bluuebunny/crossref_metadata_2025 huggingface dataset:
‘‘Anastasis.’’
Authors: Mallia John
Published: October 2013

‘‘Anastasis’’ is a five-channel composition realized at the Institut de Musique Electroacoustique de Bourges (IMEB). The work is programmatic in its representation of Christ’s ‘‘Descent into Limbo,’’ a frequently treated subject in Medieval art. The majority of sounds used are derived from concrete sources, some of which carry conceptual weight. For example, the recurring sound of wax being scraped away from the metal surface of the candle trays at Bourges Cathedral St. Etienne: the residue of prayer...its removal, a daily chore (or performance ritual) captured in sound. Also, the emergence of a field recording of windmills at the work’s close: transformation, by man, of nature’s breath into energy as a storm blows in on the mountainside. The piece itself is a stormy, transformative descent. Sounds of friction and resistance represent the interpenetration of spheres of existence. Long intense strokes of sound such as the dragging of wood along wood, glass on glass, and the grinding and scraping of metals are fractured by abrupt, pointed declamations. Highly spatialized, bristling electronic textures occur as interruptions of the long descent and represent the accumulation of a mysterious, electrical energy in the empty tomb above; static glimpses of that middle sphere.
How toothed whales echolocate to find and capture prey
Authors: L. Tyack Peter , Johnson Mark , Madsen Peter T. , Zimmer Walter M. X. , Aguilar de Soto Natacha
Published: October 2013

Sperm and beaked whales are deep-diving toothed whales whose echolocation behavior has been studied using tags that record sound and whale orientation. Combining orientation data from tagged clicking whales with acoustic localization data from a towed hydrophone array allowed measurement of the three-dimensional beam pattern of regular clicks from sperm whales. These data confirm Mohl’s bent horn hypothesis for sound production in sperm whales. During deep foraging dives, beaked whales produce several thousand regular clicks with interclick intervals (ICI) between 0.2 and 0.4 s. These search clicks have a distinctive FM upsweep from 25 to 55 kHz and a pulse length of 200–250 μs. The process of echolocating on prey can be divided into search, approach, and capture phases. The approach phase starts when a series of echoes from prey is detected. The capture phase starts when the target is about 2–5 m away, with a terminal buzz with click rates to ICIs of about 0.01 s. Tagged whales do not adjust their ICI to match range to target, nor do they adjust click level to maintain a constant echo level, but rather have a bimodal echolocation pattern using two kinds of clicks each with a typical ICI.
Exploitation of sound during predator-prey interactions: Killer whales and herring
Authors: Miller Lee A. , Simon Malene , Ugarte Fernando , Wahlberg Magnus
Published: October 2013

The majority of killer whales (Orcinus orca) in Norway and Iceland feed cooperatively on schools of herring (Clupea harengus). The whales swim towards the school and, at short distances, perform underwater tail slaps that produce thudlike sounds containing impulses resembling cavitation pulses in duration, frequencies, and amplitude. Herring are debilitated by the underwater tail slaps, probably due to a combination of factors like sound pressure gradients, particle movements, hydrodynamic effects, and physical contact with the tail or other fish. Following the underwater tail slaps, killer whales can easily capture individual flaccid herring [Simon et al., J. Exp. Biol. 208, 2459–2466 (2005); a video will be shown]. Icelandic killer whales have another strategy not shown by their Norwegian relatives. A whale can emit a 3-s, 680-Hz call that ends 1 s before the tail slap. The frequency of the call falls within the herring audiogram, but outside that of killer whales. This call seems suited for herding the herring into tighter groups, making it possible to debilitate more fish [Simon et al., Behav. Ecol. Sociobiol. (submitted)]. Herring are not defenseless. The school can produce a flatulent bubble net that could hinder detection by killer whale biosonar [Wahlberg Westerberg, Aquatic Living Resources 16, 271–275 (2003)].
The Humpback Whale Acoustic Research Collaboration studies on the use of sound by humpback whales
Authors: Cato Douglas H. , Noad Michael J. , Stokes Dale , Dunlop Rebecca A. , Smith Joshua N. , Miller Patrick J.O. , Biassoni Nicoletta , Kniest Eric T. , Noad John , Thode Aaron M. , Deane Grant B.
Published: October 2013

Humpback whales produce two different types of vocalizations with apparent difference functions: songs and social sounds. There is also the potential to use the sounds of their environment, such as surf noise during migration along coasts, though this has not been demonstrated. The Humpback Whale Acoustic Research Collaboration (HARC) is a series of well-controlled, multiplatform experiments designed to improve our understanding of how humpback whales use sound, both vocalizations and sounds of their environment. There have been two major experiments with humpback whales migrating along the east coast of Australia. Whales passing within 10 km were tracked acoustically and visually during daylight hours in conjunction with behavioral observations, and DTAGs were used on some whales to record their 3D movements and the sound field to which they were exposed. There was also playback of social sounds and full characterization of the acoustics of the environment, including the ambient noise exposure. Preliminary results of interactions between singing and nonsinging whales, the use of song as a spacing mechanism, responses to playback, and context of social sounds will be discussed. [Research supported by ONR and DSTO.]
Do humpback whales exploit bioacoustic absorption spectroscopy to detect and classify fish schools?
Authors: Diachok Orest
Published: October 2013

