bluuebunny/crossref_metadata_2025 huggingface dataset:
Early and late Spanish-English bilingual adults' identification of American English vowels
Authors: Baigorri Miriam , Levy Erika S
Published: June 2017

Increasing numbers of Hispanic immigrants are entering the US (US Census Bureau, 2011) and are learning American English (AE) as a second language (L2). Accurate perception of AE vowels is important because vowels carry a large part of the speech signal (Kewley-Port, Burkle, & Lee, 2007). The present study examined the accuracy with which early and late Spanish-English bilingual adults identify AE vowels. Listeners were presented with AE vowels (/i/, / I /, /ɛ/, /ʌ/, /æ /, /ɑ/, and /o/) in a /gəbVpə/ context. They were instructed to click on the key word response from a choice of nonsense words that contained the second vowel they heard. Findings indicate that identification accuracy of L2 vowels was significantly higher with early age of L2 acquisition. However, early bilingual listeners’ vowel perception was not native-like, suggesting that the phonetic properties of their native language influenced L2 speech perception. Additionally, identification accuracy varied as a function of the particular vowel, shedding light on how the relationship between Spanish and AE vowel inventories might explain the difficulties that arise in Spanish-English bilinguals’ identification of AE vowels. Findings are examined in relation to perceptual assimilation and discrimination of the stimuli by the same listeners.
Perception and production of American English consonants /v/ and /w/ by Hindi speakers of English
Authors: Grover Vikas , Shafer Valerie , Whalen D. H. , Levy Erika
Published: June 2017

This study examined the ability of Hindi speakers of English to perceive and produce American English (AE) consonants /v/ and /w/, which are difficult for Hindi speakers to distinguish (e.g., in “vest” and “west”). It also examined whether the Hindi listeners’ length of residence (LOR) in the US affected their performance. Two groups of Hindi speakers were included: Hindi speakers who had been in the US for more than 5 years and Hindi speakers who lived in India and used English as their second language. Participants performed perception and production tasks of naturally produced tokens of word forms containing /v/ and /w/. Hindi listeners performed significantly less accurately than the English listeners on all tasks. The non-significant differences between the two Hindi groups indicated that the Hindi US groups’ experience with the /v/-/w/ contrast in the US was insufficient to allow for perceptual learning of this contrast. The findings shed light on speech perception, production and comprehension (for lexical items that differ minimally, e.g., ‘viper vs. wiper’) challenges faced by native Hindi speakers learning English. This information can also be helpful for designing perception and production training programs for this population.
Relation between acoustic-phonetic properties and speech intelligibility in noise obtained with bilingual talkers
Authors: Hochmuth Sabine , Jürgens Tim , Brand Thomas , Kollmeier Birger
Published: June 2017

An objective, language-independent way of predicting observed differences in speech intelligibility in noise across talkers based on their acoustic-phonetic properties was pursued by exploiting speech intelligibility data in stationary speech-shaped noise uttered by bilingual talkers and comparing inter-individual as well as intra-individual speech feature variations across languages. Matrix sentence materials were used that were uttered by bilingual talkers of German/Spanish and of German/Russian and by the respective original matrix test talkers. Various acoustic-phonetic parameters discussed in the literature as being related to speech intelligibility were determined for each talker. Vowel space area, between-vowel category dispersion, and energy in the mid-frequency region represented by the speech intelligibility index were found to be language-independent acoustic-phonetic properties most strongly related to speech intelligibility at least for German, Russian and Spanish. Generally larger inter-individual variation within languages than intra-individual variation across languages was found. Hence, objective phonetic criteria like vowel space area may be used in the future to objectively assess the potential of a talker to be easily understood in a noisy background. One reason of the generally poorer intelligibility performance of Spanish compared to German or Russian may lie in the usage of considerably smaller vowel space areas.
The effect of second language orthographic input on the learning of Mandarin words
Authors: Hao Yen-Chen , Yang Chung-Lin
Published: June 2017

This study examines the effect of L2 orthography on Mandarin word learning. English speakers at three proficiency levels participated in a Mandarin word-learning experiment. During the learning phase, half of the participants were provided with Pinyin (Chinese Romanization) and tone marks (the PY group), while the other half were provided with characters (the CH group). After learning, the participants judged the matching of sound and meaning of 64 pairs, half of which were matches, while the other half were either segmental or tonal-mismatch items. The results showed that the Advanced and Intermediate learners in the CH group were more accurate than their counterparts in the PY group in the tonal-mismatch and match conditions respectively. In contrast, the naïve participants in the PY group were more accurate with the matches than those in the CH group. Also, participants in the PY group were overall inaccurate with the tonal-mismatch items regardless of their proficiency levels. However, in the CH group the Advanced learners scored significantly higher with the tonal-mismatch items than the other groups. This study suggests that characters are more effective than Pinyin in helping L2 learners encode the sounds of new Mandarin words, especially in tone encoding.
Costs and cues in code-switched lexical access
Authors: Shen Alice
Published: June 2017

