bluuebunny/crossref_metadata_2025 huggingface dataset:
Estimating mode coupling effects on shallow-water propagation uncertainty
Authors: LePage Kevin D.
Published: October 2013

The introduction of unknown aberrations to the background sound speed of the ocean waveguide and sediments, as well as unknown free-surface excursions and bottom bathymetry, causes uncertainty in the characteristics of acoustic time series. Not all of this uncertainty can be adequately explained by simply assuming that energy in various paths is perturbed only in phase and travel time. Data and simulations both clearly show that significant mode coupling is introduced by even small aberrations introduced over significant ranges. This talk estimates the effects of mode coupling introduced by statistically characterized sound-speed defects on the statistical properties of time series in shallow water. In this approach EOF decompositions of the sound-speed field are used, along with the differential form of the coupled -modeequations and perturbation expressions for mode-coupling coefficients. Results are compared to previously derived expressions for the statistical properties of time series obtained under the adiabatic approximation [Work supported by ONR.]
Angle-of-arrival estimation in atmospheric turbulence
Authors: Collier Sandra , Ostashev Vladimir , Wilson D. Keith
Published: October 2013

An angle-of-arrival estimator is derived for acoustic waves that propagate in atmospheric turbulence. The estimator directly accounts for the effects of random fluctuations in the propagation environment. The first and second moments of the sound field, as derived from the theory of wave propagation in a random medium, and realistic atmospheric turbulence models are utilized. Results using this estimator are compared to results using conventional beamformers that do not account for the effects of atmospheric turbulence.
Classification across the senses: Auditory-visual cognitive performance in a California sea lion (Zalophus californianus)
Authors: Lindemann Kristy L. , Reichmuth-Kastak Colleen , Schusterman Ronald J.
Published: October 2013

The model of stimulus equivalence describes how perceptually dissimilar stimuli can become interrelated to form useful categories both within and between the sensory modalities. A recent experiment expanded upon prior work with a California sea lion by examining stimulus classification across the auditory and visual modalities. Acoustic stimuli were associated with an exemplar from one of two pre-existing visual classes in a matching-to-sample paradigm. After direct training of these associations, the sea lion showed spontaneous transfer of the new auditory stimuli to the remaining members of the visual classes. The sea lion’s performance on this cross-modal equivalence task was similar to that shown by human subjects in studies of emergent word learning and reading comprehension. Current research with the same animal further examines how stimulus classes can be expanded across modalities. Fast-mapping techniques are used to rapidly establish new auditory-visual relationships between acoustic cues and multiple arbitrary visual stimuli. Collectively, this research illustrates complex cross-modal performances in a highly experienced subject and provides insight into how animals organize information from multiple sensory modalities into meaningful representations.
The big brown bat’s perceptual dimension of target range
Authors: Simmons James A.
Published: October 2013

Big brown bats determine the distance to targets from echo delay, but information actually is entered onto the bat’s psychological delay scale from two sources. The first is the target-ranging system itself, from the time that elapses between single-spike neural responses evoked by the broadcast and similar responses evoked by echoes at different delays. These responses register the FM sweeps of broadcasts or echoes, and the associated system of neural delay lines and coincidence detectors cross correlates the spectrograms along the time axis. The second source is the echo spectrum, which relates to shape expressed as range profile. The target-ranging system extracts this by fanning out to encompass parallel representations of many possible notch frequencies and notch widths in echoes. Bats perceive delay separations of 5−30 μs and have a resolution limit of about 2 μs, but interference amplifies small delay separations by transposing them into large changes in notch frequency, so only perception of intervals smaller than 5 μs is surprising. Experiments with phase-shifted echoes show that the psychological time scale can represent two different delays originating entirely in the time domain when they are at least as close together as 10 μs. [Work supported by NIH and ONR.]
Advancing from pattern to process in Hawaii’s near-shore pelagic ecosystem
Authors: Benoit-Bird Kelly , McManus Margaret
Published: October 2013

