bluuebunny/crossref_metadata_2025 huggingface dataset:
The challenges in developing useful models
Authors: Shinn-Cunningham Barbara , Wang Le
Published: June 2017

Models can be extremely helpful in understanding the mechanisms governing hearing, providing insights into how information is processed and combined to enable perception and communication. Yet modeling is complicated and is more of an art than a science. Ideally, a model should include only those key components that are critical for describing known phenomena. Yet, models are typically under-constrained, so that modelers constantly are forced to make educated guesses based on limited data. Given this, developing a useful model requires good intuition and an eye for what is essential and what is superfluous: a useful model requires navigating a balance between realism/complexity versus tractability/interpretability. Verification is often only indirect, by using the resulting model to generate testable predictions, and comparing these predictions to new experimental data. Moreover, when a model fails (such as when predictions do not match empirical outcomes), the path to “fixing” the model is not always straightforward or clear. Some of these challenges will be illustrated by our own recent efforts to model envelope following responses in the brainstem.
Demonstration of a broadband aqueous acoustic metasurface
Authors: Guild Matthew D. , Rohde Charles , Martin Theodore P. , Orris Gregory
Published: June 2017

Acoustic metamaterials have been utilized in recent years to demonstrate extreme acoustic properties, such as those with negative or near-zero dynamic values. While effective, the use of acoustic metamaterials can lead to voluminous structures that may not be practical for some applications. Alternatively, ultrathin structures known as acoustic metasurfaces offer the same capability to achieve extreme properties as acoustic metamaterials while offering the added benefit of having negligibly small (i.e., subwavelength) thickness. In this work, we will discuss an aqueous acoustic metasurface that utilizes subwavelength structures designed to acoustically act in parallel, allowing for a thin, modular structure to be realized while achieving a broad range of effective surface properties. A theoretical formulation for the design of the flexural elements is presented, accounting for the elastic motion of the elements subject to fluid loading due to the water. Based on this design, an aqueous acoustic metasurface was constructed from a brass plate, which was machined to achieve the prescribed flexural elements on the surface, and experimentally tested in water. The results of this analysis and testing will be discussed. [Work supported by the Office of Naval Research.]
Designing beampatterns with tapered leaky wave antennas
Authors: Naify Christina J. , Woolfe Katherine. , Layman Christopher N. , Rogers Jeffrey S. , Guild Matthew D. , Orris Gregory
Published: June 2017

Leaky wave antennas (LWAs) have been shown to be an effective tool for frequency-steerable wave radiation in both the electromagnetic and acoustic wave regimes. LWA’s operate by modifying the impedance on a waveguide such that refraction occurs out of the waveguide at an angle corresponding to Snell’s Law. For a LWA with uniform leaking parameter across the waveguide length, that leakage angle is constant. Using analytical techniques, and by careful geometric design of the waveguide impedance, the leaked beampattern can be tailored. The process of the tapering process for an acoustic LWA is discussed here, and notional examples are presented including sidelobe reduction. [Work supported by the Office of Naval Research.]
Investigation of various damping measurement techniques
Authors: Geweth Christian A. , Langer Patrick , Sepahvand Kheirollah , Marburg Steffen
Published: June 2017

In order to compare experimentally determined damping values with damping values from simulations, high effort is necessary. A precise modeling of the boundary conditions with respect to its impact on the damping is often difficult to realize and often time consuming. Furthermore, the used measurement parameters, like sampling frequency or windowing can have an unneglectable influence on the experimentally determined damping value. In order to observe the sensitivity of single parameters during the determination of damping, the dynamical behavior of virtual models with a known excitation is investigated. The used numerical methods are validated with analytical solutions for the model. The obtained time data from the model are used to determine the damping with different methods. Therefore, the influence of the different methods on the model can be identified. The virtual modeling opens up the opportunity to identify and quantify different sources of errors and disturbance.
Vibro-acoustic modeling of roof panels for analysis of sound radiation from droplet impact
Authors: Park Sangmok , Kwak Yunsang , Kim Deukha , Park Junhong , Chun Kyungsup
Published: June 2017

Sound generated by impacts between raindrops and roof panels of vehicles is an important factor on automotive qualities when driving in rainy conditions. Therefore, analytical method to control this phenomenon is necessary. In this research, a theoretical model for predicting characteristics of sound radiation by droplet impacts was proposed. An experiment for measuring forces generated by falling droplets was conducted. The characteristics of the measured forces were investigated in the frequency domain. A measurement on a plate was performed to understand sound radiation formed by droplet impacts. Correlations between acoustic characteristics and properties of the plate were identified. A vibro-acoustic model was developed to analyze the experimental results. Assuming generation of sound sources at each location due to the vibrating plate, radiation of sound fields was theoretically calculated and verified by comparing with the measured results. Under single and multi-layered conditions, influence factors on acoustic properties were investigated based on the model. As a result, by using the proposed model, it is possible to predict acoustic mechanisms of vehicles due to raindrops and make them suitable for specific designs.
Clamping force diagnosis during bolting process using acoustic signatures
Authors: Toh Gyungmin , Lee Jaehong , Gwon Jaesoo , Park Junhong
Published: June 2017

