bluuebunny/crossref_metadata_2025 huggingface dataset:
Wave propagation in a fluid-filled shell excited by a dipole source
Authors: Zhang Xiumei , Wang Xiuming , Zhang Hailan , Chen Dehua
Published: May 2013

Wave propagation in a fluid filled cylindrical shell excited by a dipole source is investigated for the design of a new kind of calibration pit for dipole acoustic logging tools. Based on classical elasticity wave equations, phase and group velocity dispersion curves of each mode, excitation spectra and mode contributions to wave field in the shell are presented. The dispersion curves show that the lowest mode exists in the entire frequency range with the phase velocity smaller than shear wave velocity of the shell, higher-order modes have cutoff frequencies, below the cutoff frequencies these modes are non-propagating. Analysis on mode excitation spectra and their contributions suggest that the lowest mode has potential to be used in calibrating the velocity measurement accuracy of dipole acoustic logging tools quantitatively, provided that the contributions of this mode to the wave field dominating the first arrivals gathered by a specific dipole acoustic logging tool. [Work supported by National Natural Sciences of China, Grant No. 11134011.]
Broad-band acoustic low frequency collimated beam for ultrasonic imaging
Authors: Pantea Cristian , Sinha Dipen N.
Published: May 2013

Ultrasonic and sonic imaging from a borehole is a widely used technique for hydrocarbon reservoir characterization. A typical acoustic transducer in a borehole can produce a narrow beam only at ultrasonic frequency hundreds of kHz or higher. On the other hand, high acoustic frequencies are rapidly attenuated in the formation and result in shallow penetration. To allow deeper penetration, low frequency operation is needed. We report on the development of a lower frequency broad band collimated and steerable acoustic beam source, which is sufficiently compact to fit inside a borehole and is capable of probing for rock information in the near-borehole environment. Some of the main advantages of the source presented in this study are related to: (1) the beam collimation for better spatial resolution, (2) beam steerability (360 degree in azimuth and inclination), (3) the broad-bandwidth (20–120 kHz) and (4) specific pulse shape for simpler signal processing and data analysis. Laboratory experimental data simulating open and cased wellbores will be presented.
Modeling psychophysical gain reduction effects as a function of precursor duration
Authors: Roverud Elin , Strickland Elizabeth A.
Published: May 2013

It is known that a forward masker can make threshold for a signal poorer, but the mechanisms underlying this psychophysical effect are not well-understood. One theory, the temporal window model (TWM), proposes that masker and signal excitation are integrated within a temporal window. An additional mechanism may be cochlear gain reduction by the medial olivocochlear reflex, a sluggish sound-evoked reflex. In our laboratory, we have shown evidence of gain reduction in forward masking results. We measure off-frequency growth of masking to estimate the cochlear input/output (I/O) function. A precursor is introduced which reduces the gain of the I/O function. In the present study, we examine this gain reduction effect as a function of precursor duration for on- and off-frequency precursors. From a gain reduction perspective, a long on-frequency precursor may reduce gain for itself, while the off-frequency precursor, assumed to be linear at the signal frequency, would not. The TWM, however, does not predict differences in trends with duration for the two precursor frequencies. In our modeling, we have incorporated a gain reduction module into the TWM. We will compare predictions of the results with the standard TWM and the TWM with gain reduction. [Research supported by NIH(NIDCD)R01 DC008327.]
The effect of the medial olivocochlear reflex on click-evoked otoacoustic emissions during psychoacoustic forward-masking tasks
Authors: Beim Jordan A. , Wojtczak Magdalena , Oxenham Andrew J.
Published: May 2013

Measurements of otoacoustic emissions in animals have shown that the effects of efferent activation are greater in attentive than in anesthetized animals suggesting that the medial olivocochlear reflex (MOCR) effects can be modulated by attention. In this study, the effect of efferent activation was measured in humans using click-evoked otoacoustic emissions while listeners were performing a psychoacoustic forward-masking task. Each trial within a block started with a sequence of 50-dB pSPL clicks presented at a rate of 40 Hz that were followed by a 200-ms harmonic-complex masker. The masker was immediately followed by a 10-ms tonal probe and another click train. The listeners’ task was to detect the probe. A constant stimuli method was used to measure performance in the forward-masking task, with the probe presented at seven randomized levels around the predetermined masked threshold. Catch trials were dispersed randomly throughout the block. Click trains before and after the masker-signal segments were recorded from the ear canal and analyzed to extract effects of efferent activation at different levels of difficulty of the psychoacoustic task. The results will be discussed with respect to the role of attention and the role of the MOCR in forward masking. [Work supported by NIH grant R01DC010374.]
Combining the outputs of functional models of organs responsible for binaural cue decoding
Authors: Takanen Marko O. , Santala Olli , Pulkki Ville
Published: May 2013

