bluuebunny/crossref_metadata_2025 huggingface dataset:
Attention focusing in complex acoustical environments
Authors: Skoda Sabrina , Schulte-Fortkamp Brigitte , Fiebig André , Becker-Schweitzer Jörg
Published: June 2017

The prediction of the perceived overall sound quality of environments consisting of multiple sound sources poses a challenge. The interaction of different sound events results in a great amount of sensory information to be processed but human cognitive capacity is limited. Therefore, listeners tend to focus attention on specific events, the choice of which is influenced not only by the available environmental information but also by the current tasks being performed and individual conditions. To investigate how human attention can be drawn to singular sound sources in complex environments and how this affects the overall evaluation, a series of listening experiments was carried out at Duesseldorf University of Applied Sciences. Participants were asked to evaluate the sound quality of different acoustical environments which consisted of varying combinations of environmental sounds. The most noticeable sound events were identified and were individually rated in the same evaluation. The results show that the overall pleasantness in a complex acoustical environment can be well explained based on the ratings of singular environmental sounds.
In-situ measurements of soundscapes at outdoor gathering spaces—How to consider reliability aspects
Authors: Fiebig André
Published: June 2017

It is well acknowledged that soundscape investigations must be carried out in the original context. Original contexts like outdoor gathering spaces show usually a strongly varying behavior and are highly uncontrolled. Therefore, if outdoor spaces with highly time-variant noise conditions are considered, it appears difficult to measure reliably the status quo of the site under scrutiny, reflecting measurement uncertainties appropriately. When and how long must be measured, how must residents or visitors be interviewed to obtain reliable and valid data are emerging questions in the context of soundscape investigations. To investigate the reliability of acoustic as well as perceptual measurement data gained by in-situ measurements at specific outdoor gathering spaces, consecutive acoustic and perceptual measurements were performed in Aachen and analyzed. Based on these measurements, some basic requirements to be met regarding reliability and validity were derived and will be discussed. Such investigations are relevant for the preparation of the second part of the International Standard on Soundscape ISO 12913-2 dealing with data collection.
The Aerion AS2 and Mach cut-off
Authors: Matisheck Jason
Published: June 2017

The Aerion supersonic business jet is intended to fly at Mach cut-off conditions over land. We will outline the history of investigations into Mach cut-off flight. Aerion’s concept of operations for Mach cut-off will be discussed. We will discuss the current state of the technology and identify areas where further research is required.
Sonic boom near-field predictions and its impact on the accuracy of ground signature predictions
Authors: Shen Hao
Published: June 2017

The widely adopted sonic boom prediction process contains two steps: the near-field signature prediction from a 3D supersonic flow solver, and the ground signature prediction from a quasi-one-dimensional far-field propagation model following the acoustic ray path. The far-field propagation prediction has to start at a near-field distance sufficiently far away from the airplane flight path to ensure accuracy from the quasi-one-dimensional model. A recent study indicates that the widely adopted practice of using 2-3 body length from the flight path is not sufficient for all airplane configurations. Using a larger near-field distance, however, creates a serious challenge to the CFD based near-field prediction method which will suffer with either degradation in solution accuracy or sharp increase in computational cost, or both. A newly developed space marching approach for high fidelity and high efficiency near-field prediction is revisited here. It is capable of providing high accuracy solution at large near-field distance with a small fraction of computational cost required by conventional CFD solvers. It is applied here to study the sensitivity of the ground signatures to the near-field signature distance for a notional low sonic boom airplane configuration to find the optimal near-field signature distance.
Seismo-acoustic wavefield of strombolian explosions at Yasur volcano, Vanuatu, using a broadband seismo-acoustic network, infrasound arrays, and infrasonic sensors on tethered balloons
Authors: Matoza Robin S. , Jolly Arthur , Fee David , Johnson Richard , Chouet Bernard , Dawson Phillip , Kilgour Geoff , Christenson Bruce , Garaebiti Esline , Iezzi Alex , Austin Allison , Kennedy Ben , Fitzgerald Rebecca , Key Nick
Published: June 2017

Seismo-acoustic wavefields at volcanoes contain rich information on shallow magma transport and subaerial eruption processes and inform our understanding of how volcanoes work. Acoustic wavefields from eruptions are predicted to be directional, but sampling this wavefield directivity is challenging because infrasound sensors are usually deployed on the ground surface. We attempt to overcome this observational limitation using a novel deployment of infrasound sensors on tethered balloons in tandem with a suite of dense ground-based seismo-acoustic, geochemical, and eruption imaging instrumentation. We conducted a collaborative multiparametric field experiment at the active Yasur volcano, Tanna Island, Vanuatu, from 26 July to 2 August 2016. Our observations include data from a temporary network of 11 broadband seismometers, 6 single infrasonic microphones, 7 small-aperture 3-element infrasound arrays, 2 infrasound sensor packages on tethered balloons, an FTIR, a FLIR, 2 scanning Flyspecs, and various visual imaging data; scoria and ash samples were collected for petrological analyses. This unprecedented dataset should provide a unique window into processes operating in the shallow magma plumbing system and their relation to subaerial eruption dynamics.
Acoustical localization, reconstruction, signal, and statistical analysis of storm electrical discharges from a 2-months long database in southern France
Authors: Coulouvrat François , Farges Thomas , Gallin Louis , Lacroix Arthur , Marchiano Régis
Published: June 2017