The method of measuring the fastening force of the bolt in a non-contact manner during the fastening of the bolt is of great value in the industry. In this study, the fastening force was measured by changing the dynamic characteristics as the bolts were fastened. Experiments were carried out by measuring the vibration generated when bolts with load cells were fastened. When the bolt is fastened, the vibration characteristics of the bolt are measured by the accelerometer attached to the joint structure of the bolt by the fastener. The measured vibration signals are classified using cepstrum of bolt. Learning was performed by recognizing different axial force as each speaker. The clamping force was predicted in such a manner as to determine which studied clamping force is most similar to the present clamping force. The proposed method is verified by applying it to actual bolt structure.
A vibroacoustic analysis of pre-stressed saw blades to identify instabilities considering gyroscopic effects and centrifugal forces utilizing the finite element method
Authors: Guettler Marcus , Jelich Christopher , Marburg Steffen , Grasso Ettore , De Rosa Sergio
Published: June 2017

In various engineering fields, large saw blades on heavy machines are used for several tasks. Typically, in civil engineering, they cut large concrete structures such as walls for adding or changing doors and windows in buildings, as well as they are utilized for roads and bridges maintenance works. In the cutting process, especially large blades tend to vibrate excessively. The unstable behavior can lead to wide cutting lines, less productivity, or even jamming of the saw blade resulting in an unsafe environment for the workers on-site. For these productivity and security related issues, engineers face the challenge to investigate the dynamic behavior of large saw blades at early stages of product development. The finite element method has emerged to be a useful tool when investigating saw blade designs since various effects such as pre-stress and gyroscopic and/or centrifugal forces can be considered. In this work, the authors use the finite element method to study the effect of gyroscopic and centrifugal forces onto pre-stressed saw blades to (i) identify unstable dynamic behavior and further (ii) optimize the design to increase the vibroacoustic stability. In addition, the kinetic energy values are used as a measure for potential sound radiation.
Using reciprocity principles and sensitivity functions for the vibroacoustic response of panels under random excitations
Authors: Marchetto Christophe , Laurent Maxit , Robin Olivier , Berry Alain
Published: June 2017

The vibroacoustic characterization of panels submitted to random pressure fields is of great interest for the industry. The test means associated with those excitations (i.e., wind tunnel, reverberant room) are expensive and can hardly be controlled. An alternative method to experimentally characterize the behavior of a panel under random pressure fields is therefore proposed. The mathematical formulation of the problem allows describing the vibroacoustic behavior of a panel as a function of the cross spectral density function of the considered excitation and so-called “sensitivity functions.” These functions can be estimated experimentally using reciprocity principle, which can either be applied for characterizing the structural response by exciting the panel with a normal force at the point of interest or for characterizing the acoustic response (radiated pressure, acoustic intensity) by exciting the panel with a monopole and a dipole source. For validation purposes, the method is applied numerically and experimentally for the case of a diffuse acoustic field. Based on indicators such as the vibratory response and the transmission loss factor, the method is finally confronted to measurements in coupled anechoic-reverberant rooms facility following standards.
Asymmetrical patterns of formant variability in English vowels
Authors: Chen Wei-rong , Tiede Mark , Whalen D. H.
Published: June 2017

Previous studies have claimed that lower formants should be weighted more than higher formants in a perceptual model of vowel perception (e.g., Schwartz et al., 1997). Given this formant weighting hypothesis, and if vowels have acoustic targets, vowels should be more variable in higher formant frequencies. Here, we examined within-speaker variability for five English vowels /æ, ʌ, ɔ, ɛ, ɪ/ in various contexts as produced by 32 speakers in the x-ray microbeam database (Westbury, 1994). For variabilities of the first three formants, only /ɔ/ follows this prediction (i.e., variability: F3 > F2 > F1) while /æ/ exhibits the opposite pattern; if we ignore F3 (as being less reliably measured), most vowels conform to the prediction (i.e., variability: F2 > F1), except for /æ/. Although the F2 variability is generally consistent with the perceptual model of vowel perception, it is also consistent with a possibly greater effect of consonant coarticulation (which is extensive here) on F2 relative to F1; this requires more testing. Further, while these results do not fully conform to the prediction made by the hypotheses, coproduction effects arising from the diverse contexts likely interact with the expected tendency. Correlation with observed kinematic variabilities will also be discussed. [Work supported by NIH grant DC-002717.]
On the acoustic cues of unreleased stops
Authors: Huang Ting , Kenstowicz Michael
Published: June 2017