Humpback whales employ bubble nets for catching fish. In the Gulf of Alaska the method involves acoustic communication between whales: one whale, situated below the school, transmits sounds and drives the fish toward the surface; a second whale, situated above the school, deploys a bubble net (as wide as 30 m), which encircles the school as it approaches the surface. Before and during this process one (or more) humpback emits signals, called trumpet sounds, which consists of a series of cw tones, which are harmonics of ∼300 Hz. The target species in the Gulf of Alaska is adult, 22-cm-long herring. These signals cover the resonance frequency of the target species swim bladders, which is about 1.5 kHz at 30 m. Resonance frequencies of individual fish are determined by the radius and depth of the swim bladder; significantly lower bubble cloud resonance frequencies of schools are determined by the void ratio and the dimensions of the school. One of the functions of these vocalizations may be detection and classification: the listening whale, near the surface, may be capable of interpreting the high absorption losses at resonance frequencies [Diachok, O. ‘‘Effects of absorptivity due to fish on transmission loss in shallow water,’’ J. Acoust. Soc. Am. 105, 2105–2128 (1999)] to infer fish length, species, and size of school.
The role of the spectral characteristics of discrete calls in killer whale (Orcinus orca) communication
Authors: Samarra Filipa , Miller Patrick
Published: October 2013

Many studies of killer whale calling have focused on group-specific time-frequency contours. This study investigated variation in the spectral structure of calls recorded from identified individuals and sought to identify factors that influence call spectral structure. The energy level of the first two harmonics was measured at each 0.01-s interval and linear mixed effects models used to test the sources of variation in the relative level of the first and second harmonics. Within a call, spectral structure changes according to the frequency of the fundamental (p<0.001), but not time since call start. Between calls, variation seems related to body size. Adult males had a stronger second harmonic, whereas for females the opposite tended to be true. Size class was a significant factor in the model (p=0.0108), while duration of calls or orientation and range of the signaller were not. Further analysis indicates different energy patterns between males and females up to the fifth harmonic. These results are consistent with a source-filter model of sound production, with formants arising from filtering effects of the sound-production apparatus. However, more research is clearly needed on the sound production mechanism of this species.
Whistle characteristics of bottlenose dolphins (Tursiops truncatus) are conserved independently of whistle quality
Authors: Bazúa-Durán Carmen
Published: October 2013

Bottlenose dolphins use their acoustic sense (whistles and pulses) to communicate and inspect their environment. One of these environments is a coastal lagoon in the southern Gulf of Mexico, the Laguna de Términos, where bottlenose dolphins inhabit all year round in herds varying from 1–120 individuals, with a yearly population of about 600 dolphins. Several characteristics of dolphin whistles were measured: quality (whistles with a signal-to-noise ratio, SNR, greater or less than 3 dB), repertoire (by classifying contours as either constant, ascending, descending, concave, convex, or multiple), and time-frequency parameters (duration, average frequency, medium frequency, and frequency range) to investigate how the overall whistle structure varied. Results show that regardless of their quality (SNR), whistles were not significantly different in their parameters and repertoire. Additionally, in this area dolphins produce more whistles/min/dolphin during traveling than during social interactions and feeding (whistle production was lowest during resting). Dolphins are presumed to use whistles to maintain group cohesion and to broadcast identity, thus being important in determining dolphin social structure. The results of this work support these hypotheses, suggesting that faint (whispered and/or far range) or strong (loud and/or close range) whistles broadcast, overall, similar information. [Work supported by CONACyT-Campeche, PAPIIT-UNAM, and ICMyL-UNAM.]
Medical imaging using nonlinear ultrasound and the role of Edwin Carstensen
Authors: Parker Kevin J.
Published: October 2013

In the 1960s, with the development of weak shock theory by Blackstock and other advances, nonlinear acoustics found growing importance and applications in the atmosphere and underwater. By comparison, during this time frame the field of medical ultrasound remained largely focused on linear mechanisms. Three major subfields within medical ultrasound eventually developed major nonlinear theory and applications: cavitation, lithotripsy, and imaging. Edwin Carstensen’s collaborative research and directorship of the Rochester Center for Biomedical Ultrasound played an important role in these developments. This talk focuses on the development of nonlinear acoustics to clinical imaging, tracing benchmark developments from the 1960s to the early 2000s, under the guiding influence of Ed Carstensen.
Stress, strain, and flow produced by a vibrator in, or on the surface of, a soft solid
Authors: Nyborg Wesley L. , Frost Harold M.
Published: October 2013

