bluuebunny/crossref_metadata_2025 huggingface dataset:
Ball sensor rattle: Experimental and numerical sensitivity study for seatbelt applications
Authors: Machens Kai-Ulrich J. , Neumann Jens , Scholz Jens , Markiewicz Marian
Published: June 2017

Seatbelt systems are important elements of automotive safety systems. Most seatbelt retractors are equipped with ball sensors, enabling retractors to comply with mandatory vehicle sensitive locking requirements. The functional principle is based on ball inertia plus defined backlash of mating surfaces, which renders seatbelt retractors susceptible to rattle. Sensor ball rattle is considered as the most persistent parasitic noise source in occupant safety industry. The vibration induced noise behavior of the ball sensor is analyzed, both experimentally and by numerical simulation, predicting the sound pressure spectrum up to 5 kHz. Impact forces among mating surfaces are computed in the time domain with flexible multibody system analysis, employing Craig-Bampton modes to approximate the vibrations of acoustically relevant substructures. Acoustic radiation into the sound field is determined in the frequency domain using preprocessed acoustic transfer vectors from boundary element method analysis, significantly reducing computation time. A sensitivity study with variation of sensor mass, gap, and excitation demonstrates excellent correlation between numerical model prediction and experimental result across a large variety of test cases. The presented methodology can predict rattle induced noise, and therefore delivers substantial input for retractor design. Furthermore, other applications beyond seatbelt retractors could equally benefit from using this approach.
A methodology to design multi-axis test rigs for vibration and durability testing using frequency response functions
Authors: Sendur Polat , Ozcan Umut , Ozoguz Berk
Published: June 2017

The multi-axis simulators are designed for experimental verification of the safe functioning of large components and subsystems under real world customer usage in vibration and durability testing. Transformation of the full vehicle conditions to mast rig testing with correct system dynamics and vibration characteristics and boundary conditions is a key challenge in the development of the experimental set-up. In this paper, a systematic methodology is formalized how to design the experimental set-up on MAST rig to replicate the vehicle dynamics and vibration characteristics in vehicle conditions. System modes and frequency response functions are chosen as key performance metrics to compare the dynamics of the system to be tested for both full vehicle and rig design. Criteria on the metrics are defined to make decision if the test rig design is sufficiently replicating the in-vehicle conditions. The methodology is illustrated on a side skirt attached to a heavy duty truck chassis that demonstrates the application of the methodology in practice.
Design of in-plane functionally graded material plates for improved vibration characteristics
Authors: Alshabatat Nabeel T. , Myers Kyle R. , Naghshineh Koorosh
Published: June 2017

A method for improving the vibration characteristics of plate structures is proposed. This method uses functionally graded material (FGM) instead of isotropic material to construct the plates. The volume fraction of each material constituent is defined in the plane of the plate by a 2D trigonometric law, while the material properties through the thickness are assumed constant. The finite element method is used for modal and harmonic analysis, and a genetic algorithm is utilized for optimization of the chosen objective function. The efficacy of the method is demonstrated by two design problems. In the first design problem, FGM is used to maximize the fundamental frequencies of plates with different boundary conditions. In the second design problem, the kinetic energy of a vibrating FGM plate is minimized at a specific excitation frequency. These example design problems show that material tailoring of plate structures using FGM can result in substantial improvements of their vibration characteristics. The results can be used to guide the practical design of FGM plates to enhance their dynamic properties.
Perception of native language speech sounds does not predict non-native speech sound learning
Authors: Fuhrmeister Pamela , Myers Emily
Published: June 2017

Individual differences are often observed in laboratory studies of non-native speech sound learning. One possible explanation for this variability is that better detection of fine-grained contrasts within native language categories might facilitate non-native learning. For instance, Diaz et al. (2008) found larger MMN responses to both native and non-native speech contrasts in good compared to poor perceivers of a non-native contrast, suggesting a general speech-related skill. The current study explores whether the ability to discriminate subtle differences in native language speech sounds correlates with non-native speech sound learning. To test this, we trained participants on a non-native, Hindi dental/retroflex contrast and assessed their categorization and discrimination of a native /da/-/ta/ continuum. Additionally, participants completed a visual Flanker task in order to control for general motivation in the experimental setting. Neither native language measures nor the Flanker task predicted non-native speech sound learning abilities. Rather, using k-means cluster analysis, we found two distinct groups of learners and non-learners that did not significantly differ on native language or Flanker measures, suggesting that non-native speech sound learning may be independent of those skills. Instead, non-native learning success was best predicted by an ability to discriminate the non-native contrast at pretest.
Perceptual assimilation of Mandarin Chinese consonants by native Danish listeners
Authors: Rasmussen Sidsel , Bohn Ocke-Schwen
Published: June 2017

