bluuebunny/crossref_metadata_2025 huggingface dataset:
Calibration and assessment of noise monitoring instrumentation used by the Mine Safety and Health Administration
Authors: Homer John P.
Published: May 2015

The use of noise dosimeters is the standard method for noise exposure monitoring and assessment in the United States mining industry. The Mine Safety and Health Administration (MSHA) calibrates and maintains a fleet of various noise dosimeters and acoustical calibrators for the purpose of conducting enforcement activities and providing technical support to mine operators. The dosimeter fleet is comprised of both corded- and badge-type instruments. MSHA studies have conclusively revealed evidence in support of both types as to performing acceptably both in practice and when tested against standardized criteria, ANSI S1.25-1991. MSHA operates an acoustical calibration laboratory which maintains National Institute of Standards and Technology (NIST) traceable calibration records for all noise dosimeters and calibrators used for enforcement and support functions. The laboratory is currently in the process of modernization. Replacement test systems will provide increased reliability, reduced turn-around time, and improved accuracy through the implementation of modern computer-based components. Improvements provided by the laboratory modernization project will greatly improve quality assurance and provide the ability to pursue accredited compliance with ISO/IEC 17025:2005, through the American Association for Laboratory Accreditation (A2LA).
Measurement and analysis of noise and acoustic emission on a roof bolter for identification of joints and in rock
Authors: Rostami Jamal , Bahrampour Soheil , Ray Asok , Collins Craig
Published: May 2015

Interpretation of the data obtained from roof bolt drilling can offer a reliable source of information that can be used to characterize the ground for use in ground support design and evaluation. Drilling for installation of roof bolts is done by various drills and often it is a noisy process. The acoustic emission from the drill can be used as a source for identification of the rock formations and voids/joints in the rock mass. This paper offers a brief review of the ground support using roof bolts, followed by introduction and discussion of the roof characterization methods by instrumented roofbolters. In particular, installation of noise measuring sensors on the drill head to provide additional source of information will be discussed. The analysis and digital filtering of measured noises was used to identify the voids or joints in the full scale testing. A brief overview of the instrumentation and full scale testing, as well as review of the results of initial testing on an instrumented drills will be offered in the paper. The paper will introduce an algorithm for digital filtering of the acoustic emission to identify the discontinuities in the rock mass.
Field evaluations of a noise control for roof bolting machines
Authors: Azman Amanda
Published: May 2015

Roof bolting machine (RBM) noise is a significant health hazard in underground coal mining because the sound levels at the operator’s station often exceed 100 dB(A). Drilling the hole prior to installing a roof bolt is the most significant source of RBM operator noise exposure. The dominant source of drilling noise is the drill steel. NIOSH has developed an enclosure to surround the drill steel as it is drills the hole to reduce the noise reaching the machine operator. The collapsible drill steel enclosure, or CDSE, is designed to collapse upon itself as the drill steel is further advanced into the mine roof so the drill steel can remain enclosed during the entire hole-drilling process. Original versions of this device effectively reduced noise exposure, but were deemed unacceptable by the mining community due to various usability and durability issues. A modified version has been developed and NIOSH laboratory tests revealed a 2–4 dB(A) noise reduction. This paper describes the in-mine evaluation of the redesigned CDSE. The field tests focused on the noise reduction as well as miner acceptance of the device. The results confirm improved usability as well as a 42% reduction in noise dose at the operator position.
Mandarin Chinese vowel and tone identification in noise: Effects of native English experience
Authors: Li Mingshuang , Wang Wenjing , Tao Sha , Dong Qi , Guan Jingjing , Liu Chang
Published: May 2015

Several studies found differences in English vowel identification between Chinese-native listeners in the United States (CNU) and China (CNC) in multi-talkers babble (MTB) and temporally modulated (TM) noise, but not in quiet condition. Two possible explanations were proposed: first, CNU listeners used temporal modulation of noise more efficiently than CNC listeners; second, CNU listeners had less informational masking of MTB than their CNC peers. The current study aimed at exploring whether the difference in noise processing between CNU and CNC listeners was also presented for their native speech perception. Chinese vowel and tone identifications were measured for CNU and CNC in quiet, stationary and TM noise, babble-modulated noise and MTB. The identification scores of CNU listeners were significantly higher than CNC listeners in most noisy backgrounds, whereas both groups had the same performance in quiet. Moreover, compared with CNC listeners, CNU listeners gained greater masking releases from temporal modulation in noise at low SNRs, while the informational masking was comparable between the two groups. In conclusion, the 1–3 year residency in English-speaking country may improve Chinese-native listeners’ capacity to use temporal cues in noise, but may not improve their ability against informational masking of English babble when listening to their native speech.
Cross-linguistic vowel variation in Saterland: Saterland Frisian, low German, and high German
Authors: Heeringa Wilbert , Schoormann Heike , Peters Jörg
Published: May 2015