Unreleased stops, lacking a burst, have been claimed to have low perceptibility and are more likely to neutralize place contrasts. While this proposition has been supported by examining no-burst VC fragments spliced from released stops, little is known about the acoustic discriminability among true unreleased stops. This study fills this gap by analyzing the acoustic correlates of VC (where C = unreleased stops p̚, t̚, k̚, ʔ) in Cantonese and Taiwanese Southern Min. Specifically, duration and formant transitions were estimated across three distinct contexts: VC-V vs. VC#V vs. VC#C. The preliminary results are (a) the formant transitions are effective cues to place contrasts of the unreleased stops: the labial has low F2 offset frequency, the coronal has high F2, and the dorsal has low F3, (b) the magnitude of transition cues varies with different contexts: the cues are more significant when followed by a vowel-initial, lexical morpheme (VC#V) than by a consonant-initial or functional morpheme (VC#C, VC-V), and (c) vowel raising is resisted in the dorsal-final environment. This finding may have implications for the phonotactic constraint *[ + high][high] in the two languages.
Ultrasound study for patterns of tongue movement in diphthongs, triphthongs, and vowel sequences in Korean, Japanese, and Mandarin
Authors: Kim Boram , Mizoguchi Ai , Whalen D. H.
Published: June 2017

Diphthongs have formant transitions sensitive to speaking rate, stress, vowel quality, and language ability. Tongue movement typically shows a functional “pivot” where the palate to tongue distance is almost constant; some combinations result in an “arch,” with only part of the tongue moving [Iskarous, J. Phon. 33, 363-381, 2005]. Here, ultrasound images of the tongue in Korean, Japanese, and Mandarin diphthongs and triphthongs (Mandarin) (vowel sequences in Korean and Japanese) were analyzed. Five repetitions of 6 nonwords were presented in Hangul, Hiragana or both Pinyin and a character for a word with the same vowel on tone 1. Diphthongs were [ai, ei, au] and triphthongs/sequence of three vowels were [iau, ieu, and uai]. All the ultrasound image frames for the target vowels were traced and superimposed. Preliminary results indicate that most vowel quality pairs resulted in a pivot pattern, with some arch patterns as well. Even in Mandarin triphthongs, there were generally two pivots, even though phonologically the sequence is considered a single vowel nucleus. Several approaches to quantifying this effect will be presented. It is possible that the success in producing a pivot could indicate mastery of production, both in development and in second language learning.
A comparison of lip positions for /ɨ/ and /Ɯ/ in Bora
Authors: Parker Steve , Mielke Jeff
Published: June 2017

Bora is a Witotoan language spoken by about 750 persons in the Amazon jungle of Peru and 100 in Colombia. Its phonemic vowels are /i e a o ɨ Ɯ/ (Thiesen and Weber 2012). A contrast between a central and a back vowel which are otherwise identical is theoretically significant since it shows that a binary feature [ + /-back] is too weak to encode all phonological contrasts along the front/back dimension. The three high vowels of Bora have been acoustically confirmed with measurements of F1-F3 (Parker 2001), but there has been no articulatory investigation of these vowels. Impressionistically all of the Bora vowels except /o/ are articulated with unrounded lips. However, Ladefoged and Maddieson (1996) note that high back unrounded vowels in languages such as Japanese involve a gesture of lip compression or inrounding. Consequently, an important research question is whether the distinction between /ɨ/ and /Ɯ/ in Bora can be relegated to a difference in lip positions rather than to a primary contrast in tongue backness? To test this hypothesis, we obtained video recordings of native speakers on location in a Bora village (6 males and 7 females), and we report lip position data from these recordings.
Gradient realization of Mandarin nasal codas
Authors: Long Yanyu
Published: June 2017

Impressionistic studies suggested that Mandarin nasal codas optionally delete before vowels (/dan/ + /ai/->[dã.ai]) and assimilate to the following stops in place (/dan/ + /pai/->[dam.pai]). In this EMA study, we found that both processes are not phonological changes but are gradient processes modulated by speech rates. Three native Mandarin speakers read disyllabic words with n/ŋ codas before /a/ and /p/ in a carrier sentence at three speech rates. The tongue tip trajectories show that both nasals retain a reduced tongue gesture before /a/. The reduction INCREASEs as speed INCREASEs and is more variant in faster speech. The lower lip trajectories show that the labial gesture of /p/ occurs earlier when preceded by nasal codas. The time-normalized duration of this gestural advance DECREASEs as speed INCREASEs (and decreases at a slower rate in slower speech), suggesting less gestural overlap at faster speed. Such a relationship is opposite to the reduction-speed relationship. The articulatory evidence shows that although not perceptual salient, there is a reduced tongue gesture for nasals before vowels and gestural overlap between stops and preceding nasals. The non-linear effects of speed on gestural reduction and overlap suggest both are gradient phonetic processes; yet, their opposite relationships to speed suggest different implementation mechanisms.
Articulatory differences between glides and vowels
Authors: Burgdorf Dan Cameron , Tilsen Sam
Published: June 2017