Micronekton comprising a near-shore sound-scattering layer around the Hawaiian Islands have been shown to exhibit diel horizontal migrations, moving onshore until midnight and them moving offshore into deep waters where they remain in the day. The reasons for this daily movement pattern have remained unexamined. Moored echosounders were used to describe micronekton migration over a 5-week period. A moored acoustic Doppler current profiler (ADCP), thermistor chains, point current meters, and an autonomous vertical profiler provided a description of the physical circulation. Periodic four-frequency echosounder and ADCP surveys were used to further characterize the micronekton’s movement along with water column physics. During surveys, vertical profiles measured zooplankton abundance using the Tracor acoustic profiling system (TAPS) and integrated net tows, micronekton identity and size using an optical imaging system, and primary productivity with a fluorometer. It was found that micronekton are not simply tracers of water mass movement indicating active migration. Near-shore waters had significantly higher biomass of zooplankton during nighttime hours than offshore waters, suggesting micronekton have greater access to food resources as a result of their migration. Primary productivity was also significantly higher inshore, indicating bottom-up control of this system. These results suggest the underlying reasons behind this daily horizontal movement.
Environmental noise levels affect the activity budget of the Florida manatee
Authors: Miksis-Olds Jennifer L. , Donaghay Percy L. , Miller James H. , Tyack Peter L.
Published: October 2013

Manatees inhabit coastal bays, lagoons, and estuaries because they are dependent on the aquatic vegetation that grows in shallow waters. Food requirements force manatees to occupy the same areas in which human activities are the greatest. Noise produced from human activities has the potential to affect these animals by eliciting responses ranging from mild behavioral changes to extreme aversion. This study quantifies the behavioral responses of manatees to both changing levels of ambient noise and transient noise sources. Results indicate that elevated environmental noise levels do affect the overall activity budget of this species. The proportion of time manatees spend feeding, milling, and traveling in critical habitats changed as a function of noise level. More time was spent in the directed, goal-oriented behaviors of feeding and traveling, while less time was spent milling when noise levels were highest. The animals also responded to the transient noise of approaching vessels with changes in behavioral state and movements out of the geographical area. This suggests that manatees detect and respond to changes in environmental noise levels. Whether these changes legally constitute harassment and produce biologically significant effects need to be addressed with hypothesis-driven experiments and long-term monitoring. [For Animal Bioacoustics Best Student Paper Award.]
Ultrasound imaging for high intensity focused ultrasound therapy
Authors: Vaezy Shahram , Zderic Vesna , Crum Lawrence
Published: October 2013

We have investigated the use of ultrasound-based imaging to develop a non-invasive, safe and real-time method of guidance and monitoring for HIFU therapy. HIFU application was synchronized with the imaging frame rate to allow interference-free visualization of the region of interest. The regions treated with HIFU at intensities above the cavitation threshold appear immediately (within 30–60 ms) as hyperechoic structures in ultrasound images, confirmed to be due to microbubble activity at the focus. This HIFU dose is shown to produce minimal tissue damage, in the form of capillary rupture in an area of approximately 0.5 mm around the focus. The appearance of hyperechoic regions is potentially useful for pre-treatment targeting to ensure that the focus is located at the correct spot. The hyperechoic structures persist for 1–2 min, while the microbubbles still remain at the focus, before being absorbed. Microbubbles at the focus also provide a shield for HIFU, to prevent thermal damage of the healthy tissues located post-focally. Challenges of ultrasound-image-guided HIFU are in monitoring the tissue thermal behavior in and around the focus, and follow-up monitoring of tissues treated with HIFU. Ultrasound imaging is developing into a promising method for guidance of HIFU therapy. [Work funded by DoD, NIH.]
Speech neglect: A strange educational blind spot
Authors: Harris Katherine Safford
Published: October 2013

Speaking is universally acknowledged as an important human talent, yet as a topic of educated common knowledge, it is peculiarly neglected. Partly, this is a consequence of the relatively recent growth of research on speech perception, production, and development, but also a function of the way that information is sliced up by undergraduate colleges. Although the basic acoustic mechanism of vowel production was known to Helmholtz, the ability to view speech production as a physiological event is evolving even now with such techniques as fMRI. Intensive research on speech perception emerged only in the early 1930s as Fletcher and the engineers at Bell Telephone Laboratories developed the transmission of speech over telephone lines. The study of speech development was revolutionized by the papers of Eimas and his colleagues on speech perception in infants in the 1970s. Dissemination of knowledge in these fields is the responsibility of no single academic discipline. It forms a center for two departments, Linguistics, and Speech and Hearing, but in the former, there is a heavy emphasis on other aspects of language than speech and, in the latter, a focus on clinical practice. For psychologists, it is a rather minor component of a very diverse assembly of topics. I will focus on these three fields in proposing possible remedies.
Two centuries of French patents as documentation of musical instrument construction
Authors: Jean Haury
Published: October 2013