The field of biomedical ultrasound is greatly indebted to Edwin Carstensen for important contributions, without number, that he and his associates have made to understanding of the subject. These contributions have dealt not only with linear and nonlinear propagation of ultrasound in biological materials, but also with effects produced by ultrasound through various thermal and nonthermal mechanisms. Such understanding is important for advancing benefits and minimizing risks in applications of ultrasound. Many therapeutic applications discussed in the literature utilize focused beams of megahertz frequency, while others employ lower frequencies. In this talk, some findings will be presented from experiments in which a vibrating source of frequency in the range 20–90 kHz is brought into contact with the surface of a soft viscoelastic solid and information is obtained on resulting fields of strain. Under some conditions the mechanical properties of the solid are altered by an exposure, in an apparent change of internal structure, and the change is maintained (recorded) until erased by a later sonication. The role of radiation force and other mechanisms in producing such effects will be discussed, as well as their possible relevance to ultrasonic angioplasty and other applications.
Statistical estimation of ultrasonic propagation path parameters for aberration correction
Authors: Waag Robert C. , Astheimer Jeffrey P.
Published: October 2013

Parameters in a linear filter model for ultrasonic propagation are found using statistical estimation. The model employs an inhomogeneous-medium Green’s function that is decomposed into a homogeneous-transmission term and a path-dependent aberration term. Power and cross-power spectra of random-medium scattering are estimated over the frequency band of the transmit-receive system by using closely situated scattering volumes. The frequency-domain magnitude of the aberration is obtained from a normalization of the power spectrum. The corresponding phase is reconstructed from cross-power spectra of subaperture signals at adjacent receive positions by a recursion. The subapertures constrain the receive sensitivity pattern to eliminate measurement system phase contributions. The recursion uses a Laplacian-based algorithm to obtain phase from phase differences. Pulse-echo waveforms were acquired from a point reflector and a tissuelike scattering phantom through a tissue-mimicking aberration path from neighboring volumes having essentially the same aberration path. Propagation path aberration parameters calculated from the measurements of random scattering through the aberration phantom agree with corresponding parameters calculated for the same aberrator and array position by using echoes from the point reflector. The results indicate the approach describes, in addition to time shifts, waveform amplitude and shape changes produced by propagation through distributed aberration under realistic conditions.
Acoustic radiation force imaging of prostate: Initial results
Authors: McAleavey Stephen , Menon Menoj , Rubens Deborah
Published: October 2013

Dr. Edwin Carstensen has contributed significantly to the understanding of the mechanical forces produced by acoustic waves in biological tissues, including work on cavitation and tactile perception of acoustic radiation force. This work presents some initial results in using radiation force for remote palpation of prostate tissue. Acoustic radiation force impulse (ARFI) images of excised human prostates are presented. Fresh prostates obtained immediately after surgery were scanned in an isotonic saline bath at room temperature. Scanning was performed with a Siemens Antares scanner and VF10-5 linear array. Tissue displacement was induced by pushing pulses of 30 to 75/μ s duration at 6.67 MHz and an Isppa on the order of 1 kW. Observed peak displacements in healthy tissue were in the range of 6–12/μ m. Most prostates were scanned free-hand. One specimen was scanned with a transducer mounted to a single axis stage and imaged at 1-mm steps. The resulting images are presented with matching histology images and show good correspondence. [Work supported by the Wallace H. Coulter Foundation Early Career Award for Translational Research program.]
Microphone bandwidth extension by digital correction of low-frequency roll-off
Authors: Marston Timothy , Gabrielson Thomas
Published: October 2013

When the low-frequency roll-off of a condenser microphone needs to be extended, the standard method of achieving extra bandwidth is to place a shunt capacitor in parallel with the input capacitance of the preamplifier. The result increases the bandwidth in the desired region, but sacrifices dynamic range across the entire bandwidth. It is possible to digitally extend the useful bandwidth of a microphone and only compromise dynamic range in the extended region. A technique for doing this has been developed and applied to microphones used to record sonic boom data. Microphones that have an insufficiently low-frequency response to capture the characteristic N-wave shape of sonic booms are corrected using the developed methods, and the results are compared to data captured by microphones with adequate low-frequency response. During the development of the filtering technique, it was found that phase response is critical in the correction process and its importance is demonstrated. [Research funded by the Applied Research Laboratory Educational and Foundational Fund.]
Infrasonic pistonphone calibration of acoustic transducers
Authors: Marston Timothy , Gabrielson Thomas
Published: October 2013

