bluuebunny/crossref_metadata_2025 huggingface dataset:
Three-dimensional spatial analysis of concert and recital halls with a spherical microphone array
Authors: Clapp Samuel , Guthrie Anne , Braasch Jonas , Xiang Ning
Published: May 2013

The most well-known acoustical parameters—including reverberation time, early decay time, clarity, and lateral fraction—are measured using data obtained from omnidirectional or figure-of-eight microphones, as specified in ISO 3382. Employing a multi-channel receiver in place of these conventional receivers can yield new spatial information about the acoustical qualities of rooms, as well as the potential for new parameters that could have greater predictive power in terms of listeners' subjective preferences. In this research, a spherical microphone array was used to measure the room impulse responses of a number of different concert and recital halls. The data were analyzed using spherical harmonic beamforming techniques, along with other direction of arrival estimation algorithms, to understand how the soundfield evolves spatially over time at different points in the room. The results were compared to geometrical acoustic simulations and used to differentiate between listener positions which exhibited similar values for the standard parameters. In addition, new parameters were examined, including soundfield homogeneity and other spatial ratios.
Listening space measurements resolved by direction and spectro-temporally
Authors: O'Donovan Adam , Zotkin Dmitry N. , Duraiswami Ramani
Published: May 2013

Measurement of a listening space might be done to characterize it in a gross way, or to identify some deficiencies in the space, which can then be corrected. Alternately, these measurements might be performed to create inputs to an auralization software, which might seek to recreate a virtual listening experience. We propose that it might be possible to perform audio-visual measurements of a listening space that allow the entire response of the listening space to be understood and visualized. The goal is to understand the response completely in terms of its components: along direction, frequency, early and late characteristics, and finally at the level of the structural elements of the scattering surfaces. Measurements with spherical arrays of cameras and microphones provide measurements that allow the response to be decomposed in the desired fashion. Post-processing software that allows the measurements to be analyzed instantly following the measurement will also be described and demonstrated.
Large-scale multiple input/multiple output system identification in room acoustics
Authors: Schneider Martin , Kellermann Walter
Published: May 2013

In audio reproduction scenarios, room acoustics may be described as a MIMO system response from multiple loudspeaker to multiple microphones in the listening space. This system response may, e.g., be used for an equalization of the listening room and must be identified from observing the available loudspeaker and microphone signals in real-world systems. For few transducers this task is mostly solved, but massive multichannel reproduction with dozens to hundreds of loudspeakers left many research questions open. This contribution points out the fundamental challenges, previous solutions and recent advances. As a key issue, the so-called nonuniqueness problem for MIMO system identification by adaptive filtering will be discussed along with decorrelation schemes for the loudspeaker signals to alleviate this problem. Successful adaptation algorithms suitable for these scenarios imply considerable computational demands and require additional measures to ensure robustness. Recently emerging system models in spatial transform domains allow for approximative models and seem to be promising for robust real-time implementations.
Robustness analysis of room equalization for soundfield reproduction within a region
Authors: Talagala Dumidu S. , Zhang Wen , Abhayapala Thushara D.
Published: May 2013

Recent works on soundfield reproduction have presented several methods of recreating a desired soundfield within a region. Estimation or prior knowledge of the inverse reverberant channels now becomes an essential element of equalizing the room effects. However, it has been shown that designing point-to-point equalizers by sampling the reverberant soundfield is only practical within a few tenths of a wavelength of the sampled locations. This work investigates the robustness of the equalization process applied to a region, with respect to changing of actual microphone positions from their expected locations. We use a modal description of the equalized soundfield to obtain theoretical results for region equalization error due to positioning errors. Simulation results suggest that equalizing the reverberant soundfield recorded at multiple positions around the edge of the reproduction region is more immune to the positioning errors.
A numerical and experimental validation of the room acoustics diffusion theory inside long rooms
Authors: Visentin Chiara , Prodi Nicola , Valeau Vincent , Picaut Judicäel
Published: May 2013

The paper focuses on the validation of the recently proposed room-acoustics diffusion theory by means of numerical simulations and experimental measurements. The analysis aims to verify the equation underlying the theory (Fick’s law of diffusion) which relates the energy density gradient and the sound intensity inside a room through a constant diffusion coefficient. In this work, the acoustic quantities are numerically/experimentally derived under stationary conditions, and their ratio is employed to estimate the effective value of the diffusion coefficient inside long rooms. The numerical study was carried out with particle-tracing simulations. The measurements were performed with a Microflown® three-dimensional sound intensity probe inside a 1:16 scale model of a long room, varying the absorption and the scattering properties at the boundaries. A comparison between numerical and experimental results is carried out with a least-square algorithm, showing a fair agreement between the diffusion coefficients estimated with the two methods. The results lead to the conclusion that the reverberant sound field inside long rooms can be described by a non-homogeneous diffusion process: the local diffusion coefficient is not a constant inside the room but increases with the distance from the source and depends on the acoustical properties of the room boundaries.
Telehaptic interfaces for interpersonal communication within a music ensemble
Authors: Braasch Jonas , Oliveros Pauline , Van Nort Doug
Published: May 2013