A perceptual assimilation experiment examined the cross-linguistic mapping of Mandarin Chinese initial consonants to Danish consonants. 24 native Danish listeners were auditorily presented with naturally produced CV syllables which consisted of the Mandarin initial consonants [p, ph, t, th, k, kh, x, ts, tsh, s, tɕ, tɕh, ɕ, tʂ, tʂh ʂ, ɻ, w, j] and vowels from the set [a, u, i, y] so that none of the CV syllables violated the permissible combinations of C and V in Mandarin. The Danish listeners identified the initial consonant of the stimuli with phonetically unambiguous Danish orthographic symbols and provided goodness ratings for each match. We found that assimilation patterns for Mandarin consonants differed greatly as a function of the following vowel, suggesting that native expectations regarding coarticulatory effects of V on C importantly affect perceptual assimilation. For example, Mandarin [tɕ, tɕh, ɕ] were assimilated to Danish , respectively, when followed by [a, y], but to Danish  when followed by [i]. The detailed results allow us to generate precise predictions for the discriminability and thus learnability of Mandarin consonants for native Danish listeners and learners.
Can second language suprasegmentals be learned? A study on Japanese learners of Italian as foreign language
Authors: Pellegrino Elisa
Published: June 2017

One of the biggest challenges for L2 learners is to develop native-like prosodic competence. There are evidence that computer-assisted pronunciation training helps learners perceive and produce L2 suprasegmentals. In this study we test to the effectiveness of one of the techniques developed in the area of spoken language technology for education and language learning—self-imitation—to facilitate the acquisition of the rhythmic and prosodic characteristics of Italian. 7 Japanese learners of Italian as Foreign language (NNSs) and 2 Italian native speakers (NSs) were asked to read aloud and record two sentences in Italian conveying different pragmatic functions. The utterances of NNSs were manipulated as they receive the segmental durational characteristics as well as the f0 characteristics of the corresponding NSs’ utterances. NNSs imitated their own voice previously modified to match the reference NSs and recorded the new performance. To quantify the degree of approximation to the native prosodic and rhythmic pattern after self-imitation, pre- and post-training utterances were compared to those of the native models by speech rate, f0, and segmental durational characteristics. Preliminary results show that after the training utterance duration and vocalic intervals length better match the target duration.
Improving speech recognition in noise through speaking style modifications for native and non-native listeners
Authors: Meemann Kirsten , Smiljanic Rajka
Published: June 2017

It is well established that native listeners outperform non-native listeners on word recognition tasks involving both speech-shaped noise (SSN) and competing speech (speech babble). The present study examined whether this non-native disadvantage can be compensated for by speaking style enhancements. We also explored how these acoustic-articulatory modifications interact with energetic and informational masking at different signal-to-noise ratios to determine intelligibility for the two listener groups. Native and non-native participants heard noise-adapted (NAS) and clear speech (CL) sentences mixed with either SSN, two-talker (2T), or six-talker (6T) babble. CL and NAS significantly improved word recognition in noise, but native listeners were better able to use the intelligibility-enhancing modifications. Results revealed an interaction between noise type and SNR such that the intelligibility gain was larger for SSN at an easier SNR, but for 6T babble at a harder SNR. The speaking style modifications enhanced intelligibility least in 2T babble for both listener groups. Speaking style adaptations improve word recognition under energetic masking (SSN), but are most beneficial when informational and energetic masking are combined (6T babble) and presented at a low SNR. The intelligibility benefit was smallest in listening conditions with less energetic masking (2T babble) that resulted from larger spectro-temporal dips.
Vowel undershoot in the production of nonwords by English and Mandarin speakers
Authors: Yang Chung-Lin , Lin Yu-Jung , Chao Kuan-Yi
Published: June 2017

In a previous study (Yang, 2011), it was found that both Mandarin and English speakers showed vowel undershoot (characterized by decreased vowel duration and lowered first formant) in the production of English vowels while reading a list of real words, but Mandarin speakers could not make a clear tense-lax distinction. The current study aims at examining the degree of undershoot and tense-lax distinction when speakers had to reproduce what they heard without any visual input. In a nonword repetition task, Mandarin and English speakers were auditorily presented with a list, consisting of 8 English nonword triplets with the target vowels /i, ɪ, eɪ, ɛ/ embedded: monosyllables, disyllables and trisyllables. Each trial began with a short training session where participants listened to the nonwords in each triplet as many times as they wanted. After training, each nonword were played three times and participants repeated after each token. Our preliminary data showed that English speakers, while maintaining the tense-lax distinction, showed undershoot when producing nonwords across the three syllabic conditions. On the contrary, Mandarin speakers showed very limited undershoot and unclear tense-lax distinction across the three syllabic conditions, especially between /eɪ/ and /ɛ/. [Yu-Jung Lin and Kuan-Yi Chao contributed equally to this project.]
Acoustic comparison on syllabic rates between stress-timed and syllable-timed language speakers
Authors: Kim Myungsook , bae myungjin
Published: June 2017

