bluuebunny/crossref_metadata_2025 huggingface dataset:
Audio system requirements for remote operation of unmanned ground systems.
Authors: Domme Daniel J. , Reichard Karl M.
Published: July 2011

Remotely controlled robotic ground vehicles can perform a variety of tasks where a human presence is undesired or dangerous. These unmanned vehicles are capable of assisting in explosive ordinance disposal, search and rescue operations, as well as other tasks in hazardous environments. Due to the often volatile nature of such scenarios, a more comprehensive understanding of the acoustic environment is often desirable or required by a remote operator to aid in critical work. This presentation summarizes the limitations of selected current architectures of acoustic sensors in unmanned ground vehicles. The presentation also reviews the potential benefits to operator immersion in the acoustic environment by using two-channel audio in tandem with the remote video camera feed to more accurately recreate sound directionality.
Analyzing acoustic response of orifices using transfer matrix method.
Authors: Liu Fei , Oyarzun Matias , Cattafesta Lou
Published: July 2011

The impedance of an orifice is critical in many applications such as sound absorption, fluidic actuation, and stability prediction of hydraulic piping systems. In this work, a transfer matrix analysis of orifices (circular orifice, slit, and perforated plate) is presented, which provides physical insights into the acoustic behavior of orifices under unsteady excitation. Specifically, the acoustic transfer matrix (TM) for an orifice in the presence or absence of mean flow is developed and compared to a lumped element model (LEM). An experimental investigation is conducted in a plane wave tube (PWT) for circular and slit orifices in the absence of mean flow for a variety of frequencies and sound pressure levels. The experimental results are compared with TM and LEM predictions. The TM predictions for circular orifices in the presence of mean flow are also compared with other available experimental data.
Speckle imaging techniques for visualizing deflection shapes.
Authors: Moore Thomas
Published: July 2011

Visualizing the motion of musical instruments during play is often crucial to understanding the underlying physics. Yet the equipment required to view deflection shapes of large or oddly shaped objects is typically expensive and difficult to build, and the cost of commercially available systems is typically out of the price range of all but the most well-funded institutions. Over the past several years we have developed imaging techniques based on electronic speckle pattern interferometry that can be used to visualize the deflection shapes of vibrating objects, with the emphasis being on low cost and easy implementation. In this presentation we will review some of these techniques and discuss the details of construction and use. Each apparatus can be built by undergraduate students in a relatively short period of time and the results are suitable for journal publication. Several examples of images of deflection shapes of musical instruments will be presented.
Mode studies of plucked stringed instruments: Application of holographic interferometry.
Authors: Richardson Bernard
Published: July 2011

The acoustics group at Cardiff have used holographic interferometry for many years to study the vibrations of musical instruments. After a review of the technique and equipment and the particular strengths and weaknesses of this analysis tool, the paper will describe measurements on historic, modern, and experimental guitars and related instruments. These studies highlight the effects of strutting and bracing patterns used on the underside of the soundboard and the size and positioning of the bridge, which give insight how the design and construction of these instruments affect their mechanical vibrational properties and their acoustical function.
Visualization of weak shock waves emitted from a trombone.
Authors: Takayama Kazuyoshi , Ohtani Kiyonobu , Ogawa Toshihiro , Kikuchi Takamasa , Takayama Reiko , Takahashi Toshinori
Published: July 2011

The coalesce of compression waves propagating in pipes into weak shock waves is one of the topics of shock wave dynamics. We have worked for weak shock waves generated in automobile exhaust pipe lines [Sekine et al. (1990)] and train tunnel sonic booms in Japanese high speed train entry into a long tunnel [Takayama et al. (1995)]. Hirschberg et al. (1996) reported, for the first time, the emission of weak shock waves from a trombone blown in ff and Pandya et al. (2003) visualized weak shock waves emitted from brass instruments. So far we understood, these belong to our continuous academic curiosity. It is a highlight of brass instruments to produce dramatizing sounds. In the 631-bar of the fourth movement of Mahler’s symphony No. 1, fff is specified for a third trombone. We then visualized, by using a set of 1 m diameter schlieren mirrors in schlieren optics and holographic interferometry, weak shock waves emitted from a trombone blown in ff and fff and measured pressure at the muzzle and horn and velocity at the horn.
A subspace tracking method for detection, identification, and estimation of acoustical transient sources.
Authors: Wachowski Neil , Azimi-Sadjadi Mahmood R.
Published: July 2011

This study introduces a new method for detecting, identifying, and estimating transient signal and interference sources whose signatures may be present in vector-valued observations with additive Gaussian noise. It is assumed that, for each source type, the subspace it lies in and the dependencies between its successive signatures are known and that a maximum of one signal and one interference source is present at a given time. This framework accounts for the possibility of the presence of either no sources, a single source, or both signal and interference and, in the latter case, separate estimates of each source can be extracted from the observations. Results on simulated data and one third octave vector sequences representing real acoustical measurements attest to the effectiveness of the proposed method at performing these different tasks. [This work is sponsored under a cooperative agreement from the National Park Service (NPS) Contract No. H2370094000 (WASO).]
Aircraft noise-dose-visitor-response relations for national parks.
Authors: Anderson Grant S. , Rapoza Amanda S. , Hastings Aaron L.
Published: July 2011