Visual communication is an important aspect of music performance, for example, to pick up temporal cues and find the right entries. Visual cues can also be instrumental to negotiate the solo order in improvized music or enable social exchange, for example, by signaling someone that her solo was well received. The problem with visual communication is that one has to catch someone else’s attention, and visual cues outside someone’s visual field cannot be detected, even more so if the addressee is busy reading a music score or closing his eyes in a Free Music session. Acoustic communication does not encounter these challenges, but of course someone does not want to disturb the music with other acoustic signals. The haptic modality has the advantage that it does not necessarily interfere with the acoustic signal and does not require attention. However, it allows interpersonal communication if both parties are within close proximity. Using telematic interfaces solves the problem of proximity by allowing participants to communicate over any physical distance. In the project presented here, haptic interfaces were explored in connection with an intelligent music system, CAIRA, to examine both the effect of human/machine and inter-human communication. [Work supported by the National Science Foundation, No. 1002851.]
Stage floor vibrations and bass sound in concert halls
Authors: Askenfelt Anders , Guettler Knut
Published: May 2013

The double bass and cello sections in the orchestra transmit vibrations to the stage floor through the end pins. Whether or not these vibrations may contribute to the perceived sound in the hall has been investigated since the 1930s. In this study, the conditions for an efficient transfer of instrument vibrations to the floor, as well as the radiation from the floor to the audience area, are investigated. The study includes measurements of the impedance matching between bass and stage floor, the vibration velocity transfer to the floor via the endpin, and radiation from point-driven bending waves in the stage floor well below the coincidence frequency. The impedance conditions and radiation properties for the stage floors of five concert halls were investigated. In the most promising hall, a full-scale experiment was run with an artificially excited double bass supported via the end pin on the stage floor, and on a concrete support below, respectively. The contribution from the stage floor radiation to the sound level in the audience area was 5 dB or more between 30 and 60 Hz. This range covers the fundamental frequencies over one octave starting from the lowest note (B0) of a five-string bass.
Acoustic communication in crocodiles: How do juvenile calls code information?
Authors: Mathevon Nicolas , Vergne Amélie , Aubin Thierry
Published: May 2013

In spite of its importance for the understanding of the evolution of sound communication, information concerning the vocal world of crocodilians is limited. Experimental works have brought evidence of the biological roles of juvenile sound signals, with “hatching calls” eliciting care by the mother and synchronizing clutch hatching, “contact calls” gathering groups of juveniles, and “distress calls” inducing maternal protection. Recently, we investigated the question of species-specific information coding within juvenile calls. The analysis of signal acoustic structure shows inter-specific differences between calls. However, using playback experiments, we bring the evidence that these differences are not relevant to animals, either juveniles or adults. By using calls modified in the temporal and the frequency domains, we isolate the acoustic cues necessary to elicit a behavioral response from receivers, underlying the importance of the frequency modulation slope. Considering previous results underlying the absence of information about individual identity in juvenile calls, we make the hypothesis that these signals basically support a “crocodilian” identity.
Design and field test of a low-cost-portable linear array for marine mammal localization
Authors: Bustamante Omar A. , Romero Vivas Eduardo , Beristain Sergio
Published: May 2013

Marine mammals are reliable bioindicators of aquatic systems health. Within this group, cetaceans are well known by their high dependence on sound for many of their vital activities such as socialization and mating, prey catching, and navigation. Due to its high dependence on sound, bioacoustic methods become very important for the study of these species. Acoustic monitoring in the field is usually performed using omnidirectional hydrophones to assess the presence of mammals, but for some behavioral studies, it is also important to locate the animals, something which is not possible with that arrangement. Although there are very well known techniques to detect the direction of arrival of the sound, the equipment required is highly specialized and expensive. In this paper, the design and field test of digital and analog versions of a portable linear array of hydrophones capable of locating animal sounds by beamforming, using low cost and easily available equipment is presented. The array was tested in La Paz bay, Mexico, by experts of the Marine Mammals Research Program of the University of Baja California Sur, which were able to locate dolphins (Tursiops truncatus) only by their sound, despite strong sources of noise in the area.
Threshold of hearing for swimming Bluefin tuna (Thunnus orientalis)
Authors: Popper Arthur N. , Dale Jonathan , Gray Michael D. , Keith William , Block Barbara A. , Rogers Peter H.
Published: May 2013

