the ice was not an issue for this test, laser alignment was crucial. Since sensor reliability depends on receiving laser reflections from the ice surface, the laser was steered nearly perpendicularly onto the ice surface that had both smooth and rough features. The broadband optical sensor provides a remote sensing capability for measuring ice surface vibrations in response to underwater acoustic signals such as from marine mammals, passive or active sonar, and from underwater acoustic communication systems. The results of this landmark experiment will be presented, which demonstrate the feasibility for detecting underwater sound through an ice layer by probing the ice surface with a laser vibrometer, paving the way for in-air sensing in arctic regions.
Laser nucleation of bubble clusters in a spherical resonator.
Authors: Anderson Phillip A. , Murray Todd W. , Holt R. Glynn
Published: October 2013

Due to the strong energy focusing found in sonoluminescence, there is much interest in high-energy bubble collapses. There is evidence in the literature that the collective collapse of a bubble cluster is more violent than a single bubble collapse under similar conditions. Precise control over the spatial and temporal placement of bubbles in an acoustic field would seem critical for achieving the strongest collapses, but nucleating bubbles acoustically is not precise or repeatable and does not allow for the creation of arrays of bubbles. A method is presented for creating two- and three-dimensional bubble arrays in a controllable way. A pulsed Nd:YAG laser is used with custom diffraction gratings and focusing optics to nucleate bubble arrays in a spherical resonator at high static pressure. A specific implementation will be presented, along with results addressing uniformity and repeatability. [Work supported by the US Army Space and Missile Command.]
Detecting cavitation in liquid mercury exposed to a high-energy pulsed proton beam.
Authors: Manzi Nicholas J. , Cleveland Robin O. , Holt R. Glynn , Roy Ronald A.
Published: October 2013

The Oak Ridge National Laboratory spallation neutron source (SNS) employs a high-energy proton beam incident on a liquid mercury target to generate short bursts of neutrons. Concomitant with neutron production is the rapid heating of the mercury, resulting in the formation of acoustic shock waves and the nucleation of cavitation bubbles. The subsequent collapse of these cavitation bubbles may result in the eventual erosion of the target’s steel walls. We report on preliminary measurements using two passive cavitation detectors (megahertz frequency focused and unfocused PZT transducers), installed in a mercury test target to monitor cavitation activity for proton beam energies ranging from 0.041 μC to 4.1 μC. Cavitation was initially detected for a beam “charge” of 0.205 μC by the presence of an acoustic emission approximately 120 μs after arrival of the incident beam, which is characteristic of inertial cavitation collapse. As beam energy was increased, the collapse time increased until the lifetime of the bubbles exceeded the reverberation time of the chamber (∼300 μs) at which point complex emissions signatures were detected due to the interaction of the reverberation signal and the cavitation bubbles.
Production of cavitation erosion damage by means of an electromagnetic shock wave source.
Authors: Wang Qi , Manzi Nicholas J. , Holt R. Glynn , Roy Ronald A. , Cleveland Robin O.
Published: October 2013

Central to a spallation neutron source (SNS) is a vessel of liquid mercury. During SNS operation acoustic pulses, with pressures in excess of 10 MPa, are generated in the mercury likely resulting in cavitation, which may erode the walls. We developed an electromagnetic shock wave source to generate similar pressures and cavitation. An electromagnetic source consists of a coil placed close to a metal plate, which is in contact with a fluid. The source is driven by discharging a capacitor through the coil, which results in a repulsive force on the plate launching acoustic waves in the fluid. A 75 mm diameter source coupled to water was fabricated, and the plate motion was measured by laser Doppler vibrometry and the acoustic field by a piezoelectric needle for different capacitance, charging voltage, number of coils, and plate properties. For a 2 μF capacitor charged to 12 kV and discharged through a 28-turn coil with a 0.8 mm thick aluminum plate (spherically focused) the peak pressure measured in water was 20 MPa. Cavitation clouds were produced over a wide range of voltages (imaged with 15 μs exposure) with lifetimes around 300 μs and produced erosion craters on a porous solid. [Work supported by ORNL-SNS, UT-Battelle, US-DOE Contract DE-AC05-00OR22725.]
Ultrasonic thermoacoustic prime movers.
Authors: Flitcroft Myra , Symko Orest G.
Published: October 2013