Syllabic rates (i.e., phonation rate for each syllable) of a speaker provide us with a lot of interesting information about the language in question. Especially between syllable-timed language and stress-timed language, we may expect that speakers will show a gap in syllabic rates as they have their own ways to pronounce. Syllabic rates are closely related with information density in speech communication although the Rosetta Project (2011) found a negative correlation between the two illustrating the existence of encoding strategies for each of 7 popular languages in the world. Since Korean was not on the list for the Project, this paper further investigates and compares acoustic characteristics on syllabic rates between two speakers, one of English, stress-timed language, and the other of Korean, syllable-timed language, when speaking both Korean and English. The result shows that the English speaker speaks Korean 1.39 times faster than the Korean speaker in syllabic rate. The English speaker also shows higher energy distribution in high frequency range while the Korean speaker shows a relatively even distribution in all frequency ranges. When speaking English, the Korean speaker speaks slower than the English speaker, showing not much difference in duration, pitch, and intensity between the stressed and unstressed syllables. The paper concludes that keeping a proper syllabic rate for a target language might be important in language acquisition.
Information loss due to environmental variability and uncertainty in Bayesian localization of a narrowband source
Authors: Hayward Thomas J.
Published: June 2017

Performance degradation of Bayesian localization of a low-frequency narrowband acoustic source due to variability and imperfect knowledge of the acoustic environment is investigated in a computational study. The environmental variability is modeled as arising from water column fluctuations associated with a diffuse random linear internal wave field in a shallow-water ocean waveguide. The ambient noise spatial cross-spectrum is represented by a Kuperman-Ingenito model. For the case of complex Gaussian internal wave spectral amplitudes, a closed-form expression is derived for the conditional pdf, given source location, of the signal spectral values received on an acoustic array. Examples computed for a vertical receiver array quantify localization performance degradation as an increase in the entropy of the Bayesian source-location posterior. The effects of model bias, model spectral uncertainty, and medium variability as determined by the internal wave power spectrum are quantified separately and jointly. Potential extensions to more general models of medium variability are discussed. [Work supported by ONR.]
Arctic soundscape measured with a drifting vertical line array
Authors: Reeves Emma , Gerstoft Peter , Worcester Peter F. , Dzieciuch Matthew
Published: June 2017

The soundscape in the eastern Arctic was studied from April to September 2013 using a 22 element vertical hydrophone array as it drifted from near the North Pole (89° 23'N, 62° 35'W) to north of Fram Strait (83° 45'N 4° 28' W). The hydrophones recorded for 108 minutes on six days per week with a sampling rate of 1953.125 Hz. After removal of data corrupted by nonacoustic flow-related noise, 19 days throughout the transit period were analyzed. Major contributors include broadband and tonal ice noises, seismic airgun surveys, and earthquake T phase arrivals. Statistical spectral analyses show a broad peak in power at about 15 Hz similar to that previously observed and a mid-frequency fall off of about 20 dB/decade. Observations of the median noise levels with depth demonstrate the change in dominant noise sources between high (200-500 Hz) and low (10-50 Hz) frequencies as the array transited southward. The median noise levels observed are among the lowest of the sparse observations in the eastern Arctic, but comparable to noise levels reported in the western Arctic.
Acoustic measurements of a controlled gas seep
Authors: Rychert Kevin M. , Weber Thomas C.
Published: June 2017

To verify existing models for conversion of acoustic target strength to estimates for the total volume of methane gas released from the seafloor through the water column, a synthetic seep system was designed and fabricated. This system creates individual bubbles of a specific sizes most commonly found in gaseous methane seeps, 1 to 5 mm radii, which can be released at any interval and at any water depth. The synthetic seep system was deployed off the coast of New Hampshire in an approximate depth of 50 m. Acoustic backscatter from 10 to 100 kHz was collected by steaming over the synthetic seep multiple times, each with a predetermined and calibrated bubble size created by the system at depth. These data represent a direct field measurement which tests models describing bubble size evolution during ascent through the water column, as well as models for acoustic scattering from bubbles of different sizes. Validating these models directly tests the ability of broadband sonar systems to acoustically monitor the transport of gas from the seabed to the atmosphere.
Passive elastography: A shear wave tomography of the human body
Authors: Catheline Stefan
Published: June 2017

Elastography, sometimes referred as seismology of the human body, is an imaging modality recently implemented on medical ultrasound systems. It allows to measure shear waves within soft tissues and gives a tomography reconstruction of the shear elasticity. This elasticity map is useful for early cancer detection. A general overview of this field is given in the first part of the presentation as well as latest developments. The second part, is devoted to the application of time reversal or noise correlation technique in the field of elastography. The idea, as in seismology, is to take advantage of shear waves naturally present in the human body due to muscles activities to construct shear elasticity map of soft tissues. It is thus a passive elastography approach since no shear wave sources are used.
A tomography experiment using ships as sources of opportunity
Authors: Kuperman William A. , Cornuelle Bruce , Gemba Kay L. , Hodgkiss William S. , Sarkar Jit , Tippmann Jeffery D. , Verlinden Christopher M. , Sabra Karim G.
Published: June 2017