Hearing thresholds for three pairs of 1 m long Pacific bluefin tuna (Thunnus orientalis) were measured utilizing operant conditioning procedure with a food reward and a staircase psychophysical technique. Fish, swimming at 1–4 m/s, quickly learned to approach the feed when they heard a sound. Measurements were made at the Tuna Research and Conservation Center (Stanford University) in a 9.14 m diameter, 1.65 m deep indoor cylindrical tank. The acoustic stimulus was produced by radially oriented piezoelectric line sources centered at the bottom of the tank, which produced a circumferentially uniform sound field. The acoustics of the tank was thoroughly characterized for both acoustic pressure and particle motion using hydrophones and two neutrally buoyant accelerometers with response axes oriented in the radial and vertical directions. Thresholds, expressed in terms of pressure and particle acceleration, were obtained at six sinusoidal frequencies between 325 Hz and 800 Hz, a range that was limited by source and tank acoustics. The lowest mean threshold for the three fish pairs, expressed in terms of acoustic pressure, was 83 dB re 1 µPa at 500 Hz. [Work supported in part by ONR/CNR Challenge Grant: “Mitigation of flow noise effects by fish.”]
Investigation of acoustic gaze strategy by Pipistrellus abramus and Rhinolophus ferrumequinum Nippon during obstacle avoidance flight
Authors: Yamada Yasufumi , Oka Arie , Hiryu Shizuko , Ohta Tetsuo , Riquimaroux Hiroshi , Watanabe Yoshiaki
Published: May 2013

We investigated the acoustic gaze (angle between pulse and flight directions) and the beam width of echolocation pulses emitted by bats during obstacle avoidance flight in a chamber (7×3×2 m). Echolocation pulses were recorded by a telemetry microphone mounted on the bat’s back and a horizontal 20-ch microphone array set up in the chamber. Flight path measurements were conducted using two high-speed video cameras. While the bat showed a circular flight avoiding the surrounding walls, the acoustic gaze showed significant linear correlation to the angular velocity of the flight. This means that the bat adjusted the pulse direction to precede its own flight direction. The correlation coefficient increased with complexity of obstacle conditions. We compared changes in acoustic gaze between FM bats (mean beam width: ±50°) and CF-FM bats (mean beam width: ±22°). We found that FM bats smoothly shifted the acoustic gaze within 10° during the flight whereas the CF-FM bats frequently shifted the acoustic gaze within 25°. These results indicate that the shifting acoustic gaze by CF-FM bats compensates their own narrow beam width. Both bat species may keep approximately ±50° of their echolocation sights in order to sense the space for moving forward safely.
Multimodal ultrasound microscopy for biomedical imaging
Authors: Saijo Yoshifumi
Published: May 2013

Acoustic microscopy provides not only high resolution imaging but also basic data for interpreting clinical ultrasound images and information on biomechanics of the tissues. Multimodal ultrasound microscope is developed for quantitative measurement of sound speed of the tissue. The frequency dependent characteristics of the amplitude and phase of a single pulse deduce the tissue thickness and sound speed. Specific acoustic impedance and elastic bulk modulus are derived by the sound speed and density of the tissue. Ultrasound impedance microscope visualizes microscopic image of the tissue surface by just touching the probe to the tissue. The reflection from the interface between the tissue and plastic plate is obtained to visualize two-dimensional distribution of specific acoustic impedance of the tissue. The multimodal ultrasound microscope realized conventional C-mode, surface impedance mode, B-mode, 3D mode, and combination of photoacoustic imaging. The series of the ultrasound measurements of gastric cancer, renal cancer, prostatic cancer, myocardial infarction, atherosclerosis, cartilage-bone complex, and brain have provided important information for clinical ultrasound imaging and pathophysiology from the point of view of biomechanics. Development of higher frequency transducer or arrayed transducer with newest technologies would realize higher resolution imaging and easier handling.
Ultrasonic biomicroscopy and micro-Raman spectroscopy for the mechanochemical characterization of atheromatous lesions
Authors: Anastasiadis Pavlos , Sharma Shiv , Matter Michelle L. , Allen John S.
Published: May 2013

Atherosclerosis is defined as a focal, inflammatory, and fibro-proliferative response to endothelial injury. The development of atheromatous lesions in the coronary tree is predominantly a quiescent asymptomatic process without any clinical manifestations. The unpredictable and acute nature of cardiovascular complications such as vulnerable plaque rupture makes diagnosis and treatment of this disease an outstanding medical challenge. We investigate non-invasive techniques that facilitate mechanical measurements at the microscopic level, which can then be directly correlated to biomarker localization within lesion sites. To characterize these sites in vitro, we used time-resolved scanning acoustic microscopy (TRSAM). This technique allows for non-invasive interrogation of tissue samples with optical resolution at the micrometer scale. Furthermore, we combined TRSAM with micro-Raman (micro-RS) spectroscopy to investigate plaque morphology with regard to specific biomarkers. We characterized mechanoelastic and biochemical regions containing high cholesterol, phosphate, and carbonate apatite that are characteristic of atherosclerotic lesions. The mechanoelastic evaluation of these regions was determined using TRSAM. Calcified lesions, for example, exhibit ultrasonic velocities of 1810 m/s ± 25 m/s and are more rigid and stiffer than normal blood vessel tissues.
Acoustic characterization and modeling of poly-lactic acid-encapsulated contrast microbubbles
Authors: Sarkar Kausik , Paul Shirshendu
Published: May 2013

