bluuebunny/crossref_metadata_2025 huggingface dataset:
Auroral infrasound associated with ionospheric electron precipitation.
Authors: Oldham Justin , Wilson Charles R. , Olson John V. , Fee David
Published: July 2011

Periods of persistent, high-trace velocity infrasound signals lasting several hours or more have been observed in the data from the CTBT/IMS I53 infrasound station in Fairbanks, AK. Early studies showed that the infrasound activity was associated with times of geomagnetic disturbance. The imaging riometer at the Poker Flat Research Range near Fairbanks collects cosmic noise absorption (CNA) data from an array of 16 × 16 beams that cover a region that is approximately 200 × 200 km2 in the overhead ionosphere. Also available from the PFRR site are magnetometer data and all-sky camera videos showing auroral events when the sky is dark. The CNA event data give direct evidence of the precipitation of high energy electrons into the D-region of the lower ionosphere that produce both auroral displays captured in all-sky images and disturbances in the ground magnetometers. The simultaneous occurrence at I53US of high trace-velocity infrasonic waves, geomagnetic perturbations, and cosmic radio noise absorption provides verification that the observed infrasound is generated in the lower ionosphere. Examples of the high-trace velocity signals along with the CNA and magnetometer data will be shown.
Porosity effects in large wind screening structures.
Authors: Abbott JohnPaul R. , Raspet Richard , Webster Jeremy
Published: July 2011

Recently completed research indicates that the dominant source of wind noise for infrasonic microphones placed on open ground is the interaction pressure of the average wind velocity profile and the vertical turbulence. The source region at infrasonic frequencies is quite large and therefore can only be reduced with relatively large structures. It is hypothesized that such a structure does not need to completely block the wind from the source region; it only has to reduce the wind velocity gradient above the microphone and perhaps modify the turbulence field. If so then a porous wind barrier or screen may be used. To investigate this hypothesis a 3 m high decagonal wind barrier with variable porosity has been constructed. Initial results indicate that reductions are strongest for intermediate porosities and for frequencies between 0.5 and 7 Hz. In addition, a near constant 3–5 dB reduction was also observed for frequencies below 0.5 Hz. The noise reduction results will be related to the measured wind profiles and turbulence spectra inside the enclosure. The enclosure is quite open and should have little effect on acoustic waveforms, unlike pipe arrays and porous hose arrays.
Lizard ears and simple solutions to auditory coding.
Authors: Manley Geoffrey
Published: July 2011

The variety of lizard auditory organs provides an optimal substrate for examining structure-function relationships. What does an auditory organ need to perform the basic tasks in the coding of acoustic stimuli? The single-ossicle tympanic middle ears of lizards are connected through the head, providing for sensitive directional hearing with little neural processing. Lizards evolved hair cells whose frequency responses were determined by the morphological details of their stereovillar bundles and tectorial material, enabling a tonotopic arrangement of frequency sensitivity. Modern lizards achieve this with few hair-cell rows, showing that tonotopicity does not demand an extensive epithelium. Finally, different lizard families achieved dissimilar frequency selectivity through manipulations of anatomical features, especially of the tectorial membrane. There is a pay-off between the size of the auditory papilla and its ability to code different frequencies. Long papillae allow very local coupling of hair-cell bundles with very selective frequency tuning. Short papillae generally abandon tectorial coupling to allow for useful tuning but this results in poorer sensitivity and poorer tuning selectivity. Lizards demonstrate that sensitive and selective hearing organs need only a few hundred hair-cells organized along a straight axis. [work supported by the German Research Foundation DFG (MA 871-10.)]
The teachings of anurans: Mechanisms of auditory processing in the frog.
Authors: Meenderink Sebastiaan W. F.
Published: July 2011

Amphibians are one of the four classes of tetrapod vertebrates. The majority of amphibian species are anurans, better known as frogs and toads. Frog hair cells have served as a model for studying fundamental cellular processes including electrical tuning, forward and reverse transduction, and “cochlear” amplification. In most frogs, these processes act at much lower frequencies compared to the mammalian cochlea, and extrapolation of results to higher-frequency epithelia must be made with caution. The gross anatomy of the anuran inner ear is unique among vertebrates in that it possesses two distinct organs specialized in the detection of airborne sounds. Moreover, there is no analog of the basilar membrane in these organs; hair cells are situated directly over the stationary, cartilaginous labyrinth. These structural differences are reflected in how sounds propagate within the inner ear. Specifically, traveling waves seem absent in frog. Despite this, otoacoustic emissions in anurans and mammals share many characteristics, and their comparative study may help to elucidate universal mechanical properties of the inner ear. These examples, combined with numerous other types of experiments, have made the frog a useful substrate for the examination of cellular mechanisms, transduction, and macro-mechanical inner-ear properties underlying normal vertebrate hearing.
Otoacoustic emission delays as a probe to measure cochlear tuning: Comparative validations.
Authors: Bergevin Christopher
Published: July 2011