A simple infrasonic pistonphone was developed for the low-frequency calibration of acoustic sensors. The pistonphone, which utilizes a variable speed dc motor and a crank-driven piston, has a frequency range of 20 mHz to 20 Hz. Digital techniques have been implemented to correct for the inherent distortion in the crank-driven piston design, enabling simpler mechanical construction without significant loss in calibration accuracy. As in similar design geometries [H. E. Dahlke and John J. Van Houten, J. Acoust. Soc. Am. 37, 1209 (1965)], the transition from an adiabatic to an isothermal pressure-volume relation is readily observed within the specified frequency range and results in a 0.5-dB reduction in calibration signal amplitude. A digital model for this transition is compared to data acquired using the pistonphone, and possibilities for increasing the calibration accuracy by use of this digital model are presented. [Research funded by the Applied Research Laboratory Educational and Foundational Fund.]
Multimicrophone method for measurement of acoustic absorption
Authors: Oppenheimer Charles H.
Published: October 2013

A multimicrophone method for measurement of the acoustic absorption of small material samples using impedance tubes is presented. The multimicrophone method may be implemented with actual or synthetic microphone arrays, the latter involving successive measurements and a roving microphone, and is an alternative to the two-microphone method of ASTM E 1050. The effects of absorption measurement inaccuracy due to microphone response (magnitude and phase) bias and measurement noise are determined by simulation. Simulation results indicate that the multimicrophone method is more robust against microphone bias and noise and is therefore more accurate than the standard method, especially as microphone counts increase, while requiring minimal additional effort and cost.
Impulse response of a spherical microphone array (eigenmike)
Authors: Barnhill Colin , West James , Busch-Vishniac Ilene
Published: October 2013

Spherical microphone arrays are capable of complete three-dimensional sound field capture and robust noise cancellation [J. Meyer & G.W. Elko, ‘‘A Highly Scalable Spherical Microphone Array Based on an Orthonormal Decomposition of the Soundfield,’’ in Proc. IEEE Int. Conf. Acoust., Speech, Signal Processing, 2002, Vol. II, pp. 1781–1784]. The spherical array tested has 24 omni-directional pressure microphones arranged on a rigid sphere. The sound pressure from each sensor is decomposed into spherical harmonics (standard eigen analysis) which results in rotationally symmetric output along any axis (three dimensionally) through the center of the sphere. An accurate impulse response of this system is important to sound localization and tracking methods. Time history can also be used to enhance the prediction model for source movement. The impulse measurements on this array were made in a semi-anechoic chamber and are in good agreement with expected results. The three main characteristics of the impulse response that will be discussed are the delay times, amplitude differences, and frequency response.
Multiphysics analysis of a loudspeaker
Authors: Zahui Marcellin
Published: October 2013

A coupled physics analysis of a loudspeaker is presented. This finite-element analysis of a theoretical loudspeaker is performed using a commercial finite-element package installed on a Window-based personal computer. The objective is to use multiphysics modeling to analyze the loudspeaker coupled fields (electric, magnetic, structural, fluid, and acoustic) that are solved in a single step. All the components of the electro-acoustic transducer, i.e., the rear plate, the magnet, the voice coil, the pole piece, the spider, the frame, the cone, and the dust cap are incorporated in a single finite-element model. The system is then analyzed using an electrical input circuit also modeled using finite element to evaluate the acoustic radiation from the cone. Even though the solution is obtained in a single analysis, each physics field is separately validated with known and well-established data. First the magnetic field is validated, then the resulting structural displacement of the cone, and finally the fluid field, followed by the acoustic field. The work is an attempt to provide a global design and optimization environment for electro-acoustic transducers and other acoustic multiphysics systems such as active noise control.
Microelectromechanical-systems-based parametric trans- mitting array in air—Application to the ultrasonic ranging transducer with high directionality
Authors: Lee Haksue , Moon Wonkyu
Published: October 2013

Reduction of the transducer size decreases the efficiency of the secondary wave generation in the parametric transmitting array. To overcome this problem, MEMS-based transducer radiating high intensity sound is required in the parametric array. A high-performance PZT MEMS ultrasonic transducer composed of many small membrane-type radiator units was designed and fabricated by bulk micro-machining, and the secondary wave generated by the transducer was observed. This experiment proves that a MEMS-based parametric transmitting array is possible and applicable to some devices. A new ranging ultrasonic transducer with high directionality as an application was proposed because ultrasonic transducers generally need to be designed for high directionality to enhance the spatial resolution in the pulse-echo measurement in air. The 40-kHz difference tone, the measuring signal, was generated using 100- and 140-kHz primary tones by the PZT MEMS ultrasonic transducer. The difference tone had a half-power beam width of around 5 deg and a sound pressure level of over 85 dB at the peak. For the real application, higher sound pressure level should be achieved, and this will be included in the future work. [Research supported by MIC.]
A stepped plate transducer as an ultrasonic loudspeaker
Authors: Yi Dong Hoon , Lee Hak-sue , Moon Wonkyu
Published: October 2013