The French Patent Office I.N.P.I. has preserved the originals of ca. 12000 French patents filed between 1791 and present days that are concerned with music-related inventions. As an I.N.P.I. pilot project, these were identified, collected, and classified by the present author, and the actual database named ‘‘Musique & Brevets’’ is going to be expanded with English, American, and German material, bringing currently a knowledge base up to 1900. It is expected to be made available on an I.N.P.I. website. This is an unequaled initiative that covers all branches of musical instrument manufacture, mechanical musical instruments, early recording and reproducing of music, but also educational material and methods for printing music. There already exists a number of websites presenting inventions on musical instruments, but these are restricted to one particular instrument and its related patents. ‘‘Musique & Brevets’’ intends to be exhaustive and make links between patents filed in different countries at the same time. The paper will present the content of the database, the access to texts and drawings of the patents via specific links, and their importance for the study of history and construction of musical instruments.
Noise absorption characteristics and modeling for quiet pavements
Authors: Tavossi Hasson
Published: October 2013

In this study, various techniques for noise attenuation by quiet pavements and its modeling are investigated in order to reduce traffic noise in urban environments. Noise absorption in selective frequency ranges by pavements can reduce its reach, the degree of noise annoyance, and general background noise level in the environment. Different methods of noise energy absorption are considered, including internal attenuation by multiple scatting, and selective frequency absorption by cavity resonance inside the pavement structure. Noise energy dissipation in the undesirable frequency ranges, by multiple scattering and absorption in the pavement and by sound-absorbing barriers, are also considered. Dispersion and scattering of high-frequency components of the noise result in the long-range reach of the low-frequency components of the traffic-generated noise. Selective attenuation by quiet pavements of the low-frequency components of the noise reduces its rage and improves significantly the overall noise pollution in the urban environments. A general background of the modeling and the experimental findings on sound attenuation by absorption, cavity resonance, and multiple scattering techniques, at low and high frequencies, will be presented.
Quieting of Portland cement concrete highway surfaces with texture modifications
Authors: Donavan Paul
Published: October 2013

In recent years, various types of asphalt surfaces have become identified as ‘‘quiet pavements’’ due to their ability to reduce tire/pavement noise and, ultimately, traffic noise. Often lost in this perception is the fact that substantial reductions in tire/pavement noise can also be made by texture modifications to existing Portland Cement Concrete (PCC) or by novel constructions. PCC surfaces have been found to span a range of as much as 16 dB. As a result, there is the potential to achieve large noise reductions depending on the existing and final surfaces. In California, grinding of bridge decks and elevated structures has been found to reduce tire/pavement source levels 3 to 10 dB with comparable reductions in wayside measurements. In Arizona, grinding of PCC has reduced source levels up to 9 dB relative to some transversely tined surfaces. Measurements conducted in Europe using the same measurement methodology indicated a range of 11 dB including more novel porous PCC surfaces. In this paper, measurement results and case histories are reviewed for situations where PCC modifications were successful and unsuccessful in producing quieter pavement.
Noncontact modal testing of hard-drive suspensions using ultrasound radiation force
Authors: Huber Thomas M. , Calhoun Daniel , Fatemi Mostafa , Kinnick Randall R. , Greenleaf James F.
Published: October 2013

The head-gimbal assembly suspension is a cantilever-like structure that holds the heads on a hard drive. We will discuss a noncontact method for modal testing, of suspensions in air, that utilizes the radiation force at the difference frequency generated by two intersecting ultrasound beams. The resulting low-frequency excitations were measured using a scanning vibrometer. This excitation technique has been demonstrated for MEMS and other small devices. There are several unique advantages of the ultrasound radiation force relative to mechanical shakers. Since the ultrasound radiation force is noncontact, a specialized test fixture was not needed; the technique was relatively insensitive to distracting resonances of fixtures and support structures. Another advantage is broadband excitation; a 550-kHz confocal ultrasound transducer excited suspension resonance frequencies from under 1 kHz to over 50 kHz. Other advantages include the ability to selectively excite different modes. For example, the amplitude of the suspension’s 2.28-kHz transverse mode was suppressed by an order of magnitude by shifting the modulation phase between the two ultrasound beams by 90. In another test, the amplitude of the 6.01-kHz torsional mode was doubled by moving the ultrasound focus point from near the center to near the edge of the suspension.
Speech formant frequency estimation method based on Hilbert–Huang transform
Authors: Huang Hai , Pan Jiaqiang
Published: October 2013

