bluuebunny/crossref_metadata_2025 huggingface dataset:
Cross-dialect perception of English vowels by native Japanese speakers
Authors: Frieda Elaina M. , Fox Robert A.
Published: October 2013

The present study will examine the influence of dialect on second language acquisition in terms of perceptual abilities. Our lab is currently comparing vowel productions from native Japanese (NJ) speakers with native American English speakers residing in two divergent dialectal regions of the United States (Alabama and Ohio). This study is an elaboration of this work that explores the extent to which there is regional variation in the perceptual responses in NJ as a function of local dialect. We recorded sets of words from four groups of subjects: NJ subjects residing in Alabama (JA) and Ohio (JO) and native English (NE) subjects from Alabama (EA) and Ohio (EO). These tokens were then used in an identification experiment utilizing the same four subject groups. The experiment addresses at least two different questions: (1) Does the intelligibility of Japanese vowels change as a function of dialect for the English listeners? (2) Does the perceptual responses of the Japanese listeners to the EA and EO tokens vary as a function of their ambient linguistic context? The results will be discussed in terms of second language acquisition and dialect acquisition. [Work supported, in part, by an INRS Award from the NIH to Fox, P.I.]
Developmental changes in the discrimination of Hindi dental-retroflex consonants by American–English children between childhood and puberty
Authors: Pruitt Jesica C. , Pruitt John S. , Nelson Tobey L. , Kuhl Patricia K.
Published: October 2013

There are many studies comparing adult and infant perception of non-native speech sounds, with results typically showing that infants outperform adults on non-native phonetic discrimination. However, there is a lack of research that investigates the developmental change in native and non-native speech perception, particularly from early childhood to puberty, when plasticity for learning a new language appears to decline. In an attempt to better understand the effects of language experience on native and non-native speech perception during this period, the current study examined 6 to 15-year-old American–English children’s ability to discriminate Hindi dental-retroflex consonants. Discrimination data were obtained using four phonetically different consonant–vowel contrasts that are phonemic in Hindi but not in English. Discrimination data were also obtained using a native-language contrast (AE /r/ vs /l/). For comparison, American–English and Hindi adults were tested. A newly developed computer-based testing method was used with all subject groups to present the various contrasts in an engaging and efficient manner. Findings suggest that there are interesting developmental trends in the age range of 6–15 years, and that the computer-based testing method will provide a valuable tool for assessing speech perception across a wide age range. [Work supported by NICHD and Talaris Research Institute.]
Project Artemis—A retrospective view
Authors: Berman Alan
Published: October 2013

Approximately 45 years ago, the Underwater Acoustics Community of the U.S. undertook a massive research program called Project Artemis. The objective of this endeavor was to determine what were the necessary capabilities needed to build an active mono-static sonar that was capable of detecting a submerged submarine at ranges of about 1000 km. Although no operational capability ever resulted from this effort, the research undertaken by this project identified the limitations in existing technology and in the community’s knowledge of underwater water acoustics that precluded achievement of the original objective. In the area of technology, the most obvious limitation was the limited speed of available computers that forced the use of cumbersome analog devices for signal processing and for beam steering. Techniques for controlling the location of the source dynamically and for the construction and for the operation of large-scale acoustic high-powered phased arrays were developed successfully. Unresolved issues that formed the basis for future research efforts related to signal coherence time, low-frequency acoustic cross sections of submarines, the development of reliable computation models for propagation loss, low-frequency acoustic absorption processes in ocean, and the development of algorithms that accounted for source Doppler. Project Artemis terminated in the mid-1960s.
A versatile wavetable-based model for synthesis of piano tones
Authors: Beauchamp James W. , Zheng Hua , Lee Bowon , Lakatos Stephen
Published: October 2013

A synthesis model has been developed based on short-time spectral analysis of a wide range of Yamaha Diskclavier notes performed at a variety of velocities and articulations. Frequency components are sorted by critical band, and each band is reduced to a wavetable controlled by the fundamental frequency and the rms amplitude envelope for that band. Inharmonicity is controlled by appropriately stretching the fundamental frequency for each wavetable. In some cases, it is possible to combine critical bands into larger bands, thus improving the data reduction with only slightly reduced quality. In addition, transient noise, obtained by subtracting a full sinusoidal synthesis from the original signal, is used to improve attack and release authenticity. Preliminary results of listening tests indicate that on average subjects correctly identify full-critical-band-model synthetic tones only about 60% of the time when compared to original sounds. An intelligent computer synthesis instrument has been coded which allows production of arbitrary musical scores of high quality using parameter values dictated by note and velocity. However, the user may also vary certain parameters such as transient noise level, attack rate, and inharmonicity to achieve greater variety.
Airgun technology for undersea long-range acoustic detection systems
Authors: Bouyoucos John V.
Published: October 2013