Infrasound and low frequency sounds are discussed as a method to characterize lightning flashes in a complementary way to electromagnetic (EM) observations. Thunder and EM data result mainly from a 2-months long observation campaign in Southern France, dedicated to monitor atmospheric electricity as part of the hydrological cycle in Mediterranean (HyMeX program). Possibilities and limitations to follow storms by sound or infrasound (in the 1 to 40 Hz frequency range) at various distances are outlined. The influence of distance, wind, and ambient noise is examined. Several examples of individual lightning flashes acoustical reconstruction are compared to EM reconstruction by means of a Lightning Mapping Array. Both Intra-Cloud or Cloud-to-Ground (CG) discharges are investigated. Special emphasis is brought to the lower part of CGs, as many acoustic signals are localized inside the lightning CG channel. A statistical comparison between the acoustical versus EM approaches is performed, thanks to a significant number of recorded discharges in a single storm. Performances of acoustical reconstruction are detailed as function of observation range. Detailed signal analysis compared to a theoretical model shows that the tortuous channel geometry explains at least partly the low frequency content of our observations of thunder spectra.
Association of impulsive infrasonic events at medium ranges
Authors: Alberts W. C. Kirkpatrick , Tenney Stephen M.
Published: June 2017

Multiple, widely spaced, infrasonic arrays are routinely used to detect and localize impulsive events of unknown origin at medium ranges (<100 km). Event data are subsequently processed to yield line of bearing (LOB) information and localization is accomplished manually. This method of analysis could significantly benefit from automatic association and localization. Because infrasound arrays are often separated by many tens of kilometers and signals reaching the arrays can be significantly altered along the propagation path, the task of associating signals is difficult and time consuming. Further, confidence in an event association is difficult to assign to a signal due to arrival timing and local interferers. By using beamforming methods and coherence between signals, it is possible to automatically associate a given recorded event. At each array, a delay and sum beamformer is used to calculate the LOB to an unknown source. The delayed and summed beam at each array is then used to calculate the pairwise coherence between all beams. Impulsive events due to sources recorded by widely spaced infrasound arrays often exhibit high coherence at many of the frequencies in the signal. Examples of successful associations between widely spaced arrays will be discussed.
Experimental study of the angular momentum transfer capacity of grating vortex beams
Authors: Muelas H. Ruben D. , Ealo Joao L. , Pazos-Ospina Jhon F.
Published: June 2017

Acoustic vortices (AV) are special beams with a screw-type dislocation, a pressure null along their principal axis and the ability to carry angular momentum. Mono-element sources, metamaterials, and phased arrays can be used to generate an AV. Among them, phased arrays are employed in the most of works that report particle manipulation with AV because of their ease to shape beams. However, special care must be taken at the design stage of the array because additional zones of constructive interference may appear, i.e., the so called grating lobes surrounding the main beam. When generating vortex beams using phased arrays, we have experimentally verified that these grating lobes have similar characteristics than the main beam, so we called them grating vortices (GV). However, GV exhibit certain level of distortion in both phase and magnitude. In this work, we present an experimental study of the angular momentum transfer capability of GV of different topological charge. We estimate the mechanical torque induced and the angular momentum transferred to disk-like samples of different size. The vortices are generated using a 30-element array operating at 40 kHz in air. A discussion on the potential of use of GV in the manipulation of particle/objects is given.
Waves in non-conducting continuum with frozen-in magnetization
Authors: Sokolov Victor
Published: June 2017

The report reviews the new approach to the ferrohydrodynamics and magnetoelasticity, based on the concept of frozen-in magnetization. Up till now, there were well-known two frozen-in vector fields. The first one is the vorticity field was introduced by Helmgoltz. The second frozen-in field is a magnetic field in a perfectly conducting fluid was introduced by Alfven. The acoustic approximation of the ferrohydrodynamic equations with frozen-in magnetization allowed us to describe the experimental results on the anisotropy of the ultrasonic velocity in magnetized magnetic nanofluids and predict new waves: Alfven-type hydrodynamic wave and slow magnetosonic one. Alfven-type wave is accompanied by oscillations of the magnetization. It is shown that, in a non-conducting solid with a frozen-in magnetization, the propagation of three types of waves are possible: the longitudinal wave, pure shear wave, and new wave which have mixed form of Alfven-type and shear waves. The theoretical results are found to agree well with the experimental data on the dependence of the velocity of longitudinal and transverse waves in polycrystalline nickel on the magnetizing field strength. The set of dynamical equations that we have derived can be used to tackle many problems in ferrohydrodynamics and magnetoelasticity.
Disrupted auditory nerve activity limits peripheral but not central temporal acuity
Authors: Pham Carol Q. , Zeng Fan-Gang
Published: June 2017