The U.S. National Parks Overflights Act and the Air Tour Management Act require management of air tours over national parks. Unfortunately, past noise-dose-response relations do not suffice for predicting response of national park visitors who are not at home, are not exposed for months/years, and are not subject to jets on approach or departure, but instead to low-flying tour aircraft. Toward filling that insufficiency, this study was designed to understand the complex relationship between in-park noise exposure and park-visitor response. The study derives from a decade of visitor surveys and simultaneous sound measurements at ten frontcountry sites (scenic overlooks and short hikes) within four scenic national parks. This talk describes the analysis of these measurements and documents the six resulting dose-response relations—-two responses (annoyance and interference with natural quiet and sounds of nature) paired with three response dichotomizations (slightly to extremely, moderately to extremely, and very to extremely). In these relations, acoustic-dose predictors are augmented with visitor-specific percentages (visited site before, only adults in visitor group, natural quiet, and sounds of nature are very important). This augmentation further reduced site-to-site variability, suggesting that the current model is more applicable to other sites and settings.
The effects of hydrostatic pressure on conditions in and near a collapsing cavitation bubble.
Authors: Church Charles C. , Gaitan D. Felipe , Pishchalnikov Yuri A. , Matula Thomas J.
Published: July 2011

It has long been understood that the conditions within a collapsing cavitation bubble become more extreme as hydrostatic pressure increases, but quantification of these conditions requires estimating the temperature, pressure, and density of the plasma in the bubble, a difficult task. To provide this information, we conducted numerical simulations using the plasma physics hydrocode HYADES, a 1-D, three-temperature, Lagrangean hydrodynamics, and energy transport code. The contents of a bubble at the center of a sphere of water at 1–3000 bars were specified at time = 0, and the bubble was driven by a spherically converging pressure wave of various frequencies (2.5–26 kHz) and amplitudes (10–3000 bars). Results were obtained for temperature, pressure, and density within and immediately outside the bubble. Calculations for bubble radius and the velocity and amplitude of the radiated shock wave compared well with experimental measurements at modest hydrostatic pressures (1–300 bars). At higher pressures, the maximum temperature within the bubble increases above 100 eV, the shock amplitude becomes greater than 1 Gbar, and its propagation speed is up to Mach 100. Also, the shock front heats the fluid, stimulating photon emissions in the liquid [Impulse ACPT contract No. W9113M-07-C-0178.]
Analysis of acoustic quasi-Gaussian beams and scattering by spheres at the focus of this type of beam.
Authors: Marston Philip L.
Published: July 2011

A paraxial Gaussian beam is an approximation sometimes used to describe the focusing of ultrasonic waves. In this research an exact solution of the linear Helmholtz equation is examined that is similar to a Gaussian beam when weakly focused. This superposition has advantages for relatively tightly focused beams not describable with a paraxial approximation. The quasi-Gaussian beam considered is an appropriate superposition of zero-order Bessel beams [P. L. Marston (unpublished)]. This way of representing a focused beam has the additional attribute that an analytical result is known for the scattering by an isotropic sphere placed on the axis of a Bessel beam [P. L. Marston, J. Acoust. Soc. Am. 121, 753–758 (2007)]. In the focused case the scattering by a sphere centered on the focal point of the quasi-Gaussian beam follows by superposition. In comparison with the usual case of plane-wave illumination, mode amplitudes in the scattering are modified by a function depending on a ratio of incomplete gamma functions and the size of the focus of the beam. The analysis is useful for predicting the level of increase in scattering when a sphere is placed in a strongly focused beam. [Work supported by ONR.]
Processes for interaural time and level differences: To what extent are they independent and where are they integrated?
Authors: Furukawa Shigeto
Published: July 2011

Two psychophysical experiments examined the degree to which the processes for interaural and level differences (ITD and ILD) are independent and the central-processing stage at which the information about the two cues is combined. The first experiment measured the detectability of individual or simultaneous changes of ITD and ILD. The results showed greater interaction of the two cues for high-frequency stimuli (“transposed stimuli” centered at 4 kHz) than for low-frequency stimuli (tones at 125 or 500 Hz). An analysis adopting the framework of signal detection theory indicated that the two cues are processed by partially independent “channels” at low frequencies. Focusing on low-frequency stimuli, the second experiment measured the detectability of simultaneously modulated ITD and ILD, with a varying rate and phase relationship between the modulations. Although the pattern of the results varied among listeners, there was evidence that the detectability depends on the relative phase even at a modulation rate as high as 100 Hz. This indicates that a cue integration stage in the auditory system, in which ITD and ILD interact additively or subtractively, is located before a stage where temporal modulation information is lost, which could be the source of the “binaural sluggishness.”
Temporal weighting in binaural hearing: Distinct contributions of interaural time and level differences following sound onset.
Authors: Stecker G. Christopher , Brown Andrew D.
Published: July 2011