The binaural cue decoding in the human auditory pathway occurs in the medial superior olive (MSO) and the lateral superior olive (LSO). The MSO is sensitive to interaural time difference (ITD), whereas the LSO is sensitive to interaural level difference as well as to ITD at low frequencies. Functional models of such organs have been presented previously [Pulkki and Hirvonen, Acta Acoustica united with Acoustica 95, 883–900 (2009)]. However, the outputs of those models are not as such applicable as the level of the output varies for a point-like broadband stimulus depending on the frequency and between the models. Here, a method is presented to combine the outputs of such models and an additional model of the MSO designed to decode directional cues based on broadband envelope time-shifts between the ear canal signals. Applicable cues are obtained by mapping the outputs into azimuth direction values following the idea of self-calibration, and by favoring the cue values suggesting more lateral directions. Furthermore, it is shown how the resulting directional cues can be applied to form a binaural activity map, and that the activity map corresponds to the human perception in several scenarios of psychoacoustical experiments.
Frequency-domain analysis of cochlear gain reduction due to disruptions in the outer hair cell feedback loop
Authors: Liu Yi-Wen , Lin Kuang-Yi , Chen Yong-Zing
Published: May 2013

A frequency domain equivalent model was implemented to match the small-signal responses produced by a time-domain cochlear mechanics model [Liu and Neely (2010)]. In the present model, the outer hair cell feedback is characterized by physical parameters, including a hair-bundle transduction ratio (HBTR) and a prestin-associated capacitance (PAC). When either of them is reduced, the model predicts lowered magnitude responses along the cochlea; however, HBTR and PAC seem to play different roles in facilitating cochlear amplification. It appears that the gain drops more drastically with respect to reduction in the HBTR, whereas the degradation is more graceful with respect to lack of prestin. Simulation also suggests that HBTR is more crucial for high-frequency hearing whereas PAC boosts up low frequency responses. Finally, we present attempts on modifying the frequency-domain model iteratively to simulate nonlinear responses. The saturating cochlear responses to high-intensity tones can be predicted by the frequency domain model as long as HBTRs are adjusted appropriately. Currently, high precision is achieved (as compared against time-domain simulation) by usage of Fourier series analysis in determining the HBTR adjustment factor. This numerical approach has a potential to accelerate simulation by orders of magnitude. Its physical meaning will also be discussed.
A physiology-based auditory model elucidating the function of the cochlear amplifier and related phenomena. Part II: Model parameters and simulations
Authors: Becker Sebastian , Hudde Herbert
Published: May 2013

In this second of two associated papers, the properties of the physiology-based auditory model are investigated. This includes finding of appropriate parameters and simulating various responses. In the end the model is intended to reproduce the human ear, hence human data is used for fitting. Only the trend of active tuning curves is based on chinchilla measurements, as human data is not available. To achieve such tuning curves the cochlea amplifier feeds energy into the system basal to the characteristic place, resulting in a locally restricted negative real part of the basilar membrane impedance. Realistic level dependent tuning curves show a reasonable input-output function and a maximum cochlear gain of 55 dB. The growth of distortion product otoacoustic emissions is consistent with measurements and shows a slope of 0.5 dB/dB. The physiology-based model approach shows the origin of the distortion products within the overlap region of the stimuli and elucidates the propagation within cochlea. As reflections are a dominant factor in the generation of transient evoked otoacoustic emissions, parameters need a certain degree of roughness to achieve results corresponding to measurements. In spite of its simplicity the model is able to reproduce a variety of cochlea results with one parameter set.
Wave finite element analysis of an active cochlear model
Authors: Ni Guangjian , Elliott Stephen J.
Published: May 2013

The wave finite element method has previously been used to understand the various types of wave in a passive cochlear model. In this paper, the model is extended to give an initial representation of an active cochlea by making the real and imaginary components of the Young’s modulus, that defines the local dynamics of the plates representing the basilar membrane, position and frequency dependent. At a given excitation frequency, the distribution of the Young’s modulus is chosen so that the mechanical impedance of the plate elements correspond to that obtained from a lumped parameter model of the active cochlea. The types of wave predicted in this representation of the active cochlea are similar to those observed for the passive cochlea model and consist of a fast wave, a slow wave and a large number of higher-order fluid modes, which are evanescent. Although the results of the full finite element analysis for this active model are very different from the passive one, the decomposition into wave components still shows that the slow wave dominates the response along most of the cochlear length, until the response peaks, when a number of higher-order fluid modes are locally excited.
Can cochlear mechanics contribute to amplitude modulation perception?
Authors: Lee Jungmee , Dhar Sumitrajit
Published: May 2013