Auditory neuropathy affects synaptic encoding or neural conduction of signals in the cochlea or the auditory nerve. Subjects with auditory neuropathy poorly recognize speech in noise which correlates with poor temporal processing. The integrity of temporal processes in the auditory system can be assessed with detection of just-noticeable differences in gap between sounds. Disorder in the auditory periphery appears to alter the precise timing or latency of synchronous neural discharges important for temporal coding. However, the relative contribution of auditory nerve activities to central temporal processing is unknown. Auditory neuropathy produced significantly worse than normal gap detection within a frequency but normal gap detection between different frequencies. No correlation between same- and different-frequency gap detection supports two temporal processes: a peripheral mechanism dependent on overlapping nerve fibers mediating same-frequency gaps and a central mechanism dependent on cross-correlated activity of non-overlapping fibers mediating different-frequency gaps. The fast, peripheral mechanism enables temporal acuity on the order of milliseconds and is likely limited by neural synchrony, the amount of total nerve activity, or both, whereas the sluggish, central mechanism is likely limited by switching time between perceptual channels on the order of a hundred milliseconds. The results demonstrate auditory nerve activities limit peripheral but not central temporal acuity.
Metamaterial-based manipulation of orbital angular momentum for sound
Authors: Liang Bin , Jiang Xue , Zhao Jiajun , Cheng Jianchun , Zhang Likun , Qiu Chengwei
Published: June 2017

The existing wave-steering devices generally control acoustic beams carrying only linear momentum. But acoustic vortices imprinted with orbital angular momentum (OAM) obviously opens new degree of freedom to control wavefront, with wide applications such as in the design of acoustic “screwdrivers” capable to generate a rotation torque to rotate objects contactlessly. To overcome the drawbacks of the traditional methods for producing acoustic OAM, we have designed and fabricated an acoustic vortex emitter with multi-arm coiling slits that utilize diffraction effect to generate vortex beam, with broadband functionality and stable topological charge. Based on this, we further propose a new mechanism for producing acoustic OAM by converting acoustic resonances to OAM. As an implementation, we have designed and fabricated a thin planar device with high efficiency to verify our scheme. Compared with existing ways for OAM production by phased spiral sources that need sophisticated electronic control and by physically spiral sources that need screw profiles and may also have a bulky size, our acoustic resonance-based OAM production bears the advantages of high efficiency, planar profile, compact size, no spiral structure, and can be freely tuned to produce different orders of OAM. I will also discuss some potential applications of our proposed scheme for OAM manipulation by metamaterials.
Omnidirectional sound shielding with acoustic metacages
Authors: Shen Chen , Xie Yangbo , Cummer Steven , Jing Yun
Published: June 2017

Omnidirectional sound barriers are useful for various applications in noise reduction. Conventional sound insulating structures like micro-perforated plates or porous materials prevent the exchange of airflow. Here, we propose the design of an acoustic metacage which can shield acoustic waves from all directions and have the ability of allowing air pass through freely. The mechanism is that the strong parallel momentum along the surface rejects sound regardless of the directions of the incident wave. Structures based on open channels and Helmholtz resonators are designed at an operation frequency of 2.49 kHz with thickness less than half of the wavelength. A prototype is fabricated using 3D printing and further verified experimentally in a waveguide. Simulation and measurement results clearly show that the proposed metacage can shield acoustic waves when the sources are placed either interior or exterior. An average energy decay of more than 10 dB is achieved when a loudspeaker is placed inside the metacage within a certain frequency band. Our metacage can have applications where ventilation is required.
Modeling and estimation of focused ultrasound radiation force for modal excitation
Authors: Chen Songmao , Niezrecki Christopher , Sabato Alessandro , Avitabile Peter
Published: June 2017