The ability of a listener to make use of interaural level differences (ILDs) or envelope interaural time differences (ITDs) carried by modulated high-frequency sounds depends critically on the modulation period. Specifically, periods shorter than 4–5 ms substantially reduce the availability of ongoing cues, with the consequence that localization and discrimination increasingly rely on onset cues as the period decreases. Over the past several years, the authors have studied this dependence by measuring listeners’ detection of dynamic ITD and ILD, their temporal weighting of both cues during localization tasks, and their perception of simulated sources and echoes (i.e., precedence effects) carrying one or both cues. This presentation will review the results of those studies, which suggest that (a) onsets dominate processing of both cues at high rates; (b) postonset ILD sensitivity is better maintained, compared to postonset ITD, at high rates; (c) sensitivity to postonset ILD, but typically not ITD, exhibits a temporally increasing profile consistent with binaural temporal integration of that cue; and (d) maintained sensitivity to postonset ILD allows changes in that cue, but not ITD, to cause “breakdown” of precedence effects. [Work supported by NIH Grant Nos. R03 DC009482 and F31 DC010543, and NSF Grant No. IOB-0630338.]
Effects of dynamically changing interaural level differences brought about by amplitude compression.
Authors: Wiggins Ian M , Seeber Bernhard U
Published: July 2011

Amplitude compression is a feature of most hearing aids and cochlear implant processors. When compression acts independently at each ear in a bilateral fitting, interaural level differences are altered dynamically, potentially affecting spatial perception. A lateralization task was used to measure the position of sounds processed with a simulation of hearing-aid compression. Normal-hearing listeners indicated the leftmost and rightmost extents of the sound image(s) and selected from three response options according to whether they heard (1) a single, stationary image; (2) a moving image; or (3) a split image. Fast-acting compression applied at high frequencies significantly affected the perceived position of sounds. For sounds with abrupt onsets and offsets, compression shifted the entire image to a more central location. For sounds containing gradual onsets and offsets, including speech, compression shifted only the innermost extent toward the center, resulting in a wide separation between the leftmost and rightmost extents. In such cases, compression increased the occurrence of moving and split images by up to 57 percentage points. The severity of the effects was reduced when undisturbed low-frequency binaural cues were available to listeners, indicating the importance of preserving these cues in bilaterally fitted hearing devices.
Quantifying dynamic interaural level differences introduced in modulated electrical stimuli.
Authors: Goupell Matthew J. , Kan Alan , Litovsky Ruth Y.
Published: July 2011

Clinical mapping of bilateral cochlear implants (CIs) is often performed by measuring individual single-electrode currents that elicit threshold and comfortable loudness. This is done one ear at a time, where considerations for simultaneous bilateral stimulation are often disregarded. In contrast, synchronized bilateral stimulation of CIs in controlled research experiments often use constant-amplitude pulse trains to measure sensitivity to interaural level differences (ILDs) and interaural time differences. This is typically done using a single pair of subjectively pitch-matched electrodes, where the amplitudes of the electrical pulses elicit a near-comfortable loudness and produce a binaurally centered auditory image. Current clinical mapping of the processors do not consider possible ILDs introduced across the ears during simultaneous bilateral stimulation. Additionally, because loudness growth curves are often extremely variable across electrodes and ears, dynamic ILDs will possibly be introduced for modulated stimuli, like speech signals. Data will be shown that quantify the ILDs introduced by a typical bilateral clinical mapping, along with incoherence detection and binaural masking level difference threshold measurements, all in bilateral cochlear-implant listeners. Results will be considered in the context of theories regarding binaural processing and potential applications to clinical mapping strategies. [Support provided by the NIH Grant Nos. K99-DC010206 (J.G.) and R01-DC003083 (R.Y.L.).]
Factor analyzes of critical-band-filtered infant babbling.
Authors: Nakajima Yoshitaka , Shimada Yoko , Motomura Hirotoshi , Ueda Kazuo , Seno Takeharu
Published: July 2011

In order to investigate the development of human speech communication, babbling of Japanese infants was analyzed through 19 critical band filters below 7 kHz. Smoothed power fluctuations derived from these filters were submitted to factor analyzes, i.e., principal component analyzes followed by varimax rotation. The first two factors explained about 25% of variance. One of these factors appeared in a stable manner in a frequency range above 2500 Hz. This factor is different from any factors obtained in similar analyzes of adult speech in which 500, 1700, and 3300 Hz were typical boundaries to separate factors across eight different languages/dialects including Japanese.
Improved signal detection in non-Gaussian deep ocean noise.
Authors: Jemmott Colin W. , Barclay David R. , Buckingham Michael J.
Published: July 2011

