bluuebunny/crossref_metadata_2025 huggingface dataset:
Exact wide-angle formulation of the Beilis-Tappert method
Authors: Gilbert Kenneth E. , Di Xiao , Hart Carl R.
Published: April 2018

The Beilis-Tappert method was originally developed for narrow-angle acoustic propagation under a rough sea surface [A. Beilis and F. D. Tappert, J. Acoust. Soc. Am. 66, 811–826 (1979) ]. The method has also been applied to narrow-angle propagation over irregular terrain for acoustic waves and radar. It is shown here that an exact wide-angle formulation of the Beilis-Tappert method can be derived simply by replacing ∂/∂z with ∂/∂z + ik0 tanφ, where k0 = 2π/λ, λ is the physical wavelength, φ is the slope angle, and i= √-1. The exact formulation makes clear that for large slope angles, much of the acoustic field does not propagate, but decays exponentially with range. Existing finite difference methods and all narrow-angle methods fail to properly account for the exponential decay with a range of the non-propagating components of the acoustic field. The exponential decay with this range is qualitatively explained in terms of rays and quantitatively explained in terms of waves. Properly accounting for the propagating and non-propagating components of the acoustic field is explained.
Investigation of broadband attenuation with fractal diffusers as noise barrier top edge devices using indirect boundary element method
Authors: Priyadarshinee Prachee
Published: April 2018

Computation of broadband noise barrier performance in three-dimension is computationally expensive. Indirect boundary element method with double layer potentials has been developed as a numerical tool in this acoustic study. It naturally permits noise barriers to be modelled as thin structures, thus reducing the computational cost when compared to the more abundant direct boundary element tools employed for noise barriers. The present numerical model has been validated with analytical solution. Its computational capabilities are compared with a direct boundary element tool, developed in-house. The applicability of this tool has been demonstrated with the study of fractal acoustic diffusers as noise barrier top-edge devices. Schroeder diffusers have been reported to provide good noise attenuation at their design frequency, when used as noise barrier top-edge devices. This study investigates the broadband performance of fractal diffusers as noise barrier top-edge devices.
Trends that are shaping the future of hearing aid technology
Authors: Edwards Brent
Published: April 2018

The development of hearing aid technology has accelerated over the past decade. Hearing aids are converging with consumer electronics in the area of hearables, and a recent government law mandating the creation of an over-the-counter hearing aid category will continue to bring a more consumer electronics focus to hearing aids. Meanwhile, new advances in hearing science are redefining the criteria of who needs hearing help. This talk will review these new intersections of technology and hearing need. It will also detail the technological and psychoacoustical challenges that face the ability of these new technologies to meet the needs of current hearing aid wearers, the needs of this emerging segment of the hearing impaired, and changes to hearing health delivery.
Tracking eye and head movements in natural conversational settings: Effects of hearing loss and background noise level
Authors: Lu Hao , McKinney Martin , Zhang Tao , Oxenham Andrew J.
Published: April 2018

Although beam-forming algorithms for hearing aids can produce gains in target-to-masker, the wearer’s head will not always be facing the target talker, potentially limiting the value of beam-forming in real-world environments, unless eye movements are also accounted for. The aim of this study was to determine the extent to which the head direction and eye gaze track the position of the talker in natural conversational settings. Three groups of participants were recruited: younger listeners, older listeners with clinically normal hearing, and older listeners with mild-to-moderate hearing loss. The experimental set-up included one participant at a time in conversation with two confederates approximately equally spaced around a small round table. Different levels of background noise were introduced by playing background sounds via loudspeakers that surrounded the participants in the conversation. In general, head movements tended to undershoot the position of the current talker, but head and eye movements together generally predicted the current talker position well. Preliminary data revealed no strong effects of hearing loss, or background noise level on the amount of time spent looking at the talker, although younger listeners tended to use their eyes, as opposed to head movements, more than the older listeners. [Work supported by Starkey Laboratories.]
Multimodal signal processing and machine learning for hearing instruments
Authors: Zhang Tao , McKinney Martin
Published: April 2018

With advances in wireless technology and sensor miniaturization, more and more non-audio sensors become available to and are being integrated into hearing instruments. These sensors help not only improve speech understanding and sound quality, enhance hearing usability and expand the hearing instruments' capabilities to health and wellness monitoring. However, the introduction of these sensors also present a new set of challenges to researchers and engineers. Compared with traditional audio sensors for hearing instruments, these new sensor inputs can come from different modalities and often have different scales and sampling frequencies. In some cases, they are not linear or synchronized to each other. In this presentation, we will review these challenges in details in the context of hearing instruments applications. Furthermore, we will demonstrate how multimodal signal processing and machine learning can be used to overcome these challenges and bring a greater degree of satisfactions to the end users. Finally, future directions in multimodal signal processing and machine learning research for hearing instruments will be discussed.
Acoustic correlates of auditory object perception: Speakers, musical timbres, and environmental sounds
Authors: Ogg Mattson , Slevc L. Robert
Published: April 2018