The ear is not only sensitive to sound but selective as well: Tonotopic tuning of the inner ear provides a means to resolve incoming spectral information. Measurements of frequency selectivity have traditionally relied upon either subjective psychophysical or objective (but invasive) physiological approaches. Sounds emitted from a healthy ear, known as otoacoustic emissions (OAEs), have been proposed to both objectively and non-invasively estimate peripheral auditory tuning. Despite diverse inner-ear morphological variation across animals, OAEs are a universal feature and correlate well to an animal’s range of active hearing. Recent studies focusing on emission delays in response to a single stimulus frequency (SFOAEs), conducted systematically across species in a variety of classes (mammals, aves, reptiles, and amphibians), support predictions relating emissions and tuning. Longer SFOAE delays presumably reflect the sharper tuning associated with resonant build-up time of the underlying auditory filters. Differences in tuning estimated from OAEs appear generally congruous with known anatomical and functional considerations: Larger sensory organs (i.e., more “filters”) with smaller ranges of audition exhibit sharper tuning. Comparisons made both broadly (inter-class) and within phylogenetically-matched groups (intra-family) indicate that SFOAE delays in humans are longer than any other species so far examined, suggestive of exceptionally sharper tuning.
Response properties and local connectivity of the cochlear nucleus of the big brown bat.
Authors: Simmons Andrea M. , Horowitz Seth S. , Barchi Jonathan R. , Simmons James A.
Published: July 2011

We characterized responses of the cochlear nucleus (CN) in big brown bats using local field potentials and extracellular unit responses to tone bursts, forward and reversed FM sweeps, and pulse-echo pairs. Neurobiotin-filled pipettes were lowered through the inferior colliculus of anesthetized bats to depths from 3.2 to 4.3 mm based on stereotaxic coordinates. Response properties were correlated with local anatomical connectivity as shown by transport of neurobiotin from the recording site and immunohistochemical localization of GABA and of connexin 35/36 in alternate brain sections. In dorsal AVCN, response properties were similar to those seen in the nuclei of the lateral lemniscus. Recording sites in ventral AVCN near the insertion point of the auditory nerve showed unique characteristics, including very short latencies (1.5–3 ms) and oscillatory responses extending past the duration of the sound. Most sites were sharply tuned to low frequencies corresponding to the first harmonic of the FM sweep, and responded equally well to forward and reverse FM sweeps. Data indicate that early stages of auditory processing in the big brown bat are critical to echolocation hyperacuity and may be dependent on anatomical specializations of the AVCN. [Work supported by the NIH, ONR, and RI Space Grant (NASA).]
Aircraft cabin noise control: Challenges and opportunities.
Authors: Viswanathan Krishna , Hoffman Herb , Lin Alex
Published: July 2011

Increasingly stringent limits on community noise from aircraft operations have been imposed over the past three decades. However, no comparable limits have been in place for cabin noise levels until recently. The introduction of regulations by the European Union on the allowable levels for noise exposure inside the aircraft cabin for pilots, flight attendants, and passengers has brought this problem to the forefront. Several noise sources contribute to high noise levels inside the cabin; the dominance of any particular source varies depending on the location. In addition to the noise due to the turbulent boundary layer, engine vibrations, and equipment, the noise from the engines plays an important role. The nozzles of a dual-stream turbofan engine are operated invariably at super-critical pressure ratios at cruise, thereby producing shocks in the jet plume. Consequently, broadband shock-associated noise is generated in addition to the turbulent mixing noise component. The engine noise impinges on the fuselage and is transmitted into the interior of the aircraft cabin. Control strategies typically focus on appropriate designs for reducing source noise and optimizing acoustic treatment, as the added weight is undesirable. This talk provides an overview and concrete examples for noise control.
Cockpit door module for A380 and AXP A340 aircraft.
Authors: Dickerson Mike , Dickerson Michael
Published: July 2011

The cockpit door module for the A380 and A340 aircraft was assessed for specification compliance. Per the manufactures specifications, the noise/vibration levels exceeded performance specifications at various frequencies during the testing phases. Each noise contributor in the overall system was identified evaluated and assessed. The real world practical application of active/passive noise control was utilized in a superposition system. Due to strict FAA requirements, multiple paths of mitigation measures were explored. Mitigation measures include product redesign, material design, absorptive material, and constrained layer damping technology. Noise measurements were conducted to assess the results of the migration efforts. The data and results of this assessment are presented and discussed.
Reconstruction of normal surface velocities on a baffled plate using Helmholtz equation least squares method.
Authors: Natarajan Logesh Kumar , Wu Sean
Published: July 2011