Thermoacoustic devices that generate sound with frequencies in the near ultrasonic range (∼21 kHz) have been developed. These devices consist of a wave resonator that is 4.1 mm in length, with hot and cold heat exchangers made of copper mesh placed at the resonator’s midpoint. Between these is sandwiched a stainless steel stack; the working fluid is air at 1 atmosphere. Heat is injected to the hot heat exchanger, creating a temperature gradient across the stack. When this exceeds a critical temperature gradient, acoustic oscillations ensue with intensities over 140 dB. The performance of a given engine depends drastically on the alignment achieved in the assembly process. Due to this variability, temperature differences at onset ranged from 85°C to 180°C. In order to increase positive feedback in the systems, single engines were coupled to a resonant cavity, the end of which was fitted with a pressure transducer. The use of a cavity also provides an acoustic coupling mechanism in which two ultrasonic engines can be attached to the same cavity, allowing for the investigation of synchronization of these devices in this regime. [Research supported by the U.S. Army Space and Missile Defense Command/U.S. Army Forces Strategic Command.]
A three-dimensional Wiener–Hopf technique for general bodies of revolution, Part I: Symmetrization and factorization of the integral equation’s kernel.
Authors: Martinez Rudolph , Ting Carina
Published: October 2013

This is the first of a two-part paper on the development of analytic solutions of acoustic scattering and/or radiation from arbitrary bodies of revolution under heavy fluid loading. The approach followed is the construction of a 3-D Wiener–Hopf technique with Fourier transforms that operate on the finite object’s arclength variable (the object’s practical finiteness comes about, in a Wiener–Hopf sense, by formally bringing to zero the radius of its semi-infinite generator curve for points beyond a prescribed station). Unlike in the classical case of a planar semi-infinite geometry, the kernel of the integral equation is nontranslational and therefore with independent wavenumber spectra for its receiver and source arclengths. The solution procedure applies a symmetrizing spatial operator that reconciles the regions of (+) and (−) analyticity of the kernel’s two-wavenumber transform with those of the virtual sources. The spatially symmetrized integral equation is of the Fredholm second kind and thus with a strong unit “diagonal”–a feature that makes possible the Wiener–Hopf factorization of its transcendental doubly transformed kernel via secondary spectral manipulations. The second of this two-part paper describes how the theory addresses departures from axisymmetry through substructuring techniques and demonstrates the analysis for canonical problems of fluid-structure interaction.
Eigenanalysis in structural acoustics.
Authors: Cipolla Jeffrey L.
Published: October 2013

Determination of characteristic frequencies and solutions (mode shapes) for vibrating systems is a staple of linear dynamics in engineering, so it should be no surprise that analysts strive for the same in coupled structural-acoustic systems. Computation of these eigensolutions confers not only physical insight into the behavior of the system, but also a means to reduce the mathematical dimension of frequency-response and other engineering computations. As in other mechanical vibration problems, the eigensolutions of coupled systems form a nearly optimal space for the approximation of the forced-response solutions. However, the coupled structural-acoustic eigenproblem is not trivial, and can be prohibitively expensive if not handled properly; this is particularly true for exterior problems. Notably, identification of a physically pertinent self-adjoint operator for the system of interest is a critical challenge. Here we will discuss the coupled structural-acoustic eigenproblem, various approximations common in practice, as well as alternative approaches to model reduction.
Sonic boom propagation into urban landscapes: Preliminary study.
Authors: Lefkowitz Kimberly , Sparrow Victor W.
Published: October 2013

In order to characterize the sonic boom response in the interiors of buildings in urban settings, first the loading forces impinging on such buildings must be understood. To do this in an urban setting, many factors must be taken into account including the shape and surface structure of the building of interest, the kind of boom being propagated, and the scale of the propagation space. Nearby buildings and their features also require consideration. In addition, the importance of specular reflection versus diffuse reflections should be addressed. In this study, these factors are discussed and evaluated relative to the impact on the overall sound field. Preliminary results on a simple case are presented. [Work supported by NASA.]
The effect of boundary recoverability on geminate length in English.
Authors: Oh Grace E. , Redford Melissa A.
Published: October 2013

[Payne (2005)] argues that fake geminates are longer than true geminates, and [Ridouane (2007)] shows that their preceding vowel duration is also significantly longer. These effects are likely due to the boundary that distinguishes fake from true geminates. If this is correct, then we might expect that boundary strength will also affect geminate realization. We investigated this possibility by comparing the absolute and relative durations of assimilated and concatenated word-internal and cross-word boundary fake geminates in English (e.g., immoral versus unnamed versus fun name). Eight speakers produced five repetitions of 32 stimuli (four types: three geminate, one singleton) in two speech styles. The results showed that although cross-boundary geminates were longer than word-internal concatenated and assimilated geminates in absolute terms, both types of concatenated geminates were shorter than assimilated geminates in relative terms. A follow up experiment, comparing geminates in compound words to those emerging across words showed no differences in relative duration between the two. These results suggest that boundary strength may be less important than boundary recoverability in production. Overall, we argue that boundary recoverability impacts the phonetic implementation of geminates and likely does so whether these are true or fake.
Articulatory comparison of Tamil liquids and stops using real-time magnetic resonance imaging.
Authors: Proctor Michael , Goldstein Louis , Byrd Dani , Bresch Erik , Narayanan Shri
Published: October 2013