To date, conventional excitation techniques such as impact hammer or mechanical shaker excitations are commonly used in experimental modal testing. However, these excitations require that the excitation device be in direct contact with test articles, resulting in measurement distortions, particularly for small structures like MEMS cantilever. In addition, it is physically difficult or even impossible to apply these contact type excitations to certain structures, for example, biological tissues and thumb nail sized turbine blade. Moreover, these conventional excitations have limited bandwidth, usually below than 10 kHz, and thus not applicable for structures with interest in higher frequency modes. Focused ultrasound radiation force, having a much broader frequency bandwidth, has recently been used to excite structures with sizes ranging from micro to macro-scale. Therefore, it can potentially be used as an alternative non-contact excitation method for experimental modal analysis. Yet, this force remains to be quantified in order to obtain the force-response relationship, i.e., the frequency response functions (FRFs) of test articles. The dynamic focused ultrasound radiation force is modeled and estimated using the calibrated sound pressure fields generated by a spherically focused ultrasonic transducer (UT) driven by amplitude modulated signals. Its application for modal excitation is to be discussed.
Spatial distribution of acoustic radiation force modal excitation from focused ultrasonic transducers in air
Authors: Huber Thomas M. , McKeag Ian , Riihiluoma William , Niezrecki Christopher , Chen Songmao , Avitabile Peter
Published: June 2017

Recent studies have utilized the acoustic radiation force for non-contact modal excitation of structures in air. When two ultrasonic frequencies, for example, f1 = 610 kHz and f2 = 600 kHz, are incident on an object, the acoustic radiation force produces a driving force at a difference frequency f1-f2 = 10kHz. The current study compared the spatial distribution of driving force from a pair of co-focused transducers emitting f1 and f2, to a single focused transducer emitting an amplitude modulated signal of both f1 and f2. The difference frequency ranged from 400 Hz to 80 kHz. Ultrasonic transducers, with focal spot diameters of ~2 mm mounted on translation stages, could be directed at a 100kHz PCB-378C01 microphone or a 19.8 x 6.8 x 0.37 mm clamped-free brass cantilever monitored by a Polytec PSV-400 vibrometer. When mixing of frequencies f1 and f2 was solely due to the acoustic radiation force, the driving force was localized to a region a few mm in diameter. However, in other cases, very broad spatial distributions of difference frequency excitation were measured; this indicated non-acoustic radiation force mixing of f1 and f2, such as within the transducer. The practical implications for non-contact modal excitation using acoustic radiation force will be discussed.
Articulatory data for a five-way liquid contrast: 3D ultrasound of Marathi
Authors: Berkson Kelly , Elston Abigail H.
Published: June 2017

Lateral and rhotic consonants show great crosslinguistic variation, and are traditionally described as articulatorily complex (Ladefoged & Maddieson 1996; Proctor 2011; Wiese 2001, 2011). A good body of work has investigated the characteristics of liquids in languages like English (Dellatre & Freeman 1968; Guenther et al. 1998; Sproat & Fujimura 1993; Westbury, Hashi, & Lindstrom 1998; many others), which contains a two-way contrast. What of South Asian languages, however, which often contain a greater number of liquids? Tamil liquids have been imaged using palatography and electropalatography (McDonough & Johnson 1997) as well as MRI (Narayanan et al. 1999), and Malayalam liquids have been imaged using mid-sagittal ultrasound (Scobbie, Punnoose, & Khattab 2013). Little has been done with Marathi, though. Like Tamil and Malayalam, Marathi—an Indic language spoken in the Indian state of Maharashtra—contains a five-way liquid contrast. This work utilizes recent advances in 3D ultrasonography to provide detailed articulatory data for Marathi's five liquids (/l/, /lɦ/ /r/ /rɦ/ /ɭ/) (Dhongde & Wali 2009; Pandharipande 1997). Real-time images of tongue motion are combined with digitized impressions of the palate to provide new insights into the complex articulatory gestures involved in production of these sounds.
Vowel acoustics in three dialects of Spanish: Iberian, Dominican, and Mexican
Authors: Fermin Stephanie C. , Tyrone Martha , Koenig Laura L. , Barriere Isabelle
Published: June 2017

A growing number of studies have begun to investigate vowel variability among Spanish speakers. The purpose of this study was to measure the acoustics of vowels in three dialects of Spanish and to compare how these dialects vary in their vowel production. This information is important for speech and language clinicians working with dialectally diverse individuals to recognize the difference between typical dialectal variation and a speech/language disorder. We specifically examined dialects that have developed separately from each other and also have large numbers of speakers. Data were obtained from five female speakers in each of these groups: Iberian speakers, Dominican speakers, and Mexican speakers (N = 15). To analyze the effect of speaking task on production variation, we elicited a controlled speaking task and a naturalistic speaking task. For the controlled task, the participants were asked to read aloud randomized phrases on a computer screen. For the naturalistic task, participants were presented with a simple map from which to give navigation instructions. The results showed differences in average vowel placement and token-to-token variability. These data disprove previous hypotheses that vowels are stable across Spanish dialects.
Exertive modulation of coordinative structures in speech
Authors: Tilsen Sam
Published: June 2017