This paper provides comprehensive experimental validations of the Helmholtz equation least squares (HELS) method for reconstructing the vibro-acoustic responses of a highly non-spherical object such as a baffled square plate. This study highlights that a computationally simple HELS code based on the spherical wave functions can accurately and effectively reconstruct vibro-acoustic responses of a planar surface. The key to a successful reconstruction is to select an optimal origin of the coordinate system behind the planar surface, and a hybrid regularization scheme. Tests are conducted inside an anechoic chamber and plate is excited by a point force. The radiated acoustic pressures are measured using a planar array of microphones at very close distance to the surface. The reconstructed normal surface velocities are compared against the benchmark data measured by a laser vibrometer. The reconstruction effectiveness is analyzed by comparing the reconstructed operation deflection shapes at the natural frequencies against the theoretical natural modes and the measured resonance modes. The results revealed that the HELS codes, when coupled with a hybrid regularization procedure through a modified Tikhnov regularization and least squares method, can yield the very accurate reconstruction of the vibro-acoustic responses of a vibrating plate in both amplitudes and surface distributions.
Vibration isolation by frequency and temperature sensitive elastomers.
Authors: Rosenhouse Giora
Published: July 2011

Damping is the most important factor in vibration isolation due to dissipating mechanical energy into heat, energy absorption under impact, imposing finite amplitude bound amplitudes at resonant frequencies, and mitigating vibration amplitudes in the vicinity of those frequencies while increasing the amplitudes in other frequency domains. Thus, many kinds of available elastomers of high damping ratio are in common use as anti-vibration materials. The choice of polymer depends on the specification (loads and environmental conditions) and the isolation purpose. Most of these commercial materials properties were tested and defined by specific viscoelastic models. Also, their properties depend on frequency, temperature, and time that can be measured following test regulations. This dependence leads to the dynamic response functions of single or multi-degree of freedom systems (SDF or MDF systems) that differ in shape from those of systems with independent (constant) parameters. A solution is developed here to response function of an SDF system with frequency and temperature dependent elasticity and loss factor that can be expanded for MDF systems analysis. Consequently, the sensitivity of parameters of typical elastomers leads to large changes in the response function that should be taken into account in designing elastic mountings and vibration isolation.
Analytical modeling of the acoustic field during a Direct Field Acoustic Test.
Authors: Rouse Jerry W. , Stasiunas Eric C. , Mesh Mikhail
Published: July 2011

The acoustic field generated during a Direct Field Acoustic Test (DFAT) has been analytically modeled in two space dimensions using a properly phased distribution of propagating plane waves. Both the pure-tone and broadband acoustic field were qualitatively and quantitatively compared to a diffuse acoustic field. The modeling indicates significant non-uniformity of sound pressure level for an empty (no test article) DFAT, specifically a center peak and concentric maxima/minima rings. This spatial variation is due to the equivalent phase among all propagating plane waves at each frequency. Predicted spatial variation is shown to agree well with experimental measurements. The excitation of a simply supported slender beam immersed within the acoustic fields was also analytically modeled. Results indicate that mid-span response is dependent on location and orientation of the beam relative to the center of the DFAT acoustic field. For a diffuse acoustic field, due to its spatial uniformity, mid-span response sensitivity to location and orientation is nonexistent. Extension of the modeling to three space dimensions and numerical methods is underway.
Sound reduction of a vibrating plate via dimpling design.
Authors: Alshabatat Nabeel , Myers Kyle , Naghshineh Koorosh
Published: July 2011

The vibroacoustic performance of plates can be altered by different methods known as structural dynamic modification methods. One of these methods is the shape modification of plate surface. In this study, a method for reducing the sound radiation of vibrating plates is presented. The method based on creating dimples on the surface of a plate. The dimple can be defined as a local modification in the surface of a structure, which has a spherical shape. The dimples change the local stiffness of the plate without changing its mass. Also, they alter the mode shapes so as to reduce sound power, i.e., the radiated sound at some modes is inefficient due to low net volume velocity. The design method couples finite element method, for predicting plate vibration response, with optimization technique based on a genetic algorithm to minimize sound power radiation. The sound radiation is minimized either at a single frequency, or over a broad frequency band. The results show that dimples forming on the plate can achieve effective reductions in radiated sound power.
A new approach for material characterization of anisotropic plates using ultrasonic guided waves.
Authors: Jamali Jalil
Published: July 2011

Nondestructive testing methods play an important role in physical characterization of materials and in assessment of their quality and serviceability in structures. Ultrasonic NDT methods are effective instruments for evaluation of elastic modulus, stiffness, and other essential parameters which are vital for analysis and design of structures. In this paper, a novel method for material characterization of anisotropic plates using ultrasonic guided wave is presented. For this purpose, the ultrasonic guided wave propagation in anisotropic plate structures is modeled and the parameters affecting the symmetric and antisymmetric modes are studied. To investigate reliability and efficacy of the proposed approach, the theoretical and experimental results are compared for a thin carbon fiber reinforced plate.
An acoustic description of Maku vowels.
Authors: Puderbaugh Rebekka , Tucker Benjamin V.
Published: July 2011