It has been hypothesized that liquid consonants differ from stops in that they exhibit more global control over tongue shapes. This has been demonstrated by ongoing work showing greater vowel context effects in the production of stops than liquids in Spanish and Russian. Languages with rich inventories of coronal consonants, like Tamil, provide an interesting challenge for this view, as the presence of retroflex-dental contrasts among the stops may require substantial global tongue control, and therefore inhibit context effects. To test this, dynamic magnetic resonance imaging (MRI) was used to investigate the midsagittal production of Tamil liquids in intervocalic environments. MRI sequences were acquired at a frame rate of 22.4 Hz. The five liquids of Brahmin Tamil were elicited from three speakers in three different vowel contexts. Nasal stop consonants were also elicited at the same places of articulation to compare the influence of vocalic coarticulation on liquids and stops. Greater coarticulatory influences were observed during the production of nasals than during the production of liquids in the same vowel contexts, suggesting that the production of liquids involves a more active control of dorsal articulation than that used in the production of stops. [Work supported by NIH.]
Revisiting the role of the sublingual cavity in the /s/-/∫/ distinction.
Authors: Shadle Christine H. , Proctor Michael I. , Iskarous Khalil , Berezina Maria A.
Published: October 2013

The sublingual cavity (SC) has been shown to play an important role in shaping the spectra of consonants, potentially distinguishing /s/ from /∫/. This work reports on acoustic-articulatory experiments using MRI and mechanical modeling designed to investigate the details of how the SC acts as an acoustic filter and whether it also affects the aeroacoustic source in fricative production. Five American English subjects were imaged while producing fricatives in various vowel contexts. Two subjects that show opposite patterns were studied in detail. In M1, the /s/-/∫/ distinction is mainly carried by SC presence and lip protrusion in /∫/ versus absence in /s/, resulting in marked spectral differences. M2 exhibits significant variability in SC shape and size, and tongue and lip position, in both fricatives; the acoustic spectra likewise vary. Mechanical model experiments show that the noise generation changes as the sublingual cavity is filled in. The main resonance frequency does not necessarily change. It seems thus that the sublingual cavity is just one of many articulatory variables available to the speaker and may not be the principal cause of observed acoustic differences in all subjects. [Work supported by NIH NIDCD DC 006705 to Haskins, NIH NIDCD T32 DC00038 to MIT-SHBT.]
Acoustic cues to stop coda voicing contrasts in 1 to 2-year-olds’ American English.
Authors: Demuth Katherine , Shattuck-Hufnagel Stefanie , Song Jae Yung , Evans Karen , Kuhn Jeremy , Sinnott-Armstrong Miranda
Published: October 2013

One limitation in understanding the mechanisms underlying children’s variable productions has been the reliance on perception-based segmental transcription. This raises the possibility that children may make covert, acoustic distinctions that are not perceived by the transcriber. Shattuck-Hufnagel et al. [S. Shattuck-Hufnagel, K. Demuth, H. Hanson & S. Stevens, submitted] investigated this issue employing Stevens’ [K. N. Stevens, J. Acoust. Soc. Am. 111, 1872–1891 (2002)] feature-based acoustic model of perception/production. They found that 2,6–3,6-year-olds exhibited systematic acoustic cues to coda voicing contrasts (e.g., dog versus duck): voice-bar was more likely to precede voiced codas, whereas vowel glottalization was more likely to precede voiceless codas. The present study extended this investigation to velar codas in three 1,6–2,6-year-olds and their mothers, showing similar results: both exhibited more use of voice-bar before voiced compared to voiceless codas. For mothers, the duration of voice-bar was also longer for voiced codas, and children showed a trend in this direction. However, only mothers showed a significantly higher use of vowel glottalization before voiceless codas. Thus, although younger children also produce some acoustic cues to voicing distinctions, others take time to become adultlike. Physiological and environmental factors are discussed to explain these results. [Work supported by R01 HD057606.]
Segmentation of speech based on perceptual equivalence: Case of alveolar trill.
Authors: Stojanovic Diana
Published: October 2013