Research on the ultrasonic loudspeaker has been under way since Mary Beth Bennett and Blackstock verified the existence of parametric array phenomenon in air experimentally. Although several transducers that make use of piezoelectric films have been proposed, an ultrasonic loudspeaker system is not developed enough to be practical due to its high cost and high power consumption. In the 1970s, Gallego-Juarez et al. developed an ultrasonic transducer exploiting flexural modes of circular radiating plate, which shows highly efficient and directional performance. The feasibility of this type of transducer as ultrasonic loudspeakers, however, has not been investigated. Thus, a transducer with a stepped radiating plate of 283 mm diameter and a resonance at 40 kHz was designed, manufactured, and tested. In order to maximize the pressure radiated, piezoelectric ceramics were placed at the nodal point of the structure. The features of the transducer manufactured are over 130 dB of maximum primary wave at resonance on the acoustic axis, half-power beamwidth of primary ultrasound less than 10 deg, 40 to 60 dB of secondary waves from 1.5 to 20 kHz at 1m, and half-power beamwidth of secondary sound less than 10 deg.
Electrostatic negative stiffness and coupling factor of micromachined capacitive ultrasonic transducers
Authors: Ge Li-Feng
Published: October 2013

A theoretical model for micromachined capacitive or electrostatic ultrasonic transducers (mCUT or cMUT) was presented [L.-F. Ge, Theoretical and Computational Acoustic 2001, edited by E.-C. Shang et al., World Sci., 459–469, 2002; Proc. 18th Intl. Conf. Acoustics, Vol. III, 2255–2258, 2004]. The model takes into account the bending stiffness of diaphragm tension in diaphragm, compressibility of air within air-gaps, the effects of the metal electrode coated on diaphragm, and a negative stiffness caused by electrostatic attraction, providing a comprehensive and accurate description of the behavior of mCUTs. The electrostatic negative stiffness is derived from the electrostatic force based on the parallel plate capacitor assumption and is expressed as Kneg=−ε0V20/x30, where ε0 is the permittivity of air, V0 the bias voltage, and x0 the effective separation between two electrodes. It corresponds to a negative capacitance Cneg or negative impedance Zneg at the mechanical port in the equivalent electrical circuit for mCUTs. Thus, the electromechanical coupling factor K can be defined by K2=(−Zneg)/ZMO, which is a ratio of the electrostatic negative impedance to the open-circuit mechanical impedance of the mCUT. The definition may give a new view for the coupling factor of electromechanical transducers. [Work supported by NSFC (60374044).]
Ultrasound imaging instruction for veterinary students at Colorado State University
Authors: Wrigley Robert H.
Published: October 2013

Didactic ultrasonography instruction to the veterinary students begins with the physical principles of sonography, machine selection, and operating controls. Subsequently, image artifacts and normal sonograms of the heart and abdominal organs are presented. Sonograms of pregnancy and abnormal sonograms of common diseases are discussed. In the final-year practicum course, small groups of students (2–4) spend a week in the echocardiography lab and the soft-tissue imaging lab. Here, students acquire hands-on sonography skills and become proficient in sonography of small animals and horses. An Internet-based interactive instruction module on the equine limb was developed to enable veterinary students to better learn ultrasonography of tendons/ligaments of the metacarpus. Interactivity was achieved by creating clickable zones on the tendons and ligaments. Students are challenged to apply the knowledge gained studying normal ultrasound anatomy to clinical patients affected with tendon/ligament injuries. Students are asked to identify (by clicking on) the location of the sonographic lesions. The program provides immediate feedback on their ability to recognize the site of the injury. In addition, having the program web-based allows students to review the instructional material on a time schedule that best fits their needs and from remote locations.
Teaching acoustics in the medical and related fields
Authors: Raichel Daniel R.
Published: October 2013

Acoustics is playing an ever-increasing role in the medical and related fields. Besides the more obvious applications such as otology, audiometry, stethoscope usage, effects of sound on hearing, and psychological well-being, more modern applications include ultrasound diagnostics and therapeutics, fetal monitoring, surgical applications, removal of dental plaque, musical therapy, etc. This gives rise to the question: how much acoustical theory needs to be taught to future practitioners, many of whom were not science or engineering majors during their undergraduate years? A motor vehicle operator, for example, does not need to understand the fundamentals of internal combustion and mechanics of power transmission in order to develop the skill to handle a vehicle; he/she needs to learn applicable motor vehicle laws. In the same vein, a prospective medical practitioner does not need to learn solutions to the wave equation and understand the basis of how frequency analyzers function, but he/she needs to develop the skills to use applicable acoustic technology, interpret the results with understanding of their ramifications, and be aware of technical limitations such as permissible ultrasound dosages. Acoustic education requirements in a number of medical subfields are discussed in terms of depth and breadth of coverage.
Acoustic education and the Bolognan process in Russia
Authors: Zagrai Nikolai , Zakharevich Vladislav
Published: October 2013