Human listeners must identify and orient themselves to auditory objects in their environment. What acoustic features support a listener’s ability to differentiate the variety of sound sources they might encounter? Typical studies of auditory object perception obtain dissimilarity ratings between pairs of objects, often within a single category of sound. However, such an approach precludes an understanding of general acoustic features that might be used to differentiate sounds across categories. The present experiment takes a broader approach to the analysis of dissimilarity ratings by leveraging the acoustic variability within and between different sound categories as characterized by a large, diverse set of 36 sound tokens (12 speech utterances from different speakers, 12 instrument timbres, and 12 everyday objects from a typical human environment). We analyze multidimensional scaling results as well as models of trial- level dissimilarity ratings as a function of different acoustic representations including spectral, temporal and noise features as well as modulation power spectra and cochlear spectrograms. In addition to previously noted differences in spectral and temporal envelopes, results indicate that listener’s dissimilarity ratings are also related to spectral variability and noise, particularly in differentiating sounds between categories. Dissimilarity ratings also appear to closely parallel sound identification performance.
Predicting timbral and perceptual characteristics of orchestral instrument combinations
Authors: Antoine Aurelien , Miranda Eduardo
Published: April 2018

Orchestration is a compositional practice that consists of writing for several instruments. This process often involves harnessing each instrument's sound to create sonic textures that could not be achieved with a single instrument. These sound fusions are usually sought by composers to express specific perceptual effects. However, the number of potential combinations is significant. Testing and analyzing all combinations to identify the ones matching the desired perceptual effects is logistically and computationally complex. Using supervised learning methods to create regression and classification models, it is possible to predict specific timbral and perceptual characteristics from information about a combination of different orchestral instruments. Such developments would provide methods to estimate the perception of instrument timbre fusions directly from abstract information. Similar methods could potentially be applied to other types of sources and predict specific perceptual characteristics without the need to perform an acoustical and psychoacoustical analysis on every audio sources.
Mechanical sound similarity and categorization
Authors: Rosen Annamarie , Srinivasan Nirmal Kumar , Gaston Jeremy , Perelman Brandon
Published: April 2018

Recent studies suggest that perceptual similarity among sounds can be used to predict accuracy in perceptual tasks (Dickerson & Gaston, 2014; Gaston, et al., 2017). We operationalize this similarity as distance in a 2D similarity space generated using multidimensional scaling (MDS) on pair-wise similarity stimulus ratings. We tested listeners’ ability to categorize mechanical environmental sounds, and modeled the relationship between stimulus categorization and similarity. Stimuli were 18 mechanical sounds selected hierarchically from three broad categories (vehicles, power tools, and household appliances), and three subcategories. Thirty-five normal hearing listeners completed pair-wise similarity rating and categorization tasks. Perceptual similarity ratings from all paired stimuli were used to develop an MDS solution. Stimuli in the solution generally were segregated by broad category membership, with some exceptions. Categorization performance for each broad category varied, with vehicles being the easiest and household appliances being the most difficult to categorize. MDS distances among the stimuli were used in a simple regression model to predict performance in the categorization task and explain confusions in categorization. The results of this study indicate that perceptual similarity is a strong predictor of variance in listeners’ judgments of complex environmental sounds.
The effects of carrier bandwidth and intensity on spectral ripple perception in listeners with hearing loss
Authors: Davies-Venn Evelyn E. , Oeding Kristi , Haug Andrew
Published: April 2018

Listeners with hearing loss often need to listen to speech signals at high intensities to ensure proper audibility. Spectral processing deteriorates at high intensities, but signal acoustics such as bandwidth and filtering can be used to mitigate this deterioration. This study evaluated the effect of carrier bandwidth on broadband spectral processing at high intensities for individuals with hearing loss. Spectral modulation detection thresholds were measured using a rippled noise carrier with varying bandwidths from 1 to 4 octaves, to assess whether individuals with hearing loss were more susceptible to the deleterious effects of high-intensity compared to their counterparts with normal hearing. Results show that spectral processing degrades at high intensities. Listeners with hearing loss benefited from the increase in signal bandwidth at high intensities much more than their counterparts with normal hearing. Our findings suggest that spectral processing for broadband signals involve within and across channel resolution and both succumb to the negative effect of level-induced broadening of auditory-filter bandwidths. A better understanding of how filtering can be used to alleviate the adverse effect of high-intensity signals could prove useful for improving outcomes for those individuals whose only viable treatment option often involves listening to speech signals at high intensities.
Multiple mechanisms in pitch perception revealed by individual differences
Authors: McPherson Malinda J. , McDermott Josh
Published: April 2018

