bluuebunny/crossref_metadata_2025 huggingface dataset:
Signal processing strategies for autonomous underwater acoustic systems.
Authors: Hursky Paul , Siderius Martin , Porter Michael B. , McDonald Vincent K. , Stevenson John M. , Granger Brian
Published: October 2013

Designing autonomous systems for underwater acoustic applications presents a number of competing challenges—these systems must adapt to a wide variety of possible events without human intervention, and they must do so without using much power. To address these challenges, we have explored algorithms borrowed from software-defined radio, octave processing (aka proportional processing), parametric approaches (that do not require continuous sampling), and algorithms amenable to parallelism. Important functions for realizing autonomy include reducing the dimensionality of the data in stages, associating observations within and across platforms, maintaining multiple hypotheses, and opportunistic specialized processing to resolve outstanding ambiguities. We will describe our resulting embedded processing system and how we adapt this system to two related applications: environmental mapping and marine mammal observation. We will address the following questions: Does mobility help? Do greater numbers of less capable platforms help redress loss of individual platform capability? How much communications bandwidth do we need? We will close by presenting processing results produced by this system during several experiments at sea.
Geometrical distortion correction in attitude estimating Hough transformation.
Authors: Shiba Hisashi
Published: October 2013

In the previous meeting, a new underwater vehicle attitude estimation procedure was presented. It is based on a three dimensional expansion of the Hough transformation detecting the sea surface. It is robust for noise and does not require a priori knowledge whether the sea surface and/or the seafloor are in the obtained sonar image. After a rough investigation, it was found that two types of geometrical distortions sometimes affect the Hough transformation results. The distortions are intrinsic in the Hough transformation. One of them is caused by nonlinear relationship between the real space and the parameter space. Another originates from digital geometrical measurements. The former is able to be suppressed by the inverse Hough transformation. The latter is resolved by applying a Euclidean distance area measurement. The two methods are explained in detail in this presentation. These problems tend to be distinguished especially in severe noise environments and it is possible to emerge in usual line detections on two dimensional images. After explaining the two methods, the Hough transformation effectiveness for a real data is also shown by tank experiment results.
Robust adaptive beamforming: Evolution of approaches, analysis, and comparison.
Authors: Vorobyov Sergiy A.
Published: October 2013

A so-called worst-case-based robust adaptive beamforming approach has been proposed a few years ago. This approach has been followed up by a number of works, which significantly improved the implementation issues. Recently, two new approaches have been developed: the probability constrained based and sequential quadratic programing based approaches. The probability constraint based design requires the distortionless response constraint to be kept with a certain selected probability, while the worst-case-based design requires this constraint to be kept for the worst-case operational conditions. The sequential quadratic programing based approach uses the iterative estimation of the signal steering vector and, therefore, is significantly different from two two aforementioned designs. In this paper, we overview, analyze, and compare all the aforementioned approaches to robust adaptive beamforming design.
Broadband high frequency matched-field processing.
Authors: Debever Claire , Kuperman William A.
Published: October 2013

Adaptive matched-field processing (MFP) is extremely sensitive to environmental uncertainties. While conventional and adaptive techniques may work for low-frequency signals in well-studied environments, the localization performance usually degrades rapidly as frequency increases, such that MFP in the 3.5 kHz regime, in shallow water environments, is typically problematic. A broadband coherent method [IEEE J. Ocean. Eng. 21, 384–392], combined with white noise constraint and principal component techniques, is implemented to construct robust replicas from experimental data. Matched-field tomography is then used to better understand the origin of the frequency dependent MFP mismatch (uncertain bottom structure, sound speed fluctuations, or both), and the results are compared with simulations. Ultimately, we want to gain some insights into how to implement a robust matched-field processor for high-frequency scenarios without using experimental data to create replica vectors. In particular, we are seeking to understand the thresholds for adaptive processors as function of signal to noise ratio and frequency dependent environmental mismatch. [Work supported by ONR.]
From the sublime to the scientific: What musicians and acousticians can learn from each other.
Authors: Campbell Murray
Published: October 2013

Many university music programs include an acoustics module, often taught by a physicist. At the University of Edinburgh, such a module has existed since the 1850s; taking over this course as a junior lecturer was my introduction to the fascinating world of musical acoustics. It rapidly became clear that a meaningful communication between scientists and musicians required humility and willingness to learn from both sides. This lecture explores aspects of that mutual learning process, focusing on some controversial areas in which the reconciling of scientific and musical viewpoints has not always proceeded in a spirit of humility.
Hot topics in engineering acoustics.
Authors: Brown David A.
Published: October 2013