While perceiving code-switches incurs processing costs [Soares & Grosjean (1984, Memory & Cognition 12(4):380-386)], bilingual listeners use acoustic cues to anticipate switches and facilitate processing [Fricke et al. (2016, J. Memory Lang. 89:110-137)]. This study investigates the role of anticipatory prosodic cues in the online processing of a code-switch from a non-tonal to a tonal language. Experiment 1 compares reaction times for perceiving Mandarin and English target words in English frames, to test whether recognizing code-switches is costly. Although reaction times for code-switched stimuli (475 ms) were not significantly slower than monolingual stimuli (466 ms), all participants self-reported as Mandarin-dominant speakers who frequently code-switch, suggesting that language dominance and experience may modulate switch costs. Reaction times to naturally-produced code-switched stimuli (426 ms) were faster than to spliced code-switched stimuli (511 ms), suggesting that anticipatory cues facilitate the perception of code-switches. Experiment 2 is a visual world eye-tracking task. The proportion of looks toward images corresponding to the target word (e.g., [mɑʊ̯4tsɨ5] “hat”), a cross-language phonetic competitor (e.g., [maʊs] “mouse”), and a within-language phonetic competitor (e.g., [mɑʊ̯2tɕin1] “towel”) are compared to assess any influence of anticipatory cues on target and non-target language activation levels during auditory recognition of code-switches.
Assimilatory and dissimilatory L1 English vowel drift in early learners of Japanese
Authors: Schuhmann Katharina , Huffman Marie K.
Published: June 2017

In contrast to predictions of the Speech Learning Model, Chang’s (2012) study of novice English-speaking learners of Korean finds no clear segment level assimilation between phonetically similar English and Korean vowels. The relative complexity of the Korean and English vowel systems may have made L2 to L1 vowel association inconsistent across speakers, leading to contradictory segment level effects. We examined vowels in L1 English:L2 Japanese learners, hypothesizing that the less dense vowel space in Japanese would simplify L1:L2 segment associations. Specifically, English [ɑ] and Japanese [a] should be associated by learners in a way that could lead to segment level L1 drift effects, allowing us to determine whether assimilatory L1 drift would occur in English for novice learners of Japanese, as Flege (1987, 1995) and Chang predict. Formant data for students in their first and second semester of Japanese instruction show mostly L1 assimilatory drift in F1, and some L1 dissimilation in F2, with most speakers making one change but not both. Overall, English [ɑ] variants stay within L1 norms, highlighting the importance of L1 phonetic repertoire in constraining L1 drift effects. Results will be compared to data for [i] and [u] to determine whether systemic level drift also occurs.
Top-down influence on phonetic categorization of native vs. non-native speech
Authors: Schertz Jessamyn L. , Hawthorne Kara E.
Published: June 2017

Speech perception requires integration of multiple sources of information, including bottom-up acoustic information and top-down contextual information, and listeners may adjust their reliance on a given source of information depending on the communicative context. This work tests the hypothesis that listeners increase reliance on contextual, relative to acoustic, information when listening to a talker with a foreign accent, under the assumption that the bottom-up information (non-native pronunciation) may be less reliable. Native English listeners categorized an utterance-final target word, where the initial consonant systematically varied in voice onset time (VOT), as either “goat” or “coat.” Target words were embedded in carrier sentences contextually biased towards one of the words (e.g., “The girl milked the [coat/goat]” vs. “The girl put on her [coat/goat]”). Stimuli were created from productions by two talkers: a native English talker and a native Mandarin/L2 English talker with a discernable foreign accent. As expected, acoustic information (VOT) was the primary cue for categorization, but sentence context also influenced perception in both talker conditions. Furthermore, preliminary results indicate that the semantic context effect is larger in the Accented than in the Native condition, suggesting that listeners do indeed increase reliance on contextual information when listening to foreign-accented speech.
Task differences do not impede overall learning when adapting to a novel sound
Authors: Saltzman David , Myers Emily B.
Published: June 2017

Lexically guided perceptual learning (LGPL) and second-language learning (L2) research seeks to understand how listeners adapt to novel speech sounds. In LGPL, listeners shift their perception of a native phonetic contrast in response to hearing an ambiguous token embedded in an unambiguous lexical context. In L2 tasks, often involve categorizing non-native sounds, usually with explicit feedback. In general, L2 learning is seen as more effortful and individually variable than LGPL. However, paradigms differ in terms of stimuli (native vs. non-native phonetic contrasts) as well as tasks (lexically-guided implicit feedback vs. explicit feedback). To test whether L2-type vs. LGPL-type tasks yield differences in learning, participants were trained using an L2-style task to shift their native boundary along an /s/ to /sh/ continuum. With feedback, participants categorized the midpoint token as one novel object, and an endpoint token (counterbalanced across subjects) as another novel object. After training, a boundary shift comparable to previous studies using the LGPL task was found, suggesting that explicit and lexically-guided feedback produce similar magnitude of learning. Despite this, participants in the L2-style task experienced lower accuracy and more variability in perception of the continuum endpoints, suggesting that task differences partially explain less consistency across individuals in L2 research.
Perception of Russian palatalization contrasts by English listeners
Authors: Roon Kevin , Whalen D. H.
Published: June 2017

