bluuebunny/crossref_metadata_2025 huggingface dataset:
Frequency and intensity difference limens in mice
Authors: Toal Katrina , Radziwon Kelly E. , Dent Micheal L.
Published: May 2014

The ability to distinguish between different frequencies and intensities is a fundamental auditory process, yet it has not been explored in CBA/CaJ mice. Previous researchers have used behavioral approaches to examine frequency and intensity discrimination abilities of the NMRI mouse, feral house mice, and other strains of mice with known hearing impairments. The present experiments use operant conditioning procedures to investigate the basic hearing abilities of the normal-hearing CBA/CaJ mouse. Intensity difference limens (IDLs) were obtained for six subjects and frequency difference limens (FDLs) were obtained for three subjects. For both experiments, the Method of Constant Stimuli and a threshold d' of 1.5 were used. IDLs and FDLs were obtained for 12, 16, 24, and 42 kHz tones. FDLs were obtained at 10 dB SL and 30 dB SL whereas the background for the IDL task was only 10 dB SL. At higher frequencies, the calculated FDLs increased. Furthermore, the thresholds were higher when sounds were presented at 30 dB SL compared to 10 dB SL. In the FDL experiment, the mice had a mean just-noticeable-difference of 3.5% Weber fraction across all four frequencies and sound levels. Interestingly, IDLs were similar across all frequencies.
Enhance beam formation by airsacs and skull in Chinese river dolphin (Lipotes vexillifer)
Authors: Wei Chong , Au Whitlow , Song Zhongchang , Zhang Yu
Published: May 2014

The melon of dolphins is considered by many as the structure responsible for the focusing of the biosonar beam. However, finite element numerical simulation of the head of the Chinese river dolphin (Lipotes vexillifer) indicates that the biosonar beam is formed by reflections off the airsacs and bony structures in the skull. The finite element approach was applied to numerically simulate the acoustic propagation through dolphin's head in four several situations (complete head, skull only, skull plus melon, and skull plus airsacs). The acoustic intensity distribution and the corresponding polar plots showed that the melon causes the beam to narrow slightly and affects the angle of the main beam. The airsacs kept the sound propagating to the anterior and focused the energy into the main lobe. The bony structure prevented the sound from propagating below the rostrum and contribute to energy in the main beam. The results suggest that the airsacs and the complex bony structure play a dominant role in the formation of the biosonar beam of a dolphin, more so than the melon.
Biofilm mitigation by ultrasound-assisted liposome treatment applied to a national aeronautics and space administration project
Authors: Wu Junru , Ma Dong , Willsey Graham , Wargo Matthew
Published: May 2014

Space exploration requires an effective means of biofilm control for water reclamation systems that minimizes use of non-recyclable chemicals (such as iodine and antibiotics) and does not contaminate water in the water treatment system. Uncontrolled biofilm growth due to ineffective mitigation has been the cause of water reclamation system failures both on the Russian Mir Space Station and on the International Space Station, as well as corrosion problems in thermal systems. The challenge of biofilm migration mainly comes from: its matrix of extracellular polymeric substances, in which biofilm organisms embed themselves, inhabiting bacterium in biofilm treated by chemical and mechanical stresses. The goal of the project is to develop a new biofilm mitigation approach using targeted liposomes, which encapsulate an anti-microbial chemical agent, assisted by ultrasound to enhance mixing and attachment rate of the liposomes to the bacterial colonies within the biofilm. In this presentation, we will present some preliminary results of enhancement of penetration of liposomes of nanometer scales into biofilms using mild nonfocused ultrasound. (The spatial average-temporal average power and intensity are 15.1 W and 2.99 W/cm2, respectively, duty cycle = 50%.)
Acoustic power delivery for sub-millimeter dimension and deeply implanted medical devices
Authors: Weber Marcus J. , Charthad Jayant , Chang Ting Chia , Arbabian Amin
Published: May 2014

We propose to use acoustic power delivery for sub-mm3medical implants, and we have designed acoustic receivers for investigating this technique of wireless power transmission. Compared with radio frequency and inductive transfer, acoustic power transfer gives more favorable impedance and available power for miniaturized and deeply implanted medical devices. Sub-mm3dimensions are attractive for many different medical applications; however, there is little literature describing the properties or capabilities of miniaturized acoustic receivers, which is the topic of our investigation. Design of efficient miniaturized implants is challenging because of increased losses due to tissue absorption and coupling to parasitic resonant modes. We will present power transfer and impedance measurements of volumetrically scaled acoustic transducers through several thicknesses of tissue. Our measurements show significant available power with high output voltage, resulting from large transducer impedance, which is useful for overcoming threshold voltages of rectifier circuits. Preliminary measurements show the delivery of 340 μW of average AC power to a 1 mm2 receiver through 3 cm of tissue with an intensity well below the FDA limit. In addition, we will compare our measurements with piezoelectric theory and discuss trends and limits of available power and impedance as a function of volume and transmit distance.
Measurement of ultrasonic tissue characteristics of malignant colon cancer cells
Authors: Möller Guðfríður Björg , Mendiola Madilena , Daniels Aislinn , Johnson Dalton , Kyvelou-Kokkaliaris Rodoula , Watkins Kenzi , Herd Maria-Teresa
Published: May 2014