Amplitude modulation (AM) detection has been successfully used as a psychophysical measure of auditory temporal processing. Our understanding of the role of the auditory periphery in processing AM signals is emerging through physiological and psychophysical studies. Unfortunately, direct physiological estimates of the cochlea’s mechanical response to AM signals are not obtainable in humans. This study tries to fill this critical gap in knowledge by exploring the relationship between perception (through psychophysical AM detection) and mechanics (through otoacoustic emissions). Psychometric function for AM perception was measured for a 2-kHz carrier frequency and 10-Hz modulation frequency (fm). Distortion product otoacoustic emissions (DPOAEs) were recorded with amplitude-modulated f1 with fm = 10 Hz and steady-state f2. The frequencies of f1 and f2 were chosen to yield a 2f1 − f2 DPOAE around 2 kHz near a peak in the fine structure. The ratio between the DPOAE pressure at 2f1 − f2 and that of the sidebands separated by fm (AMOAE depth) was calculated as a function of different modulation depths. Results indicate that there might be a correlation between AM perception performance and AMOAE magnitude, suggesting that cochlear mechanics might play a role for AM perception. [Work supported by the Knowles Hearing Center and Northwestern University.]
Temporal integration near threshold fine structure–The role of cochlear processing
Authors: Epp Bastian , Mauermann Manfred , Verhey Jesko L.
Published: May 2013

The hearing thresholds of normal hearing listeners often show quasi-periodic variations when measured with a high frequency resolution. This hearing threshold fine structure is related to other frequency specific variations in the perception of sound such as loudness and amplitude modulated tones at low intensities. The detection threshold of a pulsed tone also depends not only on the pulse duration, but also on the position of its frequency within threshold fine structure. The present study investigates if psychoacoustical data on detection of a pulsed tone can be explained with a nonlinear and active transmission line cochlea model. The model was successfully applied to other psychoacoustical data at low intensities, various types of otoacoustic emissions and physiological data. The simulations show differences in detection thresholds for tones placed in a minimum or a maximum of the fine structure, but lack a decrease of thresholds with increased pulse duration. The model was extended by including a temporal integrator which introduces a low-pass behavior of the data with different slopes of the predicted threshold curves, producing good agreement with the data. On the basis of the model simulations, it will be discussed to which extent temporal and spectral aspects contribute to the data.
Measuring subcortical and cortical neural activities for music perception: A multilevel electroencephalography study
Authors: Choi Inyong , Bressler Scott , Shinn-Cunningham Barbara G.
Published: May 2013

Music perception requires the activation and coordination of many neuronal centers and pathways of the peripheral and central auditory pathway, which are highly overlapped with those of speech communication. Previous experiments have shown influences of musical training on brainstem encoding in the auditory periphery and long-term plasticity in the cortex. By testing listeners with different musical experience we hope to better to understand differences in central auditory processing across individual listeners. Here we explore methods for measuring subcortical and cortical neural activity in response to musically relevant stimuli by electroencephalography (EEG). A passive mismatch negativity (MMN) paradigm using familiar musical intervals was presented to subjects to measure late evoked potentials in response to deviations in absolute musical interval and musical consonance. Brainstem frequency following responses (FFRs) for carrier frequencies and phase locking values to the beat-related envelopes were simultaneously measured. Results from these experiments can provide a means to objectively quantify individual differences in central auditory processing related to musical ability through non-invasive, electrophysiological methods.
Phonetic convergence, communicative efficiency, and language distance
Authors: Bradlow Ann , Kim Midam , Kim Minyoung
Published: May 2013

Many English conversations across the globe today involve talkers with different language experiences. Here we show that, while language barriers challenge communicative efficiency, the detrimental effect of language distance may be mitigated by phonetic convergence. We analyzed a corpus of 42 conversations in which talker pairs solved a spot-the-difference puzzle by verbally comparing two scenes only one of which was visible to each talker (“diapix” task). Language distance was varied by pairing talkers who either matched or mismatched in language background and in native/nonnative status relative to the target language. Communicative efficiency was measured by task-completion-time and word type-to-token ratio. Phonetic convergence was assessed by perceptual similarity tests in which listeners (n = 161) compared samples from one talker’s speech to samples from his/her partner’s speech from either early or late portions of the conversation. In this test, greater similarity for late than early samples indicates convergence. Results showed a negative correlation between language distance and communicative efficiency, a negative correlation between language distance and phonetic convergence, and a mitigating effect of phonetic convergence on the negative correlation between language distance and communicative efficiency. This suggests that convergence may be an effective mechanism for overcoming the detrimental effects of a language barrier.
Time-frequency analysis with Bayesian filtering methods for dispersion tracking and geoacoustic inversion in the ocean
Authors: Aunsri Nattapol , Michalopoulou Zoi-Heleni
Published: May 2013

Iterative and sequential Bayesian filtering methods have been previously used in dispersion tracking for long range sound propagation in oceanic environments. The methods rely on accurate modeling of (i) the acoustic field in the frequency domain as a function of time and (ii) the statistical model governing the behavior of errors in the measured data. Normal distributions are typically used for the latter but may not necessarily be the most accurate models for the description of the data. We investigate alternative methods for describing the statistical errors in power spectra, which we then use for linking the extracted time-frequency information to geoacoustic inversion. Probability density functions computed for frequencies and arrival times via filtering are propagated “backwards” through sound propagation models for quantification of the uncertainty in the estimation process. [Work supported by ONR].
Time-frequency analysis of transient high-frequency dispersive guided waves on tilted cylindrical shells: Review
Authors: Marston Philip L. , Morse Scot F.
Published: May 2013