Biodegradable polymers like polylactic acid hold potential for better stability and control over encapsulation properties of ultrasound contrast microbubbles. We report here several interesting acoustic properties of air-filled PLA shelled microbubbles through both in vitro experiments and mathematical modeling. Attenuation measurements with PLA microbubbles (average diameter 1.9 micrometer), indicated a resonance frequency of 2.5–3 MHz, which, in contrary to other encapsulated microbubbles, is lower than the resonance frequency of a free bubble of similar size. Pressure dependent scattering measurements at two different excitation frequencies (2.25 and 3 MHz) show strongly non-linear behavior with distinct second and subharmonic responses. Subharmonic responses are registered above a relatively low generation threshold of 100–150 kPa. To investigate the underlying mechanisms, we utilized several preexisting interfacial models describing encapsulated bubble dynamics. The attenuation data were utilized to determine the interfacial rheological properties of the encapsulation for each of these models. The model predictions are then compared with scattered nonlinear—sub- and second harmonic—responses. Our studies indicate that the extremely low surface elasticity (around 0.01 N/m) and reduced surface tension (0.01–0.03 N/m) along with the polydispersity of the bubble suspension play a critical role in determining the acoustic properties of PLA microbubbles.
Transcranial spatial and temporal assessment of microbubble dynamics for brain therapies
Authors: Arvanitis Costas , McDannold Nathan
Published: May 2013

Harnessing ultrasound/microbubble interactions in the brain may make possible a number of therapeutic ultrasound applications, such as targeted drug delivery, sonothrombolysis, and cavitation-enhanced ablation. However, methods to guide these emerging therapies are presently lacking. Here, we integrated a linear US imaging transducer with a clinical transcranial MRI-guided focused ultrasound (MRgFUS) system and evaluated passive cavitation imaging to monitor microbubble-enhanced sonications. A nonhuman primate skull filled with brain-mimicking phantom was used for the experiments. First, we sonicated the phantom over a range of powers (20–60 W) to induce cavitation-enhanced heating. Using transcranial passive cavitation mapping and MR thermometry, we assessed the ability of the integrated system to simultaneously visualize temperature changes and microbubble activity. In another experiment, we traversed the phantom with a 2 mm channel through which microbubbles could flow and applied burst sonications (5 W) to generate stable and inertial cavitation. In the first experiment, cavitation activity and heating were colocalized. In the second, the location of the cavitation activity was coincident with the targeted location in the channel within the expected resolution of the passive imaging. We conclude that combined MR/ultrasound imaging can provide comprehensive guidance to simultaneously localize and quantify both acoustic cavitation activity and heating.
Real-time three-dimensional passive cavitation detection for clinical high intensity focused ultrasound systems
Authors: Collin Jamie , Coviello Christian , Lyka Erasmia , Leslie Tom , Coussios Constantin
Published: May 2013

Bubble activity during high intensity focused ultrasound (HIFU) surgery has been linked with desirable effects, such as an enhanced heat deposition caused by inertial cavitation, and undesirable effects, such as lesion migration caused by boiling bubbles. There is presently no reliable way of achieving spatiotemporal monitoring of cavitation activity during clinical HIFU treatments. In the present work, a near-acoustically transparent two-dimensional 32-element PVDF array was designed and mounted on the therapy transducer of a clinical HIFU device (Model JC200, Chongqing Haifu) to enable detection of acoustic emissions arising from cavitation during therapy. The signal detected by each of the elements was digitized and processed in real time on a graphical processing unit (GPU), and beamformed using our previously described passive acoustic mapping (PAM) algorithm to produce real-time three-dimensional (3D) maps of cavitation activity with a frame rate in excess of 5 Hz. The system was initially validated in agar-based tissue-mimicking materials, demonstrating that the displayed volume of cavitation activity agreed with predictions based on in situ pressure calibrations. The system was further validated during clinical HIFU treatments of kidney tumor, liver tumor, and uterine fibroid ablation, and was found to enable accurate localization of the HIFU focus at sub-lesioning intensities.
Passive acoustic mapping using optimal beamforming for real-time monitoring of ultrasound therapy
Authors: Coviello Christian , Kozick Richard , Choi James J. , Gyöngy Miklós , Collin Jamie , Jensen Carl R. , Probert Smith Penny , Coussios Constantin C.
Published: May 2013