Colon cancer is the third most common cause of death by cancer resulting in over 50 000 deaths a year. The most common method for the detection of colon cancer, a colonoscopy, is quite invasive, and although non-invasive methods are available, they have not proven to be as effective. There have been successful studies on using ultrasound as a diagnostic tool for colon disease in rats. This suggests that ultrasound may be able to be a viable clinical tool for detecting colon cancer and gastrointestinal disease. Here, we explore using quantitative ultrasound to differentiate between benign and malignant colon cells. We made measurements of tissue characteristics of malignant colon cell pellets at different cellular densities. Using ultrasound frequencies ranging from 5 to 20 MHz, we measured the speed of sound, attenuation, and the backscatter coefficients (BSCs). Here, we present the results for the ultrasonic properties of cancerous colon cells and compare these for different densities of the cells.
Criteria for the acoustic environment—What should we do?
Authors: Schomer Paul D.
Published: May 2014

The questions are many; the answers I have are few, so I may call upon attendees of this session for help. Who should create policy for the acoustic environment? The F AA(aviation)? FHW A(roads)? DOE(energy)? DOD(defense)? or EPA? or DOI(interior/Park Service)? For example, it has been estimated that about 20 to 30% of the population are noise sensitive? Should policy be based on this minority or on the less sensitive majority? Currently, FAA and DOD allege that their criterion, DNL equal to 65 dB results in about 10 percent highly annoyed; the real percentage is 20 to 30%, so their criterion “protects” only the less sensitive. In a National Park, we are finding that hikers on a moderate length hike (about 4 to 10 km; 2 to 5 h) judge the pleasantness of the acoustic environment during the entire hike largely on the presence or absence of anthropogenic sound. Again there are factions to consider. Roughly 1/3 rate the overall pleasantness on the most pleasant portion of the hike, 1/6 rate on the least pleasant (most unpleasant), 1/6 on the average, and 1/3 on the most recent. What do we do? What should ASA do? Standards? WHY?
Future directions in psychoacoustic research facilities
Authors: Gordon Samuel , Ellingson Roger , Browning David , Janisch Raymond , Gallun Frederick
Published: May 2014

The future of psychoacoustic research will involve the measurement of individual differences from a broader range of participants including those with physical disabilities. Auditory testing of physically disabled research participants in a fully anechoic environment presents challenges to the people being tested, to the research team, and to the facility. At foremost concern are the risks of personal injury to physically disabled persons while moving them into, and out from, the testing position in the anechoic chamber. Additional risks of injury exist to the researchers who assist with moving subjects into and out of the chamber. These risks need to be mitigated without compromising the acoustical performance of the anechoic chamber. This paper presents the requirements and the implemented design solutions for an ‘Americans with Disabilities Act of 1990' compliant anechoic chamber that is currently being used for auditory research at the Department of Veterans Affairs, National Center for Rehabilitative Auditory Research facility in Portland, Oregon. We advocate that others consider accessibility and safety issues in the development of future psychoacoustic research facilities as we believe such factors are essential to the future of human testing and physical sciences.
Public complaints about wind turbine noise and adverse health impacts justified
Authors: Ambrose Stephen E. , Rand Robert W. , James Richard R. , Nissenbaum Michael A.
Published: May 2014

Significant proportions of IWT facility neighbors complain about turbine noise and sleep disturbances, among other adverse health complaints. We undertook an independent evaluation of several wind turbine projects located in Maine, Massachusetts, Vermont, New York, Illinois, Michigan, West Virginia, and Wisconsin to assess if common etiological factors exist. Adverse effects appear to relate to a basket of common factors that were overlooked or not included in preconstruction planning including noise predictions and assessments of likely community reactions. Correcting oversights in future projects should result in quieter IWT projects with reduced or no adverse community reactions. A unified methodology for doing so, enabling wind turbine developers, governmental agencies, municipal boards, and private citizens to assess for potential adverse noise impacts during the permitting phase is presented. Our results are consistent with prior USEPA studies, WHO assessments, and Pedersen and Waye research, among others.
Examination of the predictions versus measurements of an acoustic interaction model for spinning modes, and concurrent low frequency amplitude modulation acoustic signatures from a 3MW wind turbine
Authors: Dooley Kevin A. , Hansen Kristy , Zajamsek Branko
Published: May 2014