DeepSound is an autonomous, high-bandwidth acoustic recording system designed to profile ambient noise to depths of 9 km. Recent ambient noise measurements recorded by the DeepSound probe well below the conjugate depth of the channel exhibit significant non-Gaussianity (the hypothesis of Gaussianity is rejected for 97% of 5 s samples using the large sample size corrected Anderson–Darling test at a 95% confidence level). A common sonar signal processing task is the automatic detection of a signal corrupted by ambient ocean noise. The standard solution is matched filtering, which is the optimal detector in the maximum likelihood sense assuming additive white Gaussian noise. Because matched filter is derived under the assumption of Gaussian noise, its performance suffers when implemented in real world non-Gaussian noise. This paper describes a signal detection algorithm for non-Gaussian noise based on the generalized Gaussian probability density function. The generalized Gaussian detector is locally optimal for small SNR, and the processing chain resembles a matched filter with a non-linear preprocessing stage. The detection performance of the generalized Gaussian detector is shown to exceed that of matched filtering for synthetic signals injected into the noise measurements recorded by the DeepSea probe. [Work supported by ONR.]
The influence of ambient field directionality on wave coherence.
Authors: Walker Shane , Kuperman W. A.
Published: July 2011

The directionality of the ambient noise field influences the expectation value of the wave coherence measured between a pair of spatially separated sensors. It is demonstrated that diffraction acts to suppress the coherence associated with wave components that do not causally visit both sensors. Conversely, wave components that do causally pass between the sensors are not suppressed. As it is the latter that carries information about the point-to-point propagation of waves between the sensor locations, the tomographic relationship between the measured wave coherence and sensor-to-sensor propagation is robust to even highly directional features of the ambient field. While this robustness is helpful for tomographic extraction applications (with a caveat on the required observation time), it can prove detrimental to applications designed to characterize the ambient field distribution. Practical experimental implications are discussed.
Quantifying the emergence rate of spatio-temporal correlations of the ambient wave field from finite duration sample realizations.
Authors: Walker Shane , Kuperman W. A.
Published: July 2011

The spatiotemporal correlations measured between receivers in a diffuse wave field convey information about the point-to-point propagation of waves between the receiver locations. An issue of practical experimental importance is how much data must be accumulated to generate a useful estimate of the expectation value of the spatiotemporal correlations. The uncertainty associated with a finite duration realization of the sample cross correlation function for an arbitrary environment is derived. Using this, a method for modeling the emergence rate of the expectation value of the spatiotemporal correlations is discussed. As examples, the cases of free space and the ocean waveguide are considered. Practical experimental implications are discussed.
Impulse signal reconstruction using bi-receiver data.
Authors: Wang H. Z. , Wang N. , Gao D. Z.
Published: July 2011

Signal reconstruction is used widely in target identification and communication in underwater. A novel method for impulse signal reconstruction, using the observed data of two receivers which are arranged in the same depth with a certain horizontal interval, is proposed in this talk. This method needs no a prior environmental information but the ranges between the source and the receivers. Although Green function depends on the range, frequency, and weakly on source/receiver depth, spectrum of signal, however, is only dependent on the frequency. On the other hand, dispersion characteristic in shallow water environment provides a compensation mechanism between the frequency and range shift, using this mechanism, the amplitudes and phases of Green function spectral ingredients can be extracted, respectively. Then the impulse signal is obtained by deconvolution processing to the received data of one receiver with Green function. The method is validated using numerical simulation and the correlation coefficient between the reconstructed and original signals is above 0.95 in the cases of high signal-to-noise ratio.
Digital audio watermarking using psycho-acoustic frequency masking and Gaussian mixture model.
Authors: Seo Yejin , Cho Sangjin , Chong Uipil
Published: July 2011

Most of papers related to the watermarking techniques are currently focused on the development of a blind watermarking detection algorithm and a watermark embedding algorithm based on the psychoacoustics. This paper proposes a blind watermark scheme based on psycho-acoustic frequency masking (PAFM) and Gaussian mixture model (GMM). PAFM is used for watermark embedding into each frame and GMM is used for detecting watermarks. This paper compares robustness and sound quality between the proposed method and informed watermark scheme. Informed method is implemented by using errors-in-variables (EIV) and linear predictive coding (LPC) and is also based on spread spectrum. In this method, target frames are chosen by comparing the average energy for whole signals with the energy of every frame and watermarks are embedded into principal peaks around estimated formants computed by EIV and LPC. In order to evaluate robustness of proposed method, we attacked the sound by using LPF, cropping, and additive noise. [This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea Government (MEST) (No. R01-2008-000-20493-0).]
Iterative motion compensation algorithm for heart rate detection with ultrasound data.
Authors: Mehmood Asif , Goldman Geoffrey
Published: July 2011