Measurements of the back scattering by bluntly truncated tilted cylindrical shells in water reveal a dependence on the aspect angle, which can be interpreted using geometrically described coupling mechanisms [Morse et al., J. Acoust. Soc. Am. 103, 785–794 (1998)]. By exciting a shell with a suitable acoustic pulse localized in time, the recorded backscattering response reveals a significant evolution of the spectrum as a function of time and tilt angle. This evolution was interpreted using the dispersion relations of the relevant high-frequency shell guided waves [Morse and Marston, J. Acoust. Soc. Am. 111, 1289–1294 (2002)]. The coupling conditions are affected by the mode properties. This interpretation was facilitated by also computing the scattering properties of an infinitely long titled shell [Morse and Marston, J. Acoust. Soc. Am. 106, 2597–2600 (1999)] and by measuring and modeling the contributions of helical and meridional rays [Morse and Marston 112, 1318–1326 (2002); Blonigon and Marston, 112, 528–536 (2002)]. One of the shells investigated was also convenient for a quasi-holographic imaging of the bistatic scattering of short pulses [Baik et al., 130, 3838–3851 (2011)]. [Work supported by ONR.]
Precise order tracking analysis of time-varying vibro-acoustic signature from rotating machines
Authors: Bae Jin-Ho , Ih Jeong-Guon , Kim Sang-Ryeol
Published: May 2013

Transient operation of rotating machines usually exhibit a large variation in rotating speed and frequencies of interest often fluctuate due to RPM variations. Order tracking is useful for the transient analysis of vibro-acoustic signal from a rotating machine. A fine resolution is required both in time and frequency domains to trace the spectral magnitude of the interested frequency in precision. In this study, characteristics of popular order tracking methods using short time Fourier transform (STFT) and Vold-Kalman filter are studied in the viewpoint of calculation time and resolution. They are compared with a new tracking method using variable frequency resolution STFT (VFR-STFT), being suggested for the sound quality analysis. For a test signal, vehicle interior noise measured in an idle run-up condition is used. Under the same signal processing conditions, time and frequency domain resolutions produced by three methods are compared. It is observed that VFR-STFT detects bandwidth of high order components of engine firing frequency precisely and it produced the finest resolution in time and frequency domain among three methods. Although VFR-STFT needs a bit more calculation time compared to the other methods, it is useful for the cases that do not require a real time analysis.
Tracking a human walker with a fiber optic distributed acoustic sensor
Authors: Ku Emery M. , Duckworth Gregory L.
Published: May 2013

Traditional ground sensors can be used as security systems to detect third party intrusion, but are costly and cumbersome to scale up to cover a large area. Fiber optic distributed acoustic sensing (DAS) offers a solution that economically and instantaneously monitors up to 40 linear km of a border or perimeter with a single system. The output of the OptaSense third generation fiber interrogation unit is spatially dense, coherent, and exhibits characteristics expected of traditional strain sensors. In this paper, DAS data are shown to indicate a walker’s directionality and support beamforming algorithms for localization.
A towable combustive sound source for ocean surveys and ocean acoustics experiments
Authors: McNeese Andrew R. , Wilson Preston S. , Wareham David K.
Published: May 2013

The Combustive Sound Source (CSS) is a broadband impulsive sound source that generates a wide bandwidth underwater acoustic signal, similar to explosives and airguns, yet allows for a reduced and controllable acoustic output, suitable for meeting modern environmental regulations. The source consists of a submersible combustion chamber filled with electrolytically generated hydrogen and oxygen ignited via spark. Upon ignition, the combustive mixture is converted into high temperature water vapor and the ensuing bubble activity radiates broadband acoustic energy. CSS has previously been used in the water column from stationary platforms, and has been deployed on the bottom to generate seismic interface waves. We now report the successful implementation of a self-contained CSS system deployed in a tow body. No hazardous gas is ever stored on board the ship, as it is produced in situ while at depth. The system can produce high amplitude acoustic pulses while being stably towed behind a ship with an electro-mechanical cable. Discussion will focus on the functionality, capability, and expandability of the system. [Work supported by ONR.]
Is there really a whispering gallery at the Great Ballcourt at Chichen Itza, Mexico?
Authors: Lubman David
Published: May 2013