Maku is believed to have originated in Venezuela and migrated into Brazil in the 19th century though there are no longer believed to be any living speakers. Field recordings of a single adult male speaker made in 1953 and 1965 by Migliazza [1978] are used in the current project for an acoustic analysis of the phonemic vowel inventory of Maku. Early impressions of the vowel space indicate five to seven vowels: /i, ī, u, e, o, a/ as well as the areally unique /y/, with possible length and nasal/oral vowel distinctions. All vowels and their surrounding context in the original recordings were identified and coded. Vowel duration and values for the first three formants at 25%, 50%, and 75% through the vowel were extracted. Vowel categories were modeled from formant values using conditional inference trees [Hothorn et al. (2006)]. These models showed the likelihood of five vowel categories on the basis of the formant measures as well as the length of the vowel segment. Additional analyzes focus on consonantal context, word position, stress and pitch. The acoustic data are also used to reconstruct the vowel space from the bottom up without the influence of investigators’ perceptual judgment.
Unsupervised learning of linguistic tone systems from field-recorded audio.
Authors: Hou Joshua S.
Published: July 2011

This study presents a system that uses unsupervised learning algorithms on field recorded audio data of a tone language and induces the underlying tone system from the data. Most of the previous work on tone and machine learning has focused on supervised learning of tone. This requires large amounts of annotated data, which exists only for major languages. Unsupervised learning opens up the possibility of automatic tone recognition without the large amounts of training data needed for supervised learning. A number of studies have been done on unsupervised learning of tone. However, these studies used learning algorithms which assume prior knowledge of the number of tonal categories in the data. This study presents a proof-of-concept system that uses a clustering algorithm that does not require prior knowledge of the number of tonal categories and describes the experiments that demonstrate the efficacy of these methods on audio data with field recording quality.
Tonal variations in Anong.
Authors: Thurgood Ela
Published: July 2011

This study presents an acoustic analysis of Anong tones. It has three aims: (1) to present some detailed documentation of instrumental-acoustic data on citation tones, (2) to compare the acoustic features of the citation tones with the same tones used in disyllabic utterances, and (3) to analyze tones in disyllabic utterances. Anong citation tones are characterized by three features. First, the tonal space is small. Second, onset consonant type correlates with the pitch height of the following vowel. Third, non-modal phonation is not an acoustic cue to any of the five tones. Neither is it a contrastive property of vowels. In disyllabic utterances, the F0 shapes and heights on the first-syllable tones can be readily related to the F0 shapes and heights in the citation forms. The F0 value of the second-syllable tones depends on the offset value of the tone in the first syllable. However, disyllabic forms with the prefix /a31/ follow a different pattern, one in which the first-syllable tone is raised. This pattern correlates with vowel laryngealization and vowel duration.
Airflow and duration patterns in Tunisian Arabic fricatives.
Authors: Maddieson Ian , Saghrouni Rachid
Published: July 2011

Airflow and duration patterns in Tunisian Arabic fricatives were examined in data from six male speakers. TA is conventionally described as having eight fricative phonemes, five voiceless (labio-dental, alveolar, uvular, pharyngeal and “glottal”) and three voiced (dental, alveolar, and pharyngeal). These segments occur as singletons and geminates. Tokens of both types were collected in word-medial position following an initial /Ca/ sequence, where C is a single stop and /a/ a short low back vowel. Duration of this vowel preceding singleton and geminate fricatives was compared with its duration preceding a medial fricative + consonant (/FC/) cluster, where a syllable boundary is assumed to occur between /F/ and /C/ (e.g., /kafara, kaffara, kafra/). Vowel duration before the geminate is similar to that observed before the cluster, arguing for a syllable boundary within the geminate. However, airflow patterns do not suggest that any “re-articulation” occurs during the geminate constriction [unlike in French pseudo-geminates, Smith (1996)]. Airflow shows the expected elevation at the transitions between vowel and fricative and a single low trough during the constriction, except for /h/. Because there is no supraglottal constriction, /h/ has peak airflow near the center of its duration. Thus /h/ does not pattern with other “gutturals.”
Coarticulation and consonant cluster production in Iwaidja.
Authors: Fletcher J. M. , Butcher A. R. , Loakes D. , Stoakes H.
Published: July 2011

Articulatory analyzes of consonant cluster production have provided a rich source of information for modeling the production of speech over the years. It has been suggested that Australian indigenous languages show remarkable stability in heterorganic C1C2 sequences where C1 is coronal and C2 is noncoronal as in /nk/ sequences. In other words they show little or no anticipatory place of articulation assimilation. In this paper, the focus is on consonant cluster production in Iwaidja, an endangered Australian indigenous language spoken in the Northern Territory, Australia. Like most Australian languages, Iwaidja has a rich set of oral stop, lateral, and nasal place of articulation contrasts. Results of an acoustic phonetic and electropalatographic study show that assimilation is resisted in various ways in order to maintain place contrasts in certain sequences. Strategies include gestural delay and associated lengthening of initial consonants in C1C2 sequences. Nevertheless there is also clear evidence of a range of other effects including blending in situations of gestural conflict. Implications for models of coarticulatory processes are presented in the light of prevailing speech production models and compared to earlier findings based on analyzes of two other Australian languages: Warlpiri and Arrernte.
An acoustical study of American English diphthongs.
Authors: Yang Byunggon
Published: July 2011