Russian contrasts palatalized vs. non-palatalized consonants across primary oral articulator, manner, voicing, and word position, in both stressed and unstressed syllables. This palatalization contrast is challenging for native English speakers to master, possibly due to English speakers not being able to discriminate the relevant linguistic contrast in all the environments in which it exists in Russian. Previous studies have shown that English listeners are good at discriminating this Russian contrast pre-vocalically, but there is no experimental evidence indicating how well they discriminate this contrast in the wide variety of environments in which it is used in Russian, and when produced by different talkers. The present study tested how well English listeners could perceive the Russian palatalization contrast across manner, word position, primary oral articulator, and talker. 24 listeners performed an AX discrimination task in which A and X were always produced by two different speakers, one male and one female. Trials on which A and X mismatched differed in palatalization (e.g., /p/-/pj/) or manner (e.g., /t/ vs. /s/). The results show the combinations of environments that present the greatest challenges for English listeners in discriminating the Russian contrast, with syllable-final obstruents being especially hard.
Perceptual similarity spaces of British English vowels by speakers of Pakistani Urdu
Authors: Rehman Ishrat , Arvaniti Amalia
Published: June 2017

Free classification was undertaken with 70 listeners from Lahore, Pakistan with Punjabi and Urdu as their first languages in order to shed light on the English vowel features that have been most relevant in developing the “new English” variety spoken by them (Pakistani English). The stimuli were 19 hVd words carrying the Southern British English (SSBE) vowels. The responses were statistically analyzed using hierarchical clustering and multidimensional scaling. Listeners were sensitive to both F1 and F2, but could not distinguish the high-mid from the low-mid vowels. The central vowels /ɜː/ and /∧/ were in different groups indicating greater sensitivity to backness (F2): listeners classed /∧/ as back, but /ɜː/, which is more fronted in SSBE, as front. Diphthongs were grouped with monophthongs, sometimes based on the initial, sometimes on the final element; /aʊ/ /aɪ/ and /ɔɪ/, however, formed a separate group, possibly because their first and last element are most distinct. Listeners were not sensitive to duration: /iː/~/ɪ/, /ʊ/~/uː/, and /ɔː/~/ɒ/ were grouped with each other. Overall, the results indicate that Punjabi-Urdu listeners are sensitive to both height and backness, but possibly prioritize the latter, while they lack an intermediate (central) space, all features consistent with characteristics of Pakistani English.
Interdental-stopping among older-aged bilingual and monolingual Finnish- and Italian-heritage Upper Peninsula Michiganders
Authors: Cornillie Paige , Fosgard Julianne , Gibbs Samantha , Griffin Delani , Lawson Olivia , Rankinen Wil A.
Published: June 2017

The realization of interdental fricatives as coronal oral stops, referred to as interdental-stopping, is often attributed to substrate effects of ethnicity and immigrant-heritage. Michigan’s Upper Peninsula (UP) is an excellent case to examine this feature’s complex variation within bilingual and monolingual older-aged cross-sections of a rural immigrant speech community. To what degree, if any, is interdental-stopping occurring among Michigan’s UP Finnish and Italian-heritage speech communities? Interdental-stopping has been documented in UP English [3, 2], but only a more recent report has provided any quantitative account that tracks this salient feature and its sociophonetic trends within the community [1]. The present study examines this feature among 41 Finnish-Americans and 30 Italian-Americans, whom are all older-aged residents from Michigan’s Marquette County. Both samples are stratified by gender, socioeconomic status and lingua-dominance. All data is obtained from a reading passage task. This study reveals interdental-stopping occurring most often among Italian working-class males and least among English-dominant bilinguals. Such findings goes beyond the claim that this feature of UP English indexes working-class [2]. Interdental-stopping indexes working-class masculinity—held with prestige and used by older-aged, working-class males, primarily among Italians, as a linguistic marker of local identity in the UP English speech community.
Identification of vowels of two different varieties of English by native speakers of Japanese and Korean
Authors: Nozawa Takeshi , Cheon Sang Yee
Published: June 2017

Native speakers of Japanese and Korean heard and identified /i, ɪ, eɪ, ɛ, æ, ɑ, ʌ/ uttered in /bVd/, /dVd/ and /kVd/ frames by native speakers of American and New Zealand English. New Zealand English has gone through an idiosyncratic vowel shift. For instance, /æ/ and /ɛ/ are raised and /ɪ/ is centralized. Overall American English vowels are identified more accurately by the two listener groups. Both listener groups identified American English /ɛ, æ/ better than New Zealand English equivalents, but on the contrary American English /ɑ/ is less accurately identified than New Zealand English /ɑ/ (or /ɒ/). Despite these similarities, some differences are observed between the two listener groups. While Japanese listeners identified New Zealand English /i, ɪ,/ less accurately than American English /i, ɪ/, Korean listeners identified New Zealand English /ɪ/ more accurately than American English /ɪ/. Japanese listeners outperformed Korean listeners in identifying American English /eɪ/ and New Zealand English /ɑ,/, but Korean listeners identified American English /ʌ/ and New Zealand English /ɪ/, /æ/ and /ʌ/ better than did Japanese listeners. The results point to the effect of L1 phonology and the differences in what each listener group believe each English vowel sounds like. For instance, Korean non-high front vowels are acoustically more similar to New Zealand English vowels /æ/ than to American English corresponding vowel. [Work partially supported by Grant-in-Aid for Scientific Research (C)16K02650.]
Development of semantic context facilitation for nonnative-accented speech
Authors: Miller Katherine E. , Holt Rachael F. , Bent Tessa , Blank Andrew
Published: June 2017