The maturation of single crystal piezoelectric materials in the past decade has spawned a renewed interest in traditional and new transducer designs for underwater acoustic and medical imaging applications. The engineering of acoustic devices based on piezoelectric crystals began in the first half of the 20th century and was overtaken by developments in ferroelectric ceramic compounds such as barium-titanate and lead-zirconium-titanate (PZT). These materials are now being challenged by engineered relaxor piezoelectric single crystals materials such as lead-magnesium (or zirconium or indium)-niobate-lead-titanate (PMN-PT, PZN-PT, and PIN-PT) in many applications. The new materials have tremendous improvements in piezoelectric properties including electromechanical coupling coefficients exceeding 90%, which can double the power factor bandwidth for underwater projectors, sound speeds that are a factor of 3 lower than PZT that enable compact low frequency sources, and strain levels as high as 1% for high drive and actuator applications. The hot topics related to engineering acoustics involve the development and commercialization of devices based on new and traditional transducer designs that exploit the novel properties of the new crystal materials. Examples of broadband underwater communications transducers, tonpiltz sonar projectors, pressure and pressure-gradient hydrophones, mechanical actuators, and medical devices are presented.
Enhancing the left edge: The phonetics of prestopped sonorants in Australian languages.
Authors: Butcher Andrew , Loakes Debbie
Published: October 2013

The consonant systems of Australian Aboriginal languages are very similar to one another but very different from those of most other languages of the world. They have unusually few contrasts in manner of articulation and an unusually large number of places of articulation. Previous research has shown that speakers appear to employ a number of strategies to preserve place of articulation distinctions, particularly in intervocalic (coda) consonants. One such strategy is that in vowel + nasal sequences speakers avoid lowering the velum until the latest possible instant, presumably to preserve spectral clarity at the VC boundary. This often results in a brief homorganic oral stop occurring before the nasal. Phonetically prestopped nasals occur in a large number of languages across Australia and have become distinctive phonemes in a number of languages in the center and south. Less well documented is the parallel phenomenon of prestopped laterals, which is taken to be the outcome of a similar coarticulation avoidance strategy. This paper describes the wide distribution and distinctive phonetic characteristics of prestopped nasals and laterals in a number of Australian languages and proposes that both strategies are aimed at the enhancement of the left edge of the sonorant consonant.
Comparing acoustical requirements of green building assessment systems.
Authors: Costello Amy , Roy Kenneth
Published: October 2013

As the Green Building movement gains momentum, more buildings are being evaluated and rated using the environmental assessment systems. A number of these systems now include acoustical requirements or award points for achieving a certain level of acoustical performance. However, how do these environmental assessment systems compare in terms of acoustical requirements? This paper examines and compares some of the leading national and international environmental assessment systems including LEED, BREEAM, Green Globes, and Collaborative for High Performance Schools, and evaluates the importance that acoustical performance is playing in green building rating systems.
Green hospitals: Acoustical challenges and opportunities.
Authors: Van Wyk Kenric
Published: October 2013

The United States Green Building Council and Green Guide for Healthcare have each adopted portions of the new American Institute of Architects (AIA) Interim Sound and Vibration Design Guidelines as the Reference Standard as points for their rating system. This paper gives a brief overview of the AIA guidelines, how they are addressed by these two leading sustainability rating systems, and how they impact the design of future healthcare facilities. Sustainable practices are changing to include acoustics and vibration design. However, even the best intent has some of its own challenges. How will healthcare facility design benefit from these design changes to include sound and vibration and what are the potential pitfalls?
Case study of the acoustical analysis for three leadership in energy and environmental design for school applications.
Authors: Robinson Threcia , Siebein Gary , Bettcher Adam , Jones Chris
Published: October 2013

Case studies of the leadership in energy and environmental design (LEED) analysis of an elementary school, a high school, and a college academic building were conducted. The case studies included field measurements of reverberation times within core learning spaces, noise insulation class ratings of walls between classrooms and other rooms as well as between classrooms and the exterior, and noise from building systems. The field measurements demonstrated that reverberation times generally met the criterion as designed. The walls between classrooms and walls between classrooms and other spaces generally required improvements to meet the LEED criteria. Noise from building systems generally met the 0 EQ point criterion. Few if any rooms met the +1 or +2 point requirement without special acoustical design including reduced air velocities, adding silencers in supply and return ductwork and moving terminal boxes and fan coil units out of the classroom spaces. Rooms adjacent to the mechanical rooms also generally exceeded the 45 dBA criterion for background noise due to both sound transmitted through the walls and through short duct runs. The study shows that standard school construction practices will have to be modified to meet the LEED for school criteria.
Leadership in energy and environmental design for schools 2009 acoustics prerequisite and credit evolution and future direction.
Authors: Kurtz Alexis , Bruck Daniel , Lubman David , Salter Charles
Published: October 2013