Pitch perception is traditionally assumed to involve the estimation of fundamental frequency (F0) from sound. Some pitch-related tasks, such as those involving musical intervals, are more difficult with inharmonic sounds (lacking a clear F0). Other tasks, such as up-down pitch discrimination, are unaffected by inharmonicity, suggesting that listeners track the spectrum, not the F0. To test whether these effects reflect distinct mechanisms, we measured individual differences among large sets of participants on a battery of tasks. Performance on tasks using a common mechanism should be correlated across participants. Two tone up-down discrimination for wideband harmonic tones was highly correlated with performance for wideband inharmonic tones. To isolate F0-based pitch, we also measured discrimination for pairs of harmonic tones with non-overlapping sets of harmonics. Harmonic and inharmonic discrimination did not strongly correlate with this latter task. These results suggest that the same mechanism subserves up-down change detection for harmonic and inharmonic tones, and that this mechanism is distinct from F0-based pitch estimation. We also found weak correlations between spectral centroid discrimination and all other pitch tasks, suggesting separate mechanisms for fine and coarse spectral comparisons. The results suggest an additional pitch mechanism for tracking shifts in the spectrum rather than F0.
Short- and long-term memory for pitch and non-pitch contours in congenital amusia
Authors: Graves Jackson , Fornoni Lesly , Pralus Agathe , Oxenham Andrew J. , Caclin Anne , Tillmann Barbara
Published: April 2018

Congenital amusia is a disorder characterized by deficits in music and pitch perception, but the degree to which the deficit is specific to pitch remains unclear. Amusia often results in difficulties discriminating and remembering melodies and melodic contours. Non-amusic listeners can perceive contours in dimensions other than pitch, such as loudness and brightness, but it is unclear whether amusic pitch contour deficits also extend to these other auditory dimensions. This question was addressed by testing the identification of ten familiar French melodies and the discrimination of changes in the contour of novel four-note melodies. Melodic contours were defined by pitch, brightness, or loudness. Amusic participants were impaired relative to matched controls in all dimensions, but showed some ability to extract contours in all three dimensions. In the novel contour discrimination task, amusic participants exhibited less impairment for loudness-based melodies than for pitch- or brightness-based melodies, suggesting some specificity for pitch (including spectral pitch). Impairment in loudness contours for familiar melodies may have reflected the fact that the long-term memory representation of the familiar melody was defined in pitch. [Work supported by Erasmus Mundus Auditory Cognitive Neuroscience Network, NIH grant R01DC005216, LabEx CeLyA, and Cortex (ANR-11-IDEX-0007).]
Frequency difference limens as a function of fundamental frequency and harmonic number
Authors: Mehta Anahita H. , Oxenham Andrew J.
Published: April 2018

Several studies have investigated the relation between the lowest harmonic present in a complex tone and fundamental frequency (F0) difference limens (F0DLs). It is generally assumed that F0DLs are smaller when lower harmonics are present and that the ability to discriminate small changes in F0 worsen as harmonic number increases. This worsening of performance has been attributed to a lack of peripherally resolved harmonics. This assumption was tested by measuring F0DLs for harmonic complexes where the lowest harmonic present in a twelve-harmonic complex tone varied from the 3rd to the 15th harmonic, with F0s varying from 30 Hz to 2000 Hz. The harmonics were presented in either sine or random phase and were embedded in threshold-equalizing noise. Aside from F0s between 100 and 400 Hz, performance did not follow the expected pattern of good performance with low-numbered (resolved) harmonics and poorer performance with high-numbered (unresolved) harmonics. At lower F0s, performance was relatively constant across the harmonic range; at higher F0s, performance generally degraded more than would be predicted based solely on harmonic resolvability. No clear effects of phase were observed. Overall, the results do not match the patterns expected from current models of complex pitch. [Work supported by NIH grant R01DC005216.]
Late negative response revealed language-specific processing of word-level prosodic phonology in the adult brain
Authors: Yu Luodi , Zhang Yang , Wang Suiping , Zeng Jiajing
Published: April 2018

Native speakers develop specialized neural architectures in the processing of auditory patterns found in their language. However, little is known about the neural basis of language-specific processing of phonological patterns beyond the syllable level. The current event-related potential (ERP) study investigated cortical processing of native vs. nonnative prosodic phonology in a disyllabic context. The participants were 18 normal native Chinese-speaking adults who had at least six years of English-as-a-second-language course work in school. The speech stimuli included disyllabic nonsense words spoken in Chinese and in English, which were matched in syllabic structure and digitally edited for matching in overall duration and intensity. The control nonspeech stimuli were hummed versions of the speech stimuli, which preserved the acoustic prosodic features but not the phonetic content. The ERP data were obtained with a passive listening paradigm, showing an enhanced late negative response (LNR) for the native vs. nonnative comparison in the speech condition but not in the nonspeech condition. These results provided the initial evidence that the LNR component can reflect language-specific differences in prosodic phonology beyond auditory processing of the critical acoustic cues at the supra-syllabic level.
Analysis of the effect of different patologies on the sound transmission through the middle ear by means of a finite-element model
Authors: Lobato Lucas C. , Paul Stephan , Cordioli Julio A. , Maccarini Evandro
Published: April 2018