Miguel Junger and this author occupied a basement office at Harvard University’s Acoustics Research Laboratory under the tutelage of Professor F. V. Hunt during the mid-1950’s. Subsequently, Dr. Junger and his staff at Cambridge Acoustical Associates provided consulting support on numerous occasions to the evolution of hydroacoustic transduction technology carried out by the author and his engineering staff at General Dynamics Corporation and later at Hydroacoustics, Inc. in Rochester, NY. A key contribution was made by Dr. Junger and his associates to the evolution of the MULTIPULSETM* airgun array technology in defining the influence of the bubble cloud emitted from the vertical gun array on the azimuthal directivity of the transmitted broadband energy. This paper discusses the evolution of the vertical airgun transmit array and includes some far-field, at-sea measurements that generally support the analytical findings of Dr. Rudolph Martinez, one of Miguel Junger’s colleagues at Cambridge Acoustical Associates, as referenced in paper 3aEA9 in this session, entitled ‘‘Diffracting Open-Ended Duct of Finite Length: Flow Effects.’’ *MULTIPULSETM is a registered trademark of Hydroacoustics, Inc.
Optimizing selection of acoustical measurement equipment to meet educational needs
Authors: Lewis Noland , Raichel Daniel R.
Published: October 2013

As part of their learning experience, students of acoustics need to know and understand measurement techniques, particularly those involving sound pressure levels, sound intensities, spectrum analyses, and signal generation. It is important to realize that students not only should obtain hands-on experience, but also gain a keen appreciation for significant factors affecting accuracy and long-term stability of the equipment being chosen for use. The requisite equipment may not be inexpensive but some economies can be effected by judicious selection of devices without seriously compromising the validity of experimental results. For example, Type 2 microphones, rather than Type 1, may suffice to yield revealing trends in measurements of ‘‘real life’’ situations; and due consideration must be given to the ruggedness of equipment with respect to storage conditions and environmental exposure during use. Fundamental experiments include measurements of SPL, spectrum analyses, measurement of room reverberation time, testing of loudspeaker response including THD, sound absorption effects, etc. Selection of equipment with due regard to costs can be eased by the purchase of a ‘‘university package’’ of sensing devices that can be applied with FFT and sound generation cards and special purpose computer programs.
Star in a jar
Authors: Eskue Roman G.
Published: October 2013

The hypothesis that sonoluminescence can be produced using a signal generator, an acrylic chamber, piezoelectric speakers, and water was tested. Proving this hypothesis took many experiments, most of which failed. For the first five experiments the speakers were connected to the outside of the acrylic chamber and wineglass. The chamber and glass were filled with different types of water: tap water, distilled water, chilled distilled water, and a chilled mixture of 80% distilled water and 20% glycerin. When the ultrasonic sounds were produced and bubbles were introduced in the water, nothing happened. In the sixth experiment the speakers did not fit well enough in the wineglass to produce enough resonating sound in the water. Finally, the speakers were placed in the acrylic chamber with the 80/20 mixture. As the signal generator was adjusted to a frequency of 28.3 KHz, there it was, that tiny blue light, the Star in a Jar. The hypothesis was correct: sonoluminescence can be produced using a signal generator, an acrylic chamber, piezoelectric speakers, and water.
Community noise modeling of industrial facilities
Authors: Parzych David
Published: October 2013

Community noise prediction is often based on point source radiation models. Sound radiation models are exercised to account for attenuation due to atmospheric absorption, ground effects, barrier effects, and sound reflections. Often, industrial facility noise models ignore obvious factors, such as partial screening or partial reflections of large sound sources, directivity effects, and physical source dimensions as well. This paper addresses sound modeling issues including input data resources, dealing with large radiating surfaces, directivity, and decisions on whether to use simple screening models or sophisticated commercial software. Large equipment modeled as a point source is discussed and how point source noise models can be adapted to accurately estimate sound from large sources.
Reradiation of acoustic waves from circumferential waves on elastic shells
Authors: Ahyi A. Claude , Cao Hui , Raju P. K. , Überall H.
Published: October 2013

We consider evacuated thin semi-infinite shells immersed in a fluid, either of cylindrical shape with a hemispherical endcap, or formed two-dimensionally by semi-infinite parallel plates connected by a semi-cylinder. The connected shell portions are joined in a steady fashion although with discontinuous curvature. Acoustic waves are considered axially incident onto the curved portion of the shell, where they, at the critical angle of coincidence, generate Lamb and Stoneley-type waves in the shell. A computer program was written, based on a previous investigation by Cao et al. [Chin. J. Acoust. Soc. Am. 14, 317 (1995)] in order to computationally visualize the waves in the fluid that have been reradiated by the circumferentially propagating shell waves at the critical angle. The results will be used in order to interpret experimental results in which the reradiated waves are optically visualized by the Schardin–Cranz Schlieren method; the latter experimental results will be reported elsewhere.
Periodicity of linear and nonlinear surface acoustic wave parameters in the (111) plane of cubic crystals
Authors: Lomonosov A. , Hess P. , Kumon R. E. , Hamilton M. F.
Published: October 2013