A recently presented hypothesis and model relating to the generation of spinning modes from wind turbines, as a direct result of acoustic interaction involving the tower, results in a far field infrasound sound pressure level prediction, which is higher than that predicted by point source method. The model also predicts a significant attenuation of the fundamental blade passing frequency component relative to the second and higher harmonics. The model concurrently predicts a low frequency (~20 Hz), amplitude modulated harmonic series as a side effect of the acoustic interaction on a 1.6 MW 80 m diameter wind turbine. This study examines the model predictions of a 3.0 MW 90 m diameter wind turbine, and compares the predictions to measurements of the low frequency harmonic series and blade passing frequency harmonics at several different distances from the wind turbine.
A comprehensive water tunnel test of a horizontal axis marine hydrokinetic turbine for model validation and verification
Authors: Fontaine Arnie A. , Bagwell Ted G. , Johnson Michael L. , Capone Dean
Published: May 2014

As interest in waterpower technologies has increased over the last few years, there has been a growing need for a public database of measured data for these devices. This would provide a basic understanding of the technology and means to validate analytic and numerical models. Through collaboration between Sandia National Laboratories, Penn State University Applied Research Laboratory, and University of California, Davis, a new marine hydrokinetic turbine rotor was designed, fabricated at 1:8.7-scale, and experimentally tested to provide an open platform and dataset for further study and development. The water tunnel test of this three-bladed, horizontal-axis rotor recorded power production, blade loading, near-wake characterization, cavitation effects, and noise generation. Additionally, preliminary comparisons are mode from unsteady CFD for the flow fields measured.
Characterization of noise from an isolated intermediate-sized wind turbine
Authors: Piacsek Andrew A.
Published: May 2014

Community-based wind power companies provide subscriptions to individual homeowners and businesses for power generated by a locally installed turbine. Typically, such turbines are of an intermediate size, such as the Vestas V20 120-kW turbines operated by the Cascade Community Wind Company in several locations within Washington state. This model turbine has a tower height of 80 feet with a rotor diameter of 60 ft. Each turbine is installed individually on leased land, with no other turbines nearby. Noise measurements of a turbine located in Thorp, WA, were obtained in a variety of weather conditions. On several occasions with low to moderate wind speeds, the turbine was stopped, enabling the calculation of noise due to the turbine only. Results will be presented showing spectral content and sound pressure level contours for a range of wind speeds.
Materials and fabrication techniques for resonant ultrasound spectroscopy at high and low temperatures
Authors: Migliori Albert
Published: May 2014

Measurement of the mechanical resonances of materials of interest to condensed matter science is becoming increasingly common because it reveals important thermodynamic signatures such as phase transitions, as well as providing sound speeds and stiffness information for technology. Often done using Resonant Ultrasound Spectroscopy, the ultimate precision of measurements is determined by the mechanical Q, not unusually 104 or higher, thereby making it possible to determine changes in elastic moduli at the sub pert-per-million level. However, resonances and changes in the acoustic response of the cell that holds transducers and the specimen to be measured can introduce artifacts as temperatures change, clouding otherwise important observations. We describe here solutions to such problems with acoustically “dead” materials capable of operation from below 1 K to 900 K using easily available starting components. We also describe strategies for electrical contacts at temperature above the melting point of lead-tin solder. Some unusual results are presented.
Nuclear material identification using resonant ultrasound spectroscopy
Authors: Pantea Cristian , Saleh Tarik A. , Migliori Albert , Betts Jonathan B. , Luther Erik P. , Byler Darrin B.
Published: May 2014

Resonant ultrasound spectroscopy (RUS) is a well-established method for determination of the full tensor of elastic moduli of a solid sample in a single frequency sweep. The elastic moduli, together with density, can provide information related to materials fabrication processes, providing a unique signature, or fingerprint, of a material. The goal of this study was to provide forensics for nuclear materials in solid ceramic or metallic form, including composition. The premise of this study was that it is really difficult to find two materials whose density and shear and /or bulk modulus match. We used RUS to determine the bulk and shear modulus for a total of 27 samples. The samples consisted of depleted uranium oxide (MOX) with different doping of Ce, Pu, and Nd oxides, and different methods of fabrication. They were in form of cylinders with flat and parallel faces. Two-dimensional and three-dimensional spaces were investigated, using shear modulus, bulk modulus, and density as variables. The densities varied between 9.0 and 10.6 g/cc, while the shear modulus was 55–80 GPa, with a bulk modulus of 150–240 GPa. The results obtained suggest that there is a good correlation between the elastic moduli and density for samples of different compositions/origins.
Identification of conductive hearing loss in infants using maximum likelihood analysis of wideband acoustic absorbance and admittance
Authors: Prieve Beth , AlMakadma Hammam
Published: May 2014

Wideband acoustic absorbance (WAA)/reflectance measures of the middle ear identify conductive hearing loss (CHL) in infants and children with excellent accuracy. Recent literature has indicated that WAA analyzed using maximum likelihood ratios in children with conductive hearing loss were more accurate than the clinical standard of single-frequency tympanometry at one frequency. In infants, single-frequency tympanometry is as effective in identifying conductive hearing loss as wideband acoustic reflectance in one frequency band. The question that arises is whether identification of conductive hearing loss in infants is different than that from children, or, if multiple variable analysis of WAA contributes to the highly significant outcomes. The current project used maximum likelihood ratios to analyze both WAA and admittance measured through tympanometry using three probe tone frequencies. WAA and tympanometry identified CHL equally well in infants, and WAA results are similar to those reported for children. The results suggest that including several frequencies to measure conductive properties of the outer and middle ear is more powerful than single frequencies or bands.
Development of a finite element model for normal and pathological middle ears: Impedance, reflectance, and sweep frequency impedance
Authors: Puria Sunil , Cai Hongxue , Hamanishi Shinji , O'Connor Kevin N. , Steele Charles
Published: May 2014