An experiment was performed in the Santa Barbara Channel using four vertical acoustic receive arrays placed between the sea lanes of in- and outgoing shipping traffic. The purpose of the experiment was to determine whether these sources of opportunity can be utilized for tomographic inversion of water column properties. The environment was continuously monitored throughout the duration of the experiment. Ship tracks were obtained from the Automatic Identification System (AIS). Processing was developed to extract relative time delays between the arrays from the ships’ random radiation fields. This information, together with AIS constraints were used for inversion. Initial results are presented that also include an error analysis of the inversion.
Deducing environmental properties from broadband matched-mode processing ambiguity surface striations generated from baleen whale data
Authors: Thode Aaron , Bonnel Julien , Berchok Catherine L.
Published: June 2017

Numerous multi-year shallow-water recordings of several species of baleen whale have been obtained from shallow-water arctic environments, including the Bering Sea. When non-linear time sampling is applied to the single-hydrophone data, these broadband signals yield individual normal mode arrivals, which in turn permit incoherent matched-mode processing (MMP) techniques to be applied for source localization and geoacoustic inversion. When continuously broadband MMP ambiguity surfaces are constructed from pairs of modes and plotted as a function of range and frequency, both the mainlobe and sidelobes form striations that embed information about the type and amount of environmental mismatch present between the modeled and true environment. These striations are useful for identifying bandwidths of inversion-quality data within whale calls. Acoustic invariant theory explains how mismatched waveguide replicas from simple environmental models, when applied to sufficiently low-frequency data, produce ambiguity surface striations that reveal the true bottom interface sound speed and bottom sound speed gradient. During summer, whenever highly downward-refracting sound speed profiles exist, mismatched MMP striations also contain information about the sound speed gradient. Examples of this visual approach to inversion are shown on endangered North Pacific Right whale “gunshot” signals. [Work sponsored by the North Pacific Research Board.]
Determining the bottom surface in the randomly inhomogeneous media
Authors: Sushchenko Andrei , Prokhorov Igor , Sushchenko Kristina
Published: June 2017

The authors study a problem of determining the bottom topography of a fluctuating ocean using the data of side-scan sonars. Based on a kinetic model of acoustic radiative transfer authors obtain a formula for determining a function describing small deviations of the bottom surface from a middle level. The impulse parcels of source and width of the directivity pattern of the receiving antenna are constructed unfocused sebottom image. For solving it, authors used iterative algorithm for focusing objects on the seabottom. Numerical experiments have been done on modeling data that demonstrate the accuracy of the obtained formula. Numerical analysis of the volume scattering influence is done. The volume scattering filter allows to reconstruct sea bottom relief from long range, e.g., signal from 150 m includes more than 50% of volume scattering, hence object recognizing is not possible without filtering. The width of directivity pattern affects to the object defocussing. This effect is increased with slant range increasing. Moreover, authors designed the algorithm of determining shaded areas on the sea bottom. It allows to recognize each invisible point on the sea bottom in case of non-static source. Thus, authors researched influence of volume scattering on the seabottom relief reconstruction.
Computation of acoustic wave responses due to moving underwater acoustic sources in complex underwater environments using a spectral element method
Authors: Lloyd Stephen , Jeong Chanseok , Gharti Hom Nath , Tromp Jeroen
Published: June 2017

This work presents a new numerical approach for computing underwater acoustic wave responses due to moving underwater acoustic sources in complex underwater environments using a Spectral Element Method (SEM). The SEM is similar to the Finite Element Method (FEM), but uses a higher-order shape function with Gauss-Lobatto-Legendre quadrature, naturally creating a diagonal mass matrix. Thus, we can use fast explicit time integration, taking advantage of a diagonal mass matrix, without compromising accuracy. Therefore, the SEM is much more suitable for large-scale parallel 3D time domain wave analyses than the conventional FEM. In our numerical experiments, we used a large-scale parallel SEM wave simulator, SPECFEM3D. We verified the SEM solution of acoustic (fluid pressure) waves in a 3D acoustic fluid setting of an infinite extent, induced by a moving point source, by using its analytical counterpart. Numerical experiments showed that our tool accurately accommodates wave behavior at fluid-solid interfaces of complex geometries and infinite extents of water and solids, truncated using absorbing boundary conditions. Due to such versatility, our tool can be used for forward and inverse acoustic wave analyses in any complex underwater systems of large extents (e.g., shallow water and deep ocean).
3D acoustic propagation modeling of the construction of the Block Island Wind Farm
Authors: Ragusa Anthony F. , Potty Gopu R. , Miller James H , Lin Ying-Tsong , Newhall Arthur , Vigness-Raposa Kathleen J. , Giard Jennifer , Ross Michael , Roberts Jesse
Published: June 2017