The middle ear is part of the human auditory system and its function is to transmit acoustical energy to the inner ear by means of mechanical vibrations. Finite-Element (FE) models of the human middle ear have been studied since 90s, making it possible to evaluate its dynamic behavior in different ways. In this work, an accurate FE model of the human middle ear is described and used for assessing the relationship between the reduction of sound transmission through the ossicular chain and hearing loss due to three different pathologies: tympanic membrane perforation, stapedial tendon ossification and stapes fracture. For these three pathologies, case studies from the literature with experimental hearing loss data are reviewed and clinical results are compared to the FE model predictions. In all cases a good relationship between sound transmission reduction predicted by the FE model and the hearing loss measured through audiometric tests were found. Results show that an accurate FE model of the human middle ear can be a powerful tool for clinical applications and research in otology, allowing to predict the effect of middle ear pathologies and to evaluate the results of corrective surgeries on hearing.
A framework for evaluating perceptual interactions of various dimensions of sound for data sonifications
Authors: Chabot Samuel , Braasch Jonas
Published: April 2018

Due to its multidimensionality, sound is a powerful medium for presenting data. Various parameters, including pitch, loudness, timbre, rhythm, and spatial location, may be utilized to convey information. Interactions between dimensions can affect perceptions of this information. Experiments evaluating these interactions in the context of sonifications are important in designing more accurate auditory displays. Oftentimes, these experiments focus on a single pair of parameters. This project offers a framework for utilizing different combinations of parameters to streamline evaluations. A user interface allows for the direct manipulation, and subsequent juxtaposition, of these combinations. [Research funded by the Cognitive and Immersive Systems Laboratory at Rensselaer.]
Testing for evidence of cochlear synaptopathy in normal-hearing young adults with varying noise exposure history
Authors: Paul Brandon T. , Tran Natalie , Waheed Sajal , Roberts Larry E. , Bruce Ian C.
Published: April 2018

Loss of high-threshold cochlear synapses following mild noise exposure is suggested to degrade amplitude modulation (AM) encoding in cases where hearing thresholds are normal. However, the relationship of AM encoding to noise exposure history has not been consistent in previous studies. We investigated this relationship in young adults with normal audiograms in two studies using different methods. Study 1 (N = 25) measured the ~80 Hz electrophysiological envelope following response (EFR) and behavioural AM detection thresholds. Both measures were taken in quiet and in a narrowband background noise designed to attenuate low-threshold synapse contributions. When subjects were divided into two groups based on their noise exposure history, subjects with more noise exposure had smaller EFRs (p = 0.0198). AM detection was also poorer in these subjects, but this difference fell short of significance (p =0.067). Study 2 (ongoing) also measures the EFR but employs an additional wider band of background noise to attenuate possible off-frequency contributions of low threshold fibers to AM coding. In addition, AM discrimination is tested instead of AM detection. The question is whether these modifications will reveal a more robust effect of noise exposure history on AM coding than did Study 1. [Work supported by NSERC of Canada.]
Importance of time-frequency units for sentence recognition as a function of signal-to-noise ratio
Authors: Apoux Frederic , Carter Brittney , Velik Karl P. , Healy Eric
Published: April 2018

Speech recognition in noise may be viewed as a classification problem, in which the auditory system selects a subset of time-frequency (T-F) units to build a representation of the signal. The present study introduces local signal-to-noise ratio (SNR) importance functions, an approach to determine the contribution to speech intelligibility of T-F units as a function of their SNR. Consistent with previous work from this group on auditory-channel independence, it was hypothesized that T-F units with a relatively equal mixture of signal and noise (around 0 dB SNR) may be the most disruptive for intelligibility because they should be the most difficult to classify. This hypothesis was assessed by measuring the intelligibility of sentences presented in a competing-speech background while discarding a fixed proportion of units all with the same local SNR. The stimuli were either vocoded or left unprocessed to evaluate the influence of fine-structure cues on classification and also help better understand why cochlear implant (CI) users experience greater difficulties in noise. Results were consistent with the ambiguity hypothesis. More importantly, they suggest that discarding the noisiest units may not be the most advantageous way to improve speech intelligibility in noise by CI users.
Characterizing stress corrosion cracking in stainless steel using nonlinear resonant ultrasound spectroscopy
Authors: Hogg Stephen M. , Anderson Brian E.
Published: April 2018