A 3D ‘virtual middle ear model' using finite-element modeling techniques was developed to simulate the dynamics of the human middle ear. COMSOLMultiphysics software was used to solve the resulting acoustics-structure interaction problem. The model is validated by comparing numerical results with experimental data measured in the ear canal (EC), on the tympanic membrane (TM), umbo, stapes footplate, and cochlear pressure. The model consists of anatomy from μCT imaging and material parameters from the literature (Cai et al., PLOS One, in review). The EC impedance Zec, reflectance Rec, and the pressure Pec due to a constant displacement Dec (Wada et al., 1998) were calculated for the normal middle ear, with the stapes blocked, and with the stapes disarticulated. The results in this virtual model are consistent with experiments performed in both cadaveric and living ears. The model is used to analyze the sensitivity and specificity of Zec, Rec, and Pec due to variations in the material properties of the middle ear including the TM, ossicles, malleus-incus, and incus-stapes joints, and the footplate. [Work supported in part by grant R01-DC05960 from the NIDCD of NIH and by a Fellowship from the Institute of National Colleges of Technology, Japan.]
Effects of cognitive load on selective and divided auditory spatial attention
Authors: McCloy Daniel , Lee Adrian KC
Published: May 2014

In a previous experiment [McCloy and Lee, 2013, J. Acoust. Soc. Am. 134, 4230 (2013)], we reported an asymmetry between phonetic and semantic detection tasks with respect to spatially separated vs. spatially adjacent attended word streams: phonetic tasks showed high false alarm rates when to-be-attended streams were spatially divided, while semantic tasks did not. In this experiment, we manipulate the difficulty of the semantic task to investigate the effect of cognitive load on task performance. We compare trials in which the two to-be-attended streams comprise words drawn from either one or two semantic categories, and from categories with either a small or large number of words. Effects of these manipulations on target hit rate and false alarm rate are discussed in relation to previous work.
Extent of lateralization caused by interaural time differences of high-frequency click-trains
Authors: Baumgaertel Regina M. , Dietz Mathias
Published: May 2014

Hafter and Dye [J. Acoust. Soc. Am. 73, 644 (1983)] measured threshold interaural time differences (ITDs) for high-frequency click-trains. They found that, given a fixed duration, threshold ITDs were better (lower) for lower pulse rates. Studies by other authors measured lateralization for broad band click-trains and were generally not focused on how the low-frequency fine-structure ITD may influence the results. Such an influence may become prominent at ITDs > 600 μs when fine-structure ITDs alone are subject to a cue reversal. The current study therefore focused on high-frequency click-trains and a broad range of ITDs (up to at least 2 ms). The extent of lateralization elicited by these click-trains was determined using an acoustic pointer procedure. Interclick intervals of 5, 10, 20, and 50 ms were investigated. Subjects show an increase in lateralization with increasing ITD even when exceeding the physiologically plausible range of 600 μs. Inter-click intervals of 5 ms generally cause the lowest extent of lateralization, in line with the threshold ITD data. The results will be discussed in the light of spatial cue enhancement for cochlear implants, assuming a similar extent of lateralization for interaural pulse time differences at low pulse rates.
Mapping spatial release from informational masking with one or two masker talkers
Authors: Thompson Eric R. , Iyer Nandini , Romigh Griffin D. , Simpson Brian D.
Published: May 2014

Spatially separating a target talker from a colocated masker can improve intelligibility, an effect referred to as spatial release from masking (SRM). In this study, listeners' ability to identify speech was measured using the Coordinate Response Measure (CRM) corpus with one or two same-sex CRM maskers as a function of the position of the maskers and the target-to-masker ratio. The target and maskers were each filtered into non-overlapping bands to reduce energetic masking. The target was always straight ahead of the listener, and the masker(s) were presented on the horizontal plane at positions from −90° to + 90° in azimuth using individualized head-related transfer functions (HRTF). Consistent with prior results, performance is worst when the target and masker(s) are colocated and improves as the distance between target and maskers increases. Also, performance is better when the two maskers are colocated with each other than when they are separated, and is better when the two maskers are both on the same side of the target than when one masker is on each side of the target. The data suggest spatial filtering strategies that listeners may adopt to improve performance in multitalker scenarios.
How high frequency envelopes influence spatial localization in rooms
Authors: Masud Salwa , Bharadwaj Hari , Shinn-Cunningham Barbara
Published: May 2014