Turk et al. (2006) proposed a set of rules for segmentation in durational studies. R-sounds were not included in the recommended class due to their variable realizations. The authors suggested segmentation of tap variants was straightforward but that of approximants prohibitively difficult. In this paper, we discuss the issue of segmentation of the alveolar trill in Serbian. Three native speakers read a set of minimal pair phrases in which consonants /d/, /n/, and /r/ occurred intervocalically. Phrases were matched for the position and type of pitch-accent. The four-syllable phrases produced by each speaker were judged by the native listeners as being rhythmically equivalent. When /r/ is segmented to include only the closure, vowels matched for quality, position, and accent type are significantly longer before /r/ than before /d/ or /n/. The three consonants are all voiced thus compensatory lengthening is not likely to affect the length of the preceding vowel. Based on perceived rhythmic equivalence of the examined phrases, we formulate a segmentation rule that places the start of /r/ during the vocalic portion preceding the closure. This strategy equalizes measured durations of the preceding vowels and additionally enables us to treat /r/ equivalently in all environments.
Effect of tone on consonant + vowel interaction.
Authors: Agwuele Augustine
Published: October 2013

Examining consonant + vowel coarticulation for American English [Agwuele et al., 16th ICPhS, 1, 617–620 (2007) and Lindblom et al., J. Acoust. Soc. Am. 121, 3802–3813 (2007)], the effect of speech tempo and emphatic stress on F2onset and F2mid of the following vowel were quantified and dissociated from the underlying traditional coupling of consonant and vowel. Thus, these two prosodic factors were shown to pose additional confound to CV coarticulation. Adopting the approach of these works, this present study examines VCV sequences in Yoruba, a tonal language, in order to determine whether lexical tone produces as additional confounding effect to the interaction between consonant and tone bearing vowel that could be shown to be separate from the traditionally expected CV bonding. The study shows that the changing pattern of tone configuration in VCV sequences, e.g., from VMCVM [M=midtone] to VLCVL [L=low tone] produces differing consonant + vowel interaction. The study provides acoustic evidence for a possible independence of the “source” from the “filter,” i.e., the resonances of the vocal tract [Fant, G. Acoustic Theory of Speech Production (1960)].
Real-time MRI tracking of articulation during grammatical and ungrammatical pauses in speech.
Authors: Ramanarayanan Vikram , Bresch Erik , Byrd Dani , Goldstein Louis , Narayanan Shrikanth S.
Published: October 2013

Grammatical pauses in speech generally occur at a clause boundary, presumably due to parsing and planning; however, pausing can occur at grammatically inappropriate locations when planning, production, and/or lexical access processes are disrupted. Real-time MRI of spontaneous speech production (responses to queries like “tell me about your family,” etc.) was used for seven subjects to examine the articulatory manifestations of grammatical and ungrammatical pauses (manually classified as such by two experimenters depending on the presence/absence of a clausal juncture). Measures quantifying the speed of articulators were developed and applied during these pauses as well as their immediate neighborhoods. Results indicate a consistently higher articulatory speed and spatial range for grammatical compared to ungrammatical pauses, and an appreciable drop in speed for grammatical pauses relative to their neighborhoods, suggesting that higher-level cognitive mechanisms are at work in planning grammatical pauses. On the other hand, ungrammatical pauses show only a slight decrease in articulator speed at the pause but are followed by a spurt in speed immediately after, suggesting that the planning mechanism has been re-engaged only at that point, giving an indication of how much time it takes to “recover” from the perturbation of the linguistic structural integrity of the utterance. [Work supported by NIH.]
Prosodic planning: Local and distant effects of phrase length on pause duration.
Authors: Krivokapic Jelena
Published: October 2013

Prosodic boundaries, as manifested in pause duration, are known to be influenced by structural properties of the phrases immediately preceding and following the boundary, such as their syntactic structure, prosodic structure, and phonological length. Little is known, however, about how phrases at a distance from a boundary, i.e., not immediately preceding or following it, may affect the durational characteristics of pausing at that boundary. An experiment is presented that investigates the effects on pause duration of prosodic phrases of different length, both immediately at the boundary and farther away from it. The goal is to (a) examine local and distant effects of prosodic phrase length on pause duration and (b) to examine incrementality in production of prosodic structure, i.e., to examine how far ahead speakers plan an utterance, and how prosodic structure affects the planning process. Subjects read 24 English sentences varying along the following parameters: (a) length in syllables (two or four syllables) of the intonational phrase immediately following a target pause and (b) length in syllables of the second, distant, intonational phrase following the pause (10 or 16 syllables long). The synchronous speech paradigm [F. Cummins (2002); E. Zvonik, F. Cummins (2002)] was used to minimize variability in production.
Formant frequency development and gender differences in Mandarin-learning children before 5 years of age: A longitudinal analysis.
Authors: Chen Li-mei
Published: October 2013