Children can use sentence context to facilitate their understanding of both native and nonnative speakers and this benefit increases with age. In this study, 5- to 7-year-old children (n = 90) and adults (n = 30) were compared on their ability to benefit from sentence context. In addition, we examined whether receptive vocabulary accounts for variability in spoken word recognition differently for words spoken in sentences versus in isolation. Stimuli were produced by either native- or nonnative-accented (Japanese and Spanish) speakers. Listeners first identified words in isolation that had been extracted from meaningful sentences. Then they completed the NIH Toolbox Picture Vocabulary Test. Finally, they identified the same spoken words embedded in the original sentences. Children and adults showed significant word recognition advantages for the sentence condition compared to the isolated word condition for both native and nonnative speakers. However, adults showed a much larger benefit from sentence context than the children in the nonnative but not the native condition. Further, older children benefited from context more than younger children. Finally, receptive vocabulary was positively correlated with nonnative recognition of words in sentences but not in isolation for both children and adults, suggesting that better receptive vocabulary enhances use of context for nonnative speech.
Non-native word recognition in babble and white noise
Authors: Li Bin
Published: June 2017

Noise causes degradation in speech signals, which poses difficulties for non-native perception. In this study, we examined impacts of noisy conditions on word recognition in naturally produced sentences by Chinese speakers of English (CE) and native speakers of English (NE). We also manipulated the linguistic contexts where targeted words occur, in order to assess how syntactic and semantic information may contribute to facilitate speech perception in adverse conditions. We recorded and compared the mean accuracy of keyword rewriting, to examine effects of noise and linguistic cues across listener groups. Results show that babble noise had more severe influence on CE groups' performance, which was also found commensurate with their English proficiencies. NE listeners, however, showed different patterns in their tolerance of noise and in use of linguistic cues.
Do linguistic and cognitive processing differences impact vocoded speech understanding?
Authors: Waked Arifi N. , Goupell Matthew
Published: June 2017

Normal-hearing individuals presented vocoded speech show great variability, even after explicit training. Assuming similar neural encoding, this variability might be explained by linguistic and cognitive factors. Therefore, we measured vocoded speech understanding in participants that should show a range of linguistic and cognitive abilities; namely, children (8-10 years) and adults (≥18 years), and monolingual English speakers and bilingual Spanish-English speakers. We hypothesized that bilingual adults have a “cognitive advantage” in their understanding of vocoded speech, related to reinforcement of executive function skills by using multiple languages. We also hypothesized that children may rely relatively more on their linguistic knowledge, as they may not have developed these same cognitive skills and strategies. Participants were trained on speech understanding simulating shallow cochlear implant insertion depth (6-mm frequency-to-place mismatch) with auditory and visual feedback. Between training trials, participants were tested without feedback on standard (0-mm) or shallow (6-mm) simulated insertion depths. Participants were then tested on measures of phonological awareness and vocabulary in English and/or Spanish and the five cognitive measures of the NIH Cognitive Toolbox. Associations between these measures and speech perception may allow us to better tailor therapy methods to members of particular age/language groups. [Work supported by NIH grant R01AG051603.]
Effects of linguistic experience on brainstem encoding of speech sounds
Authors: Zhao Tian , Kuhl Patricia K.
Published: June 2017

Linguistic experience has been demonstrated repeatedly over the past decades as an important factor influencing the perception of speech sounds. At the behavioral level, speakers of different languages identify and discriminate speech sounds differentially (e.g., categorical perception). This has been observed at the cortical level as a reduced Mismatch Response, a measure that can reflect the sensitivity of the cortex to the differences between sounds. Yet, the effect of linguistic experience at an earlier stage of speech processing, namely, the brainstem, is scarcely studied. In the current study, we therefore aimed to examine specifically whether linguistic experience affects speech sound processing at the brainstem level. Twenty native Spanish speakers and twenty monolingual English speakers are recruited and their brainstem response to speech sounds will be measured with EEG. Specifically, we will use synthesized speech sounds: /ba/ with a + 10 ms and a -40 ms voice-onset-time (VOT). We hypothesize that while the encoding by the two groups will be similar for the + 10 ms /ba/ (common to English and Spanish), English speakers’ encoding of -40 ms prevoiced /ba/s (Spanish only) will be reduced relative to Spanish speakers. Data will be analyzed and interpreted with regards to these hypotheses.
Analysis of allophones based on audio signal recordings and parameterization
Authors: Czyżewski Andrzej , Piotrowska Magdalena , Kostek Bozena
Published: June 2017