Previous numerical and experimental studies of surface acoustic waves (SAWs) in the (111) plane of cubic crystals have shown that linear properties, including the wave speed and the direction of power flow, exhibit sixfold symmetry. However, recent measurements by Lomonosov and Hess of finite-amplitude SAW pulses propagating in opposite directions in the (111) plane of crystalline silicon have demonstrated that the same periodicity does not hold for the nonlinear distortion. Calculations based on a model for nonlinear SAWs in anisotropic media [Hamilton et al., J. Acoust. Soc. Am. 105, 639–651 (1999)] indicate that complex-valued nonlinearity matrix elements, which describe the coupling between harmonics, have sixfold symmetry in magnitude but only threefold symmetry in phase. As a result, pulses traveling in opposite directions exhibit different nonlinear phase shifting between harmonics that give rise to the distinctly different types of observed distortion. Threefold symmetry of nonlinearity is also predicted for other cubic crystals besides silicon. Additional computations show that the complex-valued eigenvalues and eigenvectors of the linearized equations (physically corresponding to the depth decay coefficients and component amplitudes, respectively) also have sixfold symmetry in magnitude but only threefold symmetry in phase. [Discussions with A. P. Mayer are gratefully acknowledged.]
Multichannel resonant scattering theory applied to the determination of polarization state of surface waves
Authors: Danila Emilian , Rembert Pascal , Izbicki Jean-Louis
Published: October 2013

In the case of scattering by a fluid filled cavity in elastic solid, the scattering appears into two channels, the P-channel and the S-channel. Then the scattering S-matrix is a block diagonal matrix. The elements of this matrix characterize the scattering with or without change of polarization state. From the multichannel resonant scattering theory it results that resonance widths are the sum of two partial resonance widths. This is an expression of the energy conservation law in the scattering process. It is difficult to analyze the distribution of the energy over the P respectively S channel, in the complex plane associated to the poles of S-matrix elements, especially in the neighborhood of the repulsion points on the dispersion curves. A complete analysis is then made using the complex planes associated to the zeros of the numerators of the S-matrix elements.
Analysis on infant speech with longitudinal recordings
Authors: Amano Shigeaki , Kondo Tadahisa , Kajikawa Sachiyo
Published: October 2013

The utterances of five infants with their parents was recorded every month from their birth until five years old to investigate spoken language development from the viewpoint of acoustic characteristics. Recording time was at least one hour per month. An infant speech database is now being developed from the recordings. Each entry of the database contains a speech file of an utterance and its transcription with some tags such as speaker, utterance category, and clarity. Using a beta version of the database, preliminary analyses were conducted on utterance duration, speaking rate, interutterance interval, and utterance overlap. Some tendencies were observed. For example, utterance duration became longer for infants as a function of infant age, but it was almost constant for parents. On the other hand, the speaking rate was almost constant (about 4 mora/s) for infants but became faster (from 6 to 8 mora/s) for parents as a function of infant age. An interutterance interval of ‘‘Parent to Infant’’ correlated with that of ‘‘Infant to Parent,’’ even before infants spoke a word. Parent utterance often overlapped infant utterance only after infants spoke two-word sentences. The implication of these tendencies for spoken language development is discussed.
The relation between reading level and vowel production variability in real and nonsense words
Authors: Lydtin Kimberly , Fowler Anne , Bell-Berti Fredericka
Published: October 2013

Past research has indicated possible links between phonological difficulty, speech production variation, and reading problems. This study examines the relations between spelling ability (a measure of reading ability for first graders), on the one hand, and the variability of vowel production, on the other, of poor and good readers in the first grade. The focus of this study was to examine the variability of vowel formant frequencies in real and nonsense words produced in random order by poor and good readers. The vowels chosen for this study are /ɪ/, /ε/, and /æ/, occurring in real words (/bVt/) and nonsense (/bVp/) monosyllabic words. Vowel duration and F1 and F2 frequencies, at vowel onset and at 50-ms intervals through the vowel, will be compared for the poor and good readers (spellers), to determine if the word-status of read items affects production variability. [Work supported by U.S. Dept. of Education, McNair Scholars Program.]
Auditory-visual speech perception examined by functional MRI and reaction time
Authors: Sekiyama Kaoru , Sugita Yoichi
Published: October 2013

In face-to-face communication, auditory and visual speech cues are easily integrated as demonstrated by the McGurk effect. The integration processes are investigated by measuring brain activity (fMRI) and reaction time. The subjects were 10 native speakers of Japanese. The stimuli were /ba/, /da/, and /ga/ uttered by three female talkers. The audiovisual stimuli were the McGurk type stimuli consisting of discrepant auditory and visual syllables (e.g., audio /ba/ was combined with video /da/ or /ga/). We compared brain activity during audiovisual speech perception for two sets of conditions differing in the intelligibility of auditory component of speech. In each condition, the subjects were asked to identify spoken syllables. When the auditory speech was intelligible, a brain area for visual motion processing was quiet, whereas the same visual area was active when speech was harder to hear. Thus visual information of the mouth movements was processed more intensively when speech was harder to hear. Reaction time was faster for the low-intelligibility condition than for the high-intelligibility condition, suggesting a top-down suppression of visual processing when auditory speech was intelligible. The integration processes seem to involve a process to actively find the optimal weight of different modalities under given circumstances.
Objective evaluation of nasality using laser Doppler vibrometer
Authors: Kumada Masanobu , Kaneko Toshiaki , Ono Takahiko , Ohashi Masanao , Ishida Koji , Nakayama Kazuo , Kobayashi Noriko , Hirose Hajime , Tayama Niro , Niimi Seiji
Published: October 2013