In ultrasound therapy, passive acoustic mapping (PAM) has been shown to be an effective method for imaging the acoustic emissions generated during treatment providing the potential for real-time therapy monitoring. In both high intensity ultrasound (HIFU) ablative surgery and targeted drug delivery, imaging artifacts at higher amplitude exposure conditions have been observed, which make the localization and dosimetry of therapeutically relevant cavitation activity a challenge. Due to these artifacts, correlating drug release or lesion volumes to the PAMs is hindered for many exposures. It is proposed that incorporating optimal beamforming techniques into the PAM framework can reduce and remove these artifacts, allowing determination of the extent of cavitation activity during ultrasound therapy. Additionally, optimal beaforming is found to yield improved resolution, good interference suppression, and robustness against steering vector errors. A description of the origin of the artifacts as well as reduction of them by implementing optimal beamforming within PAM will be demonstrated in the context of targeted drug delivery.
A two-component speckle model for detection of microbubble signals in linear contrast-enhanced ultrasonography
Authors: Lowerison Matthew R. , Hague M Nicole , Chambers Ann F. , Lacefield James C.
Published: May 2013

Contrast-enhanced ultrasound (CEUS) serves oncology by imaging tumor blood supply to enable quantification of longitudinal vascular changes and monitoring of treatment responses. Unfortunately, the linear subtraction methods commonly used for preclinical imaging are susceptible to registration errors and motion artifacts that lead to reduced contrast-to-tissue ratios. In this presentation, an alternative approach is proposed to improve discrimination between the contrast and tissue signals by comparing the first-order speckle statistics of images acquired before and after injection of microbubbles. The microbubble signal component is modeled as a temporally varying random process superimposed on a Rayleigh-distributed speckle signal representing backscatter from tissue. Images were acquired at 18 MHz from a murine orthotopic (mammary fat pad) xenograft breast cancer model following a bolus injection of microbubbles. Images were processed using gold-standard pulse inversion nonlinear CEUS, conventional linear subtraction, and the proposed statistical method. In comparison to conventional linear CEUS, the statistical method produced a wash-in curve that showed closer agreement to the gold-standard nonlinear CEUS data. The statistical method eliminates baseline image subtraction from linear CEUS processing, which should streamline the imaging workflow, improve the robustness of image quantification, and enable real-time perfusion imaging with linear CEUS.
Effect of standoff distance on the reconstruction of in-duct velocity field and regeneration of pressure field
Authors: Heo Yong-Ho , Ih Jeong-Guon
Published: May 2013

Identification of in-duct acoustic source characteristics is essential in the design of fluid machinery system for reducing and predicting the flow-generated noise. To this end, the inverse estimation method can be employed by using the measured sound field and matrix formulation for wave propagation within a duct. In this paper, the effect of the distance between source and measurement plane is investigated. At each standoff distance, pressures are measured at three planes with two different spacings to widen the estimation frequency range, and measurements are conducted with three different standoff distances. Modal decomposition is applied to estimate modal amplitudes, and the result is used to reconstruct the velocity field at the source plane and to obtain the regenerated pressure field at the measurement planes. It is shown that the modal amplitude identified by measured pressure field at the short standoff distance, i.e., at nearfield, can yield an accurate reconstructed velocity field of the source and regenerate the pressure field with smaller error, which is similar to the other inverse techniques such as equivalent source method and nearfield acoustical holography. A field reduction example by suppressing some parts of source velocity field is shown for demonstrating the effectiveness of the method.
The threshold of the difference between a mathematical model applied to active noise control and data recorded
Authors: Quintana Ricardo A. , Gallego Adriana P.
Published: May 2013

Nowadays, there are many methods used to obtain mathematical models applied to active noise control, especially when the transfer function is required. Inside rooms, the global active sound control has bad results due to the reflections and the diffuse field. Then, authors have applied system identification to find more complex mathematical models based on measured data. Also, the number of system identification methodologies is increasing and it carries to having many unexplored models. In order to know which models are useful for global active noise control inside rooms, a relationship between the sound pressure level decreased and the error of the mathematical model is presented. First, the concept of “a useful mathematical model” is defined under any context based on an analysis of the error (FIT). In addition, this concept is delimited to the active noise control context. Finally, an example is presented.
Performance of transducers with segmented piezoelectric stacks using materials with high electromechanical coupling coefficient
Authors: Thompson Stephen C. , Meyer Richard J. , Markley Douglas C.
Published: May 2013