Glides bear similarities to both consonants and vowels, and align with different classes of phonological patterns in different languages. Limited prior studies have suggested that glides are realized with a greater degree of constriction and a shorter duration than vowels, but articulatory studies are rare and we do not know the relative importance of these properties. To determine how glides differ from vowels gesturally, an articulatory study was conducted with EMA. A two-dimensional stimuli continuum was constructed by manipulating the intensity and duration of high vowels (i, u) flanked by a low vowel (a), from a vowel-like extreme to a glide-like extreme, and participants were asked to imitate these stimuli immediately after hearing them. Results show interesting asymmetries and interactions; while intensity was not directly imitated through degree of constriction, it did affect intergestural timing, with low-intensity stimuli yielding shorter durations in production. The relationship between glides and vowels is more nuanced than any single featural difference.
Articulation and adaptation to altered auditory feedback
Authors: Bakst Sarah , Houde John F. , Johnson Keith
Published: June 2017

Speakers listen to themselves while talking, and they use this auditory feedback to modify their speaking plans on-line [Houde and Jordan, Science 20;279(5354):1213-1216 (1998)]. This altered auditory feedback experiment uses ultrasound tongue imaging to investigate individual differences in adaptation under three conditions: (1) raising F1 in /ɛ/, (2) raising F2 in /ʊ/, (3) raising F3 in /r/. Pilot data suggest that speakers may change both F1 and F2 in response to an altered F1, replicating Katseff et al. (2010, JASA 127(3), 1955). Principal components analysis of the ultrasound data reveals that these two acoustic changes are independently controlled. We will also test the role of individual differences in vocal tract morphology. Hard palate curvature affects variability in both articulation and acoustics [Brunner et al. (2009, JASA 125(6), 3936-3949)]: flatter palates have less acoustic stability (and greater flexibility) [Bakst & Johnson (2016, JASA 140(4), 3223-3223)], requiring greater articulatory precision to maintain acoustic consistency. We hypothesize that people with flatter palates will adapt to altered feedback faster and more completely because they (a) may have more detailed knowledge of their articulation-acoustics mapping and (b) have greater flexibility in their acoustic output.
Non-linear dimensionality reduction for correlated tongue measurement points
Authors: Kang Jaekoo , Whalen D. H. , Nam Hosung
Published: June 2017

The tongue surface is a good indicator of the main supralaryngeal articulation of speech, and quantifying it with more points to measure increases accuracy. However, unlike acoustic variables (e.g., formants), articulatory variables (e.g., flesh-point pellets or multiple measurement points on an ultrasound image) are highly correlated to one another. Projecting the correlated variables with high dimensionality to lower is necessary. This study employs a nonlinear reduction method, Autoencoder (Hinton & Salakhutdinov, 2006), and compares its performance to that of Principal Component Analysis, which assumes orthogonality and linearity of dimensions. The two methods were applied to eight English vowels in clear speech from Wisconsin X-ray Microbeam dataset (Westbury, 1990). Root-mean-squared errors measured after the data reconstruction were analyzed by vowel type and pellet locations. Preliminary results with one speaker exhibited a slightly better performance than the nonlinear method, especially for some vowels (/i,u/). More speakers and time frames are predicted to lead to larger improvements of the nonlinearity analysis over the linear PCA. Similar tests of the two methods will be performed on the variabilities of the corresponding acoustic data. It is predicted that nonlinear analyses will make the variabilities in the acoustic and articulatory domains more comparable than previously assumed.
Are idiosyncrasies in vowel production free or learned? A study of variants of the French vowel system in biological brothers
Authors: rapin lucile , Schwartz Jean-Luc , Menard Lucie
Published: June 2017

Speech production displays a number of idiosyncrasies that are individual variations in the way speakers achieve phonetic contrasts in their language. It was shown previously [Ménard L. et al., Speech Commun. 2008, 50(1), 14-28] that idiosyncrasies in the production of the height contrast in oral vowels in French are characterized by large variations in the distribution of F1 values, which are associated with a stability of F1 for a given height degree, independent of the place of articulation (front vs. back) and rounding. The current study aimed to assess whether these idiosyncrasies are random or induced by the learning environment. Ten pairs of French Canadian adult male siblings were recruited, and each individual was asked to produce ten repetitions of the ten French oral vowels, which were recorded. F1 values were extracted using linear predictive coding algorithms. There was a trend towards imposed variations, since the distances between F1 values for brothers for a given vowel were significantly smaller than the corresponding distances between speakers who were not brothers. However, the F1 values within pairs of brothers were significantly correlated for only two of the six mid-high or mid-low vowels. Thus, it appears that a large part of the idiosyncrasies in the pronunciation of vowels were random and differed between brothers.
A landmark-based approach to transcribing systematic variation in the implementation of /t, d/ flapping in American English
Authors: Yun Suyeon , Choi Jeung-Yoon , Shattuck-Hufnagel Stefanie
Published: June 2017