The aim of this study is to develop an allophonic description of English plosive consonants based on recordings of 600 specially selected words. Allophonic variations addressed in the study may have two sources: positional and contextual. The former one depends on the syllabic or prosodic position in which a particular phoneme occurs. Contextual allophony is conditioned by the local phonetic environment. Co-articulation overlapping in time demands a precise determination of allophonic pronunciation in the context of phonemic transcription. The presented study is focused on creation of speech recordings that may serve for the analysis of allophone variation. Two sets of recordings are prepared. The first one consists of words read by the non-native speakers. Tempo of reading is forced by a teleprompter. In the second case, every word is played back from the recordings of the phonology expert and then the speaker repeats a particular word. The last stage is the assessment of recordings by the same expert. Scores assigned by the expert are included as a reference for signal analysis and parametrization. [Research sponsored by the Polish National Science Centre, Dec. No.2015/17/B/ST6/01874.]
Bayesian classification of environmental noise sources
Authors: Nykaza Edward T. , Blevins Matthew G. , Hart Carl R. , Netchaev Anton
Published: June 2017

Classification algorithms are an essential component of continuously running environmental noise monitors. Without them, one does not know which noise sources are responsible for the levels recorded by the monitor. This is problematic given that continuously recording monitors may accumulate millions of triggered events and terabytes of data. In this study, we look at the utility of Bayesian classification methods. We compare the performance of these methods to some of the top performing environmental noise classifiers (e.g., support vector machines, random forest, and bagged trees), and discuss the advantages and disadvantages of the Bayesian approach. In particular, we compare the accuracy, number of observations needed to achieve an accurate classification, computation time, and feature importance.
Speaker localization in a reverberant environment using spherical statistical modeling
Authors: Rafaely Boaz , Schymura Christopher , Kolossa Dorothea
Published: June 2017

Estimation of the direction of arrival (DoA) of speakers in reverberant environments is an important audio signal processing task in a wide range of applications. Recently, a reverberation-robust method for DoA estimation has been developed. It is based on the identification of time-frequency bins that are dominated by the direct path from the source. As the DoA statistics was found to have a multimodal distribution, clustering using Gaussian mixture modeling improved localization accuracy. However, this method employed linear statistics over the azimuth and elevation angles, therefore introducing between 0 and 360 degrees azimuth. This work explores the use of spherical statistics in the direct-path dominance approach to speaker localization in reverberant rooms, providing a more suitable angular representation. Theoretical and experimental aspects of the proposed approach are investigated and validated using a computer simulation of a speaker in a room.
Passive acoustic source localization with multiple horizontal arrays in shallow water
Authors: Tollefsen Dag , Gerstoft Peter , Hodgkiss William S.
Published: June 2017

This paper considers concurrent matched-field processing of data from multiple, spatially separated acoustic arrays with application to towed-source data received on two bottom-moored horizontal line arrays from the SWellEx-96 shallow water experiment. Matched-field processors are derived for multiple arrays and multiple-snapshot data using maximum-likelihood estimates for unknown complex-valued source strengths and unknown error variances. Starting from a coherent processor where phase and amplitude is known between all arrays, likelihood expressions are derived for various assumptions on relative source spectral information (amplitude and phase at different frequencies) between arrays and from snapshot to snapshot. Processing the two arrays with a coherent-array processor (with inter-array amplitude and phase known) or with an incoherent-array processor (no inter-array spectral information) both yield improvements in localization over processing the arrays individually. The best results with this data set were obtained with a processor that exploits relative amplitude information but not relative phase between arrays. The localization performance improvement is retained when the multiple-array processors are applied to short arrays that individually yield poor performance.
Geophysical inversion by dictionary learning
Authors: Bianco Michael J. , Gerstoft Peter
Published: June 2017

Dictionary learning, a form of unsupervised machine learning, has recently been applied to ocean sound speed profile (SSP) data to obtain compact dictionaries of shape functions which explain SSPs using as few as one non-zero coefficient. In this presentation, the results of this analysis and potential applications of dictionary learning techniques to the inversion of real acoustic data are discussed. The estimation of true geophysical parameters from acoustic observations often is an ill-conditioned problem that is regularized by enforcing prior constraints such as sparsity or energy penalities, and by reducing the size of the parameter search. Traditionally, empirical orthogonal functions (EOFs) and overcomplete wavelet and curvelet dictionaries have been used to represent complex geophysical structures with few parameters. Using the K-SVD dictionary learning algorithm, the representation of ocean SSP data is significantly compressed relative to EOF analysis. The regularization performance of these learned dictionaries is evaluated against EOFs in the estimation of ocean sound speed structure from ocean acoustic observations and the limitations of such unsupervised methods are considered.
Simulations of the influence of sound speed profile and sensor configuration in the measurement of radiated noise from ships in deep and shallow waters
Authors: Audoly Christian
Published: June 2017