Abstract underwater acoustic transducers often include a stack of thickness polarized piezoelectric material pieces of alternating polarity interspersed with electrodes and bonded together. The stack is normally much shorter than a quarter wavelength at the fundamental resonance frequency, so that the mechanical behavior of the transducer is not affected by the segmentation. When the transducer bandwidth is less than a half octave, as has conventionally been the case, stack segmentation has no significant effect on the mechanical behavior of the device. However, when a high coupling coefficient material such as PMN-PT is used to achieve a wider bandwidth, the difference between a segmented stack and a single piezoelectric piece with the same overall dimensions can be significant. This paper investigates the effects of stack segmentation on the performance of wideband underwater acoustic transducers, particularly tonpilz transducer elements. Included is discussion of transducer designs using single crystal piezoelectric material with high coupling coefficient compared with more traditional PZT ceramics.
Velocity control with class D amplifiers
Authors: Randall Robert C. , Brown David A.
Published: May 2013

A SONAR array’s radiation pattern is affected by the acoustic interactions, which may limit the effectiveness of beamforming algorithms when transmitting. A negative feedback system with a velocity sense signal fed back to the power amplifier can mitigate the array interactions proportional to the loop gain, and be effective across a broad frequency range without requiring a priori knowledge of the input signals. The tradeoffs between motional current velocity control and accelerometer based velocity control are summarized. Class D switching amplifiers can achieve greater than 90% efficiency and are increasingly being used to drive SONAR arrays. When a velocity control system is used with a Class D amplifier, feedback stability becomes a significant concern due to obtaining the feedback signal after the amplifier’s LC output filter. The array equations are still obtained by converting the amplifier into a Thevenin equivalent force and output impedance, which now includes the amplifier’s output filter and the synthesized impedance due to the velocity control loop. Sample beampatterns both with and without velocity control are shown, concluding that velocity control is well suited for use with complex dynamic transmit beamforming.
A system for ultrasonic transmission of power and signal to an implanted hearing aid
Authors: Vihvelin Hugo , Leadbetter Jeffrey , Brown Jeremy A. , Adamson Robert
Published: May 2013

We will report on development of a system for efficiently powering implanted hearing aids by transmitting ultrasonic acoustic energy across the skin. As compared to traditional magnetic induction coil power delivery systems, ultrasound-based systems offer a more compact form factor for the same power handling capability and lower electrical loss. Part of the challenge of building such a system for implanted hearing aids is developing efficient modulation and demodulation electronics that can deliver both electrical power and an acoustic frequency signal to the implanted device. We present the design and implementation of an amplitude modulated system in which the power is delivered on the carrier and signal in the modulation sidebands. The transmitter consists of an efficient PWM encoder driving an LC resonator tuned to the ultrasound transducer resonance frequency. The receiver consists of an efficient rectifying demodulator that provides supply voltages to internal electronics as well as the acoustic signal. Power loss mechanisms, form factor considerations, linearity, and overall system performance will be discussed.
Measuring lips control on flute-like instruments using active vision
Authors: Carriquiry Benjamín , de la Cuadra Patricio , Fabre Benoit
Published: May 2013

Flute-like instruments operate under a feedback system between an air jet and a resonator. The characteristics of the air jet and its interaction with the resonator are defined by construction in some flute-like instruments such as the organ pipes, or completely determined by the musician’s control like in the Shakuhachi, panpipe, or transverse flute. In this article, a 3D lips detection system based on active vision using laser grid triangulation has been designed and implemented. Simple musical gestures from transverse flute players have been measured and analyzed, outlying the strategies used to coordinate the parameters available, such as lips to labium distance, jet speed, and jet shape, to orchestrate an adequate sound. The analysis is presented in a non-dimensional representation capable of generalizing to other members of the flute family. The measurement system developed is compared with previous strategies and reveals a promising tool to further understand the complexity of the human control in this popular family of instruments.
Characterization of bowing strokes in violin playing in terms of controls and sound: Differences between bouncing and on-string bow strokes
Authors: Perez Carrillo Alfonso
Published: May 2013

Bowing is the main element in sound production during a violin performance and one of the most basic and important expressive resources for the musician. In the lowest level, control parameters such as force, velocity, or bow-bridge distance are directly determining the characteristics of the sound. In a higher level, bowing strokes constitute one of the main mechanisms for structuring the performance. There are many different kinds of bowing strokes, and they are commonly classified into on-string, if the attack happens with the bow on the string and off-string, if the bow is bouncing. From a database of violin performances containing multimodal data including sound and gestures, a set of spectral features and instrumental controls is extracted and the database is segmented into intra-note segments (attack, sustain, and release). A characterization of bowing strokes and a comparison between bouncing and on-string strokes in terms of bowing controls and sound at the intra-note segments is presented.
On the relation between gesture, tone production, and perception in classical cello performance
Authors: Chudy Magdalena , Pérez Carrillo Alfonso , Dixon Simon
Published: May 2013