A “whispering gallery” (WG) at the Great Ballcourt (GBC) was first reported during its excavation in the 1920s by American archaeologist Silvanus Morley (1883–1948), Director of the Carnegie Institution’s Chichen Itza project. In his 1925 National Geographic article Morley wrote: “Standing in this temple one can speak in a low voice & be heard distinctly at the other end of the court, 500 ft away.” Around 2000–2001, queries on AZTLAN, a semi-official Mesoamerican archaeology Internet discussion group, found little or no belief in a WG by mesoamericanists. Some opined that any WG would surely be a design accident or an artifact of ballcourt ageing or reconstruction. They stiffened at the suggestion that the ancient Maya might have possessed the requisite knowledge for intentional design. Was Morley mistaken? Or are modern mesoamericanists missing something? During a tour of Chichen Itza following the fall 2002 joint acoustical meeting in Cancun, Mexico, the author and two of his colleagues convincingly demonstrated a GBC WG to about 100 acousticians and their companions. This paper describes WG phenomena observed at the Great Ballcourt and suggests physical models to explain them. He also presents evidence for intentional design.
Analysis of Northern bottlenose whale pulses and associated reflections recorded from the Gully Marine Protected Area
Authors: Martin Bruce , Moors-Murphy Hilary
Published: May 2013

The Gully Marine Protected Area (MPA) is a large submarine canyon at the edge of the Scotian Shelf, south of Nova Scotia. A resident population of northern bottlenose whales are known to occur in the Gully throughout the year, and the canyon provides important foraging grounds for the population. Bottom-mounted Autonomous Multichannel Acoustic Recorders (AMAR) were deployed in the Gully for ten days in in March 2010 (sampling rate = 375 ksps) and two days in October 2011 (sampling rate = 128 ksps). Bisonar pulses produced northern bottlenose whales (likely used to echolocate prey) were recorded consistently throughout these AMAR deployments. The swept FM characteristics of the northern bottlenose whale pulses recorded were consistent over both years, and both data sets contained clear pulse reflections from bottom clutter or prey targets. In this paper, we provide a description of the northern bottlenose whale pulses recorded in the Gully and make recommendations on short-time Fourier transform parameters for analysis of the pulses. A description of the pulse reflections is also provided, based on analysis of the reflection patterns using short-time Fourier transforms and by matched filtering with the direct arrival from the whales.
Time-angle ocean acoustic tomography using sensitivity kernels: The forward problem
Authors: Aulanier Florian , Nicolas Barbara , Roux Philippe , Mars Jérôme I.
Published: May 2013

Broadband acoustic signals around 1 kHz propagate through shallow water oceanic waveguides of ~100 m in depth and ~2 km in range as multiple ray-like wavefronts. These acoustic arrivals can be characterized by the following observables: travel-time (TT), direction-of-arrival (DOA), and direction-of-departure (DOD). By applying double-beamforming on the point-to-point signals recorded between two source-receiver arrays, the acoustic contribution of each arrival can be separated from the multi-reverberated data and the TT, DOA, and DOD observable variations are accurately measured. This study deals with the use of time-angle sensitivity kernels (TASK) to estimate the observable variations induced by sound speed perturbations in the waveguide. This approach is based on the first order Born approximation and takes into account the finite-frequency effects associated with wave propagation. The robustness the TASK approach is analyzed and compared to numerical parabolic equation simulations involving different sound speed perturbations. For example, parameters such as the perturbation location, the value and shape of the perturbation in the waveguide are modified. The combination of several perturbations and the influence of the source-receiver array apertures on the TT, DOA, and DOD estimates are also studied.
Time-angle ocean acoustic tomography using sensitivity kernels: Numerical and experimental inversion results
Authors: Aulanier Florian , Nicolas Barbara , Roux Philippe , Brossier Romain , Mars Jérôme I.
Published: May 2013

In shallow water acoustic tomography, broadband mid-frequency acoustic waves (1 to 5 kHz) follow multiple ray-like paths to travel through the ocean. Travel-time (TT) variations associated to these raypaths are classically used to estimate sound speed perturbations of the water column using the ray theory. In this shallow water environment, source and receiver arrays, combined with adapted array processing, provide the measurement of directions-of-arrival (DOA) and directions-of-departure (DOD) of each acoustic path as new additional observables to perform ocean acoustic tomography. To this aim, the double-beamforming technique is used to extract the TT, DOA, and DOD variations from the array-to-array acoustic records. Besides, based on the first order Born approximation, we introduce the time-angle sensitivity kernels to link sound speed perturbations to the three observable variations. This forward problem is then inversed by the maximum a posteriori method using both the extracted-observable variations and the proposed sensitivity kernels. Inversion results obtained on numerical data, simulated with a parabolic equation code, are presented. The inversion algorithm is performed with the three observables separately, namely TT, DOA, and DOD. The three observables are then used jointly in the inversion process. The results are discussed in the context on ocean acoustic tomography.
Comparison of finite element models simulating the interaction of ultrasonic guided waves with sites of disbonding in composites
Authors: McKeon Peter , Yaacoubi Slah , Declercq Nico F. , Ramadan Salah
Published: May 2013