The ISO TC43/ SC3 standardization committee for underwater acoustics was launched a few years ago, one of the priorities being the availability of internationally agreed procedures to measure radiated noise from ships. A first step was achieved by the publication of a first standard applicable for deep waters. However, in order to study the impact of shipping noise on marine fauna in wide maritime areas, it is necessary to input sound source levels in the form of equivalent monopoles, instead of a “radiated noise level,” which is affected by the interaction with sea surface and sea floor. Therefore, the committee is currently working on correction terms to remove these effects. In that context, the objective of the present study is to determine the influence of sound speed profile and sensor configuration on the sound source level estimation, using numerical simulator. The first case study is the correction term in deep waters: here, we look at the influence of sound speed profile, whereas in previous studies, a constant speed of sound is generally assumed. The second case study deals with shallow waters: here, the main purpose is to compare different sensor configuration (number and distribution in the water column).
Underwater noise footprint measurements on a survey vessel
Authors: Brooker Alex , Humphrey Victor F.
Published: June 2017

The potential impact of man-made underwater noise on the marine environment is receiving increased attention. Shipping is one of the main sources of such anthropogenic noise. In order to understand the underwater soundscape considerable effort is being placed on generating underwater noise maps, based on using AIS data to provide details of vessel locations and operational characteristics. A key input for noise mapping models is an adequate knowledge of the source strength and characteristics for each vessel. Currently the sources are usually assumed omnidirectional, given the limited data on the true vessel radiation pattern. As part of the EU SONIC (Suppression of underwater Noise Induced by Cavitation) project measurements were undertaken on a small survey vessel, operating under realistic conditions at sea in shallow water. An autonomous recorder was used to measure the sound pressure as a function of range and azimuth. The vessel made a repeated runs past the autonomous recorder for a variety of different ranges. This has enabled the vessel noise footprint to be measured as a function of frequency and speed for the vessel, showing how the azimuthal characteristics change with frequency.
Characteristics of snapping shrimp noise in the northeastern East China Sea
Authors: Yuan Zhuqing , Cho Chomgun , Song Hee-Chun , Hodgkiss William S.
Published: June 2017

Snapping shrimp sounds are a dominant source of high-frequency ambient noise (e.g., > 1 kHz) in temperate and tropical coastal waters of depths less than 60 m. Surprisingly, a recent shallow water experiment conducted in the northeastern East China Sea (SAVEX15) revealed an abundance of snapping shrimp sounds in approximately 100-m deep shallow water from two 16-element vertical line arrays (VLAs) deployed over 10 days. Our preliminary analysis indicates the pressure amplitude statistics fits a SαS (symmetric alpha-stable) distribution due to a heavy tail over the commonly assumed Gaussian distribution, while the temporal statistics of shrimp snaps detected above some threshold appears to fit a non-homogeneous Poisson process. In addition, the VLAs allow for localization of individual snapping shrimp. In this paper, the temporal and spatial variability of the noise characteristics dominated by snapping shrimp sounds are investigated in the northeastern East China Sea.
Tsunami excitation of the Ross Ice Shelf, Antarctica
Authors: Gerstoft Peter , Bromirski Peter , Chen Zhao , Stephen Ralph A. , Aster Rick C. , Wiens Doug A. , Nyblade A.
Published: June 2017

The responses of the Ross Ice Shelf (RIS) to the September 16, 2015 8.3 Mw Chilean earthquake tsunami (>75 s period) and infragravity (IG) waves (50-300 s period) were recorded by a 34 element broadband seismic array deployed on the RIS for one year from November 2014. Tsunami and IG-generated signals travel from the RIS front as water-ice coupled flexural waves at gravity wave speeds (~70 m/s). Displacements across the RIS are affected by gravity wave incident direction, bathymetry under and north of RIS, and water and ice shelf thickness/properties. Horizontal displacements are about 5 times larger than vertical, producing extensional motions that may facilitate expansion of existing fractures. Excitation is continuously observed throughout the year, with horizontal displacements highest during the austral winter (>20 cm). Because flexural waves exhibit weak attenuation, significant flexural wave energy reaches the grounding zone. Flexural waves provide year-round excitation of the RIS that likely promotes iceberg calving and thus ice shelf evolution. Understanding the ocean-ice shelf mechanical interactions is important to reduce the uncertainty in the global sea level rise.
Extracting changes in wave velocity from chaotic data
Authors: Snieder Roel
Published: June 2017

Using seismic interferometry it is possible to extract the Green’s function from recorded measurements of noise or other incoherent signals, it is a way of creating order out off chaos. Since the noise is present at all times, this provides a way to measure seismic velocity changes over time. The seismic velocity in the subsurface, and in buildings, is not constant in time. I will present measurements taken during, and after, the 2011 Tohoku-Oki earthquake to show that deconvolution interferometry can be used to monitor the seismic velocity in the near surface, with a great temporal resolution. The recovery of the seismic velocity typically varies as log-time, which can be related to a spectrum of relaxation processes in the earth.
Imaging subsurface structures using reflections retrieved from seismic interferometry with sources of opportunity
Authors: Draganov Deyan , Nishitsuji Yohei , Boullenger Boris , Minato Shohei , Wapenaar Kees , Thorbecke Jan , Ruigrok Elmer , Rowe Charlotte , Paap Bob , Verdel Arie , Gomez Martin
Published: June 2017