On bowed string instruments such as violin or cello, the quality of sound depends mostly on the performer’s bowing technique, which determines the interaction between the bow hair and the string. An accomplished string player has numerous ways of shaping the spectrum of a desired sound. This research investigates the combination of bowing gestures necessary for production of a rich tone. In particular, bowing control parameters such as bow force, bow velocity, and bow–bridge distance captured by a dedicated sensing system are analyzed and compared against audio features. Using audio and gesture measurements of six advanced cellists recorded on two different instruments of a luthier class, we characterize a sound palette and respective bowing control patterns of each player in performed music excerpts and scales. We especially focus on how performers adjust their bowing technique to control the timber of an instrument on which they have never practiced before. Observed differences between the players on the measured audio features show consistency with the bowing parameters adapted for balancing the timbral changes due to instrument, string, and fingering position. To perceptually evaluate the recorded samples, expert musicians were asked to rank the players in terms of sound quality and tone richness.
Investigation of the role for noise canceling headphones to assist speech recall in noise
Authors: Burgess Marion , Molesworth Brett
Published: May 2013

There are many situations where it is necessary to hear, understand and be able to recall spoken information in less than ideal listening conditions. For example within an aircraft cabin where, despite improvements in modern passenger aircraft, noise generated from aircraft engines and aerodynamic airflow make it difficult to hear important on-board safety announcements such as the preflight safety brief. The benefits of headphones that incorporate active noise control in such environments are the focus of a series of research studies. In this paper, we discuss the techniques developed to investigate the use of active noise control headphones on the intelligibility and recall of speech generated outside the headsets in noise typical of that in a commercial aircraft cabin. The initial studies were directed towards assessing the effects on the recall for safety announcements. These studies have been extended to investigate if there are any benefits for those for which English is a second language. The results suggest that the use of active noise control headphones can minimize communication errors in a range of situations and this paper will discuss the methodology adopted and summarize the outcomes.
Quantifying the ambient community noise environment for optimal industry siting
Authors: Wiens Tim C. , Reusing Gordon L. , Grozev Slavi , Zehr Zachary
Published: May 2013

A road traffic noise model was developed to approximate the ambient noise levels present within a 200 km2 urban center. Road corridors that included highways, city streets, and country side-roads with varying traffic volumes were modeled to evaluate the existing ambient conditions within the project area. To calculate noise levels, an acoustical model and Traffic Noise Model (TNM) calculation standard was used to account for a variety of real-world variables such as daily average traffic counts, turning counts, speed limits, road composition, elevation, road width, and traffic composition. The model generated noise contours that were used to identify areas of elevated ambient noise levels within the project area that may prove suitable for a medium-sized industrial facility. This modeling technique and ambient community noise analysis allowed for the identification of an optimal site within the project area and also proved to be an approach that can be used to industry’s advantage. Urban noise is an emerging issue for growing communities. Locating new facilities within urbanized areas with elevated ambient conditions may minimize community noise impacts, reduce post-construction noise abatement costs, and ultimately promote complementary adjacent land use and sustainable urban densification.
Noise pollution in urban settings of the Western Amazonia and an approach to cope with
Authors: Paul Stephan , Kuniyoshi Isabel C. , de Araújo Flávio André M. , Camargo Lucinara
Published: May 2013

The Amazon Region is usually well known for its nature and not for the noise pollution that recently took over in many cities, both major ones such as Porto Velho, Manaus, or Belém, as well as minor cities. Transparent facades with large openings of places like restaurants and bars, heavy traffic, and young adults competing with high power car sound systems are the most common sources of noise pollution and annoyance. Results from noise measurements done at different moments at several “hot spots” in Porto Velho, capital of the state of Rondônia, will be presented. A-weighted equivalent sound pressure levels at all measurement points were found to be in exceedance of 70 dBA during several hours at night, causing a lot of annoyance to the population. Besides the results of measurements some results of the state authorities approach to combine a campaign to raise noise awareness and noise policy enforcement will be presented.
Acoustic bubble behavior in a standing wave field
Authors: Desjouy Cyril , Labelle Pauline , Gilles Bruno , Bera Jean-Christophe , Inserra Claude
Published: May 2013

This paper focuses on the experimental and numerical studies of acoustic cavitation induced micro bubbles in a standing waveguide filled with water. It is shown that the cylindrical geometry of the system used in this study allows the micro bubbles to self organize into particular patterns. At high pressure amplitudes, the cavitation bubbles tend to aggregate into well known cluster patterns and at relatively low pressure amplitudes, the cavitation micro bubbles aggregate into ring patterns. This study highlights that the shape of these ring patterns is directly related to the Bjerknes force distribution in the resonator. It is also shown both experimentally and numerically that cavitation bubbles may exhibit spiraling behavior around this ring pattern. This spiraling phenomenon is numerically studied and the conditions for which a single cavitation bubble follows an orbital trajectory in the cylindrical waveguide are established, and the influences of the acoustic pressure amplitude and the initial bubble radius are investigated.
On-chip acoustic sample preparation for cell studies and diagnostics
Authors: Wiklund Martin , Sadat Iranmanesh Ida , Christakou Athanasia E. , Ohlin Mathias , Russom Aman , Önfelt Björn
Published: May 2013