The Block Island Wind Farm (BIWF) consists of five turbines in water depths of approximately 30m. The substructure for the BIWF turbines consists of jacket type construction with piles driven to the bottom pinning the structure to the seabed. These jacket legs and foundation piles were driven at a rake angle of approximately 13° from the vertical. This introduced three-dimensional sound propagation effects as indicated by measurements using a towed array during construction which showed azimuthal variability. In order to model the complicated source, we will use finite element techniques (developed by Sandia National Laboratories) to provide the starting field for a 3D parabolic equation model. Eventually the model predictions will be compared to the actual measurements taken during wind turbine construction. This finite element model will be initially validated by modeling the wave propagation in an instrumented sandbox at the University of Rhode Island (URI) before applying the model to the Block Island modeling scenario. [Work supported by Bureau of Ocean Energy Management (BOEM).]
Teachers' voice parameters and classroom acoustics—A field study and online survey
Authors: Durup Nick , Shield Bridget M. , Dance Stephen , Sullivan Rory
Published: June 2017

Many studies have suggested that teachers have a significantly higher rate of voice problems than the general population. In order to better understand the possible influences of room acoustics on different voice parameters, a study has been carried out by London South Bank University which involved measurements of voice parameters for teachers working in classrooms with varying acoustic conditions. Data relating to the voice, including the average speech sound level, fundamental frequency, and phonation percentage, were captured using an Ambulatory Phonation Monitor (APM) which measured directly from skin vibrations in the neck, thereby excluding the effects of other noise sources in the environment. The measured voice parameters were compared with the room acoustic data for the classrooms involved, which were surveyed separately from the voice measurements. In addition to the field measurements, an online questionnaire was undertaken with the support of two UK teacher trade unions. This was designed to gain further information on teachers’ experiences of voice problems and school acoustics in general and indicated that over 66% of the surveyed teachers had experienced voice problems during their career. This paper will present the results of the field measurements and questionnaire survey.
Vocal fatigue in virtual acoustics scenarios
Authors: Bottalico Pasquale , Cantor Cutiva Lady Catherine , Hunter Eric J.
Published: June 2017

The overuse of the voice by professional voice users, such as teachers, is known to cause physiological vocal fatigue. Vocal fatigue is used to denote negative vocal adaptation that occurs as a consequence of prolonged voice use or vocal load. This study investigates how self-reported vocal fatigue is related to voice parameters (sound pressure level SPL, fundamental frequency f0, and their standard deviations) and the duration of the vocal load. Thirty-nine subjects were recorded while reading a text. Different acoustics scenarios were artificially created to increase the variability in the speech produced (3 reverberation time, 2 noise conditions, and 3 auditory feedback levels), for a total of 18 tasks per subject presented in a random order. For each scenario, the subjects answered questions addressing their perception of vocal fatigue on a visual analog scale. A model of the vocal fatigue to acoustic vocal parameters is proposed. The duration of the vocal load contributed to 55% of the variance explained by the model, followed by the interaction between the standard deviations of the SPL and f0 (24%). The results can be used to give a simple feedback during voice dosimetry measurements.
The effects of wind turbine wake turbulence on bat lungs
Authors: Villafranco Dorien O. , Grace Sheryl , Holt Ray
Published: June 2017

Bat mortality is known to increase near wind turbines. Recent studies are in disagreement as to the exact cause of death of these bats. Literature suggests that they are either killed upon direct contact with the turbine blades or by barotrauma. In barotrauma, a sudden change in the surrounding air-pressure causes tissue damage in biological structures that contain air, most notably the lungs. The present work develops a computational model of the bat lung, in which the lung is modeled as a gas bubble with an elastic shell immersed in a fluid, whose dynamics are governed by a Rayleigh-Plesset-like equation. Pressure gradients near the wind turbine are obtained using computational fluid dynamics. The lung’s response to pressure changes is attained by simulating the pressure’s effect on the gas bubble. The study allows for a greater understanding of bat barotrauma and its potential link to wind turbine pressure fields.
Thermodynamically viable wave equations for power law attenuation in viscoelastic media
Authors: Holm Sverre
Published: June 2017

Many complex media of great practical interest, such as in medical ultrasound, display an attenuation that increases with a power law as a function of frequency. Usually, measurements can only be taken over a limited frequency range, while wave equations often model attenuation over all frequencies. There is therefore some freedom in how the models behave outside of this limited interval, and many different wave equations have been proposed, in particular, fractional ones. In addition, it is desirable that a wave equation models physically viable media and for that two conditions have to be satisfied. The first is causality, and the second is a criterion that comes from thermodynamic considerations and implies that the relaxation modulus is a completely monotonic function. The latter implies that attenuation asymptotically cannot rise faster than frequency raised to the first power. These criteria will be explained and used to evaluate several of the ordinary and fractional wave equations that exist.
Focusing ultrasound through the skull for neuromodulation
Authors: Blackmore Joseph , Veldsman Michele , Butler Christopher , Cleveland Robin
Published: June 2017