This study investigates the vowel space of trilingual speakers of Saterland Frisian, Low German, and High German. The three vowel systems show differences in the number of distinct categories but share the majority of vowel qualities. To examine whether the size of the vowel space correlates positively with the number of vowel categories and whether distinctive vowels are positioned in the vowel space so as to increase perceptual contrast (Liljencrants and Lindblom, 1972, Lindblom, 1986) speakers were instructed to read vowels of all three languages in a /hVt/ frame. Measurements of mid-vowel F1 and F2 of monophthongs neither revealed a positive correlation between the size of the vowel space and the inventory size nor cross-linguistic differences of dispersion, except for a higher dispersion of High German vowels in the F2 dimension. Single vowel categories of Saterland Frisian and Low German were merged with respect to formant frequencies and duration. High German showed longer vowel duration and higher F2 of the front vowels than Saterland Frisian and Low German and a lower F1 than Low German. These results suggest that the trilingual speakers use the same phonetic categories for Saterland Frisian and Low German but not for High German.
Mapping vowels from American English to Taiwanese Mandarin: A perceptual study
Authors: Wang Yu-sheng , Chang Yueh-chin , Hsieh Feng-fan
Published: May 2015

It has been noted that vowel backness is largely preserved in English-to-Mandarin loanwords, but not vowel height. This asymmetry contradicts the native phonological patterns. The aim of this study is to re-examine this issue from an experimental perspective. Ten Taiwanese Mandarin (TM) speakers (aged 23–30) participated in this experiment. English Stimuli consisted in /CVmi/ sequences with C corresponding to one of the three consonants {b, d, g} and with V to one of the four vowels {ɛ, ɔ, æ, ɚ}. Mandarin stimuli also consisted in /CVmi/ sequences with C corresponding to one of the three consonants {p, t, k} and with V to one of the following vowels {i, a, u, ei, ie, au, ou, uo}. The participants were asked to rate similarity between American English and TM vowels (on scale 1–7). Our results partially support the generalizations in loanword adaptation, namely that TM speakers tend to map English [æ] onto Mandarin [ei], rather than [a], while [ɔ] is mapped to [ou/uo], [ɛ] to [ei], and [ɚ] to [ɣ]. We further measured the perceptual distance between English and Mandarin vowels by means of Euclidean distance. Given the assumption that smaller acoustic distance means greater perceptual similarity, it turned out that only this pair (English [ɚ] and Mandarin [ɣ]) can be explained away. It is thus concluded that loanword adaptation is not entirely based on raw acoustic signals. Phonological features and phonotactics also play a significant role.
Are opaque patterns what we think they are? The acoustics of the Bengali vowel chain shift
Authors: Nagle Traci C. , Berkson Kelly H.
Published: May 2015

The chain-shift pattern of vowel height harmony in Bengali, in which low and mid vowels in monosyllabic verb stems alternate with mid and high vowels, respectively (æ~e, e~i, ɔ~o, o~u), is reported in the phonological literature and by Bengali linguists to be exceptionless. Experimental evidence, however, indicates that Bengali speakers extend this pattern to nonce verbs only about half the time when low vowels are involved. This raises questions about the productivity of the attested pattern, echoing the results of experimental tests of chain shifts in other languages (e.g., Polish, Taiwanese) in which speakers fail to extend opaque phonological patterns to nonce words. One question we may ask is whether the phenomenon described in the literature as an alternation truly neutralizes the vowel height contrasts in the Bengali language. This research presents instrumental acoustic analysis of Bengali vowels produced by native speakers in real and nonce verbs in order to address this question and gain new insight into both the quality of the vowels produced as a result of harmony in real words and how speakers apply the pattern with nonce verbs.
Temporal organization of frication in fricativized vowels
Authors: Faytak Matthew
Published: May 2015

Fricative vowels are vocoids that exhibit a clear formant structure as well as fricative noise produced by a labiodental or (post)alveolar constriction (Connell 2007). Apical vowels, similar vocoids found in many Chinese languages, have known (post)alveolar constrictions, but it has been debated whether or not these actually generate substantial fricative noise (cf. Lee-Kim 2014). In order to better understand the relationship between these two segment types, acoustic data was obtained for the fricativized vowels in two Chinese languages (Standard Mandarin and Suzhou Wu) as well as Kom, a Grassfields Bantu language spoken in Cameroon. Analysis of fricativized vowel spectra and timecourses suggests two predominant types, one with steady-state fricative noise of a relatively low intensity, and a second that is more internally dynamic, exhibiting high-intensity frication toward the beginning of the vowel and lower-intensity frication towards the end. Standard Mandarin’s apical vowels are shown to be broadly consistent with the second type, with less frication than typically described impressionistically. However, Suzhou Wu and Kom speakers vary between the two types. This suggests that the language-specific phonetic implementation of this fricative noise does not neatly align with any commonly used descriptive terms.
Cross-linguistic spectral and voicing properties of [v]
Authors: Bjorndahl Christina
Published: May 2015