Objective measurement of nasality is very important in terms of clinical evaluation. But there is no definite methodology of objective evaluation of nasality. We already reported that new methodologies of the Laser Doppler Vibrometer (LDV) and Sub-miniature Electret Microphone (SEM), both of which could detect the nasal/non-nasal difference of sustained phonemes, seemed valid to evaluate nasality [Kumada et al., 140th ASA Meeting (2000); Kumada et al., 141st ASA Meeting (2001)]. LDV, used recently in an industrial field as well as medical/biological field, is the generator and the detector of the laser to detect the velocity of the object’s vibration by Doppler’s effect. LDV seemed a powerful tool for speech physiology by which vibration of a body wall can be measured during speech and singing, without any contact receiver. The objectives were to evaluate the degree of nasality of phonemes in words by LDV and SEM, and to discuss the possibility of the clinical use of these methodologies. The subjects were 5 healthy Japanese males (Tokyo dialect speakers). The materials were Japanese words /shinkansen/ and /shimbunshi/. Both LDV and SEM systems could detect a nasal/non-nasal difference in spoken words, and seemed valid to evaluate nasality in speech. Further study is planned using patients (e.g., cleft-palate) as well as healthy subjects.
A model-based acoustic time-reversal mirror for robust variable focusing
Authors: Hermand Jean-Pierre
Published: October 2013

A natural extension of the acoustic time-reversal mirror (TRM) is investigated where predicted receive array signals are backpropagated to an arbitrary virtual source location. First, large time-bandwidth product (TB), broadband signals propagating from a real probe source to the array are processed iteratively by a model-based matched filter (MBMF) receiver in searching for the environmental parameters that best correspond to the measured acoustic-impulse responses. The process ends when most of the time-spread energy across the array is recombined coherently (processing gain). Second, the resulting acoustic-channel model is used to synthesize the transmit signals that will focus their energy at the desired range and depth (the virtual source). The procedure overcomes the noise and reverberation limitations inherent to the TRM operation. The at-sea, focusing performances of a model-based TRM were predicted from related MBMF experiments: range-depth localization of a distant towed source in a duct (west sardinia 89\N90) and bottom geoacoustic characterization in shallow water (yellow shark 94\N95) [Hermand et al., IEEE J. Oceanic Eng. 18, 447–465 (1993); 24, 41–66 (1999)]. Simulation results using yellow shark 94, large TB, broadband vertical array data will be compared with trm 96\N97 experimental results [Hodgkiss et al., J. Acoust. Soc. Am. 105, 1597–1604 (1999)] obtained along the same transect.
Marine Mammal Protection Act (MMPA) and Endangered Species Act (ESA) regulations for marine mammal nonfishery interactions
Authors: Perry Roberts Simona , Wieting Donna S.
Published: October 2013

The Office of Protected Resources Marine Mammal Conservation Division develops, implements, and administers programs for the protection, conservation, and recovery of marine mammals under the Marine Mammal Protection Act (MMPA) and the Endangered Species Act (ESA). The Division’s nonfishery interaction program is tasked with implementation of Sec. 101(a)(5) (A–D) of the MMPA, which provides two types of authorizations for allowing the incidental, but not intentional, taking of small numbers of marine mammals by U.S. citizens engaged in a specified, nonfishery related activity. The first type of authorization, the Letter of Authorization (LOA), requires that regulations be promulgated. These LOA regulations may be effective for a 5 year period, with a new letter, containing specific mitigation and monitoring requirements, issued on an annual basis. The second type of authorization, the Incidental Harassment Authorization (IHA), does not require promulgation of regulations but does require a 30-day public comment period. The IHA is valid for 1 year only. The estimated time for processing LOA and IHA requests ranges from 1 year to 120 days; however, depending on other requirements, this time period may be lengthened. NMFS makes its determination to issue or deny requests based on three criteria: negligible impact, small numbers, and unmitigable adverse impacts.
Reauthorizing and amending the MMPA and ESA: Issues, status, and prospects in the 107th Congress
Authors: Buck Eugene
Published: October 2013