Acoustic education in Russia is traditionally based on a solid natural-sciences curriculum with core classes in higher mathematics, physics, continuum mechanics, and electronics. However, parallel to the so-called specialist qualification encompassing a standard 5-years engineering training, a new education trajectory of bachelor (4 years) and master (6 years) qualifications has emerged as a result of the international Bolognan Agreement recently signed by the Russian Federation. Students willing to pursue the master qualification may enroll in this program after completing either bachelor or specialist training. Aimed at making Russian educational programs more easily understood, we are implementing a smooth transition from traditional academic hours used for weighting program content and value in the Russian educational system to internationally recognized credit hours. Nowadays, mainstream technical universities include individual creative thinking approach in their modulus-rating systems with the multilevel assessment. The latter is related to direct rating educational technologies. In general, the content of Russian education programs in acoustic is equivalent to similar foreign programs.
Optical table with embedded active vibration dampers (smart table) as an educational tool in structural acoustics and vibration
Authors: Ryaboy Vyacheslav M.
Published: October 2013

The actively damped optical table contains two sensor-actuator assemblies connected to a digital feedback controller. The controller is programed to damp resonant flexural vibrations of the table. The controller can auto-tune to accommodate changes in the payload. It has a software interface that allows one to switch the damping on and off, to regulate the amount of active damping manually, to analyze the signals from embedded vibration sensors, and to display the results in both time and frequency domains. For an advanced user it is possible to completely reprogram the controller. Besides its main purpose of vibration control, the smart table can be used for laboratory demonstrations of various phenomena in structural acoustics without additional equipment or with minimal additional technical means. Among these effects: structural response in the frequency domain (resonance peaks versus forced operational peaks, damped versus undamped system); time response of damped versus undamped system; tonal sound emission in response to random excitation (damped versus undamped system); open-loop response of the control system and mechanical impedance of the structure versus closed-loop response. More experiments and demonstrations can be devised as educators and students become more familiar with the system.
Development of an acoustics program at Morgan State University
Authors: Serbyn M. Roman
Published: October 2013

This report describes the gradual implementation of one educator’s plan to introduce acoustics into the curriculum of a medium-size university. Rooted in the physics department, the program from its inception has emphasized the interdisciplinary nature of the discipline. The first course, consisting of a series of lectures within an existing format of ‘‘Great Issues,’’ was offered to seniors of the university in 1998. Subsequently one graduate and two undergraduate courses were developed and approved. The undergraduate course, Acoustics and You, has been particularly popular because of the diversity of topics. The graduate course is a typical presentation of the fundamentals of acoustics with discussion of selected applications. Acoustical research has been limited to the author’s areas of interest and subject to time and funding constraints. Recent collaboration with the departments of biology and psychology have been very beneficial to the growth of the program. The narrative will be illustrated with course syllabi, student data, as well as lessons learned, and plans for the future.
A Portable device to illustrate two methods for vibration reduction namely tuned dynamic absorber and isolation mounting
Authors: Koretas Samuel , Prasad M. G.
Published: October 2013

Mechanical vibrations can be harmful to structures as well as to humans. It is important to understand the principles of design that are used in developing various methods for reducing vibration. There are several tools at our disposal to reduce the vibrations transmitted from a vibration machine to the building structure. Two commonly available methods of vibration control are using passive vibration isolation mountings and tuned mass absorbers. This paper presents the design and working of a portable device to illustrate both methods of vibration reduction. We can examine the performance of both mounting and absorber using this physical device. The analytical and experimental work shows that such a device can effectively illustrate the principles involved in the design of mountings and absorbers. Also, the device can be used to show the influence of various physical parameters on performance. The presentation will also include the discussion on the role of such devices in enhancing the understanding of design principles in acoustics, noise, and vibration.
Real-time measurement/viewing of vocal-tract influence during wind instrument performance
Authors: Scavone Gary P.
Published: October 2013

Since the early 1980s, there have been a number of investigations into the role and influence of a player’s vocal tract on the sound production of wind instruments. While the underlying acoustic principles are relatively well understood, a general lack of agreement remains within both the music acoustics and performance communities with regard to the importance of this mechanism during playing conditions. Disparities arise in part because subtle manipulations of the oral cavity can affect the response of the instrument without necessarily producing effects audible to an observer. A real-time measurement system is demonstrated that provides a visual comparison of the relative strengths of the ‘‘upstream’’ windway and ‘‘downstream’’ air column impedances under playing conditions. The system assumes continuity of volume flow on either side of the ‘‘reed,’’ which leads to a direct proportionality between the upstream and downstream pressures and impedances. Playing experiments clearly demonstrate many instances in which vocal-tract manipulations can cause impedance peak magnitudes in the mouth cavity to exceed those in the downstream air column. In addition to providing visual ‘‘proof’’ of such manipulations, the system is expected to offer a pedagogical tool to help performers better learn how to make use of this control mechanism.
Acoustical effects of reed cells in the American reed organ
Authors: Franta Benjamin A. , Cottingham James P.
Published: October 2013