During disposal, spent nuclear fuel rods are placed into stainless steel containers and may be stored this way for decades. In order to ensure there is as little radiation leakage as possible, the structure of the stainless steel needs to be evaluated and possible damage detected. In particular, one type of damage these containers are particularly susceptible to is stress corrosion cracking (SCC). Traditional (linear) evaluation methods can detect open cracks but often a closed portion of the crack extends further, compromising the air tight seal sooner. To this end, it has been proposed to use Nonlinear Resonant Ultrasound Spectroscopy (NRUS) to quantify the degree of cracking in a structure. In order to prove this concept, cylindrical 304L stainless steel rods were immersed in a heated 42% MgCl2 solution to induce SCC in an accelerated manner to simulate the damage that is likely to occur on the actual containers. The rods were removed after different lengths of exposure. NRUS measurements were then conducted for longitudinal modes in the rods.
Acoustic reflection and transmission by sub-critical and super-critical elastic partitions with structural discontinuities forced by multiple-angle oblique broadband sound waves
Authors: Villa Mauricio , Bliss Donald B. , Franzoni Linda P.
Published: April 2018

An analysis is presented for acoustic reflection and transmission from an infinite fluid-loaded flexible barrier with spatially periodic discontinuities. The plate, with similar or dissimilar acoustic fluids on both sides, is excited by an oblique wave incident acoustic field. The fully-coupled structural/acoustic problem is treated by Analytical-Numerical Matching (ANM) which improves the numerical accuracy and convergence rate. Periodic spatial discontinuities, modelled by various boundary conditions, create deviations from specular directivity. For super-critical structural wave speeds, the scattering is characterized by a distribution of reflection and transmission angles centered around the Mach Angles. For sub-critical structural waves, energy redistribution is most pronounced at the structural resonances. These results are compared to a baffled finite barrier analyzed by approximate means. For the subcritical finite barrier, a fluid loading correction is introduced to the structural wavenumber to approximate the effects of the fluid coupling and radiation damping. For subsonic flexural waves, the radiation is analyzed in terms of the wavenumber transform and interpreted as a series of edge singularities dependent on the boundary conditions. For the super-critical configuration, the effects of the fluid loading are introduced by approximating the structural wavenumber from the dispersion relation of the free response of the unbounded structure.
A study on the oxygen generation in water molecules using sound wave
Authors: Eun Young Yi , Song Uk-Jin , bae myungjin
Published: April 2018

Life is living in a different place. There are mammals and birds living in the air through oxygen. There is a life extension using oxygen present in the water. There are fish and mammals in the water that use oxygen in the water. The whales, belonging to the mammals in the sea, breathe out of the water at regular intervals and then back into the water. Fish do not hinder the extension of life without these actions. This study uses speakers as means for generating oxygen in water molecules. It is a study to decompose oxygen in water by using the dense wave of the speaker sound wave. It is a study that removes oxygen by affecting the bonding structure of water molecules through the vibration of sound waves. Unlike other chemical methods, this characteristic can generate oxygen without generating hydrogen.
Acoustic characteristics and perception of voiced and voiceless nasals in Mizo and Angami
Authors: Gogoi Pamir
Published: April 2018

This study compares and contrasts acoustic characteristics (e.g., nasal murmur’s formant and anti-formant frequencies, vowel formant frequencies, bandwidths, spectral tilts, etc.) of voiced and voiceless nasals in Mizo and Angami, Tibeto-Burman languages spoken in North-East India. Mizo contrasts voiced and voiceless nasals at the bilabial, alveolar, and velar places of articulation, whereas Angami contrasts them at four different places of articulation: bilabial, alveolar, velar, and palatal. Similar to voiceless nasals previously described for Burmese (Danstuji,1984; Bhaskararao & Ladefoged,1991), in Mizo, voiceless nasal murmur is followed by a period of voiced nasal murmur as it transitions into the following vowel, while it remains voiceless throughout in Angami. Results of a perception experiment also suggests that the voiced nasal murmur portion in Mizo voiceless nasals aided the identification of its place of articulation, but a heavier perceptual load is placed on the following vowel for place identification of voiceless nasals in Angami. References: Dantsuji, M. (1984). “A study on voiceless nasals in Burmese.” Bhaskararao, P., & Ladefoged, P. (1991). “Two types of voiceless nasals,” J. Int. Phonet. Assoc., 21(2), 80–88.
Indic and Dravidian retroflexes: An ultrasound investigation
Authors: Bohnert Amanda , Myers Samantha , Smith James , Berkson Kelly
Published: April 2018

The languages of South Asia somewhat famously contain what might be deemed canonical retroflexes. These are often described as involving an extreme articulation with sub-apical post-alveolar or palatal contact, and imaging studies of varying types (electropalatography, MRI, ultrasound, etc.) suggest that this is an accurate characterization for Dravidian retroflexes (Kochetov et al. 2014, Krull and Lindblom 1996, Narayanan et al. 1999, Narayanan et al. 2004, Scobbie et al. 2013). Indic retroflexes reportedly involve less extreme articulations (Ladefoged and Bhaskararao 1983), but imaging data for Indic languages remains surprisingly rare. This raises an interesting question: how do Indic and Dravidian retroflexes compare articulatorily? We explore this question by presenting ultrasound imaging of retroflexes in several Indic (Marathi, Hindi) and several Dravidian (Kannada, Telugu) languages. Results indicate that all languages contain at least some of the extreme articulations often associated with South Asian retroflexes, though the within-speaker variability noted in previous work (e.g., Arsenault 2017) is also on display.
Phonation type in vowels of heritage and native Gujarati speakers
Authors: Nara Kiranpreet
Published: April 2018