In May 2008, the U.S. Green Building Council (USGBC) released an updated acoustics prerequisite and credit for inclusion in the Leadership in Energy and Environmental Design for Schools 2009 Rating System. Guidance for the update was provided to the USGBC by the four acousticians in the Indoor Environmental Quality Technical Advisory Group, which focused on identification of key acoustical metrics and development of the credit for greater acceptance within the design and construction community. This paper discusses the process and challenges of balancing market factors, cost, and effective acoustical design for classrooms. The resulting prerequisite and credit are intended to be easily attainable within reasonable cost constraints for classrooms in all geographic regions of the United States. Future direction for classroom acoustics in green design, implications arising from poor classroom design, and the need for greater involvement of the acoustics community in credit development will also be discussed.
Geothermal heat pumps and acoustics for people who do not know much about geothermal heat pumps.
Authors: Ermann Michael
Published: October 2013

Geothermal heat pumps operate more efficiently than traditional heat pumps and air conditioners–much more efficiently–and have no noisy outdoor equipment. Yet, after inquiries to mechanical system manufacturers and to the Technical Committee on Architectural Acoustics Green Building Acoustics Subcommittee listserv, I have not found instances where these systems are specified for their acoustic performance. This paper presents a short tutorial on the basics of geothermal systems (also called geoexchange systems or ground-source-coupled heat pumps) geared to those without significant prior knowledge.
Leadership in Energy and Environmental Design (LEED) for schools: Providing room acoustics for classrooms that is affordable, green, and meets requirements.
Authors: Bridger Joseph F. , Stulgin Steven S. , George Mathew M.
Published: October 2013

Leadership in Energy and Environmental Design (LEED) for schools has added classroom acoustics (based on ANSI S12.60) to the prerequisite for all K-12 schools seeking the U.S. Green Building Council LEED certification and several points for achieving additional measures. LEED for schools’ room acoustics requirements are the same as the classroom acoustics standard. The U.S. Green Building Council has made it a prerequisite to receive certification for all K-12 schools. This paper explores how to achieve the requirements, while keeping it affordable and green.
Technical challenges in the acoustic detection of manatee vocalizations.
Authors: Niezrecki Christopher
Published: October 2013

Over the past several years there has been much interest in detecting the West Indian manatee (Trichechus manatus latirostris) in heavily used waterways to reduce the number of collisions with watercraft. The successful detection of manatee vocalizations at an appreciable range in the natural environment is largely dependent on the background noise levels. The background noise consists primarily of boat and snapping shrimp noise as well as other animals and natural sources of noise. In order for effective detection to be realized, advanced signal processing techniques must be used. Within this work, the scope of the problem is presented and some of the technical hurdles are described. Several advanced signal processing algorithms (to reduce background noise) are described and their effectiveness is presented.
Field tests of a directional parametric acoustic alarm designed to alert manatees of approaching boats.
Authors: Gerstein Edmund , Gerstein Laura , Blue Joseph , Greenewald Josiah , Elasmar Narayan
Published: October 2013

The efficacy of the alarm was documented during controlled slow boat approaches under two experimental conditions: (1) approaches without an alarm and (2) same boat approaches with an alarm. Experiments conducted in a NASA security area provided controlled environmental conditions and minimized anthrogenic acoustical variables. An array of GPS instrumented buoys were deployed to acoustically and visually grid sites. HD aerial video synchronized with these buoys documented behavior and acoustic conditions at focal animal positions and throughout sites. Bathymetry and propagation measurements indicate shallow water constraints along with Lloyd’s mirror effect resulting in significant transmission losses at frequencies of 1 kHz. This could account for the lack of response observed during 94% of the boat approaches without the alarm. In contrast, 100%, of the alarm approaches elicited overt avoidance responses. The change in behavior during approach trials was significantly greater during alarm trials F=76.74, df=1, p<0.01). The distance at which manatees responded was significantly greater during alarm trials (F=143.42, df=1, p<0.01). Applying conservative critical ratio estimates for wideband noise, manatees could not detect no-alarm approaches at distances of 9 m, while manatees responded to alarm approaches up to 35 m away at levels 18 dB above their estimated critical ratios. [Work funded by the U.S. Department of Defence Legacy Resource Management Program, (Navy), Florida Inland Navigation District, and Florida Fish and Wildlife Conservation Commission.]
Detection and classification of underwater movements with an in-air biosonar system.
Authors: Wang Maosen , Zell Andreas
Published: October 2013

The aim of this work is to take advantage of the perceived properties of fishing bats. An in-air biosonar system on a mobile robot is presented for the detection and classification of tiny movements under the water surface. Detecting and classifying underwater turbulence with in-air biosonar system allows mobile agent to sense underwater movement without dipping transducers into water. In this work, both fishes—4-cm long goldfish—and waterproof motors (3-W power, 2-cm diameter) are used as sources to generate underwater turbulence. According to real-time feedback results from digital signal processing, the in-air biosonar system on an autocontrolled robot scans water surface with task oriented chirps and sensing strategies. Fishes and motors can be detected and classified in time and frequency domain with a high percentage rate. Experimental result indicates that a mobile robot with in-air biosonar system can achieve the ability of underwater movement detection and classification. However, a precise localization depends heavily on the selection of sensing strategy. [Work supported by NSFC.]
Recognizing holographic perception.
Authors: Rikoski Richard
Published: October 2013