A speech formant frequency estimation method based on Hilbert–Huang transform (HHT) is proposed in this study. After filtering with bandpass filters with the center frequencies obtained by using the FFT analysis, speed data are decomposed into a set of intrinsic mode function (IMFs) by using the HHT analysis method. The IMFs containing formant frequencies are then identified according to the energy maximum criteria, their instantaneous frequencies and Hilbert spectra are calculated, and finally the formant frequencies of speech data are efficiently determined. The results in this study show that, compared with conventional formant estimation methods, the method based on HHT not only can give clearer descriptions of the nonlinear and nonstationary characteristics of speech signals, but also the speech formant frequencies and their variations with high time–frequency resolution and veracity. [This work was supported by Grant No. 60275004 from the National Natural Science Foundation of China (NNSFC).]
Stereotyped calling patterns of a male Weddell seal
Authors: Terhune Jack M. , Dell’Apa Andrea
Published: October 2013

Underwater calling behavior between breathing bouts of a (presumed) single adult male Weddell seal (Leptonychotes weddellii) was examined at Davis Station, Antarctica. Underwater calls and in-air breathing sounds were recorded on 1 and 8 December. Thirty-six postdive and 37 presurfacing sets of calls were analyzed. Dives were 461±259 s (mean ± S.D.). The seal called every 22.7±21.7 s. The first two calls after diving were at 15.6±9.3 and 33.3±9.7 s. The last two calls occurred at 38.8±32.0 and 22.7±20.1 s before surfacing. The first call after a dive was usually (29/36) a low-frequency growl. One of three patterns of 3–5 call-type sequences was made following 26 of 36 dives. A common four-call sequence was also recorded earlier in the breeding season at this location and was absent at four other distant breeding sites. The timing and call-type sequences of underwater vocalizations after a dive were highly stereotyped, while those before surfacing were not. Territorial males may call throughout each dive and use stereotyped call patterns to identify themselves. [Work supported by Australian Antarctic Division and NSERC.]
Diurnal vocal activity of gray whales in Laguna San Ignacio, BCS, Mexico
Authors: Guerra Melania , Thode Aaron , Wisdom Sheyna , Gonzalez Sergio , Urban Jorge , Sumich James
Published: October 2013

Three sets of portable horizontal acoustic arrays were deployed during a week in February 2005 to gather acoustic recordings of gray whales (Eschrichtius robustus) in Laguna San Ignacio, one of the three major breeding/calving lagoons in Baja California, Mexico. These arrays, which were constructed by attaching a pair of autonomous flash-memory acoustic sensors to a rope, were deployed for 36 consecutive hours on two occasions, spatially covering the narrowest point of the lagoon near Punta Piedra, the area of the highest concentration of whales. Additionally a single hydrophone was deployed off a small boat to record during friendly encounters with single whales and cow/calf pairs. Each recorder’s time series was analyzed for Type 1 gray whale sounds (called pops), which are pulsive, broadband, and have substantial acoustic energy between 100 and 600 Hz. The number of automated acoustic detections per hour can be compared with population sizes estimated by two visual surveys conducted by scientists of the Autonomous University of Baja California Sur, La Paz. The results of several automated analyses of both the bottom-mounted and boat-deployed recordings will be presented, with a focus on potential diurnal patterns in the vocal activity.
Temporal patterns in marine mammal sounds from long-term broadband recordings
Authors: Hildebrand John A. , Wiggins Sean , Oleson Erin , Sirovic Ana , Munger Lisa , Soldevilla Melissa , Burtenshaw Jessica
Published: October 2013