Disbonding in composite structures is a serious defect which can dramatically reduce the structures’ life, and can lead to catastrophic failure. To avoid this, non-destructive testing or structural health monitoring techniques are needed. One such technique involves ultrasonic guided waves, which has recently found use in this field thanks to its ability to inspect in non-accessible areas and over long distances. Numerical models are often used because they can help explain experimental results, and offer the ability to simulate different damage scenarios, predicting results with less cost than experiments. In this work, sites of disbonding between an orthotropic composite plate and an isotropic polyamide plate were modeled via the finite element method. Several methods for modeling the damage site are employed, and results are compared with experimental ones. Model types range from the introduction of a geometrical void at the interface boundary to addressing boundary conditions between adjacent layers. The amount of mode conversion after interaction with the damage site is used to evaluate the validity of each model type. Results are discussed in terms of computational effort and accuracy in predicting true physical behavior.
Perception and orchestration of melody, harmony, and rhythm on instruments with “chikari” strings
Authors: Singh Punita G.
Published: May 2013

The use of “chikari” strings on instruments such as the sitar and sarod manifests principles of Auditory Scene Analysis in creating a harmonic reference, melodic contrast, and rhythmic accompaniment. Unlike the principal “baj” strings on which the main melody is played, or resonant “tarb” strings that reinforce volume, the “chikari” strings are sounded at strategic points in performance to provide a drone, add texture, outline chords, mark rhythmic positions, and keep tempo. Listening and transcription experiments conducted with recordings of interleaved notes played on “chikari” and “baj” strings validate how differences in their timbre and tuning help to keep them perceptually apart while forming more coherent patterns based on timbre similarity and pitch proximity. Such grouping and segregation can affect the perception of temporal order, maintain the illusion of melodic continuity and in some cases of virtual polyphony. These observations add to the growing body of evidence supporting the role of timbre as a structural dimension of music and illustrate how a single instrument can bring about orchestral effects via the strategic use of devices such as “chikari” strings.
Effect of scaling laws for noise reduction optimization of wind fences
Authors: Abbott JohnPaul R. , Raspet Richard , Webster Jeremy
Published: May 2013

This paper will report on an investigation to increase noise reductions at low wavenumbers for a large windscreen enclosure described in two earlier papers [J. Acoust. Soc. Am. 129, 2445 (2011); J. Acoust. Soc. Am. 132, 2048 (2012)] by first doubling its height and then doubling its diameter. According to the scaling laws developed for small windscreens, windscreens of similar shape but differing size will have nearly identical reductions for scaled wavenumbers; therefore the wavenumbers at which noise reduction for a windscreen occurs is dependent on its size and by increasing either its height or diameter, or both, reductions should shift to lower wavenumbers. Such a shift was observed when the screen’s height was doubled. Also, when scaled to height, the measured reductions for the single and double height windscreens were found to match closely, with 6 dB of reduction and greater for wave numbers between 5 and 30 1/m and max reductions of 10–13 dB.
Compliance and vegetated-barrier acoustical testing in a purpose-built sound-transmission suite
Authors: Hodgson Murray , Daltrop Shira , Peterson Rick , Benedict Paul
Published: May 2013

Random-incidence transmission losses and absorption coefficients of a vegetated noise barrier of Criblock™ construction were measured without and with plants in a sound-transmission suite built specifically for the purpose, constructed from concrete noise barriers, with the vegetated barrier separating source and receiver rooms. The suite was tested for compliance with ASTM E90-09, and found to be substantially but not completely in compliance with respect to uniformity of steady-state levels and surface absorption. It was found that the transmission loss of the vegetated barrier ranged from 42 dB at low frequencies to 66 dB at 1000 Hz; above 1000 Hz only a lower limit of the TL could be determined—values of 57–62 dB were found. These values are at least 25 dB higher than recommended by BC Ministry of Transportation guidelines. The absorption coefficients of the unplanted and planted barriers were measured; the plants decreased the absorption slightly, from NRC 0.42 to 0.37.
Remote keyless entry honking, convenience horn honking, and audible car alarms: Redundancies and quieter options
Authors: Botta Jeanine
Published: May 2013

Vehicle sound emissions, car alarms, and horn honking are the subject of many noise complaints. Auto manufacturers spent years engineering quieter vehicles, and have created cars whose approach is so subtle that they pose a danger to blind pedestrians. But while engine noise has decreased and car alarms are less reactive, horn honking that is linked with remote keyless entry (RKE) technology increasingly contributes to community noise. RKE horn noise has never been the subject of public health inquiry. In scientific literature, discussion of road noise and health does not distinguish noise among separate sources, and tends to measure aggregate ambient noise levels rather than impulsive noise. RKE horn noise violates state traffic laws and some local noise ordinances regarding horn use, but there have been no legislative attempts to address the technology. This raises questions about whether political leaders and policy setters are not exposed to RKE noise or do not discern RKE sounds from traffic noise, and are therefore unaware of it. Using available auto industry data and case studies, this paper will introduce key facts about RKE horn use in the United States and Canada, reviewing new technologies that render noisy counterparts still in use as redundant.
Categorization of street types in urban thermoacoustic analysis
Authors: Moraes Elcione L. , Franco Irving M. , Silva Marcelle V. , Rocha Isabela A. , Pinheiro Dorival F. , Freitas Mindiyarauakti P.
Published: May 2013