A model of human speech processing based on individual cues to distinctive features of phonemes, such as the acoustic landmarks (abrupt spectral changes) that signal manner features, is proposed to provide a more accurate account of American English flapping of /t/ and /d/ than an allophonic or phone-based model. To test this hypothesis, this study analyses the phonetic realization of /t, d/ in the context of flapping using the acoustic landmark cues of abrupt stop closure, abrupt stop release and glide-like amplitude minimum (Stevens 2002), in subsets of the TIMIT corpus. Results show that the majority of flapped variants of /t, d/ preserve their stop closure landmark and there are several cases where they preserve both of their stop landmarks (stop closure and stop release), while exhibiting the landmark modification for flapping (e.g., t-glide- + ). Additionally, flapped /t/ is more likely to maintain stop landmarks than flapped /d/. This is unexpected from the traditional view of the flap as a categorical phenomenon, and suggests that acoustic landmarks are useful in capturing systematic phonetic variation in flapping. It will be important to test whether this landmark-based analysis yields a better result in automatic speech recognition than (allo)phone-based approaches.
Detecting glides and their place of articulation using speech-related measurements in a feature-cue-based model
Authors: Cho Adrian Y. , Liu Anita Y. , Choi Jeung-Yoon , Shattuck-Hufnagel Stefanie
Published: June 2017

An algorithm was developed for detecting glides (/w/, /j/, /r/, /l/, or /h/) in spoken English and detecting their place of articulation using an analysis of acoustic landmarks [Stevens 2002]. The system uses Gaussian mixture models (GMMs) trained on a subset of the TIMIT speech database annotated with acoustic landmarks. To characterize the glide tokens extracted from the speech samples, the following speech-related measurements were calculated: energy in four spectral bands (E1-E4), formant frequencies (F1-F4), and the time derivatives of E1-E4 (E1’-E4’); the fundamental frequency (F0) and magnitude difference of harmonics (H1-H2, H1-H4) were also included. GMMs were then trained on a subset of the tokens to learn the characteristics of each category for two distinct tasks: distinguishing glide landmarks from the set of all landmark types (identification task), and determining the place of articulation given a glide landmark (categorization task). The classifier used the maximum posterior probability of a speech sample conditioned on each of the trained GMMs. The performance of the algorithm was evaluated with median F-scores, and results suggest that the measurements at acoustic landmarks provide salient cues to glide detection and categorization.
Toward an analysis of Spanish glides in the acoustic landmark framework
Authors: Kozloff Violet , Shattuck-Hufnagel Stefanie , Choi Jeung-Yoon
Published: June 2017

Stevens (2002) proposes that the distinctive feature [glide] is signaled by an acoustic landmark, i.e., an amplitude/F1 minimum, usually during a phonated region, but this hypothesis has not been tested extensively in languages other than American English. This study analyzes acoustic realizations of tapped /ɾ/ and trilled /r/ sounds in European Spanish, identifying a range of acoustic realizations for these consonants, including glides, and proposing criteria for identifying Spanish tap and trill landmarks in the speech signal. The speech sample of 200 tokens was drawn from the Albayzin corpus, which includes recordings of read Castillian Spanish from male and female speakers. Tokens were characterized by the number of amplitude minima (or occlusions) as well as the presence or absence of vocal fold vibration and noise. Additional factors analyzed include the rate of amplitude modification (tongue tip vibration), and contextual factors, including word and syllable position, stress, and consonant clusters. These moments of abrupt change (amplitude inflection points) provide cues to the manner features of the speaker’s intended words, and are hypothesized to play a significant role in perceptual processing and word recognition. These initial results for /r/ provide the basis for extension of this analysis to other Spanish glides.
Similarity measurement based rest position re-initialization in the MRI vocal tract image sequences
Authors: Liu Xi , Xu Kele
Published: June 2017

Magnetic resonance imaging is often used for the speech production research. One important aspect is to segment the vocal tract in the image sequence. However, during the deformation of the vocal tract, it is highly possible that the landmark deviates from its correct position and is in need of reinitialization. During the natural speech production of the subject, the vocal tract may return to its initial position during the pause at the end of a sentence. This could be used to reset the landmark to its correct position. In order to determine the pause in the image sequence, we used similarity based measurements to compare the similarity between the current frame and the first frame, which is the beginning of a sentence and the vocal tract is at the rest position. These measurements include Structural Similarity (SSIM), Complex Wavelet Structural Similarity (CW-SSIM), Visual Information Fidelity in Pixel (VIFP), Peak Noise to Signal Ratio (PSNR), etc. We found CW-SSIM outperformed the other methods. We calculated the similarity measurements and they varied periodically during the speech. CW-SSIM returned to a maximum of around 0.9, which indicated that the vocal tract returned to its initial position. The rest of the similarity measurements returned to a maximum value greatly deviated from 1, which indicated that the CW-SSIM was the best candidate.
Uncontrolled manifold method to speech production
Authors: Nam Hosung , Kang Jaekoo , Saltzman Elliot
Published: June 2017