Focused ultrasound for neuromodulation is emerging as a non-invasive brain stimulation method, whereby low-intensity pulsed ultrasound is focused through the skull to locations within the brain. The ultrasound results in excitation of the targeted brain region, and stimulation in the motor and visual centers has already been reported. One barrier is that the strongly heterogeneous skull bone distorts, aberrates, and attenuates the ultrasound beam leading to disruption and shifting of the focus. While transducer arrays can be used to correct for these aberrations, this equipment is expensive and complex. Here, numerical modeling is used to determine the optimal placement of a single element focused transducer to achieve the required focusing. Numerical simulations, using a point source at target locations in the visual cortex, are employed to determine the phase and amplitude on a spherical surface placed outside the head. The optimal placement of the transducer is determined by minimizing the weighted phase error over the transduce surface. Appropriate focusing is then confirmed by simulating the pressure field in the brain tissue for the optimal transducer location. Both elastic and fluid-type models of the skull are considered to assess the impact of shear waves on the targeting.
On challenges and considerations in designing cold end exhaust systems for current and future automotive applications
Authors: Vasudevan Raghavan
Published: June 2017

Efforts to meet ever-stringent fuel economy standards has led to increased focus on light weighting technologies, and proliferation of alternative powertrains such as hybrid vehicles. This has significantly increased the complexity of designing exhaust systems to meet high level NVH performances against thin powertrain targets. In this paper, some applications will be presented with latest efforts in addressing some of these challenges. (a) Novel methodologies in predicting exhaust high frequency flow noise using transient CFD simulations will be discussed. (b) Customized tuning applications: Case study in optimization, Daisy-chaining, and positioning of narrow frequency tuning applications (e.g., concentric tube Helmholtz resonators with tuned orifices, pipe length tuning) driven by tighter clearances and directed light weighting efforts will be discussed. (c) Hybrid applications—Hybrid powertrains pose a unique challenge as the engine can function both as power plant and a power generator, both of which have different NVH requirements. Efforts in addressing these challenges with limited packaging space will be discussed.
Application of micro-perforate tubes in motorcycle mufflers
Authors: Howell Henry C.
Published: June 2017

Regulator noise requirements, torque and horsepower goals, and sound quality targets drive the acoustic performance expected from motorcycle mufflers, but exposed motorcycle mufflers also become important styling features on bikes. Weight, shape, temperature, rider leg position, coatings, and cosmetics all become factors which influence the mufflers final design. With these factors in mind, the uses of micro-perforated metals in grazing flow applications have allowed improvements in all of these areas.
Noise suppressors with engineered compliance in fluid hydraulic systems
Authors: Cunefare Kenneth , Gruber Elliott , Pedigo Nathaniel
Published: June 2017

Fluid power hydraulic systems, common on a wide variety of industrial and construction equipment, frequently exhibit undesirable noise characteristics. The noise is primarily due to the pump-induced pressure pulsation in the fluid. One means to control this fluid-borne noise is through the use of a suppressor integrating compliance, as may be introduced using a pressurized bladder, or an elastic compliant liner exposed to the fluid. This compliance causes an impedance change at the inlet to the suppressor. Within the suppressor, the compliance leads to a reduced sound speed, which may then lead to fluid particle velocities high enough for damping to become effective. Classical dissipative noise control means, as is common in air or gas mufflers, is otherwise ineffective in fluid systems because of the low particle velocity. An engineered solid material, a syntactic foam, is under development for use in hydraulic systems. The syntactic foam of interest is comprised of microspheres dispersed in a polymer. Particular challenges include retaining functionality at high system pressures, which may be addressed by pressurizing the microspheres. The foam’s performance increases with volume fraction of microspheres, and internal pressurization. The material is enabling of a other fluid noise control devices, including water hammer arrestors.
Sound quality control of axial fan noise by using microperforated panel housing with a hollow tube
Authors: Choy Yatsze , Chiang Yan Kei , Xi Qiang
Published: June 2017

This study presents a novel passive noise control approach to directly suppress sound radiation from an axial-flow fan, which involves micro-perforated panels (MPP) backed by cavities and a hollow tube. Apart from the sound suppression performance in terms of insertion loss, sound quality of axial fan with a dipole nature is also investigated which serves as a significant supplementary index for assessing the noise control device. The noise suppression is achieved by the sound cancelation between sound fields from the fan of dipole nature and sound radiation from a vibrating panel via vibro-acoustic coupling and interference from the hollow tube boundaries, as well as by sound absorption in micro-perforations. A two-dimensional theoretical model, capable of dealing with strong coupling among the vibrating micro-perforated panel, sound radiation from the dipole source, and sound fields inside the cavity and the duct is developed. The theoretical results are validated by both finite element simulation and experiment. Results show that an addition of hollow tube enhances the sound suppression performance in the passband region of the MPP housing device. The findings of the current research have the potential to control ducted-fan noise effectively, to enhance the quality of products with a ducted-fan system.
Revisiting the Cremer impedance
Authors: Kabral Raimo , Åbom Mats , Nilsson Börje
Published: June 2017