This study is designed to investigate the longitudinal developmental process of vocalic production in Mandarin-learning children from birth. This current study focuses on the fifth year and the continuity in the process. Major findings are: (1) From three years and six months, the boy subject showed lower vowel formant values, reflecting gender differences in the development of vocal tract. In addition to three years and six months, there was another stage of decrease of frequency at four years and six months in the boy subject. The trend was especially evident in F2 values. (2) The girl subject used more high front rounded vowels /y/, which is the only late-acquired single vowel. (3) Corner vowels /i, u/ were used more often by the girl subject. (4) Diphthongs continued to show high frequency of occurrence at this stage. (5) The frequency of vowels with nasal endings showed prominent increase at this stage in both genders. However, the girl subject showed more preference in using this vowel category as was found in a previous stage. Gender differences in vowel development found in this stage can be traced in the following longitudinal observation. [This investigation was supported through funds from National Science Council in Taiwan, Republic of China (NSC 96-2411-H-006 -023).]
Variation in the phonetic realization of Thai lexical tones across speaking styles.
Authors: Laphasradakul Donruethai , Wayland Ratree
Published: October 2013

Thai is a tonal language with five contrastive tones: mid-falling, low-falling, high-falling, high-rising, and low falling-rising. Previous literature has shown that the acoustic realization of Thai lexical tones, namely their fundamental frequency or F0, is affected by the phonetic contexts in which they are produced. For example, in connected, conversational speech, Zsiga [(2006)] found that F0 contours of Thai tones produced in phrase-final position are different from those produced in non-phrase-final position. Context-dependent variation in F0 contours among lexical tones in Thai was also noted in Luksaneeyanavin [(1983)]. The main aim of this research was to further investigate F0 variations across the five lexical tones in Thai. Ten native Thai speakers (5 males and 5 female) were asked to produce Thai words in two speaking styles: slow, careful reading style; and fast, conversational style. Preliminary analyses revealed that: (1) the high-falling tone exhibited the highest degree of variation; (2) a greater amount of variation was observed among female speakers than among male speakers; and finally (3) a greater amount of variation was observed in open syllables than in closed syllables.
Sexuality and personality: The effect of pitch height and contour width on perception in Japanese.
Authors: Camp Margaret
Published: October 2013

This work investigates how Japanese listeners judge a speaker’s personality characteristics and sexual orientation. Base sentences, produced in Japanese by a male and a female native Japanese speaker, were resynthesized to manipulate specific acoustic characteristics believed to influence perceived sexual orientation or personality. Overall, the higher the fundamental frequency (f0) of the female voice, the less likely it was to be perceived as lesbian. Similarly, the flatter the intonation pattern of the female voice, the more likely it was to be viewed as lesbian. For male voices, the higher the f0, the more likely the voice would be perceived as gay. Pitch variability did not play a significant role in this perception. Finally, out of the four personality scales investigated, two showed a significant correlation to lesbian voices: masculinity and calmness. Male voices showed the same pattern, with gay voices correlating with femininity and emotionality. The influence of the sex of the listener was also investigated, but male and female listeners appear to make similar judgments about most, but not all, characteristics.
Parametrization of f0 characteristics of register (“Shiki”) in mid-western Japanese dialects.
Authors: Yoshida Kenji
Published: October 2013

Although the ToBI framework has achieved great success in modeling intonation in various languages, it may not capture the nature of certain aspects of f0 movements. This study models dynamic aspects of f0 movement in “pitch register” contrasts observed in mid-western Japanese dialects, called “Shiki” by Japanese dialectologists. An exponential function [f0 = intercept + b × time × exp(− c × time)] was fitted to the observed f0 movement of speakers of two Japanese dialects with Shiki contrasts (Kan’onji and Kishiwada). The results show that the two contrastive Shiki types are clearly discriminated in the 3-D parameter space [intercept = baseline, b = magnitude of f0-excursion, c = inverse of peak timing]. Further analysis revealed that the two contrastive Shiki types are not reliably differentiated by the baseline. The more reliable predictors of Shiki types are the other two parameters that determine f0 movement within a word. The results are more congenial to a “dynamic” definition of Shiki system by Japanese dialectologists [e.g., Uwano, (1988)] and suggests that the analysis of Shiki as an initial f0 target [(High vs. Low, Pierrehumbert Beckman, 1988 for Osaka dialect] should be reconsidered.