Gujarati, an Indo-Aryan language, contrasts phonation type in vowels: [baɾ] ‘twelve’ and [ba̤ɾ] ‘outside’ (Pandit, 1957) and the current study looked at Gujarati vowels using acoustic and electroglottographic (EGG) analyses. The participants were native and heritage Gujarati speakers. Heritage speakers were born in Canada or arrived in Canada before seven years of age and learned Gujarati as their first language. Due to limited access to their first language, such as listening more than speaking the language and using Gujarati exclusively at home, it was expected that there might not be a significant difference between the heritage speakers’ breathy and modal vowel productions. This study determined if the acoustic and EGG parameters that differentiate breathy from modal vowels were the same or different for both speaker groups. Some of the parameters used to distinguish phonation type were H1-H2, H1-A1 ('A1' refers to amplitude of the first formant), harmonic-to-noise ratio, and contact quotient. Measurements were made using VoiceSauce (Shue et al., 2009) and EGGWorks (Tehrani, 2009). ANOVA analyses conducted on vowels /a e o/ indicated that fewer parameters distinguish phonation type for heritage than native speakers and the difference between breathy and modal vowels for heritage speakers is smaller in magnitude. The results thus far indicate that heritage speakers acquire a reduced phonation type contrast.
Relation of musical experience to perceiving and producing aspirated Hindi consonants
Authors: Gupta Anmol , Gottfried Terry L.
Published: April 2018

Past research shows that those with musical experience often perceive and produce unfamiliar speech contrasts better than non-musicians (e.g., Gottfried, 2007; Lee & Hung, 2008; Marie, Delogu, Lampis, Belardinelli, & Besson, 2011; Slevc & Miyake, 2006). The present research seeks to clarify the mechanisms which underlie this relationship through a “test-teach-test” paradigm (see Vlahou, Protopapas, & Seitz, 2012). In the first session, native speakers of American English with and without conservatory training were tested on their discrimination of Hindi sentences that contained either an aspirated (e.g., [bh]) or unaspirated (e.g., [b]) consonant (“test”). In a second session, participants completed training on producing and perceptually discriminating the aspirated and unaspirated Hindi consonants (“teach”). In the third session, participants were tested on their ability to perceive and to produce these unfamiliar consonants in the same and different phonetic contexts (“test”). Preliminary results suggest that all participants benefited from the training, but Improvement was markedly greater for musicians than for non-musicians. Current studies are further testing additional musicians and non-musicians to evaluate the extent which musical experience influences perception and production of these unfamiliar Hindi phonemes.
Quantifying the manipulation of F0 as an acoustic correlate of stress in Rebkong Amdo Tibetan
Authors: Caplow Nancy J.
Published: April 2018

Quantifying the manipulation of F0 as an acoustic correlate of stress in Rebkong Amdo Tibetan Rebkong Amdo is a non-tonal variety of Tibetan spoken in Rebkong County, Qinghai Province, PRC. Speakers draw on varied acoustic resources to convey stress in disyllabic words, which are highly frequent in the language. Non-verbs (nouns, adjectives, and numerals) are stressed on the second syllable (S2); the primary acoustic correlate of stress is F0. Verbs are stressed on the first syllable (S1); stress is conveyed by both intensity and F0. For non-verbs, speakers manipulate F0 in different ways to convey S2 prominence. The pitch contour may (a) be flat in both syllables but higher in S2; (b) be flat or slope gently in S1 but fall sharply in S2; or (c) be generally flat in S1 but define a prominent arcing curve in S2. These three patterns, which occur in free variation, require different analytical approaches in order to quantify relative acoustic prominence across syllables: (a) mean F0 (Hz) is measured for each syllable; (b) pitch slope (in Hz/100 ms) is measured for each syllable; (c) F0 curves are characterized using a principal components analysis, and by determining the tonal center of gravity. In each approach, measurements are paired to determine the magnitude of the F0 contrast across syllables in individual words; these are then aggregated, demonstrating that speakers’ use of F0 to convey S2 prominence is statistically as well as perceptually significant.
Active acoustic intensity errors due to contaminating noise
Authors: Cook Mylan R. , Gee Kent L. , Neilsen Tracianne B. , Sommerfeldt Scott D.
Published: April 2018