Perception of sound laterality (left-right angle) is mediated by both interaural time differences (ITD) and interaural level differences (ILD). Previous localization studies in anechoic settings consistently show that low-frequency ITDs dominate perception of source laterality. However, reverberant energy differentially degrades ITDs and ILDs; the effects of room reflections on the perceptual weight given to ITDs and ILDs are not well understood. Here, we tested the hypothesis that high-frequency envelope ITD cues are important for spatial judgments in reverberant rooms by measuring the perceived laterality of high-pass, low-pass and broadband sounds. Results show that when ILD cues and ITD envelope cues are both available, reverberant energy has the smallest effect on localization of high-pass stimuli. When ILD cues are set to zero, localization of high-pass stimuli with strong envelopes (i.e., click trains and speech tokens) is also minimally affected by reverberant energy; however, as envelope modulation is reduced, subjects show increasing localization bias, responding towards the center. Moreover, for stimuli with strong envelopes, subjects with better modulation detection sensitivity are affected less by the addition of reverberant energy. These results suggest that, in contrast to in anechoic space, high-frequency envelope ITD cues influence localization in reverberant settings.
The role of interaural level differences in the localization of low-frequency sine tones
Authors: Rakerd Brad , Crawford Zane D. , Hartmann William M.
Published: May 2014

Five human listeners reported the azimuthal locations of low-frequency sine tones presented in free field, either by a 180-degree loudspeaker array or by virtual reality. The virtual sources were synthesized using cross-talk cancellation based on signals continuously monitored in the listener's ear canals. The experiment tested the duplex model of sound localization, especially the role of interaural level differences (fixed ILD = 0, 6, or 12 dB) for frequencies of 750 Hz or less. Trials with real sources, baseline virtual sources, and virtual sources with manipulated ILDs were always combined in all experiments. Experiments showed that the interaural time differences (ITD) dominated most fixed opposing ILDs, as previously reported, only when interaural phase differences (IPD) were less than 90 degrees. When IPDs exceeded 90 degrees, the ITD lost its influence, and localization was dominated by ILDs. Localization judgments never followed IPDs across a 180-degree boundary, except when a zeroed ILD caused judgments to become chaotic. Within the 90-degree IPD limit, judgments for fixed ILD appeared to follow the ITD better than the IPD. Abnormal interaural conditions (e.g., ITDs and ILDs of opposite sign) led to a notable increase in front-back confusions. [Work supported by AFOSR grant FA9550-11-1-0101.]
The effect of masker spatial uncertainty on sound localization
Authors: Simpson Brian , Gilkey Robert , Iyer Nandini , Thompson Eric , Romigh Griffin , Brungart Douglas
Published: May 2014

Previous research from our laboratory has shown that uncertainty about the spatial location of a masking sound (randomly selected from 1 of 239 locations) can dramatically reduce localization accuracy for a simultaneous target relative to the case in which the masker location is known exactly. One possibility is that knowing the masker location enables the listener to establish a spatial attention filter at that location to suppress the masker and better localize the target. In this experiment, the level of masker spatial uncertainty was systematically varied across blocks by varying the number of possible masker locations (1, 2, 4, 8, or 239) and informing subjects about these possible locations prior to the start of each block. Localization errors were found to increase systematically in the left/right, front/back, and up/down dimensions as the number of potential masker locations increased; this effect was most prominent in the left/right dimension, where localization errors increased by nearly 30 degrees across conditions. Moreover, for a masker in a given location, errors generally increased across these levels of masker spatial uncertainty, consistent with the notion that there is a cost to distributing attention across multiple locations.
The lowest signal-to-noise ratio at which the precedence effect operates for signals in noise
Authors: Guy Fiona , Akeroyd Michael
Published: May 2014

The precedence effect is a robust auditory phenomenon which aids localization of sound in a reverberant room. Its primary characteristic is that the perceived location of the sound is based on the first arriving, direct, sound, with subsequent reflections mostly ignored. Most research into the precedence effect uses stimuli presented in quiet. Here, we used signals in noise, and considered what is the lowest signal-to-noise ratio (SNR) at which the precedence effect remains operative. In our experiment, the stimuli were speech or click trains, presented as direct + reflection pairs over headphones. Crucially, the ITDs of the stimuli set were such that, when presented alone, the direct signal was lateralized to one side of the head but the reflection to the other. A two-interval, two-alternative, lateralization task was used to measure performance. If the reflection was truly ignored, then the perceived lateralization of the direct + reflection pair would give the correct answer to a trial, but if the reflection was not ignored, then the perception would give the wrong answer. The task is SNR dependent, allowing a “precedence threshold” to be measured using an adaptive procedure that varied the SNR of the direct + reflection pair in noise. We report results from both normal and hearing-impaired listeners. [Work supported by the Medical Research Council and the Chief Scientist Office, Scotland.]
Murray Strasberg—A lifetime dedicated to the Acoustical Society of America
Authors: Schmid Charles E. , Moran Elaine
Published: May 2014