Recent advances in the technology for long-term underwater acoustic recording provide new data on the temporal patterns of marine mammal sounds. Autonomous acoustic recordings are now being made with broad frequency bandwidth up to 200-kHz sampling rates. These data allow sound recording from most marine mammal species, including, for instance, the echolocation clicks of odontocetes. Large data storage capacity up to 1280 Gbytes allow these recordings to be conducted over long time periods for study of diel and seasonal calling patterns. Examples will be presented of temporal patterns from long-term recordings collected in four regions: the Bering Sea, offshore southern California, the Gulf of California, and the Southern Ocean. These data provide new insight on marine mammal distribution, seasonality, and behavior.
The temporal characteristics of humpback whale songs
Authors: Au Whitlow W. L. , Lammers Marc O. , Stimpert Alison , Schotten Michiel
Published: October 2013

Songs sung by male humpback whales consist of distinct, pulsed sounds that are designated as units. Units are produced in some sequence to form a phrase, a repeated set of phrases forms a theme, and repeated themes form a song. A song can last from minutes to hours. The songs of eight humpback whales were recorded with a vertical array of five hydrophones spaced 7 m apart with the array located within 100 m of the whales. At least seven distinct units were identified aurally from this data set obtained during the 2002 winter humpback whale session in Hawaii. Four distinct recurring themes were found in the songs, and for each whale at least two themes were recorded. The average duration of each unit sampled and the silent interval following the unit were determined in order to describe the temporal characteristics of the songs. From the data the temporal consistency and cadence control of unit production by each humpback whale and between whales were determined. Understanding the temporal and spectral characteristics of units within songs and how these units vary between whales could ultimately help in the design of computer algorithms to automatically identify individual whales.
Time reversal mirrors and invariants of the time reversal operator: Application to detection and imaging in biological media
Authors: Prada Claire , Fink Mathias
Published: October 2013

Acoustic time reversal mirrors have been developed in the Laboratoire Ondes et Acoustique for several years. In inhomogeneous media and especially in the presence of multiple scattering, these systems provide outstanding focusing properties. While used in pulse echo mode, the time reversal process can be iterated, leading to selective focusing on the most reflective point among a set of scatterers. This iteration is also used to enhance the echo from a defect like a kidney stone or a microcalcification in the breast. The iterative time reversal process is described by a matrix call the Time Reversal Operator (TRO). The eigenvectors of this matrix provide the invariants of the iterative time reversal process, their analysis is the base of the D.O.R.T. method. It allows the separation of the echoes from several scatterers in an inhomogeneous medium and the selective focusing on any of them. Furthermore, when an estimate of the medium’s Green function is available, high-resolution and low-noise images can be achieved using the backpropagation of the dominant eigenvectors. The principle of acoustic time reversal mirrors and the D.O.R.T. method will be described through several examples.
Acoustically induced tissue displacement for shear wave elasticity imaging using MRI
Authors: Haworth Kevin , Kripfgans Oliver , Steele Derek , Swanson Scott , Sutin Alexander , Sarvazyan Armen
Published: October 2013

Palpitation detects tissue abnormalities by exploiting the vast range of elastic properties found in vivo. The method is limited by tactile sensitivity and the inability to probe tissues at depth. Recent efforts seek to remove these limitation by developing a medical imaging modality based on radiation force shear wave excitation. Our approach uses an acoustic source to launch a shear wave in a tissue-mimicking phantom and MRI to record microscopic displacements. Gelatin (10% wt/vol) was used for the tissue-mimicking phantom. Results for in situ elasticity were obtained using an air-backed 10-cm-diam piezoelectric crystal. To correct for future in vivo beam aberrations, we also employ a high-pressure 1-bit time-reversal cavity. Frequency and pulse duration were selected to optimize the TRA system for acoustic output pressure. Shear wave displacements were recorded by MRI in 1-ms time increments in a complete basis that allowed for 3-D reconstruction and analysis. The Lamé coefficients are then derived from the shear wave velocity and attenuation.
A method to classify piezoelectric crystals
Authors: Dang Changjiu
Published: October 2013