Recent robotics work has demonstrated that the holographic property of synthetic aperture sonar images can be used to enable object or terrain recognition using real aperture sonars. For instance, it was shown using Gulf of Mexico data from the small synthetic aperture minehunter that terrain can be recognized using as little as a single sonar element and a single ping. Similar capabilities have been ascribed to marine mammals, raising questions about whether the techniques are similar. This paper describes the basics of holographic perception and a series of experiments, which can be used to rule out its use.
A biomimetic acoustic system for threat detection and localization.
Authors: Deligeorges Socrates , Karl Christian , Field Leah , Xue Shuwan , Soloway Aaron , Lichtenstien Lee , Zosuls Aleks , Gore Tyler , Hubbard Allyn
Published: October 2013

As part of our development efforts to transition cutting edge algorithms to practical devices for use in the field, hardware and software systems using the biomimetic approach are being designed for real world battlefield conditions. A new digital system has been developed that not only improves on existing sniper detection and localization technology but also enables many other capabilities useful for enhanced situational awareness. Capabilities include detection of vehicles and personnel sounds such as speech and footsteps. Systems in development include soldier-worn, vehicle-mounted, and robot-mounted systems, as well as unattended ground sensor systems. Our systems can integrate acoustic target data with GPS and other sensor information using simple GUIs. These systems are modular with multiple interface ports for USB, Ethernet, RS-232, and standard audio jacks. As these systems are transitioned to dismounted soldiers, power, weight, and size become the driving factors in design choices. Additional capabilities such as tracking/identifying a variety of acoustics targets, enhancing warfighter hearing, and fusing information with other sensors (for no additional increase in size, power, and weight) can make these acoustics systems an even more valuable asset. Authors associated with BMS may realize financial profit with the success of this work.
Enhancing the functionality of a biomimetic acoustic direction finding system with back-end algorithms.
Authors: Pu Yirong , Kelsall Sarah , Hubbard Allyn
Published: October 2013

Increasing battlefield awareness can improve both the effectiveness and timeliness of response in hostile military situations. The front-end of the existing biomimetic acoustic direction finding system provides the back-end system with spike trains. The back-end algorithms, transportable to FPGA platforms and other general-purpose computers, are tailored to extract specific information for a variety of possible applications. The gunshot classification and localization (C&L) neural network algorithm can recognize and trace supersonic and muzzle-blast acoustic signals in an environment with a minimum SNR value of 1dB and a temporal resolution of 10 s. The C&L algorithm outperforms cross-correlation algorithms in computational efficiency, memory requirements, and noise robustness. Algorithms under development for speech processing are aimed at determining whether speech is present, identifying the speakers’ gender and classifying the language spoken. The gender identification algorithm is composed of single pitch-related measures that are weighted based on their estimated performance. Using a variety of speech record lengthens a type I error of 6–16%.
Improved time reversal focusing in complex media with inverse filter.
Authors: Callaghan Thomas , Papanicolaou George
Published: October 2013

We analyze the problem of improving time-reversal refocusing in a complex medium through the use of a noninvasive filter. A source at an unknown location emits a pulse, which is recorded by an active set of, possibly distributed, transducers called the focusing array. The goal is to use only the information available at the focusing array to refocus at the source location while minimizing the received energy away from the source. It has been shown that time-reversal in a random medium exhibits superresolution. However, we investigate further improvement of the resolution by first applying an inverse filter. In general, the construction of such a filter requires invasive measurements on a control array in the vicinity of the source, which we assume are not available. The noninvasive inverse filter utilizes only backscattered signals recorded when the focusing array probes the medium. The result is sharp refocusing at the source comparable to the improvement from use of the invasive filter. Possible applications include communications in complex environments where the goal is to send information to a particular location with low probability of intercept. Temporal compression is also important in communications and we investigate the effect of the inverse filter on this as well.
Fabrication and measurement of polypeptide-based piezoelectric composite polymer film.
Authors: Farrar Dawnielle , West James E. , Busch-Vishniac Ilene J. , Yu Seungju M.
Published: October 2013