Urban areas suffer several environmental perturbations as a result of human activities and technological developments that contribute to the formation of heat islands and increasing noise contamination. Environmental effects are incorporated by population in urban areas and, especially, in areas near roads with heavy traffic. This paper presents a theoretical-experimental analysis on the relationship between climatological conditions and the propagation of noise in traffic corridors with high, medium, and low intensity. Some variables, such as the width of the streets, the height of the buildings, the distance between buildings, the volume flow of vehicles offer the possibility to make traditional techniques for mitigating the air temperature increase and reduce noise levels in urban zones. The results obtained in this work by measuring temperature, humidity, and noise levels, made during certain periods of time in different parts of the city of Belem/Brazil, were linked to a database georeferenced (GIS) that allowed interpolation of data in a single platform, enabling integration between data allowing to correlate them in order to assess which typological conditions are most favorable to the thermoacoustic comfort.
Study of the acoustic of Jean Nouvel's Auditorium 400, at the Museum Reina Sofia in Madrid
Authors: del Cerro Emiliano , Ortiz Silvia Mª
Published: May 2013

The Auditorio 400 is one of the buildings that make up the National Art Museum Reina Sofia in Madrid. It is the work of renowned French architect Jean Nouvel. This space was designed to accommodate primarily chamber music concerts but now can be considered as a multi-purpose venue. This hall hosts events with different content: acts with the voice as main sound source as conferences, seminars etc. and concerts with music from diverse styles, classical, contemporary, avant-garde, and electro acoustic music. This versatility assumes that the acoustic conditions required for the different uses of Auditorio 400 must be diverse and special depending on the sound source, in order to achieve the adequate sound quality for the various events that are held there. This paper presents the study of the acoustics of the Auditorium 400, analyzing various parameters for evaluating the sound quality of the room, highlighting the worst areas of listening, the reasons for the existence of such areas and the description of improvements to be made to ensure that the enclosure meets the expectations in a hall of its relevance.
Influence of visual information on sound evaluation in auditorium
Authors: Tokunaga Yasunobu , Okuie Daichi , Terashima Takane
Published: May 2013

When hearing music in an auditorium, audience is provided with aural information and visual information at the same time. Visual and auditory sense sometimes interact with each other so that the auditory sense is considered to have some influence on sound evaluation made by audience. The purpose of this study is to reveal an influence of visual information obtained in audience seats in a hall on subjective evaluation. We investigated the relationship between sound evaluation and whether a musical performance video as visual stimulus is provided or not, and between the sound evaluation and evaluation concerning the space at certain position in the audience seats. As a result, it was revealed that visual information gave statistically significant influence on sound evaluation.
Simulation of sonic logging for deviated wells in anisotropic formations
Authors: Deger Evgeniya , Charara Marwan , Valero Henri-Pierre , Sabitov Denis , Pekar Grigory
Published: May 2013

Interpretation of sonic logging data acquired in environments with complex anisotropy is a difficult problem attracting attention of researchers and oil industry. In order to better understand physics of wave propagation in highly anisotropic medium and be able explaining observations from field data there is a need for fast and accurate numerical modeling capability. To address such challenge, we developed an efficient and accurate numerical algorithm for the simulation of sonic logging experiments in highly anisotropic formation. The basis of the approach is a heterogeneous spectral element method implemented on multi-GPU applied to acoustic-elastic wave equation. The approach was designed to simulate wave propagation in 3D arbitrary anisotropic elastic media with attenuation for a constant quality factor via standard linear solid using the tau-method. Due to the use of an unstructured grid, the spectral element algorithm enables handling tools in a fluid-filled borehole with surrounding geological models of high complexity. Several examples of log simulations for deviated wells in VTI formations for monopole, dipole, and quadrupole source symmetries and their comparison with real field data will be presented in this paper. Discussion regarding complex wave propagation will be developed in view of these simulations and real data.
Numerical simulations of dipole sonic responses in a liquid-filled trough with arc-shaped section
Authors: He Xiao , Chen Hao , Wang Xiuming
Published: May 2013

To test the running performance of a sonic logging tool, it is an effective way to place the tool in a water-filled trough and record the sonic responses for an integrated check of the transducers in laboratory. Hence it is necessary to investigate the wave propagation in such a non-symmetric structure. In this study, we present the numerical modeling results of dipole sonic responses in a trough with arc-shaped section. A 3D cylindrical finite difference code as well as the irregular free-surface conditions is implemented. It is revealed that the flexural mode in a trough is evidently slower than that in a cylindrical pipe with same sizes. The flexural velocity decreases with the increasing gap angle of the trough. Moreover, the trough structure shows strong elastic anisotropy. The in-line responses (XX and YY) of the logging tool are difference in phases and amplitudes. The amplitudes of both cross-line responses (XY and YX), which reflect the level of anisotropy, become greater as the gap angle increases. The waveforms with varying dipole orientations are also illustrated. The XY and YX responses excited by an inclined transmitter are much stronger than those generated by a horizontal or a vertical dipole source.
The farfield impulse response for a rectangular piston in viscous media
Authors: Nariyoshi Pedro C. , McGough Robert J.
Published: May 2013