The CRS has provided specialized research and policy analysis to the Congress for more than 80 years. As a legislative branch agency, the CRS works exclusively for Members of Congress, Committees, and Congressional staff on a confidential, nonpartisan basis. The CRS analytical staff are internationally-recognized experts who apply multidisciplinary expertise at all stages of the legislative process to assist Congress in identifying, analyzing, and formulating legislative proposals as well as responding to constituent needs. The 107th Congress is considering whether to reauthorize and amend the Endangered Species Act of 1973 (ESA). Major issues in recent years have focused on whether to incorporate further protection for property owners and reduce regulatory impacts, or whether to strengthen species protections through a variety of procedural changes. The authorization of appropriations for the Marine Mammal Protection Act (MMPA) expired at the end of FY1999. The issue for the 107th Congress is whether, and if so under what conditions, to reauthorize and amend this Act to reflect and address the concerns of various interest groups. For both the ESA and MMPA, issues capturing congressional attention will be identified, the current status of legislation to address these issues will be summarized, and the prospects for enactment will be discussed.
Environmental compliance in naval research
Authors: Quinn John
Published: October 2013

The Office of Naval Research (ONR) promotes, coordinates, and executes the science and technology programs of the Department of the Navy. Acting principally through universities, government laboratories, and nonprofit organizations, the ONR sponsors basic and applied research, and advanced technology development, in ocean acoustics and many other disciplines. In these efforts the ONR and its associates comply with a host of environmental statutes and executive orders, and with Navy policy regarding marine environmental protection. This paper reviews these requirements as they apply to the ONR’s ocean acoustic efforts, and the processes through which the ONR carries out its environmental responsibilities.
Science and the management of underwater noise: Information gaps and polluter power
Authors: Whitehead Hal , Weilgart Linda
Published: October 2013

To regulate underwater noise rationally and efficiently, we need to know its impact on population and community biology. This link can rarely be studied directly because of logistics and the spatial and temporal scales of ecological processes. There are two principal approaches: correlational studies of noise levels with population events or measures; and experiments in which the response variables (usually short-term behavioral measures) are poor proxies for the population and ecosystem parameters about which we are concerned. Experimental studies also have costs. These may include the introduction of additional noise, delay of substantive regulation, and, when polluters are major funders, perceived gagging or biasing of knowledgeable scientists. This is a particular problem with underwater noise because the U.S. Navy (a major noise polluter) and allied organizations fund so much acoustic research. Consequently (a) managers must recognize that underwater noise is dangerous but its most important consequences cannot currently be determined; (b) following the precautionary approach, noise levels should be reduced, sources distanced from marine life, and new noises avoided; (c) correlational studies are generally preferred to experimental ones; (d) major noise polluters should not directly fund the research, instead providing fees to independent bodies which commission research and recommend regulations.
Hot topics in speech communication
Authors: Assmann Peter F. , Loizou Philipos C.
Published: October 2013

Speech communication is a robust and flexible process. For listeners with normal hearing, speech remains intelligible when a substantial proportion of the spectrum is eliminated by filtering, when portions of the wave form are replaced with silence, and in the presence of interfering sounds, including sounds made by competing talkers. The resilience of speech depends on several interacting systems which exploit the redundancy of speech in different ways. New results are reported on the perceptual processing of talker variability, monaural and binaural mechanisms of sound separation, audio-visual integration in lip reading, and perceptual compensation for channel distortion. For listeners with hearing impairment, new research in the field of cochlear implants has focused on the development of new electrode arrays, the efficacy of bilateral implants and the development of sophisticated signal processing techniques to combat noise. The new electrode arrays are designed to limit electrode interaction and thus increase the number of perceptual channels of information. The benefit of bilateral implants is investigated in terms of sound localization and speech perception in noise. New results are reported on bilateral cochlear implants, speech-processing strategies for noisy environments and acoustic simulations of cochlear implants which aim to quantify the factors contributing to speech intelligibility.
Cramer-Rao bounds for source localization and matched field tomography in a partially stratified ocean
Authors: Baggeroer Arthur B.
Published: October 2013

The performance of Matched Field Processors (MFP) for either source localization or tomography using Cramer–Rao bounds often gives overly optimistic results. This is often because the analyses to date have used fully coherent models for the acoustic propagation. This implies that the modes or rays remain sychronized, or ‘‘phase locked.’’ This is a built in assumption for most mode/ray codes and parabolic equation models. Since the phase interaction provides much of the information for MFP, any environment that leads to randomization of the mode/ray coupling cannot use a single degree of freedom replica for optimal processing. Models that address the randomness are often described as ‘‘partially saturated’’ propagation. Moreover, the closed form formulas for MFP performance analysis using Cramer–Rao bounds are not applicable for such models. Since partially saturated acoustic propagation is often a more realistic model, it is important to determine the performance of MFP in this regime. Here, we derive closed form formulas for computing Cramer bounds and provide some examples of the degradation due to partial saturation. [Work supported by ONR Code 321: Undersea Signal Processing.]
Assessment of the classroom as a communication channel
Authors: Soli Sigfrid D. , Sullivan Jean
Published: October 2013