A new class of polymer composite piezoelectric materials based on piezoactive biopolymer, poly(-benzyl,L-glutamate) (PBLG), and a matrix polymer, poly(methylmethacrylate) (PMMA), is presented. The composite polymer offers the possibility of decoupling the electrical and mechanical properties, therefore improving the overall system efficiency. By simultaneously poling and curing (at ambient conditions) PBLG and methylmethacrylate (MMA) mixture solutions, we fabricated a flexible composite film with a significant portion of the PBLG molecules oriented normal to the film surface. This film exhibited moderate piezoelectricity (d33=20 pC/N), and its mechanical characteristics were similar to those of low molecular weight PMMA. Present samples are about 40 μm thick with tensile strength of 13 MPa and Young’s modules of 450 MPa. The frequency response is ± 3 dB from 0.1 to 7 kHz and at 1 kHz is linear with acceleration more than a 10 dB range.
Better soundscapes for all workshops on continuing development of soundscape techniques standardization: Workshop introduction.
Authors: Schulte-Fortkamp Brigitte , Brooks Bennett
Published: October 2013

The perception of the soundscape can provide comfort, tranquility, and needed information to the person concerned or may be a source of annoyance. The combination of physical acoustical measurements with the scientific evaluation of perceptual responses to environmental sound, known as soundscaping, is an essential method for the assessment and actualization of positive outdoor environments. The characterization of the acoustical environment includes identifying the nature of the sound sources and the reactions of the perceivers. Soundscaping provides for the measurement, analysis, and design of environmental sound by applying the knowledge of both science and community experts. Much fundamental and practical research has been conducted to establish the bases for the soundscape field. In recent sessions and workshops researchers and practitioners have begun to standardize the available soundscape techniques to allow for more comparison of test and survey results and wider application in design. This workshop continues the discussion, evaluation, and standardization of proposed methods and techniques for soundscape analysis and design. The areas of focus will be a catalog of correlations between physical parameters and perceptual responses, the standardization of a terminology lexicon of soundscape descriptors, and the standardization of measurement procedures.
Experiments to develop soundscape design methods.
Authors: Siebein Gary , Fisher Joshua , Bettcher Adam , Robinson Threcia , Lilkendey Robert , Paek Hyun , Jones Chris , Skelton Reece
Published: October 2013

A proposed soundscape design method to evaluate acoustical impacts of planning and building projects on the surrounding community as a way to work toward net zero noise impacts is summarized. The concept of net zero impacts is borrowed from ecological planning where buildings are designed to produce as much energy as they use. The idea of a net zero noise impact is one where a building or planning project does not increase the existing ambient noise level during its use. The first step in this process is to define the nature of the existing ambient soundscape in the vicinity of the project. The method includes long term acoustical measurements of ambient sounds, short term detailed measurements of specific acoustic events, focus group meetings with residents and stakeholders to identify and evaluate acoustical issues, methods to map qualitative aspects of the soundscape, computer modeling of various types to assist in developing design alternatives, evaluation of possible weather effects, qualitative and quantitative assessments of calibrated aural simulations of design alternatives, and postconstruction verification methods. Examples from multiple case studies of large scale infrastructure and building projects are used to document strengths and weaknesses of the proposed method.
Soundscape standardization of measurement procedures.
Authors: Fiebig André
Published: October 2013

A wide range of measurement systems, questioning techniques, and analysis methods were already applied in previous soundscape studies over the past decades, but a common consent about meaningful procedures and required measurement systems is missing so far. However, a standardization of measurement procedures with respect to a uniform investigation, documentation, and description of soundscapes is required to allow for the valid comparison and analysis of different studies. Up to now, the diversity of used measurement procedures and technologies hinders the in depth derivation of cross-cultural similarities and dissimilarities in the physics of soundscapes and in the perception and assessment of soundscapes. In this paper, an overview of applied measurement technologies and procedures will be given as well as advantages and disadvantages discussed concerning the main questions: (1) how, (2) where, (3) when, and (4) how long must be measured. An initial step in the direction of a common basis of measurement procedures available for soundscape researchers was taken on the occasion of the workshop in Salt Lake City, 2007. This process must be continued. It will promote new ideas in the field of environmental noise research and enhance the acceptance of soundscape concepts in noise policy.
Implications of causality on acoustic propagation in highly dispersive bubbly media.
Authors: Orris Gregory , Dacol Dalcio , Nicholas Michael
Published: October 2013

Causality in nearly all physical systems has been a recurrent subject often causing apparent paradoxes since before the 20th century. Linear acoustic propagation through subsurface bubble clouds in the ocean offers an especially challenging physical system within which to investigate issues of causality, and has in the past had several competing fundamental theories. Signal travel times and absorption in such a system exhibit enormous variations depending on the acoustic signal frequency, bubble size distribution, void fraction, and other ambient physical parameters. In a recent work [Orris et al., J. Acoust. Soc. Am. 121, 3349–3362 (2007)] we presented a correction to some contemporary theories of acoustic propagation in bubbly media to bring them into compliance with the physical law of causality. We will discuss this theory within the context of complex analysis and some of its implications to acoustic signal propagation; also present experimental data, which commensurate with archival data, suggest that the theories are still far from offering a complete description of the physical phenomena surrounding acoustic propagation in bubbly media. Possible modifications will be explored that may lead to a complete self-consistent causal theory of acoustic signal propagation in bubbly liquids. [Work supported by the Office of Naval Research.]
Implicitly Causal Expansions in the Frequency Domain.
Authors: McDaniel J. Gregory
Published: October 2013