Noncontact active ultrasound sensors can be used to detect human physiological signals such as respiration and heart rate using Doppler processing. Target motion such as a person swaying can reduce the performance of these algorithms. To mitigate the effect of target motion or respiration on estimating the heart rate, we developed an iterative motion compensation algorithm. We low pass filter the demodulated data, estimate the motion of the target, and then compensate the data for the slow moving motion. This procedure can be repeated at different cutoff frequencies for different scenarios. Now, standard Doppler processing techniques can be used to analyze the motion compensated data. The algorithm was tested on people standing in a laboratory illuminated with a 40-KHz continuous-wave ultrasound sensor. Results for estimating the respiration rate and heart rate will be presented.
Two dimensional characterization of skeletal muscle’s natural vibrations during voluntary contractions.
Authors: Archer Akibi A. , Atangcho Perry , Shinohara Minoru , Sabra Karim G.
Published: July 2011

During voluntary muscular contractions, low frequency mechanical vibrations (<100 Hz) are naturally generated by skeletal muscles as a result of the muscle fiber activity and the overall change of the muscle-tendon geometry. Determining the temporal and spatial variations of muscle vibrations could reveal fundamental features of skeletal muscles’ physiology and activation mechanisms. These mechanical vibrations were recorded over a 3 × 5 grid of skin mounted accelerometers on the biceps brachii muscle for ten healthy subjects for various contraction levels during isometric elbow flexion. The spatial origin and propagation directionality of these natural muscle vibrations were characterized across frequencies using standard cross correlation techniques and back projection algorithms (akin to time-reversal imaging). Additionally cross-correlating these accelerometer recordings provided travel-time measurements of these natural muscle vibrations between multiple sensor pairs. Furthermore, travel-time tomographic inversions yielded spatial variations of their propagation velocity from which the local stiffness of the muscle could be estimated using elastography principles. This passive tomographic elastography technique could potentially lead to simpler, low-cost, and noninvasive monitoring of musculoskeletal and neuromuscular disorders, without using an external mechanical or radiation excitation as commonly required by conventional elastography techniques.
Integrating the energy flux method of shallow-water reverberation with physics-based seabed scattering models.
Authors: Zhou Ji-Xun , Zhang Xue-Zhen , Wan Lin , Peng Zhaohui , Li Zhenglin , Guo Lianghao
Published: July 2011

The energy flux (angular spectrum) method for shallow-water (SW) reverberation was first presented 3 decades ago in archived Chinese journals. These included closed form expressions for reverberation in SW with a down refraction or isovelocity profile. [Zhou, Acta Acust. 5, 86–99 (1980); Chin. J. Acoust. 1, 54–63 (1982)]. More papers on SW reverberation using this method have recently been published in JASA and IEEE JOE. However, most of these papers are based on semiempirical seabed scattering models, which do not have a physical basis. In the past 30 years, one of the major accomplishments in ocean acoustics is the improvement in our understanding of seabed scattering, resulting from a significant effort of both at-sea measurement and theoretical modeling. [Jackson and Richardson, High-Frequency Seafloor Acoustics, (2007)]. Benefiting from this accomplishment, this paper integrates the energy flux model of SW reverberation with the physics-based seabed scattering models in the angular domain. This integration directly and intuitively results in a general expression for SW reverberation in terms of seabed physical/scattering parameters, and this expression is almost identical with the expression derived from the boundary perturbation method. The results may be used to estimate the bottom roughness or sediment inhomogeneity from SW reverberation measurements.[Work supported by the ONR and CAS].
The impact of bottom backscatter strength modeling on active sonar optimal frequency calculations.
Authors: Jemmott Colin W. , Stevens William K.
Published: July 2011

For many active sonar problems, there exists an optimal frequency—one at which detection range maximized. The optimal frequency can be calculated using a frequency dependent analytical sonar equation to solve for the detection range, defined as the largest range with positive signal excess. The frequency with the maximum detection range is the optimal frequency. An advantage of this approach is that it combines all of the sonar equation terms into a single quantity. It might seem that such a frequency will not exist because propagation loss tends to increase with increasing frequencies, so performance might decrease monotonically with frequency. However, other terms in the sonar equation are also frequency dependent. For example, Knudsen or Wenz curves show that noise levels generally decrease with frequency, while source level and target strength may be complicated functions of frequency. In shallow water, active sonar may be reverberation limited rather than noise limited, but standard Lambert scattering strength models are frequency independent. New, more accurate bottom backscatter strength models have frequency dependence, which will impact the optimal frequency calculation. This approach demonstrates one operational impact of improved reverberation modeling, and quantifies the performance degradation caused by a suboptimal frequency selection.
Noise in the surgery area of a four hundred beds hospital.
Authors: Beristain Sergio
Published: July 2011

The studied hospital has eight surgery rooms in a U shaped installation: several sources and relevant conditions have been identified and evaluated. Some rooms are normally allocated for specific types of surgery such as eyes, brain, or heart procedures, while some others are employed for general purpose surgery, which depend on the day to day needs and programming of the hospital: none new borne surgery is performed in this surgery area, and the last one of them is reserved for all kinds of emergency surgery, colloquially known as the dirty surgery room, where patients enter directly from the street, where they have had an accident or a sudden illness. The whole surgery area represents a special noise condition because some surgeries are simple, programed, and require no special noisy tools, but, for instance, in the traumatology or bone surgery, hammers and saws are commonplace during the procedure. General noise measurements were performed during some surgeries in order to find out the prevalent noise condition in this section of the hospital.
Acoustics of interconnected nursing unit corridors.
Authors: Okcu Selen , Ryherd Erica , Zimring Craig
Published: July 2011