The classroom is an environment in which spoken language communication facilitates and enables students in the learning of essential academic, social, and cultural skills. As such, the classroom defines a communication channel for learning. Our research has focused on the special requirements placed on this communication channel by the student listener. Our strategy is to quantify the effects of age, developmental status, hearing status, and English proficiency on speech intelligibility in noise and to find the signal/noise ratios that enable all students to obtain high intelligibility. Using these signal/noise ratios, acceptable noise levels and reverberation times for the classroom communication channel are estimated. Our studies of young children for whom English is either the primary language (EPL) or the secondary language (ESL) will be reported. The method of estimating the special requirements these children place on the classroom communication channel will also be described. Acoustic measurements from six elementary school classrooms in which ESL and EPL children are taught will be presented, and these classrooms will be evaluated in relation to the communication channel requirements.
Effects of background-noise on speech listening difficulty in reverberant sound fields
Authors: Morimoto Masayuki , Kobayashi Masaaki , Hakamada Atsushi , Sato Hiroshi
Published: October 2013

The previous work [M. Morimoto et al., J. Acoust. Soc. Am. 108, 2633 (2000)] demonstrated that the listening difficulty can evaluate the quality of speech transmission more exactly and sensitively than intelligibility. In the present work two listening tests were performed to investigate the effects of background noise on the listening difficulty in reverberant sound fields. In the tests, both the listening difficulty and the intelligibility were assessed using word lists based on word familiarity. In the first test, the background noise level was changed, while the speech level was constant at 55 dBA. In the second test, both the speech and background noise levels were changed in the same manner, keeping the signal to noise ratio constant. The results of both tests supported the previous results. Furthermore, the results of the first test indicated that the difficulty did not always increase when background noise levels exceeded the absolute threshold of the noise. Namely, background noise lower than about 30 dBA does not increase the difficulty. The results of the second test demonstrated that the optimum signal to noise ratio depended on background noise level. Overamplifying speech to keep the signal to noise ratio constant increases the difficulty, though the intelligibility does not decrease.
Measuring recovery from temporary threshold shifts with evoked auditory potentials in the bottlenosed dolphin Tursiops truncatus
Authors: Nachtigall Paul E , Supin Alexendre , Pawloski Jeffrey L. , Au Whitlow W. L.
Published: October 2013

Temporary threshold shifts can be short-lived in the bottlenosed dolphin and therefore difficult to measure with conventional trained behavioral psychophysical techniques. The time course of recovery from temporary threshold shifts was measured using evoked auditory potentials collected from a bottlenosed dolphin trained to wear rubber suction cups containing human EEG skin surface electrodes. During each session, following an initial measure of hearing thresholds using the evoked auditory potential procedure, the animal voluntarily positioned within a hoop 1 m underwater while 160 dB re 1 micropascal noise between 4 and 11 kHz was presented for 30 min. Immediately following the noise exposure, evoked thresholds were again obtained. The dolphin swam down into a second hoop located one meter in front of a calibrated hydrophone. Evoked potential thresholds were obtained 5, 10, 15, 25, 45, and 105 min following the exposure for amplitude modulated pure tones of 8, 11.2, 16, 22.5, and 32 kHz. Maximum shifts occurred 5 min following exposure and rapidly recovered. As has been observed with other animals and humans, threshold shifts depended on frequency. Shifts occurred at 8, 11.2, and 16 kHz but no shifts were detected at 22.5 and 32 kHz.
It is all about SOUND science: Manatees, masking and boats
Authors: Gerstein Edmund R. , Gerstein Laura A. , Forsythe Steve E. , Blue Joseph E.
Published: October 2013

A series of controlled underwater psychoacoustic tests with captive manatees, along with comprehensive acoustic surveys of manatee habitats and boat noise propagation measurements, were conducted to investigate manatee hearing and acoustical factors that render Florida manatees vulnerable to repetitive boat collisions. Masked thresholds, critical ratios, and directional hearing of various sounds, including species-specific calls and recorded boat noise were measured against white noise and natural ambient backgrounds. Significantly high acoustic levels were required for manatees to detect approaching vessels. Slow moving boats generate relatively low power and frequency spectra compared to the louder higher frequency cavitation noise produced by faster boats. Counterintuitive to convention, the sounds of slower moving boats are more difficult for manatees to detect and they are often masked by the noise of snapping shrimp and distant faster moving boats. Furthermore, physical boundary effects inherent in shallow water attenuate and limit the propagation of dominant low-frequency sounds produced by many recreational and commercial vessels. While not adapted for hearing or localizing these lower frequencies, manatees can hear and localize an array of narrow band higher FM sounds that could be incorporated into a low-intensity directional alarm to alert them of approaching boats.
Influence of water column statistics and environmental parameters on time-domain simulations of SWARM 95 experimental data
Authors: Frank Scott , Siegmann William L. , Badiey Mohsen
Published: October 2013