Bias errors for both one and two-dimensional intensity probes have been previously calculated for both the traditional cross-spectral and the Phase and Amplitude Gradient Estimator (PAGE) methods [E. B. Whiting et al., J. Acoust. Soc. Am.142, 2208–2218 (2017); E. B. Whiting, M. S. Thesis (2016)]. Here, these calculations are expanded to include errors due to the source angle relative to the probe and due to contaminating noise. The noise can either be uncorrelated at each microphone or self-correlated, which is modeled as a plane wave with a varying angle of incidence. The errors in both intensity magnitude and direction are dependent on the signal-to-noise ratio (SNR), frequency, source properties, incidence angles, probe configuration, and processing method. The PAGE method is generally found to give more accurate results, though uncorrelated noise with a low SNR can yield large errors. For broadband signals, the PAGE method can be used beyond the spatial Nyquist frequency. [Work supported by NSF.]
A maximum likelihood estimator for spectral models of acoustic noise processes
Authors: Lyons Gregory W. , Hart Carl R.
Published: April 2018

The power spectral density of time series from many acoustic phenomena can vary rapidly through several decades of magnitude, particularly for noise processes. This property can complicate evaluation of spectral density models with respect to a non-parametric estimate of the spectral density, also known as the periodogram. Typical measures, such as the sum of squares of the residuals, can suffer from bias errors and oversensitivity to large values. A log-likelihood function is here presented for a periodogram derived from a sequence of independent, circularly-symmetric complex normal Fourier components. The bias-corrected Akaike’s information criterion of an expected-value spectral model is shown to be a useful measure for multi-model selection. A maximum-likelihood estimator is formed for spectral model parameters with respect to a known periodogram, along with approximate confidence intervals for the parameter estimates. Results from the maximum-likelihood estimator are compared with weighted and unweighted least-squares methods by estimating model parameters for periodograms from both synthetic and measured noise time series. Practical considerations for general periodogram fitting and numerical methods are discussed.
Signal and information processing in complex ocean environments
Authors: Knobles David P. , Wilson Preston S. , Badiey Mohsen
Published: April 2018

Even a cursory examination of the information theory relationship between model capacity/complexity, model error, and prediction error should suffice to convince one that to treat the ocean as deterministic by increasing the dimensionality of the number of physical mechanisms, parameters, etc., may prove ineffective in achieving desired results in complex waveguides. Instead of a deterministic approach that results from solving a high-dimensional inverse problem which can lead to poor predictive capability, the approach advocated here predicts the statistics of the Detection, Classification, and Localization (DCL) problem. Various dimensional reduction methods are utilized such as those that can be applied to images in the spectral acoustical domain. Bayesian Information Criteria (BIC) and trans-dimensional methods coupled with machine learning algorithms can then be used to construct a meaningful signal processing approach which optimizes predictive capability. Acoustic and environmental survey data collected in the New England Seabed Characterization experimental area that has a high horizontal variability are used to demonstrate the approach. [Work supported by ONR.]
Design of a signal normalizer for high-clutter active-sonar detection
Authors: Bentrem Frank W. , Botts Jonathan , Summers Jason E.
Published: April 2018

We present normalizer design considerations for detection of targets in a high-clutter environment. Several classes of constant-false-alarm-rate (CFAR) normalizers have conventionally been used to bring out a target signal from the background noise and reverberation in active sonar signal processing. The special challenges of detection in high-clutter environments are outlined, and the normalizer classes are compared for their suitability of use in these environments. We consider statistical and multiple-look normalizers and give emphasis to the class of split-window mean-power normalizers and implementations that preserve target signal-to-noise ratio (SNR) and highlight structure while mitigating artifacts that are sometimes produced near clutter edges. Statistical comparisons and specific examples are presented, and we propose an efficient CFAR normalizer for high performance in regions of high clutter.
Videos of ultrasonic wave propagation through transparent acrylic objects in water for introductory physics courses produced using refracto-vibrometry
Authors: Mehrkens Matthew R. , Rorem Benjamin A. , Huber Thomas M.
Published: April 2018

This project used refracto-vibrometry to produce full-field videos of ultrasonic wave propagation in water; these videos could be incorporated into high school and college physics courses to illustrate wave behaviors. Refracto-vibrometry (RV) is an interferometric method for optically measuring sound waves. The measurement beam from a Polytec PSV-400 scanning laser Doppler vibrometer was directed through a water tank towards a stationary retroreflective surface. Acoustic wave fronts (density variations) which pass through the measurement laser cause variations in the integrated optical path length. By superimposing tens of thousands of scan points, videos enable visualization of the ultrasound propagation. In one experiment, ultrasonic waves in water (1484 m/s) are incident on a submerged acrylic block at a non-zero angle. The waves are refracted as they travel at about 2700 m/s through the block. Students can determine this speed of sound by measuring the angle of refraction and lateral deflection of the wave fronts in the video. In another experiment, ultrasonic waves passed through an acrylic cylinder, producing a Mach cone in water. Measurement of the Mach cone angle enables determination of the acrylic speed of sound. Links for videos and sample worksheets will be provided.
Acoustically neglected and ignored building spaces
Authors: Stonestreet Megan
Published: April 2018