In a reed organ the free reed is mounted above the windchest and is typically surrounded by a reed cell cavity. The length of this tubelike cavity varies from just slightly longer than the reed in some instruments to several centimeters longer in others. Earlier research on effects of the reed cell focused mainly on the lowering of sounding frequency due to the presence of the cell [J. Cottingham, ‘‘Effects of reed cell geometry on the vibration frequency and spectrum of a free reed,’’ J. Acoust. Soc. Am. 101, 3143 (1997)]. Reed cells are shown to have a significant effect on the radiated waveform and spectrum. The length and interior geometry of the cell are significant factors in determining this effect. Changes in reed cell dimensions have a greater effect on the sound spectrum than changes in reed dimensions. It is shown that the presence of a reed cell considerably enhances the upper harmonics of the spectrum. Higher vibrational modes in air-driven free reeds have recently been observed [A. Paquette, J. Vines, and J. Cottingham, ‘‘Modes of vibration of air-driven free reeds in transient and steady state oscillation,’’ J. Acoust. Soc. Am. 114, 2348 (2003)]. The current measurements indicate that the reed cell substantially affects the higher vibrational modes of the reed, particularly enhancing the second and third transverse modes. [Research supported by the Carver Summer Scholar Program.]
Development of artificial neural network classifier to identify military impulse noise
Authors: Bucci Brian A. , Vipperman Jeffrey S.
Published: October 2013

Civilian noise complaints from urban encroachment have curtailed military exercises that produce high levels of impulse noise. Currently, monitoring stations are in place around many military installations to monitor noise levels. However, these monitoring stations do not provide real-time data and suffer from false positive detections. This project sought to develop algorithms with improved noise classification accuracy. Various types of military impulse noise and nonimpulse noise were measured and processed. Approximately 1000 waveforms were field collected (670 nonimpulse and 330 military impulse). Although several metrics were examined, the conventional time domain metrics of kurtosis and crest factor as well as two novel frequency domain metrics, weighted square error and spectral slope, were found to work best. The computed metric values were used to train and verify the performance of the artificial neural network (ANN), which was able to achieve 100% accuracy on training data and 100% accuracy on verification data. [This research was supported wholly by the U.S. Department of Defense, through the Strategic Environmental Research and Development Program (SERDP).]
NOIDESc: A novel traffic noise description scheme
Authors: Gygi Brian , Deutsch Werner , Waubke Holger , Noll Anton
Published: October 2013

A novel framework for the acoustic and psychoacoustic description of noise signals (railway and road) has been proposed in order to extend and improve traditional noise classification schemes. In addition to measures of averaged sound-pressure level and noise exposure duration, the description scheme includes psychoacoustic parameters such as spectral centroid, spectral spread, modulation spectrum, and further dynamic aspects of the sound events corresponding in part to the MPEG-7/4 standard. The dynamic changes between foreground and background are addressed in the model. The approach assumes the evaluation of several low-level acoustic parameters of the noise, to be integrated into few high-level features by means of statistical methods, such as Gaussian mixture models and cluster analysis. As the usage of noise monitoring systems is expected to increase in the near future, the cumulative collection of calibrated sound recordings will provide comprehensive regional and supraregional sound databases to serve as input for automated noise classification. [The work in progress is performed in cooperation with the division of Acoustics of the TGM Vienna and is supported by the Austrian FFG.]
New approach to studying traffic noise nuisance
Authors: Derbal Cobis Rabah , Zeghlache Hamza
Published: October 2013

More often the problem of noise and sonic pollution particularly in urban sites, is studied by different disciplines such as physics, acoustics, psychoacoustics, medicine, and others. Some studies are carried out in laboratories taking noise and sonic phenomena as samples cut off from their realistic context. Urban noise is studied as well by making abstraction of the different contextual parameters by idealizing a rather complex sonic environment. This derives often on incompatible results that can hardly be used in real situations of urban noise problems. The noise, according to this present approach, is supposed to react with the surrounding space, and it takes the form and the quality of the place by defining and requalifying it. It is found that the contextual aspects such as social, cultural, or even symbolic dimensions modulate the listening and the perception quality of the noise. The multiparameter dimension study of the noise in urban context is necessary. The small number of studies already done based on such multidisciplinary approach and the results that came out of such studies comfort well our effort and are very encouraging to go ahead with this methodological approach.
Noise in the adult emergency department of Johns Hopkins Hospital
Authors: Orellana Douglas , Busch-Vishniac Ilene J. , West James E.
Published: October 2013