This study reports on the spectral characteristics and voicing properties of [v] in English, Greek, Russian, and Serbian, specifically testing whether inventory structure and the phonological status of [v] correlate with phonetic differences. Phonologically, [v] patterns with obstruents in Greek and English, with sonorants in Serbian and with both obstruents and sonorants in Russian. The present study expands upon previous work in two ways. First, it compares the results to English, which differs from the other three languages in having [w] against which [v] contrasts. Second, it tests the hypothesis that spectral differences correlate with the degree of devoicing. Our results show that [v] is fully and consistently voiced throughout its duration in Greek, Russian, and Serbian, regardless of environment, but exhibits significant devoicing in all environments in English, and moreover varies greatly across speakers. These results show first that the correlation between the spectral properties and phonological status of [v] in Greek, Russian, and Serbian does not arise due to differences in the degree of devoicing of [v]. Second, they suggest that when phonological status is the same, as in Greek and English, other factors such as inventory structure may interact with the phonetic realization of a segment.
Dental, or retroflex, that is the question: A study of Mina stop consonants
Authors: Abell Alexandra , Lulich Steven M.
Published: May 2015

Mina (also commonly known as Gen) is a language spoken in Togo and the Mono department of Benin. Mina remains little studied in comparison to the related language Ewe. The present study attempts to shed light on Mina phonetics. In particular, the question whether Mina voiced coronal stops form a single category or two categories distinguished by retroflexion is investigated through acoustic, articulatory, and perceptual analyses.
An acoustic study of pulmonic and ejective stops in the final coda position in Yucatec
Authors: Noguchi Masaki
Published: May 2015

In this study, I present an acoustic analysis of contrast between pulmonic and ejective stops in the phrase final coda position in Yucatec, a Mayan language. Ejective consonants are found in about 16% of the world’s language, and there are a relatively large number of acoustic studies about these sounds. However, a significant empirical shortcoming of the previous studies is their exclusive focus on the acoustic realization of ejective consonants in the syllable onset position. This is partly due to a cross-linguistic tendency that ejective consonants are prohibited to occur in the syllable coda position. Therefore, data from Yucatec, which allows ejective consents to occur in the syllable coda position, fill the empirical gap. This study compared pulmonic stop /k/ and ejective stop /k’/ in the phrase final coda position taking a number of acoustic measurements. The results showed (1) stop release is shorter for the ejective, (2) stop closure duration is shorter for the ejective, (3) stop release noise intensity is higher for the ejective, and (4) the contrast between pulmonic and ejective stops affects the voice quality of the preceding short vowel (H1-H2 is lower for the short vowel preceding the ejective).
The comparison of auditory capacity between bilinguals and monolinguals by consonant–vowel dichotic test
Authors: Motlagh Zadeh Lina , Jalilvand Karimi Leila , Silbert Noah
Published: May 2015

The purpose of the present study is investigation of differences in auditory capacity between bilinguals and monolinguals using the consonant–vowel (CV) dichotic perception test. Bilingualism is one well-studied in psychology and linguistics, with a number of studies revealing that exposure to two languages can lead to the changes in the central system. Auditory capacity refers to the ability to relay information in sound patterns to higher brain centers, with observed measures of auditory capacity reflecting the maximum amount of information that can be processed by the auditory system. The present study probed auditory capacity in 80 normal individuals, 40 bilinguals and 40 monolinguals. Members of the bilingual groups spoke either Turkish or Kurdish from birth and began learning Persian as a second language at or before 6 years of age. Listeners identified distinct consonants presented to each ear in a CV dichotic perception test. Consonant identification accuracy served as a measure of auditory capacity of individual listeners. Results indicated that auditory capacity was greater in the bilingual group. In general, higher scores were gained by bilinguals relative to monolinguals. Due to the large number of bilinguals, knowledge of the similarities and differences between bilinguals and monolinguals and investigation of the effects of second language on central auditory processing are important.
Accounting for multicompetence and restructuring in the study of speech
Authors: Chang Charles B.
Published: May 2015

Phonetic studies meant to generalize to monolingual speakers of a target language have often examined individuals with considerable experience using another language, such as the immigrant native speaker. This paper presents, first, results from a meta-analysis of the literature, suggesting that conflation of ostensibly bilingual (“multicompetent”) individuals with monolinguals remains common practice and, second, longitudinal data on speech production that demonstrate why this practice is problematic. Adult native English speakers recently arrived in Korea showed significant changes in acoustic properties of their English production during their first weeks of learning Korean (“phonetic drift”) and, furthermore, continued to show altered English production a year later, months after their last Korean class and without extensive use of Korean in daily life. These patterns suggest that the linguistic experience associated with residence in a foreign language environment tends to induce and then prolong phonetic drift of the native language, making the multicompetent native speaker living in a foreign language environment unrepresentative of a monolingual in the native language environment. The speed and persistence of these effects highlight the need for language researchers to be explicit about the population under study and to accordingly control (and describe) language background in a study sample.
Adaptation to accent affects categorization, but not basic perceptual representation
Authors: Lehet Matt , Holt Lori L.
Published: May 2015