The reflection seismic method is the most frequently used exploration method for imaging and monitoring subsurface structures with high resolution. It has proven its qualities from the scale of regional seismology to the scale of near-surface applications that look just a few meters below the surface. The reflection method uses controlled active sources at known positions to give rise to reflections recorded at known receiver positions. The reflections’ two-wave travel time is used to extract desired information about and image the subsurface structures. When active sources are unavailable or undesired, one can retrieve body-wave reflections from application of seismic interferometry (SI) to sources of opportunity—quakes, tremors, ambient noise, or even man-made sources not connected to the exploration campaign. We show examples of imaging of subsurface structures using reflections retrieved from quakes and ambient noise. We apply SI by autocorrelation to global earthquake to image seismic and aseismic parts of the Nazca plate and the Moho at these places, SI by multidimensional deconvolution to P-wave coda from local earthquakes to image the Moho and the crust at the same places, and SI by autocorrelation to deep moonquakes to image the lunar Moho and to ambient noise to monitor CO2 sequestration.
Passive sensing of head wave propagation in the ambient noise field and its implications for geoacoustic inversion
Authors: Gebbie John , Siderius Martin
Published: June 2017

Under certain conditions, the ambient noise field can produce and amplify head waves with unique propagation characteristics; these are detectable with a vertical line array and can be analyzed to extract geoacoustic information. Head wave phenomenon in the seabed can be observed using point sources, but these arrivals are usually very weak and difficult to detect ahead of the strong direct-path arrival. In contrast, surface-generated noise from wind and breaking waves are effectively a planar source that insonify the entire seabed at every angle and from every direction. Ambient noise head waves are conical waves that are generated when noise first reaches the seabed at the critical angle, and are amplified upon each subsequent interaction with the seabed. This interaction involves splitting the incident wave into water-borne and seabed-borne components, each separated in time by a fixed lag. A vertical line array can observe this phenomenon by cross-correlating beams steered upward and downward at the critical angle of the seabed. Together, the steering angle and time lag depend on the seabed critical angle and ray cycle time through the waveguide. Experimental results will be presented along with full-wave simulations that help illustrate the phenomena.
Environmental characterization in the Chukchi Sea using Bayesian inversion of bowhead whale calls
Authors: Warner Graham A. , Dosso Stan E. , Hannay David E.
Published: June 2017

This paper estimates seabed and water-column properties of a shallow-water site in the Chukchi Sea using bowhead whale calls recorded on asynchronous ocean-bottom hydrophones. Up- and down-swept bowhead whale calls were recorded on a cluster of seven hydrophones within a 5 km radius. The calls excited multiple propagating modes, with modal dispersion controlled by environmental properties and whale-recorder range. Frequency-dependent mode arrival times for nine whale calls are inverted using a trans-dimensional (trans-D) Bayesian approach that estimates the whale locations (easting and northing) and range-independent environmental properties (sound-speed profile, water depth, and seabed geoacoustic profiles). The trans-D inversion allows the data to determine the most appropriate environmental model parameterization in terms of the number of sound-speed profile nodes and subbottom layers. The inversion also estimates each whale-call instantaneous frequency function, relative recorder clock offsets, and residual-error standard deviation, and provides uncertainty estimates for all model parameters and parameterizations. The sound-speed profile is found to be poorly resolved, but water depth and upper sediment-layer thickness and sound speed are reasonably well resolved. Model estimates and uncertainties are compared to those from separate inversions involving airgun dispersion and vessel noise data collected nearby (which also represent sources of opportunity).
Monitoring bubble production in a seagrass meadow using a source of opportunity
Authors: Felisberto Paulo , Rodríguez Orlando C. , Silva João P. , Jesus Sergio , Quental-Ferreira Hugo , Pousão-Ferreira Pedro , Cunha Maria Emília , de los Santos Carmen B. , Olivé Irene , Santos Rui
Published: June 2017

Under high irradiance, the photosynthetic activity of dense seagrass meadows saturates the water forming oxygen bubbles. The diel cycle of bubble production peaks at mid-day, following light intensity pattern. It is well known that bubbles strongly affect the acoustic propagation, increasing signal attenuation and decreasing the effective water sound speed, noticeable at low frequencies. Thus, the diurnal variability of bubbles may show an interference pattern in the spectrograms of low frequency acoustic signals. In an experiment conducted in July 2016 at the Aquaculture Research Station of the Portuguese Institute for the Sea and Atmosphere in Olhão, Portugal, the spectrograms of low frequency (<20 kHz) broadband noise produced by water pumps in a pond of 0.48 ha covered by the seagrass Cymodocea nodosa showed interference patterns that can be ascribed to the variability of the sound speed in the water. Preliminary analysis suggests that the daily cycle of bubble concentration can be inferred from these interference patterns.
Reflecting boundary conditions for interferometry by multidimensional deconvolution
Authors: Weemstra Cornelis , Wapenaar Kees , van Dalen Karel N.
Published: June 2017