Calculations of the transient radiation pattern in the farfield of rectangular transducers often employ the impulse response of the velocity potential. Analytical expressions for the impulse response are known for lossless media, and similar expressions are needed for propagation in viscous media. Solutions are obtained with two different Green's functions for viscous media. One solution, which is causal, is based on an approximate Green's function for the Stokes wave equation, and the other solution, which is noncausal, is based on an approximate Green's function for the Blackstock wave equation. The impulse response is calculated with these Green's functions using the Rayleigh-Sommerfeld integral, and the results of these calculations are compared to analytical expressions for the impulse response derived for viscous media. Numerical results are obtained for a 1 mm by 1 mm square transducer evaluated in the farfield region, where the Rayleigh-Sommerfeld integral provides the reference calculated with 400 abscissas in each direction. The results show that the causal and noncausal solutions are nearly identical in the farfield region, and the analytical impulse response expressions derived from the causal and noncausal Green's functions are consistently within 1% of the Rayleigh-Sommerfeld reference in the farfield. [Work supported in part by NIH Grant R01 EB012079.]
Spatial sound and its effect on visual quality perception and task performance within a virtual environment
Authors: Cowan Brent , Rojas David , Kapralos Bill , Collins Karen , Dubrowski Adam
Published: May 2013

Immersive 3D virtual environments such as simulations and serious games for education and training are typically multimodal, incorporating at the very least both visual and auditory cues, each of which may require considerable computational resources, particularly if high fidelity environments are sought. It is widely accepted that sound can influence the other modalities. Our own previous work has shown that sound cues (both contextual and non-contextual with respect to the visual scene) can either increase or decrease (depending on the sound) visual fidelity (quality) perception in addition to the time required to complete a simple task (task completion time) within a virtual environment. However, despite the importance and benefits of spatial sound (sound that goes far beyond traditional stereo and surround sound techniques, allowing users to perceive the position of a sound source at an arbitrary position in three-dimensional space), our previous work did not consider spatial sound cues. Here we will build upon our previous work by describing the results of an experiment that will be conducted to examine visual fidelity (quality) perception and task performance in the presence of various spatial sound cues including acoustical reverberation and occlusion/diffraction effects, while completing a simple task within a virtual environment.
Dominance of head-motion-coupled directional cues over other cues during walking depends upon source spectrum
Authors: Martens William L. , Sakamoto Shuichi , Miranda Luis , Cabrera Densil
Published: May 2013

Listeners who walk past a continuously presented speech sound source emanating from a fixed spatial position will typically experience veridical perception of source location. If, however, walking listeners are fitted with binaural hearing instruments that allows for the signals reaching their ears to be interchanged, left for right and right for left, the sound source is typically reported to be located in a spatial region that is reversed with respect to all three spatial axes: left for right, front for back, and above for below. This result has been taken as evidence for the relative dominance of dynamic interaural directional cues over the spectral directional cues associated with each listener’s own pinnae which should support veridical perception. In order to investigate the relative importance of the spectral energy distribution of the source on the illusory reversals of source location, bursts of broadband noise were presented rather than continuous speech. Under these circumstances, with greater energy in higher frequency bands, the reversals did not readily occur. Therefore, it has been concluded that head-motion-coupled directional cues are likely to dominate spectral cues associated with the filtering effects of the listener’s pinnae only for sources containing greater energy at lower frequencies.
Cue weighting and vestibular mediation of temporal dynamics in sound localization via head rotation
Authors: Macpherson Ewan A.
Published: May 2013

Our studies have quantified the salience and weighting of dynamic acoustic cues in sound localization via head rotation. Results support three key findings: (1) low-frequency interaural time-difference (ITD) is the dominant dynamic binaural difference cue; (2) when available, high-frequency spectral cues dominate front/rear localization; and (3) the temporal dynamics of dynamic cue processing are particular to auditory-vestibular integration. ITD dominance is shown indirectly in findings that head movements are highly effective for localizing low-frequency targets but not narrow-band high-frequency targets and that only normal low-frequency hearing is required to localize via dynamic cues. Direct evidence comes from manipulation of dynamic binaural cues in spherical-head simulations lacking spectral cues. If the stimulus provides access to dominant high-frequency spectral cues, location illusions involving head-coupled source motion fail. For low-frequency targets, localization performance improves with increasing head-turn angle, but decreases with increasing velocity such that performance depends primarily on stimulus duration; ~100 ms being required for accurate front/back localization. That duration threshold only applies in dynamic localization tasks, and not in auditory-only tasks involving the same stimuli. Correct spatial interpretation of dynamic acoustic cues appears to require vestibular information about head motion, thus the 100-ms temporal threshold is likely a property of vestibular-auditory integration.