Nursing units are composed of proportional (e.g., patient room) and nonproportional spaces (e.g., race track and hallway design nursing unit corridors). Acoustic qualities of these spaces can have a significant impact on sound task performance of caregivers such as localization of auditory cues. For example, it is well known that in reverberant environments, the human auditory system‘s ability to localize auditory cues is very limited. Various nonhospital studies documented the acoustic qualities of proportional spaces. However, the number of studies linking the design and acoustics of long enclosures in hospitals is very limited. By conducting acoustic simulation analysis, impulse response measurements, and heuristic design analysis, this study statistically analyzed the link between design and acoustics of interconnected nursing unit corridors.
Psychoacoustic measures and their relationship to patient physiology in an intensive care unit.
Authors: Hsu Timothy Y. , Ryherd Erica E. , Ackerman Jeremy , Persson Waye Kerstin
Published: July 2011

Many researchers have attempted to characterize the soundscape of hospital wards using traditional acoustic metrics. These traditional metrics, such as average sound level, are readily measured using sound level meters and have been the primary results reported in previous studies. However, it has been shown that these traditional metrics may be insufficient in fully characterizing the wards. This is a continuation of a larger study that evaluates the relationship between hospital soundscape and the effects on the hospital occupants in a medical-surgical intensive care unit. The previous study in this series showed statistically significant relationships between patient physiology and the traditional sound level meter metrics. This current study aims to expand beyond traditional sound level meters and use digital recordings to describe the ICU rooms with psychoacoustics metrics. Thus, a comprehensive catalog of these metrics for ICUs is compiled and presented. In addition to descriptive results with these measures, statistical analysis is used to reveal preliminary relationships between psychoacoustic metrics and the patient physiological responses. These results continue to reveal the importance of understanding the relationships between hospital acoustics and patient physiological arousal. [Work supported by ASA and Swedish FAS.]
Passive acoustic monitoring of cetacean at Josephine Seamount, Portugal.
Authors: Giorli Giacomo , Au Whitlow W. L. , Morrissey Ronald P.
Published: July 2011

In the past years, the development of a variety of passive acoustics recorders has provided a unique way of acquiring information about marine mammal species in remote regions of the ocean. During the NATO Undersea Research Centre Sirena 10 cruise an ecological acoustic recorder (EAR) was deployed to monitor the presence of marine mammal. The EAR was deployed on May 13, 2010 at a depth of 944 m in the vicinity of Josephine seamount (37 deg; 02.087’N, 013¢ª 51.733W, south west Portugal) and programed for a recording time of 40 s every 2 min. For the detection and classification of echolocation clicks we integrated the visual analysis of spectrograms with the analysis performed by an automatic detector/classification system called M3R, developed by the Naval Undersea Warfare Center Division. M3R has been successfully operated for the analysis of recording from different US Navy ranges. Cetaceans detected include beaked whales, sperm whales, pilot whales, risso’s dolphins, and dolphins. Hourly and daily distributions of signals were calculated. Beaked whales have been regularly detected everyday and the echolocation activity has been found to be higher at night. This suggests that Josephine seamount represents a good habitat for these deep diving cetaceans. [NATO Undersea Res. Ctr. funded and operated the sea trial Sirena 10.]
Characterizing and classifying humpback whale (Megaptera novaeangliae) song units.
Authors: Copeland Adrienne M. , Au Whitlow W. L. , Lammers Marc O. , Pack Adam A. , Oswald Julie N.
Published: July 2011

Humpback whales, Megaptera novaeangliae, are one of the most recognizable and investigated marine mammals. However, little progress has been made in automatically distinguishing and classifying individual units of their song. A Matlab script has been developed to characterize the different song units and to apply the appropriate statistics to separate and categorize each unit. The Matlab program measures 48 parameters from each song unit. The songs were recorded by a swimmer snorkeling above vocalizing humpbacks in the waters off Maui, HI. A 16 bit, digital tape recorder with the automatic gain control disabled and a sample rate of 44.1 kHz was used to record songs from different whales. The swimmer determined the range of the whale using a portable handheld fathometer. Singing whales typically suspended themselves in the water column at depths varying from 15 to 30 m, which was contingent on the bottom depth. Song units were separated into distinct categories using a principle component analysis (PCA) based on the 48 parameters describing each unit. A classification algorithm was then developed based on the categories determined by the PCA. The classifier will be integrated into a modified version of the real-time Odontocete call classification algorithm (ROCCA) for future analyzes.
Functional-anatomical imaging of tumors and vasculature using optoacoustic-ultrasonic system.
Authors: Oraevsky Alexander
Published: July 2011