Seismic interferometry (SI) takes advantage of existing (ambient) wavefield recordings by turning receivers into so-called “virtual-sources.” The medium's response to these virtual sources can be harnessed to image that medium. Applications of SI include surface-wave imaging of the Earth's shallow subsurface and medical imaging. Most interferometric applications, however, suffer from the fact that the retrieved virtual-source responses deviate from the true medium responses. The accrued artifacts are often predominantly due to a non-isotropic illumination of the medium of interest, and prohibit accurate interferometric imaging. Recently, it has been shown that illumination-related artifacts can be removed by means of a so-called multidimensional deconvolution (MDD) process. However, The current MDD formulation, and hence method, relies on separation of waves traveling inward and outward through the boundary of the medium of interest. As a consequence, it is predominantly useful when receivers are illuminated from one side only. This puts constraints on the applicability of the current MDD formulation to omnidirectional wavefields. We present a modification of the formulation of the theory underlying SI by MDD. This modification eliminates the requirement to separate inward-and outward propagating wavefields and, consequently, holds promise for the application of MDD to non-isotropic, omnidirectional wavefields.
Status and results from cabled hydrophones arrays deployed in deep sea off East Sicily (EMSO-ERIC node)
Authors: Riccobene Giorgio , Caruso Francesco , Viola Salvatore , Simeone Francesco , Pulvirenti Sara , Sciacca Virginia , Pellegrino Carmelo , Speziale Fabrizio , Ameli Fabrizio , Buscaino Giuseppa , Mazzola Salvatore , Filiciotto Francesco , Grammauta Rosario , Licitra Gaetano , Bellia Giorgio , Pavan Gianni , Embriaco Davide , Favali Paolo , Beranzoli Laura , Marinaro Giuditta , Giovanetti Gabriele , Chierici Francesco , Larosa Giuseppina , D'Amico Antonio , Papale Elena
Published: June 2017

Since 2005 a cabled deep-sea infrastructure is operative at 2100 m water depth, 25 km off the port of Catania (Sicily). The infrastructure, under continuous improvement, is the first operative cabled node of the EMSO-ERIC, hosting several multidisciplinary observatories built in collaboration by INFN, INGV, CNR, CIBRA, and other scientific partners. Hydrophones antennas, sensitive in the range of frequencies between 1 Hz and 90 kHz, have been installed on seafloor observatories. Acoustic data are continuously digitized in situ at very high resolution, time-stamped with absolute GPS time and sent to shore in real time, through optical fiber link. Together with biological sounds, noise pollution study and monitoring were the main goals of the research. Results of multi-year monitoring of anthropogenic noise are discussed. Focus of the analysis is the noise level in the octave bands centered at 63 Hz and 125 Hz, in compliance with the EU Marine Strategy Framework Directive. The contribution of ship noise was modeled, based on their data recorded via proprietary AIS antennas, and compared to data. Noise at higher frequencies was also investigated. Detection of air-guns emissions and recorded noise levels is reported. Status and coming activities at the infrastructure is also presented.
Determination of eigenvalue in elastic multi-layered waveguides
Authors: Wei Wang , Wang Bin
Published: June 2017

With the extensive use of composites in vibration and noise reduction in recent years, the properties of acoustic propagation in composite plates have come to the foreground. However, traditional root-finding methods based on contour integration and finite difference show low precision and root-missing problems on calculating the dispersion curve, especially the loss factor is excessively influential and cannot be ignored. In this paper, a multimodal approach (Pagneux et al., Proc. R. Soc. A (2006) 462, 1315-1339) is applied to solve the eigenvalue problem for elastic multi-layered waveguides. The longitudinal and transverse potential functions are expanded on a group of orthogonal basis respectively and a matrix equation is then derived with the boundary conditions, which can be solved after truncation at an adequate number of modes. Dispersion curves of composite plates with different loss are presented. The numerical simulation proves that it is more effective than traditional methods
Performance of a ray-based blind deconvolution algorithm for shipping sources in the Santa Barbara channel
Authors: Durofchalk Nicholas C. , Yang Juan , Sabra Karim G.
Published: June 2017

This paper investigates the performance of a ray-based blind deconvolution (RBD) algorithm for sources of opportunity, such as shipping noise, in an ocean waveguide recorded on a vertical line array (VLA). The RBD algorithm [Sabra et al., JASA,2010, EL42-7] relies on estimating the unknown phase of the source through wideband beamforming along a well-resolved ray path to approximate the environment’s Green’s Functions (or Channel Impulse responses) between the source and the VLA elements, as well with recovering the unknown radiated source signal. The RBD algorithm is tested here for shipping sources recorded in the Santa Barbara shipping channel (water depth ~550 meters). The four VLAs, with short (~ 15 meter) and long (~56 meter) apertures, were deployed between the north and south bound shipping lanes and collected acoustic data throughout a week in mid-September, 2016. Here, we discuss (1) the performance of conventional beamforming and adaptive (MVDR) beamforming when estimating ray-arrivals, (2) the ability of the RBD algorithm to deconvolve multiple VLAs using the only the same source phase estimated from a single VLA. The performance of the RBD results will be discussed in terms of accuracy of travel times and of the estimated Green’s Functions.