Listeners rapidly reweight the mapping of acoustic cues to speech categories in response to local changes in short-term input [Idemaru & Holt, 2011]. For instance, when encountering an accent that reverses the typical correlation of acoustic cues to speech category membership. Here, we examined the level at which this rapid learning occurs. Listeners incidentally encountered an artificial accent in Blocks 1 and 3 of a vowel categorization task. In these blocks, the typical relationship between spectral quality and duration was reversed for /ε/ and /æ/ (setch, satch) such that /ε/ had longer durations than /æ/. Participants down-weighted their reliance on the duration of spectrally ambiguous vowels after brief exposure to the accent. They rapidly returned to using duration when the English correlation was restored (Block 2). Additionally, we tested whether vowel duration exerts a durational contrast effect on adjacent consonants and, if so, whether this effect was modulated by perceptual down-weighting of duration in Blocks 1 and 3. We observed consistent durational contrast effects across blocks. Even when participants down-weighted vowel duration for categorization, vowel duration exerted a durational contrast effect on the following consonant. Learning leaves the basic perceptual representation intact. We describe a model of the results.
Nonnative phonetic category training in varying acoustic environments
Authors: Vlahou Eleni L. , Seitz Aaron , Kopčo Norbert
Published: May 2015

Past research has shown that reverberation has a pronounced detrimental effect on speech intelligibility, but no previous studies investigated how it affects the acquisition of novel phonetic categories. Here, we present a follow-up to a previous study that examined adult nonnative phonetic learning using speech stimuli presented in reverberant environments [Vlahou et al. (2014), ARO Abstract #806]. Listeners were trained to discriminate a novel dental-retroflex contrast in Hindi. Using virtual acoustics, stimuli were presented in anechoic space, in a single room, or in multiple rooms. For some subjects, training was supervised, consisting of a 2AFC categorization task with trial-by-trial feedback. For other subjects, training was unsupervised, in the form of a videogame which promoted stimulus-reward contingencies. Performance was evaluated on trained and untrained sounds presented in familiar and unfamiliar rooms. Overall, trained listeners outperformed untrained listeners. Supervised training induced more robust learning of the trained material and generalization of learning to untrained voice. Introducing multiple reverberant environments was beneficial for unsupervised, but not for supervised, training. These results suggest that phonetic adaptation to reverberation is robust and that experiencing novel phonemes in various acoustic environments can enhance unsupervised phonetic category learning. [Work supported by APVV-0452-12, TECHNICOM ITMS: 26220220182, and NSF-BCS-1057625.]
English listeners use suprasegmental lexical stress online during spoken word recognition
Authors: Jesse Alexandra , Poellmann Katja , Kong Ying-Yee
Published: May 2015

Lexical stress facilitates spoken word recognition. In English, listeners primarily rely on vowel reduction in unstressed syllables as a cue to lexical stress, but are nevertheless sensitive to suprasegmental cues (Cooper et al., 2002 Lang. Speech). In the present study, we tested with a visual-world eye-tracking paradigm whether English listeners utilize suprasegmental stress cues online during word recognition. On each trial, listeners heard one of four displayed printed words. Two of the words (critical words) were segmentally identical in their first two syllables but differed in the suprasegmental realization of stress in their first syllable. The first syllable had either primary (e.g., admiral) or secondary (admiration) lexical stress. The other two words were phonologically and semantically unrelated to the critical items. In the critical word trials, listeners looked more frequently at the targets with initial primary stress than at the competitors with secondary stress during the presentation of the first two syllables. No difference was found when the targets had secondary stress. The degree to which competitors were fixated was not modulated by stress. This suggests that English listeners use the presence, but not the absence, of suprasegmental cues to primary lexical stress during word recognition.
Perceptual scaffolding of non-native speech categories through videogame-based training
Authors: Liu Ran , Holt Lori L.
Published: May 2015

Adults learn many new tasks with ease, but acquiring the sounds of a new language is notoriously difficult. Decades of attempts to develop effective training regimens have focused primarily on highly explicit approaches to training adults to categorize non-native speech sounds. Participants are aware of the phonetic distinctions they are learning, focus their attention on the contrasts or categories of interest, and are provided with some form of overt trial-by-trial feedback. A growing body of perceptual learning research suggests that directing attention away from the task of learning sounds by embedding training in tasks with overt goals that are unrelated to sound training can lead to efficient learning gains. We leverage this idea to incidentally train native English-speaking adults on non-linguistic auditory categories that are highly relevant to Mandarin Chinese lexical tone perception. We observed significant incidental learning of the nonspeech auditory categories as a result of five days of incidental videogame training and highly significant generalization to natural spoken productions of Mandarin tones. We also observed preliminary evidence that nonspeech category learning transferred to boost Mandarin vocabulary learning. We discuss these results in the context of incidental category learning and perceptual scaffolding of non-native speech categories.
Information-theoretic optimization of multiple-sensor positioning for passive narrowband acoustic source localization
Authors: Hayward Thomas J. , Potter Mitchell A.
Published: May 2015