An articulography study was conducted to investigate variability in the relative contributions of the upper lip, lower lip, and jaw to bilabial closure and opening tasks in speech. We currently do not know the extent to which the contributions of articulator subsystems may vary in the absence of linguistic contextual variation. One hypothesis is that variation in exertive mechanisms (e.g., arousal, effort, and attention) differentially affects articulator subsystems; this predicts that variation in articulator contributions will be nonstationary and will correlate with exertive variables. In this study, head movement during responses is considered a proxy for exertive variation. Nine experimental sessions were conducted in which six participants repeatedly produced the form [i.pa], instructed to do so as consistently as possible throughout the session. It was observed that distributions of relative articulator contributions differed substantially across participants and were non-stationary for all participants. Head movement during response production accounted for a substantial amount of variation in relative articulator contributions. These results show that interactions between subsystems in a coordinative structure are nonstationary and differentially susceptible to exertive modulations. This suggests that experimental manipulation of exertion can be used to investigate the organization of articulatory control.
Lemma frequency affects the duration of homographic noun/verb conversion “homophones.”
Authors: Lohmann Arne
Published: June 2017

This paper reports empirical evidence for an effect of lemma frequency on the duration of homographic Noun-Verb homophones in spontaneous speech, e.g., cut(N) / cut(V). In previous research on effects of lemma frequency, these words were not investigated due to a focus on heterographic homophones (e.g., Gahl 2008). However, testing the frequency hypothesis on Noun/Verb homophones is of great theoretical relevance, as their representational status is especially controversial in both linguistic as well as psycholinguistic models of the mental lexicon. A mixed-effects analysis of speech data from the Buckeye corpus yields the result that the more frequent member of a Noun/Verb pair is pronounced with shorter duration, relative to its low-frequency twin. Generally speaking, this finding supports models of the mental lexicon in which entries are specified for syntactic category. Furthermore, this outcome is at odds with an account of “complete frequency inheritance” across homophones, as predicted by the Levelt production model. A separate analysis of the subsample of low-frequency words was carried out in order to further investigate possible frequency inheritance effects, as under an assumption of “partial inheritance.” No such effects were found. Taken together, the findings can be best accounted for in a model that assumes completely separate lexical representations for homophonous words.
Quantifying sonority contour: A case study from American English
Authors: Yun Suyeon
Published: June 2017

Previous studies have argued that the most reliable phonetic correlate of sonority is intensity (e.g., Parker 2002, 2008, Jany et al. 2007). However, those studies have only considered intensity of a single segment. This paper investigates the phonetic correlate of sonority contour in consonant clusters. 10 native speakers of American English (5 male, 5 female) read 33 monosyllabic English words that begin with a bi- or tri-consonantal cluster (e.g., play, stray) embedded in a frame sentence (“Father saw ‘____’ again,” used in Parker 2008). Measured first were (i) an average RMS and (ii) sound level minima of each consonant in the cluster C1C2, and the sonority contour was quantified by subtracting the intensity value of C1 from the intensity value of C2. Also, (iii) actual intensity slopes in the transition between the two consonants were measured. Results show that the intensity contours calculated based on (i) and (ii) do not always correspond to the intensity slopes (iii), while both of them are in general correlated with the sonority contour. It will also be suggested that it is intensity slopes (iii) that play a crucial role in consonant cluster perception and in phonological phenomena involving consonant clusters.
Topological features in signal processing using frame theory and persistent homology
Authors: Guillemard Mijail
Published: June 2017

We present some interactions between frame theory and persistent homology as a new way to construct classification mechanisms in signal processing. On the one hand, frame theory generalizes basic ideas from time-frequency analysis including aspects of short term Fourier transformations and wavelet theory. On the other hand, persistent homology provides new algorithms applying concepts from algebraic topology to data analysis. The question of finding adequate sparse representations of data can be seen from several points of view, including dimensionality reduction and modern developments in neural networks. Persistent homology, as a topic in topological data analysis, presents alternative mechanisms for finding adequate sparse representations of data. We explain some interactions between these tools with applications to the analysis of acoustic signals.
The performance of topological classifiers on sonar data
Authors: Robinson Michael
Published: June 2017

For various reasons, synthetic aperture sonar (SAS) target classification in various clutter contexts is usually done using a data-driven, machine learning approach. Unfortunately, the resulting feature set can be rather inscrutable—what features is it really using? Topological methods are particularly well-aligned with the goal of gaining insight into physical processes, since they highlight symmetries which are driven by these physical processes. For instance, collating multiple image looks of a round object uncovers rotational symmetries in an appropriate feature space derived from the images. The use of topological invariants allows one to infer that the object is round by reasoning about its feature space. The fact that sonar target signatures are (mostly) translation invariant in range can also be deduced from topological invariants. I will describe a principled, foundational analysis of target echo structure through the lens of topological signal processing, and then analyze the performance of this approach as compared to more traditional classification methods.
Gaussian beam tracing for calculating the broadband field in three-dimensional environments
Authors: Porter Michael B. , Henderson Laurel
Published: June 2017