In a classical paper (Acustica 3, 1953), Cremer demonstrated that in a rectangular duct, with locally reacting walls, there exits an impedance (“the Cremer impedance”) that maximizes the propagational damping for the lowest mode. Later (JSV 28, 1973), Tester extended the analysis to include a plug flow and ducts of both circular and rectangular cross-section. One limitation in the work of Tester is that it simplified the analysis of the effect of flow only considering high frequencies or well cut-on modes. This approximation is reasonable for large duct applications, e.g., aeroengines, but not for many other cases of interest. Kabral et al. (Acta Acustica united with Acustica 102, 2016) removed this limitation and investigated the exact Cremer impedance including flow effects. As demonstrated in that paper the exact solution exhibits some special properties at low frequencies, e.g., a negative real part of the wall impedance. In this paper, the exact Cremer impedance is further analyzed and discussed.
Integrating science communication into undergraduate and graduate curricula
Authors: Kloepper Laura
Published: June 2017

Effective science communication (“SciComm”) to both a technical and non-technical audience is considered a key skill for contemporary scientists. Unfortunately, most of the SciComm education occurs after individuals receive their degree, and few science students receive formal training in communication. In this presentation I will describe a course that teaches SciComm to first-year undergraduate science students and can be easily modified for graduate curricula. This course consists of a series of modules specific to various communication methods (oral presentations, formal writing, informal writing, and television/radio) and audiences. Students are exposed to SciComm through group assignments, written assignments, community experiences, and virtual lectures. I will describe these modules and give example assignments and assessment. By integrating SciComm early into science education, students can develop both the technical and communication skills necessary to be effective researchers and communicators.
Acoustics in African Music Instrument Technology: Training the Baton Bearer for Sustenance in Music Education in Nigeria
Authors: Onwubiko Stephen G.
Published: June 2017

With sparsely programs in musical acoustics located and taught throughout the country’s institutions, the role of teaching music acoustics in higher education has received no attention with less trained teachers/educators, which has also become a controversial issue among scholars exploring that aspect of education. This paper shows ideological-opinions on integrating acoustics trained educators in African music instrument technology into the curriculum, since its technology invariably stress on acoustics which is an integral part of music technology and African music instrument technology alike. Teachers possess the power to create conditions that can help students learn a great deal—or keep them from learning much at all. Teaching is an intentional act of creating those conditions according to Parker Palmer, (1998). The technology of any musical instrument is to satisfy the ear and heart acoustically speaking, for each musical instrument ranging from western instrument to the traditional African instrument has its technology, its sound, pitch, frequency and vibrations likewise these instrument vary in pitch, sound, frequency, tonal reflection, texture and color. This paper constantly explores these issues through qualitative interviews and observations with teachers and scholars on training the baton bearer in African musical acoustics for sustenance in music education in Nigeria.
Self-taught Finite Element Method implementation to the assessing of natural frequencies and modal shapes in 2D rectangular plates
Authors: Carvalho de Sousa Augusto R. , Bueno Jeferson R.
Published: June 2017

This work presents a self-taught guide to the implementation of a Finite Element Model (FEM) to assess the natural frequencies and modal shapes of 2D rectangular plates. The study offers a practical way of understanding the FEM processing in commercial software available in the market and is motivated by the Computer Vibro-acoustic module of the Graduate Program in Mechanical Engineering of the Federal University of Santa Catarina, Brazil. A steel plate with dimensions of 200 mm x 500 mm x 2 mm is implemented, and the results obtained from this algorithm are compared with results given by a commercial software. Two configurations are tested and validated: a free plate, i.e., no boundary conditions, and a door-like plate whose boundary conditions are the door hinges and the door handle. The implementation is made for the direct and superposition methods in FEM, using both symbolic and numerical approaches in MATLAB software. Results obtained present acceptable errors in most frequency bands, thus validating the algorithm and enhancing the understanding of FEM modeling for vibro-acoustic applications.
Teaching ultrasound in air
Authors: Dolder Craig N. , Leighton Tim
Published: June 2017

The use of ultrasonics sensors in laboratory exercises and robotics has become popular in recent years. That is, however, only one avenue for exploring the world of inaudible sound that is around us. This talk discusses exercises to interact with the ultrasonic world surrounding us using smartphones, computers, and tablets. Messages can be sent through analog or digital means and the very concept of what is inaudible varies significantly from one person to another. The use of ultrasound is not limited to range finding but also spans communication and art.
Approaches to pushing the limits of human brain imaging
Authors: Rosen Bruce
Published: June 2017