During the 1995 SWARM experiment acoustic data were collected at two different VLAs from an airgun source aboard the R/V Cape Hatteras. Intense nonlinear internal wave activity occurred during approximately 1 h of this data. The received signals contain significant variability, particularly of their intensity and time-frequency composition. Efforts to simulate the variability observed in the experimental data by using parabolic equation calculations and simplified analytic models have indicated the importance of bottom physical properties. Results from both methods show sensitivity to the structure of the bottom sound speed as well as the statistics of the internal waves that were present. Bottom properties are estimated from core data taken near the site and other previous studies in the area. To analyze the effects of the internal waves successfully, necessary modifications to these properties are described. Water column statistics are investigated using thermister data taken during the experiment. These statistical quantities will be compared with observed variability in the received signals. Analysis of these features provides relationships between internal wave variability and broadband interference patterns, intensity variations, and modal amplitude and arrival structure. [Work supported by ONR.]
Normal-incidence measurements of the reflection coefficient of two sand sediments in the Gulf of Mexico
Authors: Giddens Eric , Berger Thomas K. , Clark Iain , Buckingham Michael J.
Published: October 2013

In June 2001, the normal-incidence bottom-reflection coefficient, R, of two (20 m depth), sandy seabeds off Florida in the Gulf of Mexico (the SAX’99 site off Destin and another site off Panama City) was measured using tone bursts of 5, 10, 20, and 30 kHz. An omnidirectional source was suspended 2 m above the bottom and 1 m below a hydrophone, which detected the direct and reflected signals. R was determined with the sediment in its natural state and also after surface features, typically ripples of 0.5 m wavelength and 5 cm amplitude, had been smoothed. For any given run, values of R for the undisturbed sediment usually show higher variability than those for the smoothed bottom. The mean value of R for the natural sediment is −9.85 dB and for the smoothed bottom −8.0 dB, the latter being consistent with Rayleigh. Since the source–hydrophone pair was free to drift slightly relative to the seabed, the high variability of the natural-bottom returns may be due either to mild focusing and defocusing effects from the peaks and troughs of the ripple field or to scattering from small inhomogeneities such as shell fragments in the sediment. [Work supported by ONR.]
The underwater sound field from Crater Lake, Oregon
Authors: Nystuen Jeffrey A , Collier Robert
Published: October 2013

Breaking waves and precipitation on the ocean surface are primary sources of underwater sound in the frequency range from 1–50 kHz. By analyzing the underwater sound, precipitation can be detected and quantified, and wind speed can be measured. Acoustic Rain Gauges (ARGs) have been designed and deployed on oceanic moorings. An opportunity to deploy an ARG on a mooring in Crater Lake, Oregon allows a contrast between fresh water and salt water deployments. Furthermore, the possibility of acoustic snowfall detection is investigated. Acoustic signatures for drizzle and heavy rain are similar to those obtained in oceanic conditions. However, acoustic snowfall detection was not readily apparent. Most of the snowfall apparently occurred during high wind speed conditions of over 10 m/s. The marine acoustic wind speed algorithm is biased toward higher values relative to the surface anemometer when the wind speed is over 10 m/s. The spectral distortion of higher-frequency sound levels due to entrained ambient bubbles is not present in these fresh water data. This is consistent with the observation that whitecaps in fresh water are made of larger bubbles than in salt water and that the whitecaps do not persist as long in fresh water.
Lateral attenuation of aircraft sound levels due to engine installation effects: Wallops study
Authors: Fleming Gregg G. , Shepherd Kevin P. , Senzig David A.
Published: October 2013

In September of 2000, the National Aeronautics and Space Administration’s (NASA) Langley Research Center, with assistance from the John A. Volpe National Transportation Systems Center conducted a controlled aircraft noise measurement study at NASA’s Wallops Island Flight Facility on the northeast coast of Virginia. The broad objective of the study was to obtain the data necessary to support an update/replacement to SAE AIR 1751, which addresses the lateral attenuation of aircraft noise. The specific focus of the study was the engine/installation effects, or directivity characteristics of various types of civil transport aircraft. Included in the study was a 767-400, a DC-9, a Falcon 2000, and a King Air turboprop. Measurements were conducted with a 20 microphone array deployed on a combination of two construction cranes and a set of 30 ft. poles. Precision aircraft tracking data were collected using a differential global positioning system, as well as a video tracking system. This presentation will overview the results of the study.
Highway traffic noise measurements compared to predictions from FHWA’s Traffic Noise Model
Authors: Rochat Judith L. , Fleming Gregg G.
Published: October 2013

In 1998, the United States Federal Highway Administration (FHWA) released a new tool for highway traffic noise prediction and noise barrier design, the Traffic Noise Model (TNM). In order to assess the accuracy and make recommendations on the use of TNM for the FHWA, the Volpe Center Acoustics Facility performed numerous roadside measurements, obtaining over 100 h of traffic noise data from highways around the country. For each site, acoustical, meteorological, and traffic data were collected simultaneously throughout the measurement period. Spectrum analyzers were used to collect 1/3-octave band A-weighted equivalent sound levels, and the microphones were deployed at distances from 50 to 1300 ft from the roadway and at two heights off the ground, the number of microphones used being site dependent. In comparing the measured and TNM-predicted sound levels, results indicate that TNM is, on average, within 1 dB of the measured data for all types of sites combined. Grouping the data by site types shows how well TNM is performing for open (no barrier), acoustically soft ground sites; open, acoustically hard ground sites; and sites with noise barriers.
Social survey carried out in the city of Curitiba, Brazil
Authors: Diniz Fabiano B. , Zannin Paulo H. T.
Published: October 2013