Ray tracing methods have a long history in underwater acoustics going back to a paper by H. Lichte in 1919 which also predicted the SOFAR channel. They remain extremely valuable today, partly because they present an intuitive view of sound propagation that readily allows for many extensions. For instance, targets and boundaries with complicated scattering can be included in a natural way; similarly, motion of boundaries, sources, receivers, and the ocean itself are easily treated. This talk will focus on the 3D extension with particular emphasis on broadband waveforms such as chirps or waveforms due to acoustic modems.
Massively parallel structural acoustics for forward and inverse problems
Authors: Walsh Timothy F. , Aquino Wilkins
Published: June 2017

Three-dimensional structural acoustic simulations on highly complex structural models that are immersed in infinite and semi-infinite acoustic domains typically lead to large numbers of degrees of freedom that cannot be solved with commercial software packages. Typical applications include underwater acoustic simulation of submerged structures, and reverberation testing of aerospace structures. Many of these applications of interest involve large acoustic domains and complex 3D structures, thus making a finite element solution an attractive option. In addition, unknown parameters in the models can be mitigated with the solution of inverse problems. In this talk, we will discuss recent research efforts in Sierra-SD in the area of structural acoustics and will also present a partial differential equation (PDE) constrained optimization approach for solving inverse problems in structural acoustics that uses Sierra-SD for solving the forward and adjoint problems. Inverse problems are commonly encountered in structural acoustics, where accelerometer and/or microphone pressures are measured experimentally, and it is desired to characterize the acoustic sources, material parameters, and/or boundary conditions that produced the measurements. With a PDE-constrained optimization approach, the scalability of Sierra-SD can be leveraged for solving inverse problems. We will present results on the application of Sierra-SD on several large-scale structural acoustic applications examples of interest.
Effect of dispersion on the convergence rate for Green's function retrieval
Authors: Yoritomo John Y. , Weaver Richard
Published: June 2017

Much information about wave propagation in a variety of structures has been obtained from Green's function retrieval by noise correlation. Here we examine how dispersion affects Green's function retrieval and, in particular, its signal-to-noise ratio (SNR). On recalling how the inherent spread of a signal due to band limitation is augmented by spread due to dispersion and propagation distance, and how both affect amplitude, we argue that SNR in highly dispersive media can be substantially lowered by strong dispersion. We argue this is most relevant for gravity waves over large propagation distances in the ocean or atmosphere. In particular, we argue that dispersion could explain recent retrieval failure from surface gravity wave noise in the ocean. Lastly, we consider methods to ameliorate the poor SNR due to dispersion. We use numerical simulation to substantiate our analytic results.
Sound radiation efficiency of lightweight building constructions—Study on the influence of panel fastening by numerical calculations and laser scanning vibrometry measurements
Authors: Neusser Maximilian , Bednar Thomas
Published: June 2017

The aim of the presented work is to develop a calculation model for predicting vibration characteristics and consequent measures of the sound radiation efficiency of lightweight building structures including the influences of their connection means. An application of the currently normative covered processes for these structures is excluded in the relevant body of standards. Through the analysis of the velocity distribution on the surface by laser vibrometry and the simultaneously measurement of the introduced vibration energy, transfer functions could be identified. Within the scope of this work, different influencing parameters for the formation of the connecting joint between wall components are identified and their effects on the vibration characteristics are quantified. The measurement results offered not only the identification of parameters but can also be used in the development and validation of the simulation model based on the finite element method. A good correspondence between measurements and results of the introduced numerical model could be achieved. The presented simulation model offers the possibility of the consideration of the identified parameters in the formation of the connecting bodies such as the dimension of the screws, the distance between screws, the tightening torque, and the position of the screws on supporting structures.
On the use of finite-element methods to minimize uncertainties in airborne sound insulation measurements in the low frequency range
Authors: Martellotta Francesco , Ayr Ubaldo , Rospi Gianluca
Published: June 2017

Measuring airborne sound insulation at low frequencies (below 100 Hz) may be very challenging. In fact, to cope with this problem ISO 16283-1:2014 also included a dedicated procedure for smaller rooms, having a volume below 25 m3. However, even in significantly larger rooms, large spatial variations of sound pressure levels may appear, resulting in a measure which is largely affected by the choice of the measurement positions. Considering that simple rooms may be easily modeled using finite-elements tools, it may be advantageous to carry out a preliminary numerical analysis of the spatial distribution of the one-third-octave levels, so to minimize measurement uncertainty. The room space is first subdivided by means of a 3D grid where sound pressure levels are determined using a finite element model. Then, the receiver positions compatible with standard requirements are identified, and, finally, a statistical analysis of the measurement uncertainties is carried out. Comparisons between simulations and measurements are finally illustrated.
An active control method for the spectral homogenization of airborne sound insulation laboratories at low frequencies
Authors: Prato Andrea , Atzori Alessio , Schiavi Alessandro
Published: June 2017