Fundamental information-theoretic quantities, including conditional entropy of source location given received complex spectral values and per-iteration information gain (relative entropy) are applied as performance metrics to the optimization and real-time adaptation of receiver array spatial configurations for iterative (sequential) Bayesian localization of narrowband acoustic sources. Computational examples illustrate the application of these performance metrics to the adaptation of mobile-sensor spatial positioning and to the optimization of element positions for fixed vertical arrays in a shallow-water waveguide. Evolutionary search algorithms [Bäck and Schwefel, Evolutionary Computation 1(1), 1–23 (1993)] are investigated as a unified computational approach to both optimization problems. The optimized array spatial configurations are compared with configurations optimized with respect to traditional (energy-based) performance metrics, and the differences are interpreted. [Work supported by ONR.]
On the estimation of bearing using a single hydrophone
Authors: Sullivan Edmund
Published: May 2015

It is well known that a single moving hydrophone can estimate the bearing of a pure tone source if the source frequency is known a priori. It is also well known that with two or more hydrophones, a moving array can provide an improved estimate of bearing by jointly estimation the source frequency and bearing with a Kalman filter. This is due to the introduction of the phase information contained in the Doppler. This leads to the question of whether by jointly estimating the bearing and source frequency with a Kalman filter, a single hydrophone will suffice. By using a form of the observability matrix adapted to the nonlinear case, it is shown that in general, it is not possible. The reason is shown to be related to the fact that the bearing information in the Doppler is not sufficient and the introduction of a spatial phase, by introducing at least one more hydrophone is necessary.
The effect of ground sensor and UAV flight path geometry on the tomographic reconstruction of a weakly sheared daytime convective planetary boundary layer
Authors: Finn Anthony , Rogers Kevin
Published: May 2015

A signal analysis of the sound of a propeller-driven unmanned aerial vehicle (UAV) shows that its acoustic signature comprises a set of strong narrowband tones superimposed onto a broadband random component. If such a UAV overflies an array of microphones, the projected and observed Doppler shifts in frequency of the narrowband tones may be compared and converted into effective sound speed values: 2- and 3D spatially varying atmospheric temperature and wind velocity fields may then be estimated using tomography. The technique has practical application in a number of research fields. In this paper, we examine the influence of UAV flight path and ground sensor geometry on the feasibility and usefulness of UAV-based atmospheric tomography. Realistic conditions for a weakly sheared daytime convective atmospheric boundary layer are synthesized through use of massively parallel large eddy simulation code that utilizes pseudo-spectral differencing in horizontal planes and solves an elliptic pressure equation. Particular attention is paid to the accuracy with which the surface layer (lowest 50 m of atmosphere) may be reconstructed using UAV-based acoustic tomography as this region typically experiences the greatest spatio-temporal variation in temperature and wind speed; and arrangements of UAV flight path and sensor geometry do not permit ray paths to intersect without the UAV flying very low and disturbing the atmosphere. The influence of meteorological observations obtained onboard the UAV and by ground sensors is also examined.
On beyond hidden source estimates—Improving the output of blind source separation algorithms
Authors: Goldhor Richard , MacAuslan Joel , Gilbert Keith
Published: May 2015

In the presence of multiple simultaneously active acoustic sources, microphone response signals are typically additive mixtures of “acoustic images”—that is, filtered and delayed versions of hypothetical yet intangible “source signals.” Under certain conditions, Blind Source Separation (BSS) algorithms can “demix” sets of such microphone responses into output signals often called “Hidden Source Estimates” and characterized as estimates of those inaccessible source signals. However, despite the name of these algorithms and the characterization of their outputs, BSS algorithms generally do not actually reconstruct the original source signals. Indeed, it is not even clear that the notion of “source signal” is always well-defined. We argue that a valid BSS output can best be understood as an estimate of some unknown member of an entire equivalence class of related signals, and that certain members of these classes are much more useful and ontologically well-grounded than others. Notably, acoustic images are particularly interesting members of these equivalence classes. We present a method for converting arbitrary hidden source estimates into acoustic images, and explore the utility of enhancing BSS algorithms so that they output specific acoustic images rather than generic hidden source estimates.
Blind source localization in a room based on wavefield separation
Authors: Nowakowski Thibault , De Rosny Julien , Daudet Laurent , Ollivier François
Published: May 2015