English diphthongs are usually produced with more than one vocal tract shape. This study attempts to collect acoustical data of English diphthongs published by Hillenbrand et al. (1995) online and to examine acoustic features of the diphthongs for phoneticians and English teachers. 63 American males and females were chosen after excluding those subjects with different target vowels or ambiguous formant tracks. The author used PRAAT to obtain the acoustical data systematically at 11 equidistant timepoints over the diphthongal segment. Results show that the formant trajectories of the diphthongs produced by the American males and females appeared quite similar. When the female formant values were uniformly normalized to those of the males, almost a perfect collapse occurred. Second, the diphthongal movements on the vowel space appeared not linear due to the coarticulatory gesture for the following consonant. Third, the average duration of the diphthongs produced by the females was 1.156 times longer than that of the males while the pitch ratio between the two groups turned out to be 1.746 with a similar contour over measurement points. The author concludes that English diphthongs produced by various groups can be compared systematically when the acoustical values are obtained at proportional timepoints.
Toronto English vowels: Deriving the vowel space from conversational data.
Authors: Hagiwara Robert
Published: July 2011

This presentation develops an overview of the Toronto English vowel space using data derived from the unscripted, casual speech typical of sociolinguistic interviews, rather than the more “formal” avenue of laboratory speech. Drawing on a corpus of sociolinguistic interviews collected by Walker & Hoffman (“language contact, linguistic variation and ethnic identity in Toronto English” SSHRC SRG 410-2008-2048) and using multiple-point formant measurements of stressed vowels in “clean” environments (e.g., avoiding coda nasals and liquids), this study develops views of the vowel space that illustrate modal or average vowel centers, within-category scatter, between-category dispersion, and VISC. In refining this kind of vowel data collection and analysis, this research provides a baseline for further studies, such as to describe vowel differences in “ethnically” marked varieties of English, to characterize adjustments made in specific phonological contexts, to identify previously undescribed phonetic variation in Canadian English, and to compare similar data from other varieties of English.
An acoustic description of Utah English vowels.
Authors: Sykes Robert D.
Published: July 2011

Labov [30, (1991)] described Western English as a dialect where neither the Northern Cities Shift nor the Southern Shift operate. The vowel/æ/ is resistant to raising and /a/ and /ɔ/ are merged as a single low-back phoneme. Labov et al. [37, (2006)] (ANAE) predicted differential fronting of /uw/ and /ow/, a lack of Canadian Raising or glide-deletion, and a merger or near-merger of /i/ and /ɪ/ before tautosyllabic /l/. Di Paolo and Faber [(1990)] argued that the vowel system of Utah fits the Southern pattern. This would predict a reversal of /i/ and /ɪ/ in phonetic space and the deletion or weakening of the glide in the diphthong /aɪ/. This study tests this prediction in the speech of natives of Salt Lake City, UT. Sociolinguistic interviews of seven young adults were analyzed acoustically. Results show that the Utah vowel system is more complicated than either ANAE or Di Paolo and Faber suggested. The data suggest differential fronting of /uw/ and /ow/, an approximation of /i/ and /ɪ/, and an approximation of /a/ and /ɔ/, consistent with Western patterns. However, data also suggest the glide of /aɪ/ is weakened before voiced segments and in open syllables, consistent with the Southern pattern.
Ultrasound analysis of the Czech phoneme /ř/.
Authors: Howson Phil , Komova Ekaterina , Gick Bryan
Published: July 2011

Previous studies comparing the articulation of the contrasting Czech trills /ř/ and /r/ have described /ř/ as being produced with the laminal portion of the tongue at a more anterior location with a narrower channel [Ladefoged and Maddieson, The Sounds of the World’s Languages Blackwell, Oxford (1996)] and using a tighter constriction than /r/ [Dankovičová, JIPA 27, 77–80 (1999)]. These observations correspond to the IPA symbol [r] with a raising diacritic, which replaced the former symbol corresponding to a voiced strident apico-alveolar trill. The current project uses B-mode and M-mode ultrasound imaging and acoustics to test these descriptions of /ř/. Preliminary results based on a single participant revealed nearly identical constriction locations for the two trills, with the /ř/ constriction vibrating a larger tongue surface area. Overall, the tongue surface is lower and more forward in the mouth for /ř/ than for /r/, making [r] with a lowering diacritic a more appropriate choice for representing this sound. Spectrographic evidence also reveals important temporal properties for /ř/. Results for additional participants will be reported. [Work supported by the NSERC.]
The palatoglossal sphincter in French uvular /r/.
Authors: Francis Naomi C. , Klenin Anna , Mizrahi Ezra , Tom Denise C. , Gick Bryan
Published: July 2011