While the causality statement in the time domain is quite simple, the corresponding statement in the frequency domain involves Hilbert transform relations between the real and imaginary parts of the relevant transfer function. If the transfer function is minimum phase, one can go further and develop Hilbert transform relations between the amplitude and phase. Such relations are important and useful in at least two classes of problems: analysis of frequency-sweep data and active control. In both problems, one usually wishes to simultaneously enforce the causality statement while achieving some other goals. This lecture will explore various ways of accomplishing this and will focus on implicitly causal expansions of transfer functions in the frequency domain. The expansion functions are built directly from Hilbert transform pairs and therefore the series is guaranteed to be causal. One example is a complex Fourier series in frequency in which the coefficients are required to be real valued. Examples will be developed in which the causal series expansions are used to improve the quality of data, by eliminating noncausal noise and to achieve active control. [This work was supported by the Office of Naval Research under Grant N00014-99-1-1017.]
Development of temporal characteristics in the speech of hearing impaired preschoolers.
Authors: VanDam Mark , Smith Nicholas A. , Ide Helvie Dana , Moeller Mary Pat
Published: October 2013

This longitudinal study examined the development of temporal speech properties in hearing impaired and normal hearing children at 4 and 5 years of age. Children repeated a list of target words following the experimenter's model. Measures of duration for onset, nucleus, coda, and syllable were collected for children with normal hearing and children identified early (mean = 3 months) versus late (mean = 30 months) as hearing impaired. Main effects of age and group were observed for nucleus, coda, and syllable but not onset duration. Early-identified children were more similar to normal-hearing children than late-identified peers, despite early-identified children having much less hearing (mean diff. = 40 dB HL). Age and group differences were examined using (1) relationships among acoustic duration measures, (2) phone-by-position accuracy, and (3) spoken word intelligibility to assess the influence of hearing experience on development. Although there was a wide individual variation, results suggest benefits of early identification: early identified hearing impaired children performed more like normal hearing children. Results favor a “delayed-acquisition” over “different-mechanism” model for the development of temporal speech properties in children with hearing loss. [Work supported by NIH-NIDCD T32 DC00013-26; R01 DC006681; and P30 DC04662.]
Children’s articulatory constraints inferred from acoustic output: How some speech-sound errors arise.
Authors: McGowan Richard S. , Nittrouer Susan
Published: October 2013

Our investigations of children’s speech acoustics indicate that normally developing children exhibit speech behavior that is not simply scaled adult behavior. Specific anatomical differences between children’s and adults’ vocal tracts cause these effects: For example, the size of the tongue in relation to the size of mouth decreases with age. The effects of these age-related anatomical differences have been identified for preschool children as young as 1 year of age in phonetic segments, such as /ɹ/, /s/, and /∫/. These anatomic differences may lead children to produce subphonemic distinctions, as between /r/ and /w/ in English. Children’s anatomical features can also affect sounds generally not considered to be difficult for normally developing children to produce, such as syllable-initial stops. We have noted children 12–18 months old producing intended /g/ that is often transcribed as /d/ by adult listeners. However, fronted velar /g/, which could be the result of a large tongue size in relation to palate size, exhibits subphonemic distinctions with children’s /d/. The behaviors arising from early anatomical features can be preserved into school age and be labeled as aberrant articulation.
Psychoacoustic measures of stop production in Cantonese, Greek, English, Japanese, and Korean.
Authors: Arbisi-Kelm Timothy , Beckman Mary , Kong Eunjong , Edwards Jan
Published: October 2013

Spectral analyses of stop bursts have revealed that the place of articulation can be predicted based on both invariant and time-varying cues present within the acoustic signal (e.g., Stevens and Blumstein, 1978; Forrest et al., 1988). While prior studies have had some success in uncovering such cues for American English, it is not clear whether these parameters are equally pertinent in stoping consonant classification in other languages. Furthermore, one of the main limitations of a linear acoustic analysis is that it imposes different scales of loudness and frequency on the acoustic signal than does the human ear, thus generating power spectra with different frequency distributions than are produced by the auditory system (e.g., Zwicker 1961; Kewley-Port, 1983). In the present study of word-initial stops produced in Cantonese, English, Greek, Japanese, and Korean, measures derived from a psychoacoustic model of auditory perception were developed in order to more accurately isolate the front cavity resonances of the burst transient. For all languages, peak amplitude frequency and a peak compactness measure successfully distinguished alveolar from velar stops with at least 74% accuracy and were more accurate at stop classification than were spectral moments measures.
The effect of secondary labialization on stop burst spectra.
Authors: Suh Yunju
Published: October 2013