Often neglected and ignored building spaces in regard to room acoustics and building noise are corridors, stairways, and lobbies. For example, reverberant corridors in school teaching buildings are often noisy and provide an undesirable acoustic connection between classrooms; stairways are typically reverberant spaces that act as vertical corridors and are generally unpleasant spaces; lobbies are actually multipurpose spaces that serve as entrance, exit, and gathering spaces, and for performance facilities, they are also used as performance spaces. Examples of each of these building spaces will be discussed along with acoustic data and practical acoustic requirements.
Case studies of two atria to begin a conversation regarding the importance of acoustical performance of transitional spaces
Authors: Huey Michelle , Barnhardt Michael (Mick)
Published: April 2018

Transitional spaces, such as lobbies or atria, are largely forgotten spaces regarding room acoustics. These transitional spaces are widely used for presentations, meetings, and parties/gatherings. Lobbies and atria are often connected to hallways and adjacent office clusters, where sound can propagate to areas far away from the source. With the ever-increasing need for transitional spaces to also act as gathering spaces, it is important to begin a discussion of acoustical standards in transitional spaces. This paper discusses two case studies conducted by D.L. Adams Associates: (1) An atrium with a kitchen and dining area used for parties, gatherings, meetings, and throughout the day by employees; (2) an atrium with a commercial-grade kitchen at the center used for meetings, lunchtime, gatherings, and special events. This paper includes discussions of noise propagation, noise build up, reverberation time, and absorptive treatments within transitional spaces and how to make the spaces work acoustically, while isolating them from adjacent areas.
History of marine bioacoustics in Florida and the Caribbean
Authors: Mann David
Published: April 2018

The diverse fauna of Florida and the Caribbean has long attracted scientists studying marine bioacoustics. The earliest studies (1905–1945) in Florida examined species distributions and life histories. After World War II bioacoustics studies began in earnest. At Marineland, which opened to support underwater filming, Lilly studied dolphin vocalizations and attempted to link them to behavior. Melba and David Caldwell pioneered studies on the development of dolphin signature whistles. Tavolga performed fundamental work on sound production and behavior in gobies and many studies on the hearing ability of fishes at Bimini, Marineland, and Mote Marine Laboratory. Myrberg’s Miami laboratory showed that different damselfishes had distinct sounds. In the 1960’s, Breder documented diel and seasonal variation in fish sound production. Most recently, studies have focused on wild animals. Working with Wells’ Sarasota Dolphin Research Project, Tyack, Sayigh, and Janik have cataloged signature whistles and used playback experiments to study salient features. Fundamental work identifying sounds produced by fishes begun by Lobel has spread to several research groups in Florida, USVI, Puerto Rico, and the Cayman Islands. Passive acoustic studies using gliders show that much work remains to identify the sources of unknown sounds.
Geoacoustic inversion of the New England Mud Patch using modal time-frequency dispersion
Authors: Bonnel Julien , Eleftherakis Dimitrios , Dosso Stan E. , Chapman N. Ross , Dall'Osto David R. , Dahl Peter H.
Published: April 2018

This paper presents geoacoustic inversion of several low-frequency broadband signals recorded during the Seabed Characterization Experiment (SBCEX) that took place on the New England Mud Patch in March 2017. The considered sources are chirps emitted by a towed J15 source and underwater impulses created by MK64 explosions. These sources are low-frequency (f<250 Hz) so that the shallow water environment acts as a dispersive waveguide, and propagation is conveniently described by modal theory. The received signal is recorded on a single hydrophone placed 0.8 m off the bottom. In this context, inversion is carried out by matching modal dispersion curves in the time-frequency domain. Experimental dispersion curves are estimated using a non-linear sampling scheme called warping. Up to six modes can be estimated, and non-linear inversion results are consistent with what is known about the area.
Fast simulations of shear waves generated by an acoustic radiation force: Comparisons with measurements in shear wave phantoms
Authors: Yang Yiqun , Urban Matthew W. , McGough Robert J.
Published: April 2018

We recently developed a fast approach for simulating shear waves generated by an acoustic radiation force. The input for these simulations is generated in FOCUS, the “Fast object-oriented C + + simulator” (www.egr.msu.edu/~fultras-web), which rapidly models the three-dimensional (3D) pressure, intensity, and acoustic radiation force on a desktop computer. The shear waves generated by the acoustic radiation force are then quickly simulated with Green's functions for viscoelastic media in a two-dimensional (2D) plane on a high-performance graphics processing unit (GPU). For these simulations, an L7-4 linear array is electronically focused at a depth of 25 mm to generate an acoustic radiation force “push” for 200 microseconds. The simulation results are compared to shear wave data measured in three viscoelastic shear wave phantoms with low, medium, and high values of the shear viscosity using a Verasonics Vantage ultrasound system. The measured and simulated shear wave data are compared for several different combinations of the simulation parameters, where these comparisons are enabled by the rapid acoustic radiation force and shear wave simulations. The results show that the shear waves simulated in 2D planes achieve good agreement with the measured shear wave data. [Work supported in part by NIH Grants EB023051 and DK092255.]