Speech production is a highly skilled sensorimotor activity defined by articulatory or acoustic coordinates. To compare the variabilities of those two conceptualizations, issues of dimension reduction, normalization, incompleteness of information, etc., need to be taken into account. Uncontrolled manifold (UCM) method analyzes high-dimensional movement dataset with respect to the outcomes that count as successful tasks. It divides the variability in the data into two parts: “bad” variability associated with motion within the controlled manifold (CM) that would lead to an error in the task and “good” variability within the uncontrolled manifold (UCM) that do not harm to the task. The smaller ratio indicates both tighter control (less variability in the CM) and greater flexibility (more variability in the UCM). The UCM method is applied to the Wisconsin X-ray microbeam data. We first constructed a neural-net-based forward mapping from articulators to acoustics. The inter-layer weight matrices and the outputs of each layer in the trained forward model are then used to compute the elements of this forward model’s Jacobian matrices; the Jacobians are then used to compute σCM/σUCM ratios. We further compare these ratios across data obtained in various linguistic conditions.
High-resolution speech directivity measurements
Authors: Pincock Claire , Leishman Timothy W. , Whiting Jenny
Published: June 2017

A measurement system has been developed at Brigham Young University to assess high-resolution directivity data produced by human subjects. The system incorporates 2522 unique sampling positions over a sphere and has been used to acquire directivity data of several female and male talkers repeating phonetically balanced passages. Both polar and balloon plots of these data have been generated, along with similar plots corresponding to gender-specific averages and spherical-harmonic expansions. The results will be used for speech radiation studies and architectural acoustics simulations. This presentation reports the results and compares the directivity averages for both genders.
Sliding windows and persistence
Authors: Perea Jose , Traile Chris
Published: June 2017

The use of geometric and topological ideas as a means to tackle problems in signal analysis has seen a sharp increase in the last few years. The goal of this talk is to show how ideas from dynamical systems (e.g., time delay embeddings) with tools from topological data analysis (e.g., persistent homology) allows one to extract highly non-trivial features from vector-valued time series data. As an example, we describe a paradigm for quantifying (quasi)periodicity in video data and provide applications including the study of gene regulatory networks in biology, biphonation in mammals, and speech pathologies in humans.
On the general connection between wave impedance and sound intensity
Authors: Stanzial Domenico , Graffigna Carlos E.
Published: June 2017

This paper presents the generalization to non-monochromatic non-monodimensional fields of the equation linking the complex sound intensity to the wave impedance/admittance already introduced with a different form in [D. Stanzial and C. E. Graffigna “On the connection between wave impedance, sound intensity and kinetic energy in monochromatic fields,” accepted for publication on POMA, Dec. 23, 2016]. Computer simulations have been now carried out, both for wave impedance and admittance, in quasi-stationary bi-dimensional waves fields with different reflection coefficients and spectral compositions. It turns out that the equation is validated in all space points of the sound field for each spectral component. This allows primarily to calculate the active intensity vector field as the vector sum of all vector fields obtained as the spectral components of the active intensity and therefore to determine the reactive intensity magnitude by simply subtracting the modulus of the so obtained active intensity from scalar field of the apparent intensity. This grand result will allow to develop a precision device for measuring 3D sound intensity and its active and reactive spectral components.
Bias error comparison for plane-wave acoustic intensity using cross-spectral and phase-and-amplitude-gradient-estimator methods
Authors: Hawks Daxton , Neilsen Tracianne B. , Gee Kent L. , Sommerfeldt Scott D.
Published: June 2017

Acoustic vector intensity relies on the product of the acoustic pressure and particle velocity. The particle velocity is typically approximated via Euler’s equation using the gradient of the complex pressure across closely spaced microphones, which is traditionally found using the cross-spectral density. In contrast, the phase-and-amplitude-gradient-estimator (PAGE) method [Thomas et al., J. Acoust. Soc. Am., 137, 3366-3376 (2015)] relies on gradients of pressure magnitude and phase. For a broadband source this allows for the phase to be unwrapped, which extends the usable bandwidth of the intensity calculation well above the spatial Nyquist frequency. The benefits of the PAGE method are evident in plane wave tube measurements in which microphones spaced 90 cm apart yield accurate intensity values at frequencies at least ten times the spatial Nyquist frequency. This represents an increase in bandwidth of 30 times over the traditional method. The bias errors for the traditional method for calculating acoustic intensity are reviewed and compared with the bias errors for the PAGE method for the case of both two and three microphone intensity probes in a plane-wave tube environment. [Work supported by the National Science Foundation.]
Precision device for measuring the three dimensional spectral intensity
Authors: Stanzial Domenico , Graffigna Carlos E.
Published: June 2017

On the basis of processing algorithms developed by the same authors in a companion paper [“On the general connection between wave impedance and sound intensity”, 173rd Meeting of the Acoustical Society of America and the 8th Forum Acusticum, Boston MA, 25-29 June 2017] where the equation between the complex sound intensity and the specific acoustic impedance/admittance has been stated and numerically validated in general form, the block diagram of a possible device for precision measurement of 3D spectral intensity is proposed here. In order to test its functionality, some measurements have been carried out, inside a tube of 28x28 cm2 square section and 4 m long, which was terminated with panels of different materials. Measurements have been carried out at different positions along the tube's axis by means of a 3D pressure-velocity probe below and above the cutoff frequency of the tube so to include also the effects of transversal modes. Preliminary results of such measurements are reported and discussed briefly here.
Propagation over a rigid sea ridge using a three-dimensional finite element model
Authors: Cheung Fiona , Isakson Marcia J.
Published: June 2017