This lecture will discuss the current status and prospectives of optoacoustic imaging and advantages of combined optoacoustic-ultrasonic imaging systems and their biomedical applications. Optoacoustic system provides optical contrast in tissue while mapping tissue structures with ultrasonic resolution. The main advantage of imaging using optical contrast is the possibility to map distribution of blood concentration and its oxygen saturation (functional imaging) in the vasculature or other tissue of interest (such as malignant tumors). High optical contrast of blood (specifically hypoxic blood) makes visualization of the tumor angiogenesis possible, thereby providing functional information for differentiation of malignant and benign tumors. The idea that drives present developments in the field of optoacoustic imaging is that coregistration of optoacoustic and ultrasonic images would be a useful enhancement of almost every application of medical ultrasound.
Acousto-optic imaging using a powerful long pulse laser and digital holography.
Authors: Benoit Emilie , Farahi Salma , Bossy Emmanuel , Ramaz François
Published: July 2011

Acousto-optic tomography is a technique that couples ultrasounds and light in order to measure local optical properties through thick and highly scattering media, e.g. human breast tissues. Thanks to the acousto-optic effect, we can get the optical contrast information given by light and get the spatial localization from the ultrasound longitudinal waves. The use of a powerful long pulse laser (1 ms, 200 mJ) helps to improve the sensitivity of the technique by raising the optical peak power and collect more ultrasound tagged photons. Moreover, its tunable wavelength around 780 nm is appropriate for biological imaging since it is where light has its maximum penetrating depth in tissues. Detection of acousto-optic signals is done by off-axis heterodyne digital holography on a high speed CMOS camera. This enables us to make a tunable spatio-temporal filter with a high signal to noise ratio. Experimentally, this technique enables to image optical absorbers embedded within a thick scattering media (a few centimetres). It is also theoretically possible to use a conventional pulsed ultrasound scanner to generate acousto-optic signals that can at the same time record ultrasound images, which will be a step toward multimodal imaging for breast cancer detection.
Detection of macrophages and lipid using ultrasound guided spectroscopic intravascular photoacoustic imaging.
Authors: Wang Bo , Joshi Pratixa , Matthias Nadine , Amirian James , Litovsky Silvio , Sokolov Konstantin , Smalling Richard , Emelianov Stanislav
Published: July 2011

Macrophages and lipid are two key components in the development and characterization of atherosclerotic plaques. Imaging the activity and distribution of macrophages and lipid in the vessel wall would help identify the vulnerable plaques. In this study, spectroscopic intravascular photoacoustic (sIVPA) imaging was used to detect phagocytically active macrophages and deposits of lipid simultaneously. Polyethylene glycol coated spherical gold nanoparticles (Au NPs) were intravenously injected in vivo into an atherosclerotic rabbit allowing phagocytically active macrophages within the plaques to be labeled with Au NPs. Atherosclerotic aorta was harvested and scanned with a bench-top sIVPA imaging system. Au NP-labeled macrophages were detected in the 710–770 nm wavelength range because of the plasmon resonance coupling effect. Lipid was imaged in 1210–1230 nm wavelength range based on the characteristic optical absorption spectrum of fatty acids. An image processing method was developed to identify Au-NP-labeled macrophages and lipid deposits from the multiwavelength IVPA data. Coregistered sIVPA images were combined with corresponding IVUS images to demonstrate the location of Au NP-labeled macrophages and lipid within the vessel wall. Finally, histochemistry stains confirmed that combined sIVPA and IVUS imaging can successfully detect the distribution of phagocytically active macrophages and lipid deposits.
Practical and mathematical aspects of pairing microphones for hearing aid directional arrays.
Authors: Warren Daniel M. , King Charles B.
Published: July 2011

Directional microphone arrays in hearing aids are short baseline, end-fire arrays, which require tight matching of response characteristics between the microphones, as previously reported [J. Acoust. Soc. Am. 113(4,) 2219 (2003)]. Pairing tolerances for good directional performance are much tighter than normal manufacturing tolerances on individual microphones, so it is infeasible to produce entire production lots within these tolerances. Instead, microphones are selected in pairs based on their measured performance. In some cases, the pairing tolerance is on par with the measurement uncertainty of even a well-designed manufacturing test system. Standard gauge analysis is not well suited to this pairing measurement. An analysis of acoustical measurement error as it relates to the pairing problem, the statistics of successful pairing from a large quantity of microphones, and the underlying graph theory of optimum pairing will be discussed in this paper.
Distributed vertical line array receiver.
Authors: Worcester Peter F. , Dzieciuch Matthew A. , Green Lloyd L. , Horwitt David D. , Lemire Jacques C. , Carey Scott D. , Norenberg Matthew
Published: July 2011