Murray Strasberg received the Gold Medal in 2000 “for contributions to hydroacoustics, acoustic cavitation and cavitation noise, and for dedicated service to the Society” when he was 83 years old. He should have received it much earlier, but the classified nature of his work prevented the preparation of a complete nomination dossier. In addition, most members did not fully realize how much Murray did for the Society as his contributions were spread over a half-century. While serving as President (1974–1975), the Society was faced a critical emergency when Wallace Waterfall, the Society's mainstay and current treasurer passed away. Murray stepped in and worked with others to handle the financial operations of the Society until a new Treasurer was selected. He also served in many other Society roles including Associate Editor of JASA, chair of the committee that set the groundwork for the Congressional Science and Engineering Fellowship Program, and as Secretary from 1987 to 1990. We will share some personal stories about Murray recalled from the many decades working with him as a colleague and wise counsel.
Mass sensing using the time domain response of a functionalized microresonator array
Authors: Glean Aldo A. , Vignola Joseph F. , Judge John A. , Ryan Teresa J.
Published: May 2014

Energy flow between size scales in vibrating structures can be used for mass detection. This work considers structures composed of a larger scale primary resonator (transduction element) and a set of substantially smaller attached resonators (sensing elements). Functionalization of the sensing elements in the downscale realm allows for detection of specific chemical vapors, biological agents, etc. Common approaches for this type of mass detection involve monitoring a structure's frequency domain response for downward shifts in resonance frequencies as mass binds to the sensing elements, or inferring mass changes from shifts in response shapes of the sensing elements. Instead of using frequency domain information, this work describes a detection method based on observing time histories of the energy exchange between the transduction and sensing elements. The energy initially introduced to the system at the transduction element is drawn into the sensing elements. Some energy will return upscale at a later time that depends on the system characteristics. This work demonstrates that by functionalizing every second sensing element, the concentration of adhered mass can be related to the profile of energy returned to the transduction element. Sensor limitations and optimized designs based on measurement noise and fabrication tolerances are also reported.
The phonetic status of [æ] in Twi: A reanalysis
Authors: Lomotey Charlotte F.
Published: May 2014

In Akan, [æ] is regarded as an allophone of /a/ and described as “a quality that ranges from a front vowel quality close to [ɛ] in the Asante [Twi] dialect, to a more central quality in the Fante sub-dialects in which it occurs” (Dolphyne, 1988, p. 6–7). In fact, the existence of [æ] appears controversial because while it is believed to be an allophone of /a/ in the Twi dialect (Boadi, 1991; Dolphyne, 2006; O'Keefe, 2003); and in some sub-dialects of Fante (Abakah, 1978; Boadi, 1991; Dolphyne, 2006), recent studies show that [æ] is a phoneme in Fante (Abakah, 2002; Lomotey, 2008). The present study extends the results of Lomotey (2008), in which she suggests that [æ] may not be an allophone of /a/ in Twi, but another realization of [ɪ] or [e] (p>0.05). Results of acoustic analysis (duration, F1, F2) of words with [ɪ], [e] and [æ] in Twi showed similarity with Lomotey (2008). Based on the results, I argue that [æ] may be undergoing or has undergone vowel raising or merger (if it ever exists/existed). I also argue that if it exists in Twi, then it might be represented with a different vowel symbol, and not [æ].
Variability in vowel production: Exploring interactions among frequency, neighborhood density, predictability, and mention
Authors: Burdin Rachel S. , Turnbull Rory , Clopper Cynthia G.
Published: May 2014

Multiple factors are known to affect vowel production, including word frequency, neighborhood density, close predictability, and mention. In this study, we explored interactions between the effects of all four of these factors on vowel duration and dispersion in a fully crossed within-subjects design. Participants read a series of short stories that contained target words varying in frequency, neighborhood density, predictability, and mention. Vowel duration and dispersion from the center of vowel space were measured. Results from linear mixed effect modeling revealed the expected effect of neighborhood density on duration: vowels in words with higher neighborhood density were longer. Both frequency and mention had significant expected effects on vowel duration and dispersion: vowels in more frequent words and second mention words were shorter and less peripheral. An interaction between frequency and mention on dispersion was also observed, such that low frequency words underwent second mention reduction to a greater degree than high frequency words. No effects of predictability were observed. These results are only partially consistent with reported findings elsewhere in the literature, suggesting that these effects are fragile and may be substantially affected by methodological choices, including the target words, task, and statistical models.
Nuclear pitch accent in American English dialects: Truncation and compression
Authors: Jacewicz Ewa , Fox Robert A.
Published: May 2014

Dialects of the same language can differ in their use of prosody. We explored realization of nuclear pitch accent in female speech in three regional varieties of American English: Ohio, Wisconsin, and North Carolina. We found that both OH and WI speakers truncate the F0 contours while NC speakers compress them in identical environments. Our second question pertained to the effects of obstruent voicing in syllable coda on the F0 of the preceding nuclear vowel. We admitted three possibilities for the effects of a voiceless coda: shortened vowel duration may (1) “clip” the F0 contour and reduce the dialectal differences; (2) maintain the dialectal differences by preserving the F0 contour shapes found before a voiced coda; or (3) some dialects may “clip” and some may preserve the F0 contour. The results supported the third option. Ohio and Wisconsin speakers “clipped” the F0 contour so that F0 terminal values before a voiceless coda were higher than before a voiced coda. However, North Carolina speakers not only preserved the contours but their F0 terminal values before a voiceless coda were substantially lower than before a voiced coda. The effects of coda voicing on F0 fall were found to augment the dialectal differences.
Japanese children's suprasegmental imitation capability of English rhythm
Authors: Kawai Hiromi
Published: May 2014