A three-dimensional finite element model is developed to describe propagation over a rigid underwater sea ridge. Finite element models are attractive benchmark solutions since they include all orders of scattering as well as refraction. In this case, the model is calculated using an out-of-plane wavenumber decomposition technique which utilizes a series of two-dimensional models to calculate a fully three-dimensional model in longitudinally invariant environments. [Isakson et al., J. Acoust. Soc. Am. Express Letters, 136:EL206-211, 2014.] The time-harmonic model is then extended to the time domain via Fourier synthesis in order to more fully understand the dynamics of modal refraction and propagation over the ridge. The model is compared with coupled mode solutions from the University of Rhode Island. [Work supported by ONR, Ocean Acoustics.]
Time-domain reverberation modeling for rough bottom consisting of polygon facets
Authors: Choo Youngmin , Seong Woojae
Published: June 2017

In reverberation modeling for rough bottom, a surface integration is conducted along elemental scattering areas with repetitive uses of propagation and scattering strength models and a summation of scattered signals from the scattering areas provides a synthetic reverberation signal in time domain. In particular, when roughness is on a flat or sloping bottom, numerical integration schemes including quadrature by parts can be used with elemental scattering areas, which are small enough to obtain a converged reverberation signal. However, this standard approach is unavailable for a bottom having irregular geometry since the bottom cannot be divided into small element scattering areas. To acquire a stable reverberation signal by the irregular bottom, we derive an analytic integration of scattered signal for polygon facet by using Stokes’ theorem while approximating the bottom with combination of polygon facets. In this approach, a delay difference in an elemental scattering area is considered whereas a representative delay is used for the elemental scattering area in the standard approach. Results from two different reverberation models are compared and the scheme using analytic integration shows a converged reverberation signal even with large elemental scattering areas.
Estimating the speed of poroelastic interface waves using ambient noise
Authors: Barclay David R. , Zedel Len , Hay Alex E.
Published: June 2017

Pairs of hydrophones were buried at mid-tide height in a 1:10 sloped mixed gravel and coarse sand beach and used to make ambient noise recordings over a period of three weeks in Advocate Harbour, Nova Scotia, in the Bay of Fundy. The pairs were arranged in vertical and horizontal configurations and recorded pressure time series, power spectral density, and vertical and horizontal coherence measurements of the noise field in the seabed. A nearby suite of oceanographic instruments measured the water level, ocean wave properties, bed dynamics and weather during the experiment. The measured noise between 1 Hz and 1 kHz was dominated by poroelastic interface waves generated by plunging surf on the beach face. The speed of the compressional component of the interface wave was estimated by cross-correlating the noise recorded on the across-shore oriented pair of sensors while the unconsolidated sediment was water-saturated as well as drained. Additionally, the increasing and decreasing overburden pressure due to the rising and falling 10-m tide was found to drive a respective increase and decrease in the poroelastic interface wave speed. A buried acoustic source was used to directly measure the compressional wave speed in the seabed on the across-shore array.
Passive bottom reflection-loss estimation using ship noise and a vertical line array
Authors: Muzi Lanfranco , Siderius Martin
Published: June 2017

An existing technique for passive bottom-loss estimation from natural marine surface noise (generated by waves and wind) is adapted to use ship generated noise. The original approach (based on beamforming of the noise field recorded by a vertical line array of hydrophones) is retained. However, the field generated by a passing ship must be processed preliminarily, in order for it to show features that are similar to those of the natural surface-noise field and therefore become amenable to the technique. A necessary requisite is that the ship position, relative to the array, vary over as wide a range of steering angles as possible, ideally passing directly over the array to ensure coverage of the steepest angles. The methodology is illustrated through simulation and applied to experimental data.
Channel impulse response arrival uncertainty using source of opportunity for tomography
Authors: Gemba Kay L. , Sarkar Jit , Tippmann Jeffery D. , Hodgkiss William S. , Cornuelle Bruce , Kuperman William A. , Sabra Karim G.
Published: June 2017

Passive acoustic tomography exploits the acoustic energy generated by sources with unknown spectral content such as sources of opportunity (e.g., cargo ships) to study the ocean. The recording at each sensor within a vertical line array (VLA) is the channel impulse response (CIR) convolved with the noise generated by the moving random radiator. Using an incremental approach, we estimate the source signal locally at three VLAs by beamforming on the direct ray-path to deconvolve each CIR. CIR arrival uncertainty is inversely proportional to the bandwidth of the source and SNR, the latter estimated from the deconvolved time domain waveform. Over the 10 min source track, we present the time evolution of CIR arrival uncertainty computed at three VLAs horizontally separated by 1.5 km and discuss constraints on integration time. Data are presented using the Noise Correlation 2009 Experiment and application to the Santa Barbara Channel Experiment 2016 is discussed.
An alternative statistical method for characterizing low-frequency environments in sensitive laboratory settings
Authors: Davis Byron
Published: June 2017