We describe a novel platform for acoustic sample preparation in microchannels and microplates. The utilized method is based on generating a multitude of acoustic resonances at a set of different frequencies in microstructures, in order to accurately control the migration and positioning of particles and cells suspended in fluid channels and chambers. The actuation frequencies range from 30 kHz to 7 MHz, which are applied simultaneously and/or in sweeps. We present two devices: A closed microfluidic chip designed for pre-alignment, size-based separation, isolation, up-concentration, lysis of cells, and an open multi-well microplate designed for parallel aggregation and positioning of cells. Both devices in the platform are compatible with high-resolution live-cell microscopy, which is used for fluorescence-based optical characterization. Two bioapplications are demonstrated for each of the devices: The first device is used for size-selective cell isolation and lysis for DNA-based diagnostics, and the second device is used for quantifying the heterogeneity in cytotoxic response of natural killer cells interacting with cancer cells.
Acoustic separation of sub-micron particles in gases
Authors: Robert Etienne , Imani Jajarmi Ramin , Pettersson Jan B. , Engvall Klas
Published: May 2013

In several areas of science and technology, there is a strong need for concentrating, separating, and sorting small particles suspended in gaseous flows. Acoustic fields can be used to accomplish this task, an approach extensively used in liquid phase microfluidics that has great potential for aerosol treatment. This paper presents an experimental investigation of acoustophoresis for very small particles in gases, with sizes ranging from tens to hundreds of nanometers. The phenomenon is studied in a rectangular channel with variable height in which a standing acoustic field is created by a broadband electrostatic transducer operated in the 50–100 kHz range. The flow can either be seeded with particles with a known size distribution or ambient laboratory air can simply be circulated in the channel. Downstream of the separation channel, the flow is separated into enriched and depleted streams with adjustable slits for analysis. The particle number density and size distribution is measured with a scanning mobility particle sizer (SMPS) as a function of position in the standing wave pattern. From these measurement, the separation efficiency is determined as a function of the particle size, excitation frequency, bulk flow velocity, and number of nodes in the channel. Further analysis yields an estimation of the force acting on the particles, which for very small particles yields novel information on the magnitude of acoustophoretic forces in the transition and molecular flow regimes.
An improved method for head-related transfer function interpolation and grid matching
Authors: Matthieu Aussal , François Alouges , Brian Katz F.
Published: May 2013

Today, there exists a growing number of HRTF datasets available with each set often proposing a unique variation on the spatial discretization measurement grid. These differing grids, typically determined by the mechanical system employed, result in datasets, which are not directly comparable or exploitable. To alleviate the limitation of incompatible grids and assist in the adaptation of measurements performed on one grid to another, facilitating the inter-exchange of HRTF sets, a fixed radius HRTF interpolation method is proposed. The approach is based on decomposition of the sound field using spherical harmonics, allowing for a global spatial recomposition. The frequency domain HRTF is separated into its complex components and interpolations are performed independently before reconstitution. Spherical harmonic truncation order is chosen to provide a system which is roughly square, improving matrix inversion with Tikhonov regularization. A high spatial density HRTF was used as a test case for evaluating the interpolation method. A series of measures are employed to quantitatively compare the quality of the interpolation as compared to traditional interpolation methods in both the time and frequency domains.
Optimizing the simultaneous estimation of frequency selectivity and compression using notched-noise maskers with asymmetric levels
Authors: Fukawatase Tomofumi , Irino Toshio , Nisimura Ryuichi , Kawahara Hideki , Patterson Roy D.
Published: May 2013

It is important for the development of hearing aids and other audio devices to make accurate estimates of the frequency selectivity and compression of the auditory filter. Previously, we reported a technique for estimating the compression of the auditory filter that combined data from a simultaneous notched-noise experiment and a temporal masking curve (TMC) experiment. Unfortunately, the TMC data derived for individual listeners in forward masking is not stable; the cue to the presence of the signal is not entirely clear in forward masking. In this paper, we report attempts to make the traditional simultaneous notched-noise technique more sensitive to the effects of cochlear compression by varying the relative levels of the noise bands. Asymmetric-level maskers (ALMs) make it possible to estimate the filter shape and compression of the auditory filter simultaneously and reliably; the slope of the input–output function is substantially lower than with symmetric-level maskers. We also describe a procedure for incorporating a sensitivity analysis into the filter-fitting process to determine the minimum number of notched-noise conditions required to produce reliable estimates of selectivity and compression, in hopes of being able to employ the technique with hearing impaired listeners.