Narrowband localization of sources in a room is a challenging problem because of the multiple reflections off the walls. Recently, we have been developing methods to localize monochromatic sources within an array of a few tens of microphones, without any knowledge on the physical properties of the room. To that end, we use a wavefield dereverberation approach in which the diffuse part is canceled, thanks to a projection operator built from a plane wave basis. However, this basis requires that no heterogeneities are present in the space of interest between the microphones. To overcome this limitation, in the case of an heterogeneous space, we show that a new projection operator can be experimentally built from a set of measurements of the responses between the microphones and some sources. This projection operator removes the reverberation, and can be used as preprocessing to locate the sources despite the heterogeneities, for instance by using classical beamforming processing. The method is first validated with numerical simulations. Then, experiments are performed in a large room, with an array composed of 100 microphones. A source, emitting at 500 Hz, can be located close to a strong reflector with an accuracy of about 10 cm.
Three-dimensional propagation in the open ocean: Observations and modeling
Authors: Heaney Kevin D. , Campbell Richard L.
Published: May 2015

A primary feature of ocean acoustic propagation is that vertical environmental scales and gradients are generally an order of magnitude smaller than horizontal scales. As such, ocean acoustic experiments and modeling have developed with the view that the in-plane propagation is primary. There are environments, however, where the horizontal variability can be significant enough to lead to a change in the observed acoustic field due to out-of-plane refraction or diffraction. This is particularly evident at very low frequencies, where the open ocean can no longer be considered deep water and the seafloor topography is not negligible. In this paper, several recent observations of the impact of three-dimensional propagation on global propagation will be presented, as well as a fully 3-D parabolic equation, which is efficient enough to handle very long range propagation at low frequencies. The final modeling illustration will be the impact of ocean mesoscale on arrival angle of low frequency long range signals. This is implications to the detection capability of systems like the Comprehensive Testban Treaty Organization.
Bottom-diffracted surface-reflected arrivals in the Philippine Sea
Authors: Stephen Ralph A. , Worcester Peter F. , Campbell Richard L. , Udovydchenkov Ilya A. , Dzieciuch Matthew A.
Published: May 2015

Bottom-diffracted surface-reflected (BDSR) arrivals were first identified in the 2004 Long-range Ocean Acoustic Propagation Experiment (LOAPEX) in the North Pacific (Stephen et al., 2013, JASA, 134, 3307–3317). For sources at long ranges in deep water, they can be observed throughout the water column, but at depths above the conjugate depth they are obscured by ambient noise and energy propagating in the ocean sound channel (PE predicted arrivals). In deep water (deeper than the conjugate depth), ambient noise and PE predicted arrivals are sufficiently quiet that BDSR paths, scattered from small seamounts, can be the largest amplitude arrivals observed. In the Ocean Bottom Seismometer Augmentation in the Philippine Sea (OBSAPS) Experiment in April–May 2011, we observed BDSR arrivals on ocean bottom seismometers at relatively short ranges (less than 50 km). The experiment was designed to further define the characteristics of the BDSRs and to understand the conditions under which BDSRs are excited and propagate. BDSR arrivals are distinct, with little indication of coda or reverberation, and the scattering point appears to be discrete. The BDSR mechanism provides a means for acoustic signals and noise from distant sources to appear with significant strength on the deep seafloor. [Work supported by ONR.]
Bathymetric refraction effects associated with marine pile driving
Authors: Dall'Osto David , Dahl Peter H.
Published: May 2015

Measurements of underwater noise from vibratory pile driving from a marine construction site in Puget Sound, Washington, are studied using line array-based measurements made at range 16 m from the pile source and single hydrophones at range 417-m on one transect, and at ranges 207-m and 436-m on another transect running approximately parallel to a sloping shoreline. Using adiabatic modes, the field from an incoherent line source model is propagated along these two transects. This approach works well except for the 436-m measurements located on the along-shore transect, where the observed levels for frequencies <300 Hz are significantly lower than predicted. These observations are interpreted in the context of shadow zones associated with bathymetric refraction for a downward sloping beach [Deane and Buckingham, J. Acoust. Soc. Am. 93, 1319 (1993)]. The modal amplitude due to horizontal refraction is evaluated with the parabolic wave equation, written in terms of the depth dependent phase velocity of each mode [Ballard, Proc. Meetings Acoust.ics 15, 070001 (2012)]. The results are significant as sloping beaches form many of the boundaries to waters where pile driving occurs, and where protective environment underwater noise monitoring is necessary, such as in Puget Sound.
Matched mode geoacoustic inversion of broadband signals in shallow water
Authors: Dong Hefeng , Badiey Mohsen , Chapman Ross
Published: May 2015

A matched mode geoacoustic inversion is presented for broadband acoustic signals recorded in experiments at a shallow water region of the New England Bight. First the modal behavior of the waveguide in the presence of 3D effects due to the water column and bottom bathymetry is examined. Spatial measurements of the temperature and salinity profiles and bathymetry provide data for calculating 3D propagation of the broadband acoustic wave field. Frequency shift of the broadband signal along one of the source-receiver paths in the experiment is attributed to internal waves propagating in the water column. Geoacoustic model parameters of the seabed along a source-receiver track with constant bathymetry are estimated by matched mode processing through matching the phase of the mode signals recorded at a Vertical Line Array. A warping transform was applied to identify and isolate modes, and the filtered modes were inverse transformed back to the time domain to reconstruct the mode signals. The inversion results are compared with the results from other inversion methods to assess the performance of the inversion scheme for estimating reliable values of the geoacoustic parameters in the experiment region.
Horizontal coherence of sound propagation in the presence of internal waves on the New Jersey continental shelf
Authors: Wan Lin , Badiey Mohsen
Published: May 2015