Many practitioners are familiar with the collection and expression of complex noise data as Ln statistical spectra. Given suitable instrumentation, it is easy to develop Ln statistics for low-frequency sound and vibration environments, as well. However, the traditional (instrument-generated) Ln datasets have some shortcomings when it comes to understanding some environments, especially in highly sensitive settings like research laboratories. The emergence of mass data storage and manipulation tools has provided an opportunity to employ a somewhat subtler method to characterize these environments. In this presentation, we will describe this analytical technique, which provides statistical representations similar to the Ln system. However, the technique further allows an explicit invocation of timescale, allowing the user to choose an arbitrary analytical timescale relevant to sensitive operations or expected environmental transients or other forcings. We will also show examples that demonstrate why the approach might find particular use in technical settings like nanotechnology laboratories and other environments supporting research in the physical sciences.
Micro-vibration design for a cutting edge cancer research laboratory at a high-vibration site
Authors: Bayat Ahmad , Kaytt Thomas , DeLoach Alana
Published: June 2017

State-of-the art medical & material science imaging technologies are pushing the limits of ground vibration tolerance. Modern technical instruments such as Transmission Electron Microscopes are calling for tighter functional vibration limits far below the threshold of human sensitivity and at lower and lower frequencies to facilitate analysis of details on the scale of individual atoms. In one particularly demanding case, an instrument proposed for a university research building called for vibration levels not to exceed 50 µ-in/s at frequencies as low as 1 Hz, and this instrument would be needed while heavy construction is ongoing at nearby surrounding properties. Meeting this strict criterion without limiting the use of the surrounding land required special low-noise instrumentation, an in depth geotechnical analysis of the site, and a comprehensive isolation scheme to achieve up to a 95% reduction in ground vibration. This paper will discuss the steps taken to evaluate the site vibration conditions and the structural isolation & active isolation mounting measures enacted to meet this stringent instrumentation requirement.
An introduction to the new edition of AISC Design Guide 11 “Vibrations of Steel Framed Structural Systems due to Human Activity.”
Authors: Ungar Eric E.
Published: June 2017

The 2016 edition of Steel Design Guide 11, like the first (1997) edition, “Floor Vibrations due to Human Activity,” presents relatively easily used means for predicting the vibrations of rectangular bays of floors of steel-framed construction due to typical walking and for assessing the acceptability of these vibrations to personnel. However, the new edition includes better representations of the forces associated with footfalls and improved validated methods for prediction of the structural responses. In addition to floors of buildings, it also addresses footbridges and stairs. It distinguishes between “low frequency” and “high frequency” structures; the former tend to vibrate nearly steadily at resonance due to typical walking, whereas the latter tend in essence to respond to a series of separate footfall impulses. The new edition presents not only expressions for the expected peak velocities and accelerations, but also includes relations for evaluating the acceptability of vibrations for equipment and activities whose criteria are expressed in terms of one-third-octave-band or narrow-band values. It also notes how the different response measures are affected differently by changes in the structural mass and stiffness. An extensive chapter provides advice on the application of finite-element analysis.
Numerical analysis on applicability of measurement method according to ISO 16283 in small rooms at low frequencies
Authors: Schoenwald Stefan , Zemp Armin
Published: June 2017

The robustness of the new measurement method for sound pressure level in small rooms with less than 25 m3 room volume at low frequencies from 50 Hz to 80 Hz that was recently introduced in the ISO 16283 series on sound insulation measurements in buildings was investigated in an experimental study. This restricted study revealed some potential problems with the method that were already presented, but unfortunately, a further experimental investigation was not possible because of the time- and labor-intensiveness of the conducted experiments. Now the sound level distribution in the room was predicted with a simple analytical modal model and an excellent agreement with the available experimental results was found. With the prediction model, it was possible to refine the results of the experimental study, to extend it to other room geometries, and to revisit and to analyze the identified potential problems on a much more detailed and broader database. In the conference paper, the experimental study and its outcomes are briefly recapitulated, the prediction model and its validation are presented, and new conclusions are drawn based on the findings of the original experimental and the extended numerical study.
Measuring the sound insulation of an external thermal insulation composite system (ETICS) by means of vibrometry
Authors: Urbán Daniel , Roozen Bert , Niemczanowski Alexander , Muellner Herbert , Zaťko Peter
Published: June 2017

The impact of External Thermal Insulation Composite System (ETICS) on acoustic properties of external walls has been already examined. Probably the most fundamental research was carried out in Germany (Weber). The effect of thickness and dynamic stiffness of ETICS, as well as mass of external plaster, on decreasing of wall sound insulation was demonstrated. In this paper, the mass spring mass resonances (m-s-m) were investigated, in case of a massive external wall with ETICS. Application of ETICS increases the sound insulation of walls in the mass-law dominated frequency range by about 12 dB/oct. However, in the low frequencies ETICS decrease sound insulation due to resonant effects, which become very prominent in traffic noise situations. This contribution presents how vibrometry measurements can be useful for ETICS sound insulation properties measurement.