Low frequency sound insulation measurements are affected by large uncertainties and inaccuracies due to the low modal density of small laboratory rooms. For this reason, an automated measuring system for the active spectral homogenization of enclosed spaces at low frequencies has been developed. The aim is to achieve a quasi-diffuse field, reducing the amplitude of room modes, in order to apply standard procedures for sound insulation measurements at low frequencies. The homogenization method is based on the active control of the interference spatial patterns of a system of two loudspeakers using a phase steering technique. The room response spectrum, as function of frequency-dependent phase difference between source signals, is measured in different positions in order to achieve the optimal spectral homogenization. Such technique allows to decrease the modal sound pressure level fluctuations in the source and receiving volumes in the frequency range between 30 Hz and 120 Hz. Based on this, sound insulation measurements at low frequencies on a high performance triple glazing and steel structure are performed and compared with standard ones.
The acoustic design of the new University of Iowa Voxman School of Music
Authors: Cooper Russell A. , Schlaseman Steven
Published: June 2017

The University of Iowa Voxman School of Music opened for students in September 2016. Necessitated by a flood of the Iowa river in 2008 that condemned the original building, this ground up new building in the center of Iowa City features a 700 seat concert hall, a 200 seat recital hall, a 75 seat organ recital hall; band, orchestra, chamber music, and choral rehearsal rooms; an opera studio; recording, percussion, and electronic music suites; teaching studios; practice rooms; library; classrooms and social spaces. Designed on a single city block and stacked 6-1/2 floors high, the design presented many sound isolation challenges. The varied musical pedagogy also required that each performance and rehearsal space have adjustable acoustics. The concert hall, the most public space in the facility houses a brand new 3,883 pipe Klais organ. The TheatroAcoustic ceiling in the hall is a beautiful example of coordination of all design disciplines: acoustics, rigging, lighting, sound, HVAC, fire suppression, recording, and aesthetics. This paper presents the criteria and design of the facility, the innovations, as well as tried and true and the results of acoustic measurements.
Variable room design In office spaces by the use of sound insulating curtains
Authors: Schira Jonas
Published: June 2017

The use of open space design in offices has been widely used over the last years. The idea of a collaborative working zone for more than just two employees has both advantages and disadvantages. One of the disadvantages is that private meeting zones or thin tanks get lost when a simple open space architecture is used. This fact can be solved by using variable sound insulating components to create variable zones inside the open space architecture. In the field of theater, techniques such variable sound insulating elements have been used since the last decades in the form of sound insulating curtain systems. To create a good sound insulation, more than just one layer of heavy and highly absorptive fabric is needed. By combining reflective and absorptive materials and using a special track system and ceiling connection, a sound insulation of up to RW’ = 25 dB can be achieved. This lecture will illustrate the use of sound insulation curtain systems as a part of an innovative open space office design. Also, the technical aspects of building and installing such a system will be discussed.
Using acoustical modeling software to predict speech privacy in open-plan offices
Authors: Smith Valerie
Published: June 2017

Speech Privacy Index is one of the commonly used metrics to discuss an occupant’s acoustical comfort in an open-plan office. In existing open-plan offices, the Articulation Index can be measured using a qualified sound source; the Privacy Index can then be calculated from the Articulation Index. However, in the case of future office planning, the Privacy Index must be estimated. Using the ODEON acoustical modeling software, we estimated the Privacy Index in the open-plan section of our office using the existing room dimensions, material finishes, and background noise levels. The ODEON estimates were then compared with “real world” measurements of the same space. This paper summarizes the differences between the estimated and measured speech privacy index levels.
The acoustic design of a conference room: From sketches to measurements
Authors: Sicurella Fabio , Iannace Gino , Colamesta Perla , Gentilin Matteo
Published: June 2017

This paper reports the multidisciplinary approach applied for the design of a new conference room in Switzerland. This conference rooms belongs to a large new educational building realized in Delémont (CH) in 2016. The architectural approach focused on the choice of the room’s shape and materials (mainly timber) while the acoustic treatments had to provide a good insulation from exterior and adjacent rooms as well as a good intelligibility, clarity and speech definition. Simulations run with the software Odeon allowed to foresee the main acoustic indicators (T30, EDT, C80, D50, and STI) and therefore to optimize the dimension and position of the acoustic treatments for different occupancy rate. Moreover, the acoustic treatment enforced the vocal emission of the speaker without amplification systems. A measurement campaign at the end of the building construction confirmed the good acoustic quality of the conference room as well as some discrepancies with the forward analysis due to some changes during construction. The results of a survey are also reported in this paper in order to better understand the actual acoustic feeling of the users.
Acoustic design of a new museum
Authors: Nagy Attila B. , Kotschy András
Published: June 2017