By enabling visualization of physiological processes, “Functional imaging,” broadly defined, has dramatically enhanced our ability to explore and better understand human neuroscience and human disease. fMRI has become the keystone of a broad array of functional imaging methods that are revealing the links between brain and behavior in normal and pathological states. Very high strength magnets and advanced large N phased-array coils now enable ultra-high spatial and temporal resolution MRI and fMRI, while advances in MR gradient coil technology have improved our ability to assess tissue microstructure and connectivity almost an order of magnitude. Beyond MRI, positron emission tomography (PET) imaging provides the means to map neurochemical events with exquisite sensitivity, and recent work suggests the potential to extend neurochemical mapping towards quantification of receptor trafficking, and measurements of metabolism and neurotransmitter release dynamics on time frames of a few minutes; tomographic optical imaging allows for portable, bedside assessment of hemodynamics and oxidative metabolism; and densely sampled whole-head magnetoencepholography can, when combined with fMRI, permit high temporal resolution mapping of both cortical and now subcortical brain activity.
Finding and understanding cortical maps using neuroimaging
Authors: Sereno Martin I.
Published: June 2017

Much of the neocortex, as well as many parts of the brainstem, are divided into “areas” that contain internal topological maps of receptor surfaces. Previously, it was only possible to find the borders and internal organization of these areas using invasive microelectrode mapping and post-mortem architectonics studies in animals. Advances in non-invasive neuroimaging methods over the past two decades have made it possible to extend these studies to the living human brain. This talk summarizes the development and current state-of-the-art of computational methods for non-invasive neuroimaging of cortical maps and cortical areas in human brains, focusing on cortical-surface-based functional MRI, structural MRI, and diffusion-MRI neuroimaging analysis methods originally introduced by my laboratory more than two decades ago. Although topological maps of receptor sheets (e.g., retina, skin touch receptors, and cochlea) are often associated with the earliest stages of sensory processing in the brain, topological maps have turned up in many “higher level” areas. In describing these findings, we emphasize the fundamental architectural bifurcation between visual and somatosensory maps, which are based on a 2D receptor sheet, and auditory maps, which are based on a 1D line of receptors.
David Wessel—The Michigan State years
Authors: Hartmann William M.
Published: June 2017

After finishing his Ph.D. work with Estes at Stanford, David Wessel came to Michigan State as an assistant professor of psychology. Dave arrived with a strong background in mathematical psychology and with an intense passion for making music with computers. In the 1970s, Dave and I presented two electronic music concerts to standing-room-only audiences. The division of our labors was straightforward. I provided the venue and audio system. Dave provided all the music, which he was able to do because of his many connections with electronic musicians around the world. Dave also organized the first computer music conference, held in East Lansing during one of the worst snow storms of the year. This talk will also describe Dave's initial studies of musical timbre and his early years at IRCAM, as I observed them from East Lansing and in Paris.
David Wessel—A unique professor in Berkeley
Authors: Hafter Ervin
Published: June 2017

Among my best experiences during a half century in Berkeley was the opportunity to interact as friend and colleague of Professor David Wessel. His remarkable blend of scientific brilliance and creativity allowed him to look deeply into questions, figure out the good bits, and come up with new and exciting approaches to an answer. This connection between theory and solution defined his role on a student’s committees, and I found that both students and their advisors were grateful for the clarity of his advice. If you asked David for help, you found a seemingly endless fount of generosity, a gift that made him special to everyone who worked with him. Today, I will reminisce on an array of memories that range from his depth of knowledge in both the sciences and arts, on his skills as a chef, on his willingness to provide technical help to everyone, on his compulsion to get us interested in new forms of music, and even on his charming mid-western-American accented French. Yes, Wessel was a brilliant guy, but we will also remember him as a particularly sweet person who left a mark on those fortunate enough to have known him.
Tranquillity in the city—Building resilience through identifying, designing, promoting, and linking restorative outdoor environments
Authors: Watts Greg
Published: June 2017

Tranquil spaces can be found and made in the city and their promotion and use by residents and visitors is an important means of building resilience. Studies have shown that spaces that are rated by visitors as tranquil are more likely to produce higher levels of relaxation and less anxiety that should ultimately result in health and well-being benefits. Such spaces can therefore be classed as restorative environments. Tranquil spaces are characterized by a soundscape dominated by natural sounds and low levels of man-made noise. In addition, the presence of vegetation and wild life has been shown to be an important contributory factor. Levels of rated tranquillity can be reliably predicted using a previously developed model TRAPT and then used to design and identify tranquil spaces, improve existing green spaces and develop Tranquillity Trails to encourage usage. Tranquillity Trails are walking routes that have been designed to enable residents and visitors to reflect and recover from stress while receiving the benefits of healthy exercise. By way of example three Tranquillity Trails designed for contrasting areas are described. Predictions of the rated tranquillity have been made along these widely contrasting routes. Feedback from users was elicited and used to gauge benefits.