A distributed vertical line array (DVLA) receiver able to span the water column in water up to 6000 m deep has been developed to allow both modal and ray-based analyzes of acoustic propagation. The DVLA is made up of distributed, self-recording hydrophones with timing and scheduling provided by a small number of central controllers, called D-STARs. The enabling technologies for this approach are (i) flash memory modules that can store gigabytes of data in a small pressure case at each hydrophone and (ii) inductive modems that allow low-bandwidth communication between the D-STAR controllers and the hydrophone modules over standard oceanographic mooring wire for control and time synchronization. The DVLA consists of sub-arrays with a nominal length of 1000 m. The hydrophone modules are clamped to the mooring wire during deployment, making the DVLA readily configurable. It is navigated using acoustic transponders on the seafloor. The hydrophone modules make precision temperature measurements to provide the sound-speed profiles needed for beamforming. A DVLA consisting of two 1000-m sub-arrays, one spanning the sound-channel axis and the other spanning the surface conjugate depth, was successfully deployed in the Philippine Sea for 1 month during spring 2009. [Work supported by the Office of Naval Research.]
Horns as particle velocity amplifiers.
Authors: Donskoy Dimitri M. , Cray Benjamin
Published: July 2011

Horns are simple but effective means for improved performance of acoustical systems. Nowadays they are primarily used for sound emission (in loudspeakers) providing better impedance matching between the source and the medium. Applications of receiving horns as sound amplifiers are dated back to the beginning of the last century with the advent of telephones. At the present time, however, highly sensitive pressure sensors such as microphones and hydrophones rarely require additional amplifications for common applications. Recent progress in the development of the acoustic particle velocity sensors opened up many new opportunities in their utilization in air and fluids. Compared to the pressure sensors, however, the particle velocity sensors are less sensitive especially at low frequencies and may benefit from additional amplification provided by horns. Here we revisit theory and numerically analyze horn performance as an amplifier of particle velocity rather than impedance matching device or pressure concentrator.
Investigation of continuous scanning laser Doppler vibrometry for non-contact measurement of linear and angular surface deflections.
Authors: Salman Muhammad , Sabra Karim
Published: July 2011

Laser Doppler vibrometry (LDV) is a non-contact technique for sensing surface vibrations. Traditionally LDV uses one or several fixed beams to measure vibrational velocity of specific points and orientations. Measurement of angular velocity requires at least two beams. Instead, we develop a technique, continuous scanning laser Doppler vibrometry (CSLDV), using a single laser beam continuously sweeping the area of interest using a scanning mirror. Linear scans allow the measurement of normal and angular velocities while circular scans allow the measurement of normal and two angular velocities. We validated the CSLDV technique for measuring low frequency (less than 50 Hz) broadband vibrations of gel samples which mimics natural vibration of human body. Such system could potentially be used to monitor multiple DOF of the skin surface for haptic or remote control applications. There is a disadvantage of using CSLDV which is speckle noise that is generated when coherent light source is reflected back from an optically rough surface. We will discuss the effects of scan lengths, scanning frequency, target to sensor distance, and the excitation amplitude on the performance of CSLDV.
An aeroacoustic microelectromechanical systems microphone phased array.
Authors: Wetzel Drew , Bahr Chris , Williams Matthew , Meloy Jessica , Sheplak Mark , Cattafesta Louis
Published: July 2011

Phased microphone arrays are useful tools for noise source localization using a process known as beam-forming. In scale-model wind tunnel experiments, the frequency range of interest can extend as high as 90 kHz. In both open and closed wall wind tunnels, microphones with high dynamic range are required to sense large turbulent pressure fluctuations from the open jet shear layer and the tunnel wall boundary layer. Microphones that meet the frequency and dynamic range demands of such experiments are readily available but expensive. When considering the high-sensor counts typically needed for phased array measurements, total sensor cost can be a limiting factor. The presentation will discuss a proof-of-concept phased array consisting of 25 piezoelectric microelectromechanical systems (MEMS) microphones arranged in a log-spiral pattern on a single printed circuit board. The microphones were designed in-house and have a dynamic range from 40–160-dB SPL and possess a resonant frequency greater than 100 kHz. A proven MEMS-based array that leverages the benefits of batch fabrication could cost significantly less than a traditional equivalent. The MEMS array will be characterized in the UF Aeroacoustic Flow Facility and compared to a conventional array of the same pattern comprised of 0.25-in. high-frequency microphones.
Using interactive simulations to visualize Fourier analysis.
Authors: Adams Wendy K.
Published: July 2011

Fourier analysis is an elegant and powerful method for expressing general functions as a sum of simpler trigonometric functions. In this presentation the PhET sim “Fourier: Making Waves” http://PhET.colorado.edu/en/simulation/fourier, will be presented including the research behind the simulation, how students react to the sim, and ideas for use in class. Students typically learn the math needed to do Fourier transforms and learn how to express a function in time or space and in terms of wavelength, wave number, or mode. However, many of these relationships are only memorized for the short term (exam) and are not retained. This simulation is designed to help students visualize how a combination of simple sines and cosines can create a more complicated function and listen to the sounds produced by each harmonic. They can explore each of the symbols lambda, T, k, omega, and n to learn what each represents on the graph and their relationships with one another. There is also a game tab with ten different levels that challenges students to choose the correct harmonics to match more and more complicated functions. Finally there is a tab to help students visualize moving from a discrete to a continuous series.