In this paper, we report on the acoustic design of a new museum. Besides the general exhibition space, the museum building includes three larger multipurpose halls that will give place for lectures and diverse events. Defining the acoustic requirements of the multipurpose hall is always a hard to reach compromise. We demonstrate the results of the international cooperation of acoustic engineers and architects, and show how computer aided modeling helped during all design phases to achieve the fine-tuned final stage.
Effect of orchestra absorption on the reverberation time in concert halls
Authors: Kim Sung Min , Jang Hyung Suk , Jeon Jin Yong
Published: June 2017

Based on 1:10 scale models and computer simulations performed in this study, the number of players in an orchestra and their sound absorption are suggested as important factors affecting the sound in the hall. For the computer simulation, scale models of players were constructed and the absorption rates were measured in the reverberation chamber. The simulation results suggest that a sound absorption rate per person is affected by the density of the occupied area of the players, and the sound absorption coefficient is determined for the space per player. When comparing two spaces of different sizes with the same number of players, the reverberation time of the auditorium is largely affected by the players when the space is larger. If more than 5% of the sound absorbing area of the hall is occupied by players, the reverberation time is remarkably reduced because of the sound absorption of the players. Therefore, the results from this study can be utilized to more accurately predict the reverberation and clarity in the acoustic design.
Subjective and objective acoustical quality in healthcare office facilities
Authors: Hodgson Murray
Published: June 2017

This paper discusses acoustical quality in 17 healthcare office facilities. A subjective survey assessed office worker perceptions of their environments and satisfaction with the acoustics. Self-reported productivity, well-being, and health outcomes were also captured. Satisfaction was lower with acoustics than with other aspects of IEQ. Satisfaction results were related to room type and the absence or presence of a sound-masking system. Physical acoustical measurements were made in six types of rooms, some with sound-masking systems, to determine the acoustical characteristics, assess their quality and relate them to the building designs. Background-noise levels were measured in the occupied buildings. In the unoccupied buildings, measurements were made of reverberation times, and “speech” levels needed to calculate speech intelligibility indices for speech intelligibility and speech privacy. In open offices, sound-level reductions per distance doubling (DL2) were measured. The results are presented, and are related to room type and partition design. The knowledge gained from this study informs the decision-making of designers and facilities management for upgrades and future design projects.
Incorporating basic underwater sound principles into the decision making process
Authors: Vigness-Raposa Kathleen J. , Scowcroft Gail , Knowlton Christopher , Morin Holly
Published: June 2017

Research on underwater sound is continually advancing. New discoveries on sound in different environments and how sound exposure affects marine animals are just two examples of important ongoing research. To integrate underwater acoustics research into the regulatory process, a fundamental understanding of basic sound principles is required for both producers and regulators. The University of Rhode Island Graduate School of Oceanography teamed with Marine Acoustics, Inc., on the Discovery of Sound in the Sea (DOSITS) project to provide scientifically accurate resources on the current knowledge about underwater sound. The project’s foundation is a comprehensive website (www.dosits.org). It synthesizes the latest peer-reviewed science on underwater sound in a form that is accessible to a variety of audiences. The site has over 400 pages and is updated semi-annually with newly published information after a thorough review by a panel of scientific experts. Based on the DOSITS website, this talk will provide background for the decision-making community on the characteristics of sound, underwater sound propagation, and appropriate measurement units. In addition, recent developments in the harmonization of sound modeling, measurement, and reporting will be discussed, highlighting the urgent need for consistent metrics across all underwater sound disciplines.
Variability in ground-truth data sets and the performance of two automated detectors for Antarctic blue whale calls in different soundscape conditions
Authors: Leroy Emmanuelle C. , Thomisch Karolin , Van Opzeeland Ilse
Published: June 2017

Automated detectors are important tools for processing large passive acoustic databases. Assessing the performance of a given method can be challenging and needs to be interpreted in the light of the overall purpose of analysis. Performance evaluation often involves comparison between the detector output and a ground-truth data set, which often involves manual analyses of the data. Such analyses may be subjective depending on, e.g., interfering background noise conditions. In this study, we investigated the variability between two analysts in the detection of Antarctic blue whale Z-calls (Balaenoptera musculus intermedia), as well as the intra-analyst variability, in order to understand how this variability impacts the creation of a ground-truth and the assessment of detector performances. Analyses were conducted on two test datasets reflecting two basins and different situations of call abundance and background noise conditions. Using a ground-truth based on combined results of both analysts, we evaluated the performances of two automated detectors, one using spectrogram correlation and the other using a subspace-detection strategy. This evaluation allows understanding how recording sites, vocal activity, and interfering sounds affect the detector performances and highlights the advantages and limitations of each of the methods, and the possible solutions to overcome the main limitations.