This study reports on an acoustic analysis of L2 Japanese child learners' English rhythmic imitation capabilities. The participants for this study were Japanese fifth and sixth graders, all of whom had been taking English language classes since their first year of elementary school. Rhythmic chants were employed as a means to elicit oral production owing to their frequent use in the EFL classroom. Nine English sentences (including two to six stressed syllables, four downbeat sentences and five upbeat sentences) were employed in the collection of a rebus rhyme and in consideration of word familiarity. In the first of two parts of the experiment, the participants shadowed back the test sentences following the experimenter's model pronunciation. In the second part, the experimenter showed picture cards related to the test sentences during the participants' imitation of the experimenter's utterance. During both tests, the experimenter tapped rhythm in time to each participant's utterance of stressed syllables instead of using automatic rhythmic machine. Acoustic analyses and Cluster analysis were used to discriminate between the native-like rhythmic and non-native groups, and profile the 5th and 6th grade groups. Overall, the findings have clear implications for the teaching of English rhythm to moraic language speaking children.
Contextual landmark analysis of speech from typically and atypically developing children
Authors: Levy Chelsea , Mann Allison , Kenney Jess , Choi Jeung-Yoon , Shattuck-Hufnagel Stefanie
Published: May 2014

Analysis of acoustic landmarks (abrupt changes in the speech signal spectrum, Stevens 2002) has been carried out for speech from two typically and six atypically developing children. The atypically developing children include two with specific language impairment (SLI), and four diagnosed with autism spectral disorder, and two with higher and two with lower language functions (ASDH and ASDL, respectively). Recordings of non-word repetition sessions (CNREP) for each child were hand annotated with words, phones, and landmarks (42 tokens per child). Decision tree analysis was used to examine the effects of factors such as landmark type, preceding and following phone type, position in the syllable (onset, nucleus, ambisyllabic, and coda), and syllabic stress (stressed, full, and reduced) on landmark modification patterns. Results indicate that, compared with typically developing children, atypically developing children show different landmark modifications, and that these different modification patterns can be characterized by the systematic effects of contextual factors.
Lung volume initiation levels and selected acoustic measures of English consonants
Authors: Watson Peter J. , Chen Yu-Wen
Published: May 2014

Watson, Ciccia, and Weismer (2003) described the relationship of initiating speech at different lung volumes to selected acoustic variables related to vowel production. It was found that some variables, such as dB SPL were related to a ‘direct' mechanical interaction with the breathing system. They also found that a variable, such as vowel-space, was reduced at low-lung volume initiation levels suggesting an indirect link between one subsystem, breathing, and another articulation. Using a similar procedure to Watson et al. (2003), we studied selected acoustic variables of English fricatives and stops. Participants read aloud a carrier phrase with a 2 syllable V—‘CV embedded within it. Participants were trained to initiate speech at 3 different lung volume levels: normal, low, and high. Data will be discussed in relation to those acoustic variables that have a more direct interaction with the breathing system, e.g., db SPL, and those with a less direct relationship with breathing, e.g., relative duration of voice-onset-time between cognate pairs of voiced and voiceless stop consonants, and the difference of first moment measures between sibilants.
Relationship between the first two formant frequencies and tongue positional changes in production of /aɪ/
Authors: Lee Jimin
Published: May 2014

The first two formant frequencies (F1, F2) of vowels are often interpreted in terms of their relationship to tongue height and advancement, respectively. To test this interpretation, the current study examines the relationship between F1/F2 trajectories and tongue positional changes in production of the diphthong /aɪ/ by utilizing electromagnetic articulography. Ten healthy female speakers participated in the current study. Electromagnetic articulography (AG-200) and a synchronized audio recording system were utilized to obtain synchronized kinematic and acoustic data. Each speaker produced three repetitions of the word “hide” in the carrier phrase “I say a__ again.” F1 and F2 were traced along the entire vocalic nucleus of the target vowel /aɪ/. Over the same time interval, x and y coordinate values from the tongue sensor (positioned approximately 25 mm away from tongue apex) was recorded. Correlational analysis (r-values) showed that, overall, F1—tongue y position and F2—tongue x position pairs have strong relationships; however, a strong relationship was observed in F1-x and F2-y pairs as well. Results will be discussed in terms of amount of variance of formant frequencies explained by tongue xy positional changes and issues of interpretation of formant frequencies.
Using developmental data to explore frequency effects in production
Authors: Baese-Berk Melissa M. , White Katherine
Published: May 2014