Secondary labialization increases the size of the cavity before /t/ and /k/ constrictions, rendering their burst spectral energy concentrated in the lower-frequency region than when they are not labialized. However, the peak location and center of gravity of the Spanish and the Korean stop burst spectra before /(w)e/ and /(w)a/ only captured the frequency lowering effect of labialization on /k/ bursts and failed to distinguish between the plain and labialized /t/ bursts. Spectral shapes of both /t/ and /k/ bursts were altered by /w/ but in different ways: The single prominent peak of the compact /k/ burst spectra was located in significantly lower frequency when it co-occurred with /w/, whereas the two prominent peak locations did not differ between the plain and labialized /t/ burst spectra. What differentiated /tw/ from /t/ instead were the nonexistence of the high-frequency peaks (above 4 kHz) and the amplitude increase of the peak around 3 kHz in /tw/. As a result, /tw/ burst had spectral energy concentrated below 4 kHz, unlike diffuse /t/ spectra whose energy was spread over a wider frequency range. The amplitude ratio between the mid-, and high-frequency regions (Amid-Ahi) successfully captured this difference between the plain and labialized coronal stop bursts of both Korean and Spanish.
Acoustic features of American-English vowels for English, Chinese, and Korean talkers.
Authors: Liu Chang , Kamdar Sangeeta
Published: October 2013

Sixteen American-English vowels including 12 monothongs and 4 diphthongs were recorded in a phonetic context of /hvd/ from young English, Chinese, and Korean talkers. The Chinese and Korean talkers were bilingual and had stayed in US from 6 months to 6 years. Results of acoustic analysis showed that there was no significant difference in F1×F2 vowel space among the three groups of talkers. In addition, the three groups of talkers showed great similarity in F2/F1 ratio across the 12 monothongs. Vowel durations had significantly greater variability across vowel categories for the Chinese and Korean talkers than for the English talkers, indicating that, besides producing spectral differences among vowels, Chinese and Korean talkers also attempted to generate durational difference among vowels to make each vowel distinguishable from others. More acoustic features such as spectral tilt and formant transition in the diphthongs will be discussed as well as the effects of the second language experience.
Acoustic properties of clear speech in dysarthria.
Authors: Tjaden Kris , Sussman Joan , Szjata Erin , Liu Grace , Fulcher Katrina , Hilczmayer Beth , Crumb Miranda , Johnson Ken
Published: October 2013

Clear speech produced by neurologically normal speakers has been shown to be more intelligible than conversational or habitual speech, although the magnitude of the effect varies widely among speakers. Speech production strategies underlying the improved intelligibility associated with clear speech have also been described in a number of acoustic studies. Although clear speech effects would be of interest in speech disorders such as dysarthria, where habitual intelligibility may be compromised, few dysarthia studies have examined clear speech [see A. Goberman and L. W. Elmer, J. Comm. Disord. 38, 215–230(2005)]. The current study reports acoustic characteristics of clear speech for individuals with dysarthria secondary to multiple sclerosis and idiopathic Parkinson’s disease. A group of healthy control speakers was studied for comparison purposes. As part of a larger study, all speakers produced a list of 25 Harvard sentences in habitual and clear speaking conditions. Both segmental and suprasegmental acoustic measures will be reported. Group effects as well as individual speaker trends will be examined. [Work supported by NIH]
Acoustic characteristics of Lombard speech in Parkinson’s disease patients.
Authors: Al-Fwaress Firas , Boyce Suzanne , Groves-Wright Kathy , Neils-Strunjas Jean , Ball Angel
Published: October 2013

Lombard speech refers to the well-known effect by which speakers talk differently in a noisy environment than they would in a quiet environment. This difference involves both increased loudness and acoustic phonetic characteristics that enhance intelligibility. Parkinson’s disease (PD) patients who show reduced intelligibility of speech have also been shown to exhibit impaired sensory integration of auditory feedback [Kiran Larsen, JSLHR, 2001]. In this paper, we examine the Lombard effect on speech in noise by PD patients and healthy age-matched controls. The results of acoustic phonetic measures suggest that the Lombard speech behavior of PD patients without dysarthria resembles that of control subjects both in quiet and in noise. However, patients with mild-to-moderate dysarthria show fewer effects of Lombard speech, suggesting that their ability to adjust the intelligibility of their speech in noise is correlated with their level of dysarthria.
Does vowel inventory or inventory size condition the articulation of /i/ and /y/?
Authors: Jackson Michel T.-T. , McGowan Richard S.
Published: October 2013