While hospitals are generally noisy environments, nowhere is the pandemonium greater than in an emergency department, where there is constant flow of patients, doctors, nurses, and moving equipment. In this noise study we collected 24-h measurements throughout the Adult Emergency Department of Johns Hopkins Hospital, the top-ranked hospital in the U.S. for 15 years running. The emergency department is structured into pods, each of which specializes in particular types of treatment. We obtained measurements in each pod. Compared to data collected at other locations of the hospital, the average Leq throughout the emergency department is about 5 dB (A) higher. Within the emergency department the triage area has the highest Leq, ranging from 65 to 73 dB (A), primarily due to being at the entrance to the department. Sound levels in the emergency department are sufficiently high [on average between 62 to 67 dB(A)] to raise concerns regarding the communication of speech without errors, an important issue everywhere in a hospital and a critical issue in emergency departments because doctors and nurses frequently need to work at an urgent pace and to rely on oral communication.
Dynamic behavior analysis of a switched reluctance motor
Authors: Llado Juan , Sanchez Beatriz , Ortiz Jesus , Martinez Aberlardo , Perez Francisco , Martin del Rio Bonifacio , Pollan Tomas , Laloya Eduardo , Vicuna Javier
Published: October 2013

Within the home appliances sector, the series motor practically shares most applications. However, no further progress in cost reduction or control performances is envisaged. But, the switched reluctance motor, SRM, shows fairly good characteristics such as robustness, easy assembly, and low manufacturing costs. Besides, it allows accomplishment of integrated designs with the product, and an improvement of efficiency up to 90% when compared to about 45% reached by series motors used for home appliances. However, two specific drawbacks of this machine are control complexity and acoustic noise. As a first step, with respect to the acoustic noise, the target of this work is to develop a theoretical modal model of an SRM of four phases with 24 poles in an external stator and 18 poles rotor placed inside. This requires a theoretical simulation by means of an FEM software and an experimental work in a test bench to analyze the motor structure. The comparison of the results obtained by both methods will validate the theoretical model analyzed with the FEM software, and introduce structural modifications that can be used to design quiet SRMs from the knowledge of mode shapes and mode frequencies.
Laboratory experiments on nonlinear acoustic detection of buried objects
Authors: Attenborough Keith , Qin Qin , Jefferis Jonathan , Heald Gary
Published: October 2013

The surface velocity response to acoustic excitation of sand contained within a thick-walled PVC tank in the shape of a truncated cone has been investigated with and without buried objects. The excitation was provided by either tonal or white-noise spectra from a large loudspeaker, and the sound field was localized above the buried objects by means of an inverted cone and pipe arrangement. The surface velocity of the sand has been measured with an accelerometer. The loading effects of the accelerometer have been found to be minor. The surface admittance spectra above a buried plastic container are found to have uniquely resonant structures, the nature of which has been investigated. It has been found that if the surface of a granular medium, containing buried objects, is subject to high levels of sound using either a single frequency or two separate frequencies, then, as well as an enhanced linear surface velocity response at the excitation frequencies, increased quadratic and cubic nonlinear responses may be observed. The nonlinear response at a sand surface is found to be highly sensitive to the moisture content and the degree of compaction. [Work supported by DSTL (UK) Contract Number RD029 06495.]
Effect of particle friction on the vibrations of a plate loaded with granular media
Authors: Kang Wonmo , Yang Liyong , Turner Joseph A. , Rattanadit Kitti , Bobaru Florin
Published: October 2013

Acoustic methods have recently been shown to hold promise for detection of nonmetallic mines. These methods rely on the vibration response of the soil-plate system. The influence of particle size on the frequency response was previously illustrated using sieved sand as the loading material. Here, the influence of particle friction is studied using spherical glass beads. The first resonance of a plate was measured as a function of layer mass for a layer of monodispersed glass beads of various sizes (from 38 μm to 2.5 mm). The plate exhibited the same qualitative behavior as with sand loading but the response was quantitatively different. In particular, the minimum frequency attained for the glass bead layer was consistently higher than that for sand. However, the dependence on particle size followed the similar trends. Mechanisms related to both interparticle friction and layer-plate interface friction were explored. Experimental results with a roughened plate indicate that the resonance behavior is not dependent on the interaction between the layer-plate interface. Finally, numerical results based on dynamic simulations of discrete, interacting particles are discussed as applied to the experiments. The results are expected to impact quantitative aspects of mine detection by acoustic methods. [Work supported by ARL.]
Comparisons between predicted and measured acoustic scattering from a wedge
Authors: Hughes Ronald , Niemiec Jan , Uberall Herbert
Published: October 2013

Our earlier work has mainly dealt with developing a mathematical approach for predicting acoustc scattering from a wedge for various boundary conditions and wedge material properties. We initially reported scattering for wedge surfaces that satisfy a Dirichlet or a Neumann boundary condition. Recently, our approach was extended to include wedge boundary conditions that can be characterized by an impedance, including absorption. Numerical predictions are found using the Kontorovich-Lebedev transform [A. Erdelyi, Higher Transcendental Functions (McGraw-Hill, New York, 1953)] based upon MacDonald functions, requiring very high precision numerical techniques. We now apply this numerical approach to calculate the monostatic scattering amplitude for a fabricated wedge structure that has been measured in a nonlaboratory environment. Comparisons will be presented and discussed of the results obtained from the predicted and measured monostatic scattering pressures for a range of insonification frequencies at selected offset distances and angles relative to the edge of the wedge.