The knowledge of spatial coherence of sound field is required for sonar application and array design. In shallow water waveguides, the spatial and temporal evolution of the temperature field induced by internal waves will cause signal fluctuations and variations in spatial coherence. During the Shallow Water Acoustic Experiment 2006, the three dimensional temperature field of internal waves was measured and reconstructed while acoustic signals were simultaneously transmitted between various sources and an L-array. These internal wave events have been used to investigate the internal wave effect on temporal coherence and vertical structures of acoustic normal modes [Wan and Badiey, J. Acoust. Soc. Am. 135, 2014]. In this paper, the horizontal structures of acoustic normal modes are examined. The arrival angles of normal modes are analyzed. The horizontal coherence of sound field is obtained at different frequencies for these internal wave events. The relationship between horizontal coherence and internal wave parameters, such as propagation direction, speed, and amplitude, is discussed. [Work supported by ONR322OA.]
Laboratory scale measurements of three-dimensional sound propagation in the presence of a tilted penetrable bottom
Authors: Sturm Frédéric , Sessarego Jean-Pierre , Korakas Alexios
Published: May 2015

Results of laboratory-scale measurements of long-range across-slope pulse propagation in three-dimensional wedge-shaped oceanic waveguides with a sandy bottom are reviewed. The experimental data considered were collected during two laboratory-scale experimental campaigns that were led in 2006 and 2007 (after a required calibration phase) in the large indoor shallow-water tank of the LMA-CNRS laboratory in Marseille. Operational frequencies and water depths were chosen to produce a reduced number of propagating modes so as to facilitate the analysis of the received signals. The experimental data contain strong 3-D effects like mode shadow zones and multiple mode arrivals, all consistent with well-known three-dimensional effects described in the literature. The data are compared with numerical solutions obtained using a fully three-dimensional parabolic equation based model. Comparisons are performed in both time domain (received signals at distinct ranges and depths) and frequency domain (TL-versus-range curves at distinct depths for several discrete frequencies). In both cases, the experimental data are in good agreement with the numerical predictions.
Comparison of measured acoustic reflection fluctuations and estimates based on roughness
Authors: Chotiros Nicholas P. , Isakson Marcia J.
Published: May 2015

The extent to which the roughness of the seabed can account for the acoustic reflection fluctuations is investigated. The roughness of selected areas of the seabed off Panama City, FL, was measured with a laser profiler, as part of Target and Reverberation EXperiment of 2013 (TREX13). The site may be characterized as having small-scale roughness due to bioturbation overlying larger sand ripples due to current activity. It was largely composed of sand with shell hash crossed by ribbons of softer sediment at regular intervals. Simultaneous with the roughness measurement, the seabed reflection was measured with a wide beam echo sounder centered about 10 kHz. Both instruments were deployed on a remotely operated vehicle (ROV) at a height of approximately 2 m above the seabed. Significant fluctuations in the acoustic reflection were observed. By modeling the acoustic scattering due to the roughness, the extent to which the roughness can account for the acoustic fluctuations will be investigated. [Work supported by the Office of Naval Research, Ocean Acoustics Program.]
Acoustical design of schools on military bases: Meeting the needs of DoDEA’s 21st century school Initiative and LEED acoustical requirements
Authors: Clements Jessica S.
Published: May 2015

In their efforts to improve student learning environments, DoDEA (Department of Defense Education Activities) has included acoustical requirements in their 21st Century Schools initiative design guidelines. Recently, DoDEA projects have been required to also achieve LEED certification. The acoustical requirements for LEED schools outlined in IEQ prerequisite 3 (IEQp3) Minimum Acoustical Performance are referenced in part from ANSI S12.60 Acoustic Performance and Guidelines for Schools. Ideally the schools would achieve both the LEED acoustic prerequisite and the additional acoustic credit in order to achieve most of the goals of ANSI S12.60. However, meeting some aspects of the 21st Century Schools design guideline seems to preclude achieving the additional Acoustical Performance credit. Each of these guidelines includes different aspects of architectural acoustics design requirements. This leads to potentially three different design guidelines affecting a single project. The presentation will compare and contrast the design requirements of ANSI S12.60-2010 Part 1, LEEDv4 Minimum Acoustic Performance IEQp3, LEEDv4 Acoustic Performance Credit IEQc9, and the DoDEA 21st Century Design Guideline. Discussion will include examples from recent projects and resolutions used between conflicting design requirements.
Classroom acoustics for vocal health of elementary school teachers
Authors: Whiting Jennifer K. , Jensen Zachary R. , Berardi Mark L. , Leishman Timothy W. , Hunter Eric J.
Published: May 2015