Wood [J. Acoust. Soc. Am. 80, 391–401 (1986)] and dispersion-focalization theory (DFT) [Schwartz et al., J. Phonetics 25, 255–86 (1997)] have made differing predictions about variation in the articulation of /i/ and /y/. Wood claimed that there are “language-specific tendencies to either prepalatal or midpalatal tongue positions for palatal vowels … languages contrasting [i] with [y] preferring the prepalatal position for both vowels” [Wood (1986), p. 392]. However, DFT predicts that the high-front vowel /i/ is always driven to near the high-front corner of the acoustic space in order to maximize perceptual-acoustic distinctness from the rest of the vowels in the inventory of the language. In addition, it is possible that languages with smaller vowel inventories have less extreme articulations for “corner” vowels such as /i/ and /y/ overall. In this study, we compare articulatory measures of constriction location, extent, and degree in four languages (with /y/ versus without /y/ and small inventory versus large inventory).
Variation in stop consonant voicing in two regional varieties of American English.
Authors: Jacewicz Ewa , Fox Robert Allen , Lyle Samantha
Published: October 2013

This study is an acoustic investigation of the nature and extent of consonant voicing of the stop /b/ in two dialectal varieties of American English spoken in south-central Wisconsin and western North Carolina. The stop /b/ occurred at the juncture of two words such as small bids, in a position between two voiced sonorants, i.e., the liquid /l/ and a vowel. Twenty women participated, ten representing the Wisconsin and the North Carolina variety, respectively. Significant dialectal differences were found in the voicing patterns. The Wisconsin stop closures were usually not fully voiced and terminated in a complete silence followed by a noisy and voiceless closure release, whereas North Carolina speakers produced mostly fully voiced closures. Further dialectal differences included the proportion of closure voicing as a function of word emphasis. For Wisconsin speakers, the proportion of closure voicing was smallest when the word was emphasized and it was greatest in nonemphatic positions. For North Carolina speakers, the degree of word emphasis did not have an effect on the proportion of closure voicing. The results are discussed in terms of differences in the way voicing is maintained during the closure by the speakers of respective dialects. [Work supported by NIH..]
Acoustic characterization of harbors and ports.
Authors: Becker Kyle M. , Bradley David L. , Barber D. Christopher , Zucker Michael L , Kankey Andrew T.
Published: October 2013

The use of acoustics has become increasingly important in shallow waterways including ports and harbors. Applications span a range of military, commercial, and recreational interests including mine detection, port protection, and diver interaction. Harbor environments present challenges to acoustic propagation that are not encountered in the deep ocean or more open shelf environments. Characteristics that contribute to the unique acoustic propagation characteristics include typically very shallow depths, highly variable ambient noise levels, the presence of strong scatterers, and tidal effects. In a typical harbor, even a 1- or 2-m tidal variation can represent a change of 10% or more in the water depth. In this work, in situ measurements of low-frequency acoustic propagation are presented for a harbor near Newport, RI. The objective was to assess the propagation channel from a finger pier in a confined harbor out to the main shipping channel in Narragansett Bay and incorporate the findings into acoustic propagation models for this and similar environments. Of particular interest are the effects of tidal variations and changing background noise levels on the ability to detect different signals. [Work supported by ONR.]
Linear array beamforming in harbor environments.
Authors: Barber Christopher , Becker Kyle M. , Bradley David L. , Zucker Michael L. , Kankey Andrew T.
Published: October 2013

The use of linear arrays of sources to focus low-frequency sound on a target zone of limited spatial extent in a very shallow water environment is a topic of current interest for applications such as harbor defense. While linear array beamforming provides a starting point, the analytical expressions for beam response of a line array found in standard acoustics texts are developed for arrays of compact simple sources in a free-field environment. In contrast, the typical harbor environment is characterized by very shallow water depths, varying bottom conditions, irregular vertical boundaries, and the presence of multiple scattering bodies. In addition to environmental conditions, the size and cost of low- frequency sources limit the validity of the simple source assumption and impose practical limits on the number of sources and maximum aperture length. Standard beamforming calculations are compared to measured data from a June 2008 harbor acoustic propagation experiment to quantify limitations of the linear array theory in estimating the beam response and three-dimensional sound field generated by an array of a small number of noncompact low-frequency sound sources in a real harbor environment. The relative impacts of environmental factors and source characteristics are also discussed.
Acoustic propagation in a shallow water duct with large obstructions.
Authors: Zucker Michael , Bradley David , Becker Kyle
Published: October 2013

The characteristics of shallow water harbor or mooring environments present unique challenges to an acoustic propagation modeler. Established acoustic propagation codes were developed to address problems in deep water or more open shallow water environments where spherical or cylindrical geometries and one-way propagation approximations can easily be employed. In shallow harbors, large structures, including pier pilings and deep-draft vessels, that represent a significant blockage of the water-column propagation path may need to be accounted for. It is of interest to predict the received levels of the acoustic field transmitted past these obstructions. In order to more easily and accurately represent the complicated geometry of the boundary conditions encountered in this environment, a finite element model (COMSOL) is used. Using this model, predictions of the impact on low-frequency acoustic propagation by structures typically encountered in a harbor are made.