As time passes, urban noise is more and more present in big cities inhabitants. Some studies have already quantified noise levels in the city of Curitiba, but they did not have the scope of analyzing the annoyance caused by these noises in its inhabitants. People are continuously exposed to noises, at any time of the day. When they sleep, talk, or even when they rest, the noise is often present. These factors contribute to health impairments and sleep disturbances, and can cause nervousness, headaches and behavioral disorders. In the sense of seeking for people’s annoyance and a reaction against the urban noise, a questionnaire was elaborated, intended to be distributed among the inhabitants of the city and returned for further analysis. By analyzing the answers it was possible to gather information on how the inhabitants of Curitiba react toward the urban noise. According to the answers, the traffic is the main noise source, which bothers more than 70% out of the interviewed people. Also, 32% out of the respondents feel annoyed by the noise in his/her street.
A further validation of the dissociation hypothesis
Authors: Khong Anthony , Xu Ning , Apfel Robert
Published: October 2013

The Dissociation Hypothesis states that in an air bubble or, more generally, a gas bubble comprised of a noble gas and a secondary gas molecule, nitrogen for instance, all the nitrogen is eventually removed by rectified diffusion in which water-soluble nitrogen species are formed. Only the noble gas would remain in the bubble. Hence, a final state exists in which, for a given gas mixture at a given gas saturation, the bubble content should consist predominantly, if not entirely, of the noble gas. An experiment was designed to examine this question. Keeping the final argon content constant, measurements were made of the bubble intensities and radii for various gas mixture permutations of argon-nitrogen under identical conditions of driving frequency, pressure amplitude and data acquisition time. It was found that between the cases 1 : 99 Ar : N2 at 20% saturation and pure Ar at 0.2% saturation, not only were bubble intensities noticeably less in the latter, so were the corresponding Ro, ambient radii, values. Also, Ro and bubble intensity became gradually smaller over time. Reconciliation of these data in light of DH will be discussed. [Support from DARPA subcontracted through University of Washington.]
Effect of speaking rate on segment durations of voiceless stops in Korean
Authors: Morris Richard , Kim In-sop
Published: October 2013

Studies of the effect of speaking rate on speech segment durations reveal that the VOTs of long lag and prevoiced consonants vary directly with speaking rate, whereas those of short lag consonants remain relatively constant across speaking rates (i.e., Kessinger and Blumstein, 1998; Miller and Volaitis, 1989). Koreans have three voiceless stop consonants at each place of articulation. These stops vary in VOT with values in the long lag and short lag ranges. These phonemes are also marked by differing fundamental frequency patterns. The purpose of this study was to investigate the effects of different speaking rates on the acoustic parameters of the Korean voiceless stop consonants. Sixteen Korean adults (8 male and 8 female) repeated productions of the lax, reinforced, and aspirated forms of /p/, /t/, and /k/ with the vowel /i/. These repetitions were made of the isolated CV syllables and of the syllables in a Korean sentence context. The syllables were analyzed for segment durations of hold, transition and vocalic portions and fundamental frequency contours. The speech was recorded using a DAT recorder and analyzed using a CSL 4300B system. The effect of the speaking rate on the different phonemes will be discussed [R. Kessinger and S. Blumstein, ‘‘Effects of speaking rate on voice-onset time and vowel production: Some implications for perception studies,’’ J. Phonetics 26, 117–128 (1998); J. Miller and L. Volaitis, ‘‘Effect of speaking rate on the perceptual structure of a phonetic category,’’ Percept. Psychophys. 46, 505–512 (1989)].
Phonological neighborhoods and phonetic similarity in spoken word recognition
Authors: Yoneyama Kiyoko
Published: October 2013

English neighborhood literature has demonstrated that neighborhood density affects the auditory word recognition. However, an unresolved question is exactly how neighborhood density should be calculated. In this paper the definition of a lexical neighborhood is explored in Japanese. Data for the analyses were collected from Japanese neighborhood experiments using the same 700 test words and a lexicon that consisted of only nouns from the NTT psycholinguistic database [Amano and Konodo, 1999]. Three different neighborhood calculations were used to analyze the data. The first calculation was based on Greenberg–Jenkins phoneme substitution, deletion, and insertion rules. The second calculation included prosodic information as another dimension in the neighborhood calculation in order to reflect the finding that prosodic information has a vital role in Japanese word recognition. The third calculation was based on the auditory properties of the words in the lexicon. Neighborhood density was measured by comparing the similarity of cochleagrams of the 66000 audio files. The results of the analyses demonstrated that phonological similarity within the lexicon seems to be calculated based on higher-level abstract representations rather than on a lower-level acoustic-auditory representation in any of the experiments. The implications from the results to the current word recognition theories will also be discussed. [Work supported by NIH.]