School teachers have an elevated risk of voice problems due to vocal demands in the workplace. ANSI SI2.60-2002 provides a standard for classroom acoustics, but it focuses primarily on students and unoccupied classroom settings. This presentation explores a preliminary study of six elementary school teachers that included measurements of architectural acoustics parameters and noise-levels of their classrooms, as well as their speech levels and fundamental frequencies over the course of a school day. The measurement methods and speech trends are discussed for the various cases, demonstrating that classroom acoustics standards may benefit from greater attention to teacher vocal health.
Beyond Lombard: Quantitative changes due to noise and reverberation
Authors: Eyring Nathan G. , Berardi Mark L. , Leishman Timothy W. , Hunter Eric J.
Published: May 2015

Forty-five subjects performed a short vocal task in two different rooms: a variable-acoustics room and an anechoic chamber. The subjects were taken back and forth between the two rooms using a deception protocol. Each time they entered the variable-acoustics room, its acoustical characteristics had been changed without a change in visual appearance. The changing characteristics involved two background noise conditions and two reverberation conditions. Subjects responded to questions about their comfort and perception of the environmental changes. Analysis was performed on the second and third sentences of the rainbow passage. Objective acoustical metrics and perceptual responses were compared for the different settings. In contrast to males, females raised their fundamental frequency (F0) in concert with their raised vocal levels in response to changes in both loudness and reverberation. A high correlation existed between pitch strength and F0. Factor analysis also revealed that F0 and vocal level were more correlated in females than males.
Investigations on multi-slope energy decay formation within single-space monumental structures by diffusion equation modeling and intensity probe measurements
Authors: Sü Gül Zühre , Xiang Ning , Çalışkan Mehmet
Published: May 2015

Multiple domed superstructures with different volumetric and material attributes are previously investigated using in-situ acoustical measurements and acoustical simulation methods for analyzing their contributions to multi-slope energy decay formation. Relevant acoustical parameters including decay rates and decay times are computed by applying the Bayesian decay analysis. Initial results indicate double- or triple-slope decay characteristics for specific measurement configurations for selected cases. The ongoing research is aimed at explaining the probable reasons of multiple decay formation as observed in such single space enclosures. Diffusion equation modeling (DEM) and intensity probe measurements are utilized to observe spatial sound energy distributions and energy flow vectors. Both computed and measured flow vectors indicate the contribution of central dome to the later energy feedback. For a specific case the trial by DEM over virtual model with floor with marble instead of carpet resulted in a centrally concentrated energy, as a result preventing the multi-slope formation. The results support the argument that non-diffuse sound fields due to geometrical and material characteristics of superstructures provide the circumstances for non-exponential energy decay formation.
St. Bartholomew's parish hall acoustic analysis
Authors: Barnobi Christopher L. , Jaramillo Ana , Young Adam
Published: May 2015

St. Bartholomew's Catholic Church in Katy, Texas, includes a fellowship hall with a great dome. Parishioners use the space for social events including meals and regular bingo games. High reverberation times in the fellowship hall reduced speech communication and acoustic comfort. Measurements were conducted to assess the reverberation time of the room before and after applying treatment to the space. Sabine reverberation time analysis was used to specify the recommended sound absorption for the fellowship hall. EASE analysis of the space reveals more interesting characteristics.
What is the necessary level of detail for an acoustic model?
Authors: Olson Bruce C. , Jaramillo Ana M.
Published: May 2015

In order to evaluate the level of architectural detail needed in an acoustic model, several projects were selected. Using the software EASE, the authors created several models for each project and found that a high level of architectural detail was unnecessary to some extent in an acoustic model, which gained an advantage in modeling and calculation times.
The potential for acoustic communication in the “purring” wolf spider, Gladicosa gulosa
Authors: Sweger Alexander L. , Uetz George W.
Published: May 2015

Vibration is an important part of the sensory world in spiders, and many species have adapted vibration as a major part of their conspecific communication. While nearly all male wolf spiders produce vibrations during courtship, the “purring” wolf spider, Gladicosa gulosa, also produces an acoustic signal in conjunction with its vibratory display. However, with limited previous research on this species, the evolutionary significance of this component remains unknown. Given that spiders are not known to possess sensory structures for directly perceiving airborne sound, this raises a number of questions about the production, reception, and possible role of the signal. We measured male signal production and male/female responses to isolated acoustic signals on both vibrating (paper) and non-vibrating (granite) substrates. We found that male signals, both vibratory and acoustic, are only present in vibrating substrates. We also found significant differences in phonotaxis based on sex of the focal individual, stimulus type, and substrate type. These results suggest that the substrate plays an important role in both production and reception of the acoustic signal, and that under certain conditions, acoustic signaling may have a role in the communication network in this species.