Speech production models have typically defined lingual constrictions in terms of tongue motion relative to unmoving opposing surfaces, such as the palate or teeth. While such a model may apply well to hard structures such as the palate, it is not clear that this appropriately characterizes constrictions involving soft structures such as the velum and uvula. Anatomically, the uvula and velum constitute the upper surface of a muscular sphincter including the palatoglossus muscles laterally and the tongue below. The present study tests whether uvular constrictions may be better described as actions of this palatoglossal sphincter, analogous to the lips, velopharyngeal port, or epilaryngeal tube. We tested this proposal by measuring the response of the velum/uvula during production of French uvular /r/ in an x-ray film [Munhall et al., J. Acoust. Soc. Am., 98(2), 1222–1224 (1995)]. Preliminary findings indicate that, as seen with other sphincters, speakers exhibit a variety of different mechanisms for forming constrictions, but all show active involvement of the palatoglossal arch, in addition to the tongue, in producing the uvular constriction. Modifications to speech production models to accommodate these findings will be discussed. [Work supported by the NSERC.]
Time to pull out the stops: Spirantization in Pacific Northwestern English.
Authors: Riebold John M.
Published: July 2011

Anecdotal evidence suggests that English speakers in North America are spirantizing stops. Spirantization is a consonant lenition process active in many languages, but has traditionally been assumed not to be active in English, except as a lexical or affixal process. This study is an investigation into the spirantization of stops using recordings of eight age/sex matched dyads (n=16) from a small corpus of Pacific Northwestern English speech. Representative monologues were extracted for each speaker and analyzed acoustically. Alveolars and voiceless aspirated stops were excluded from analysis as alveolar stops have a large number of allophones, and aspiration may block spirantization. The resulting tokens were rated for the absence of a stop burst, the presence of frication noise, and the presence of formant structure. Scores for each factor were then used to create a coarse-grained spirantization score for each token, with lack of a release burst, and presence of frication or formants indicating incomplete closure. Preliminary results from four speakers (88 tokens total) show that spirantization is indeed occurring: 44% of the tokens were spirantized. Additionally, it appears that velars are much more likely to spirantize than bilabials: 77% of velars spirantized compared to 26% of bilabials.
Does merger happen in the three-way contrast of Korean stops?
Authors: Kuang Jianjing , Oh Mira
Published: July 2011

Most previous studies of Korean stops have focused on limited acoustic cues, e.g., VOT and F0; few have considered voice quality and if any, only H1-H2 was mostly studied. Therefore, the question of the realization of three-way stop contrast (lenis, aspirated, and tense) in Korean is not settled. Given that the contrast is undergoing sound change (VOT of lenis is increasing), there arises the question whether other acoustic cues also change over time to keep the three-way contrast. Therefore, this study comprehensively investigates various acoustic measures of Korean stops from ten young Seoul speakers (five females; five males). Other than the distinctive low F0 after lenis stops and non-distinctive VOT between lenis and aspirated stops, our preliminary results show the the following. First, females and males exhibit significantly different acoustic realizations of three types of stops. Second, compared to the other two types, lenis stops are special in the way that they have larger variations of values in various acoustic measures (VOT, F0, H1*-H2*, H1*-A1*, H1*-A3*, etc.), which may account for the conflicting results in previous studies. Third, in the young generation, although VOT of lenis stops is merging toward aspirated stops, the vowel phonation after lenis stops is moving toward that after tense stops. This study suggests that the three-way stop contrast is maintained but with different acoustic realizations.
Effects of talker experience on perceived clarity and acoustic features of clear versus conversational speech.
Authors: Ferguson Sarah Hargus , Widener Taylor Denise , Mackey Tanner
Published: July 2011

Studies of the 41-talker Ferguson Clear Speech Database [Ferguson (2004)] have found no relationship between talkers’ self-reported experience communicating with individuals with hearing loss and the magnitude of the clear speech effect for vowels presented in noise. That is, talkers with no experience talking to people with hearing loss showed just as much clear speech vowel intelligibility benefit as talkers with extensive experience. The present study explored whether talker experience effects might emerge with more meaningful materials. Clear and conversational sentences produced by eight talkers (four with extensive experience and four with no experience) were presented in quiet to young listeners with normal hearing, who rated the clarity of each sentence on a seven-point scale. Several acoustic measures were also performed on these sentences. While the average size of the clarity difference between clear and conversational speech was similar for the two groups, talker experience effects were found for some of the acoustic measures. However, considerable variability was observed among the talkers, particularly within the “no experience” group. Relationships between acoustic measures, clarity ratings, and talker experience will be discussed. The present data will also be compared to those from an earlier study using a different set of eight talkers.
Acoustic landmark analysis of speaker differences in producing clear versus conversational speech.
Authors: Hamilton Sarah , Combs Sandra , Balvalli Shruti , MacAuslan Joel , Krause Jean , Boyce Suzanne E.
Published: July 2011