Low-frequency words are produced with longer duration and more extreme articulation than high-frequency words. It is unclear whether these differences are the product of online processes occurring during production, or instead result from the nature of stored exemplars. One way to disentangle these accounts is to consider changes over development. Online accounts predict that frequency effects arise due to the structure of the lexicon. Therefore, as the lexicon develops, productions should change as a function of individual words' frequencies. In contrast, exemplar accounts hypothesize that these effects occur because listeners are exposed to and store words with these acoustic properties; on these accounts, the effects should remain relatively stable across the lifespan. We asked children to name pictures that differed in frequency in both the child and adult lexicons. The pictures were in one of four categories: high frequency adult/high frequency children, low frequency adult/low frequency children, high frequency adult/low frequency children and low frequency adult/high frequency children. If children's production patterns reflect frequency in the adult lexicon, this would be evidence for an exemplar account of frequency effects; if, instead, children's patterns reflect frequency in the child lexicon, this would suggest that online processes underlie these effects.
Use of supervised machine learning for real-time classification of underwater targets using Autonomous Underwater Vehicle sampled bistatic acoustic scattered fields
Authors: Fischell Erin M. , Schmidt Henrik
Published: May 2014

A method has been developed for the classification of underwater target geometry using bistatic acoustic amplitude data collected by an Autonomous Underwater Vehicle (AUV) as it follows a selected path through the scattered field created by a fixed source insonifying a target. The mobility of an AUV allows it to exploit features of this field in three dimensions. The classification method presented includes offline and onboard processing components, which use a combination of signal processing, vehicle behaviors, and machine learning in the form of Support Vector Machines (SVMs) to extract target geometry from collected acoustic data. The offline training and analysis step creates training and test vector sets in a selected feature space from existing scattered field data and outputs models for target classification, confidence, and feature ranking. Several algorithms are explored for selecting the feature space used by the SVM. The models produced by the offline processing step are used in the real-time classification processing chain onboard an AUV sampling an unclassified target's scattered field. The presented simulation results use scattered fields modeled using OASES-SCATT and demonstrate real-time processing and path planning in the LAMSS MOOS-IvP simulation environment. [Work supported by ONR Code 321 OA and NSF GRFP.]
Acoustic scattering from a sand layer and rock substrate with rough interfaces using the finite element method
Authors: Bonomo Anthony L. , Isakson Marcia J. , Chotiros Nicholas P.
Published: May 2014

The finite element method is used to study the acoustic scattering from a layer of sand overlying a rock substrate. All the modeling is done in two dimensions. Both the water-sand interface and the sand-rock interface are modeled as random rough surfaces following a modified power law spectrum. The rock substrate is assumed to be an elastic solid. Three sediment models are used for the sand layer: the full Biot model for poroelastic media, an effective density fluid model based on the Biot model, and a simple fluid model. The effect of the choice of sediment model used for sand is studied. The finite element results are also compared with perturbation theory and the Kirchhoff approximation in order to further evaluate the validity of considering the underlying interfaces to be flat as a rough sand-rock interface cannot be handled by these models. [Work supported by ONR, Ocean Acoustics.]
Scattering of sound by a cylindrically symmetric seamount
Authors: Pannatoni Ronald
Published: May 2014

A three-dimensional waveguide is used to model scattering of sound by a cylindrically symmetric seamount. The waveguide is “closed” in the sense that it has a boundary below the ocean bottom. This makes the spectrum of local wavenumbers discrete. Partial differential equations govern the modal expansion coefficients of the acoustic pressure and of the radial pressure gradient. Their solutions must be finite-valued at the axis of symmetry and satisfy outgoing radiation conditions at the perimeter of the base of the seamount. Direct numerical integration of this problem is unstable, but with variation of parameters and a Riccati transformation an equivalent problem is obtained for which numerical integration is stable. This approach is compared with an alternative [Pannatoni, POMA 14, 070003 (2011)] that uses leaky modes of an “open” waveguide having no boundary below the ocean bottom. It is shown how coupling between nearest-neighbor modes of the “closed” waveguide relates to the leaky modes of the “open” waveguide. This coupling restricts the step size that numerical integration can use.
Computation and accuracy trade-offs in applied reverberation modeling
Authors: Eller Anthony I. , Heaney Kevin D.
Published: May 2014

Reverberation modeling and prediction are a research area of intense interest, often involving large, high resolution databases and advanced numerical techniques, and stretching modern computers to their limits. Nevertheless, applications of underwater acoustic systems often need estimates of reverberation sooner than they can be provided by the research community. What results is that applied models for reverberation, in order to meet the pressing needs with available computer memory and allowable computation times, often employ approximations or shortcuts that fall short of current research modeling standards. This paper traces several of the approximations used in reverberation models in the past in order to meet system design and deployment needs. The results show an inherent conflict between basic research and applied interests. The traditional DOD paradigm is that basic research results transition to the applied world. History suggests the opposite, however: Applied research ignores the torpedoes and moves full speed ahead where needed, then forges the chain used to pull reluctant basic research in the needed direction.