In previous work, we have shown that landmark analysis can be used to detect acoustic changes in clear versus conversational (typical and plain) speech that are associated with changes in intelligibility to listeners. However, these results derive from studies using a small number of speakers [Bradlow and Bent, (2002); Smiljanic and Bradlow (2008)]. The degree to which landmark analysis can be used to predict intelligibility for any particular speaker or sample of speech is not known. In this paper, we present results from a study of listener intelligibility for clear and conversational speech by four speakers with widely differing scores on parameters of acoustic change as determined by landmark analysis. The data consist of intelligibility scores (# content words correct) for a set of BKB sentences produced by these four speakers and presented to four groups of listeners in quiet and in noise. We compare these data with data from studies by Krause & Braida [2002, 2004]. Results will be discussed in terms of the distribution of acoustic changes used by individual speakers to produce clear versus conversational speech, and the relationship of these changes to listener intelligibility.
Motor-induced suppression of auditory neural responses to pitch-shifted voice feedback.
Authors: Behroozmand Roozbeh , Larson Charles
Published: July 2011

Surviving in an alien world is dependent upon the ability to distinguish between sensory inputs arising from self-actions and those of the others. In the auditory system, the motor-driven predictions about expected sensory feedback (efference copies) are proposed to suppress sensory neural responses to self-voice feedback that is predicted by the efference copies. In the present study, event-related potentials were recorded in response to five different magnitudes (0, 50, 100, 200, and 400 cents) of pitch shift stimuli at voice onset during active vocal production and passive listening to the playback. Results indicated that the suppression of N1 component during vocal production was largest for normal voice feedback (PSS: 0 cents) and became smaller as the magnitude of pitch shift stimuli increased. For the largest tested PSS magnitude (400 cents), the N1 suppression was completely eliminated. One possible explanation for this effect is that the brain utilizes the motor predictions (efference copies) to suppress the auditory feedback of self-generated vocalizations. The reduction of suppression for 50, 100, and 200 cents pitch shifts in voice feedback and its elimination for 400 cents stimuli provide supporting evidence for the idea that motor-driven predictions provide mechanisms that lead to distinctly different sensory neural processing of self versus non-self vocalizations.
Statistical relationships in distinctive feature models and acoustic-phonetic properties of English consonants.
Authors: de Jong Kenneth , Silbert Noah H. , Regier Kirsten T. , Albin Aaron
Published: July 2011

The relationship between segmental contrasts, often modeled as being composed of distinctive features, and actual acoustic-phonetic properties is complex and many-to-many. Contrasts may be cued by a multiple acoustic-phonetic properties, and acoustic-phonetic properties often cue multiple contrasts. This paper presents a hierarchical multivariate statistical model of the relationship between a suite of 11 acoustic measurements and various target feature systems. Measurements are taken from 10 repetitions of 16 English consonants by 20 native speakers of English in both onset and coda position in nonsense monosyllables. Target feature systems range from models with little generalization across the various segments to ones that fully cross distinctive features to specify all of the segments. The statistical model enables analysis of within-speaker and between-speaker sources of variability in consonant production, and constitutes a principled statistical method for comparing these different distinctive feature models. Also, the role of the statistical model as a baseline for work on relations between different segments in perceptual categorization will be outlined.
The labial viseme reconsidered: Evidence from production and perception.
Authors: Mayer Connor , Abel Jennifer , Barbosa Adriano , Black Alexis , Vatikiotis-Bateson Eric
Published: July 2011

Previous studies have demonstrated that the labial stops /p,b,m/ may be impossible to discriminate visually, leading to their designation as a single viseme. This perceptual limitation has engendered the belief that there are no visible differences in the production of /p,b,m/, with consequences for research in machine recognition, where production differences below the level of the viseme have been largely ignored. Kinematic studies using high-speed cine, however, have previously documented systematic differences in the production of labial consonants. This study examines the degree to which visual /p,b,m/ are discriminable in production and perception. Two experiments—one designed to measure kinematic orofacial movement using optical flow analysis and one designed to test perceiver discrimination of /p,b,m/—were used to establish the absence/presence of systematic visual differences in bilabial productions, and to replicate the previous perception findings. Results from the optical flow analysis indicate systematic kinematic differences for the peak velocity of the lower face, which corresponds to the release of the bilabial consonant. Significant differences were found in velocity between /m/ and /b/, and between /p/ and /b/, but not between /p/ and /m/. Preliminary results from the perception task suggest discrimination of bilabial consonants is at chance level.
Implementing wave propagation on desktop graphics processing units: Split-step Fourier parabolic equation modeling example.
Authors: Hursky Paul , Porter Michael B.
Published: July 2011

The quest for raw computing power has shifted from increasing processor clock speeds to increasing the number of processing cores. Currently, mainstream CPUs can be purchased in dual-slot quad-core and hex-core configurations. On the other hand, graphic cards provide hundreds of processing cores. Although there have been various implementations of scientific applications on graphics hardware, including underwater acoustic modeling, widespread use of this technology has been hampered by the often extraordinary effort needed to program this hardware, especially if the application architecture did not match the canonical graphics pipeline for gaming. In the last few years, the major graphics board manufacturers have stepped away from designing hardware specialized for particular new graphic special effects and made a concerted effort to provide general-purpose computing capabilities, of the sort that can be exploited for scientific computing. For example, Nvidia’s CUDA environment currently provides many building blocks for scientific computing, such as (subsets of) BLAS, LAPACK, and FFTs. We will present our experiences implementing the split-step Fourier parabolic equation in the CUDA environment, showing how we have achieved a 10 times speedup relative to a multi-core CPU implementation, with a modest investment in programming effort. We will also provide some guidelines on how various applications of interest to the underwater acoustics community might benefit from use of this technology.
Finite element modeling of longitudinally invariant shallow water waveguides.
Authors: Isakson Marcia
Published: July 2011

Finite element models of shallow water waveguides are fully customizable to include effects such as range dependent bathymetry, sound speed profiles, and interface roughness. However, until recently, these solutions have been confined to 2-D environments. While these models provide benchmarks for other solution methods such as coupled modes or parabolic equations, they cannot be compared with data. Fully 3-D models of shallow water waveguides are still beyond current computational capability, but longitudinally invariant models may bridge the gap. These solutions are often known as 2.5D models. In this scheme, the waveguide is reduced to a series of 2-D finite element domains, the solutions to which comprise the Green’s function in the wavenumber-frequency domain of the 2.5D space. A cosine transform is then used to convert these into a frequency-domain solution for a longitudinally invariant space. In this study, the wavenumber-frequency Green’s function will be analyzed in order to develop more efficient computational methods for shallow water waveguides. Solutions for both flat and rough interface shallow water waveguides in 2.5D will be presented and compared with a wavenumber integration approach. [Work supported by the Office of Naval Research, Ocean Acoustics Program.]
Azimuthal variability in the “Quantifying, Predicting, and Exploiting Uncertainty” experiment: Can we reliably model the measurements?
Authors: Lynch James F. , Newhall Arthur E. , Lin Ying-Tsong , Duda Timothy F. , Emerson Chris , Abbot Philip
Published: July 2011

Using an acoustic source mounted on an autonomous underwater vehicle, measurements were made of the azimuthal variability of transmission loss (TL) in the East China Sea just northeast of Taiwan. These measurements showed substantial variability in the peak level TL (5–10 dB) and somewhat less in the pulse integrated TL. Angular peak widths were distributed between 0 and 35 deg. The variability in the acoustic field is caused primarily by oceanographic variability (and its interaction with bathymetry) and is influenced by fine scale to large scale ocean processes. We examine here whether or not we can adequately model such variability at present, and if not, what improvements in ocean and acoustic models will be needed to do so.
A measurement system for shear speed using interface wave dispersion.
Authors: Miller James H. , Potty Gopu R. , Greene Jeannette M.
Published: July 2011

Our recent work has highlighted the effect of shear on the dispersion of acoustic normal modes. Recently, Pierce et al. showed the effect of shear on compressional wave attenuation and its frequency dependence. Potty and Miller [(2010)] showed that sediment shear speed can significantly impact compressional modal arrival times near the Airy phase. We have observed that neglecting shear in compressional wave speed inversions results in a bias in our long range sediment tomography inversions. All of these factors emphasize the importance of estimating shear wave speeds in semiconsolidated shallow water sediments. One of the most promising approaches to estimate shear speed is to invert the shear speed profile using the dispersion of seismoacoustic interface waves (Scholte waves) that travel along the sediment-water boundary. The propagation speed and attenuation of the Scholte wave are closely related to shear-wave speed and attenuation over a depth of one to two wavelengths into the seabed. A shear measurement system being developed at the University of Rhode Island based on this concept will be presented. Test data collected on land will be shown and preliminary analysis techniques will be discussed. [Work supported by the Office of Naval Research.]
Calculation of wave propagation with elastic boundary conditions.
Authors: Clark Cathy Ann
Published: July 2011

Calculations of compressional and shear wave transmissions and reflections through sediment layers are utilized to derive a single bottom reflection coefficient by formulating an infinite sum of matrices and expressing the result as a convergent series. The expression of bottom loss as a single coefficient eliminates the need to search for sediment mode eigenvalues, resulting in an improvement in efficiency. When implemented in a normal mode propagation model, the bottom loss prediction is shown to successfully reproduce resonance effects due to shear wave conversion in various types of sediments. Comparisons of boundary calculations to other published results are presented and propagation predictions are compared to a number of measured data sets.