The properties of piezoelectric crystals used as the active elements in many ultrasonic transducers vary among the suppliers even if the crystals are claimed to be in the same category (say Navy I). A method of classifying the piezoelectric crystals is introduced. With this method, one can judge how similar to each other two types of crystals are by taking the crystal parameters as inputs. The parameters of a crystal include its density, velocity, mechanical Q, dissipation, frequency constants, piezoelectric constants, elastic constants, etc. They are transformed into the values around 1 to weaken the dominance of large parameter values. The transformed data form two attribute lists whose cross-correlation indicates their similarity. If two crystals are similar, their normalized cross-correlation coefficient is close to 1. Otherwise, it is close to 0. Based on this method, the available piezoelectric crystals can be further classified into different groups.
Zero-g acoustic fire suppression system
Authors: Plaks Dmitriy , Nelson Elizabeth , Hyatt Nesha , Espinosa James , Coley Zade , Tran Cathy , de Mayo Ben
Published: October 2013

The objective is to study the effects of acoustics on a flame in microgravity. This research is meant to provide a new approach to reducing and extinguishing a combustion reaction in space (where a conventional fire extinguisher is hazardous). The group proposes to test the following hypotheses: (1) as sound intensity increases, so does the magnitude of the effect on the flame; (2) there is one optimal frequency for maximizing the effects of sound waves on a flame; (3) homogeneous flames (found only in microgravity) can be affected in a single area separate from others; (4) a sustained pulse of sound, rather than a single, brief pulse, can be used to extinguish a flame. The group will describe the experimental apparatus in detail, which was flown aboard a NASA C-9B Aircraft through their Reduced Gravity Student Flight Opportunities Program (RGSFOP), and present the findings and compare data obtained in a 1-g environment with data collected in a microgravity environment. [Thanks to the following organizations for their support: Kicker Audio, Georgia Space Grant Consortium, Siemens, FLIR Systems, PCB Piezotronics, UWG Honors College, and NASAs Reduced Gravity Student Flight Opportunities Program.]
Hey kid! Wanna build a loudspeaker? The first one’s free
Authors: Garrett Steven
Published: October 2013

In 2000, Penn State University instituted a First Year Seminar (FYS) requirement for every entering undergraduate student. This paper describes a hands-on FYS on audio engineering that has each freshman, in a class of 20, construct and test a two-way loudspeaker system during eight 2-hour meetings. Time and resource constraints dictated that the speaker system must be assembled using only hand tools and characterized using only an oscillator and digital multimeters. Due to limitations on the funds made available for each FYS by the College of Engineering, the total cost of entire system could not exceed $65/side. Each student is provided with a woofer, tweeter, crossover components, and enclosure parts to build one speaker system. The students are offered the option of purchasing a second set of parts for $65 so that they can complete the course with a stereo pair. Ninety percent of the students exercise the stereo option. This presentation will describe the speaker system, using an enclosure made primarily from PVC plumbing parts, and the four laboratory exercises that the students perform and write up that are designed to introduce basic engineering concepts including graphing, electrical impedance, resonance, transfer functions, mechanical and gas stiffness, and nondestructive parameter measurement.
An air-coupled actuator array for active modal control of timpani
Authors: Rollow Douglas , Sparrow Victor W. , Swanson David C.
Published: October 2013

The timbral characteristics of kettledrums can be described by a modal formulation of the vibration of a thin, air-loaded membrane. Modification of the modal time history can be brought about with the use of a control system which has independent influence on each structural mode. By replacing the usual kettle with a shallow chamber and a planar array of piston sources, a modal controller is created when driving the sources in appropriate linear combinations. A theoretical formulation of active control of structural vibration by means of fluid-coupled actuators is expressed, and a Boundary Element simulation provides insight to the coupled modes, independence of control, and constraints due to the geometry of the chamber. Advantages and limitations of this type of control source to general problems in actively controlled musical instruments are explored.
Pitch circularity produced by varying the amplitudes of odd and even harmonics
Authors: Deutsch Diana , Dooley Kevin , Dubnov Shlomo , Henthorn Trevor , Wurden Alex
Published: October 2013

Pitch circularities have been produced using tones whose components stand in octave relation (Shepard, 1964; Risset, 1969). This paper describes two circular pitch scales produced by a new algorithm. Each scale consists of a bank of harmonic complex tones, each tone 500 ms in duration. As the scale descends in semitone steps, the relative amplitudes of the odd-numbered harmonics decrease in 5-dB steps, so that at the bottom of the scale they are 55 dB lower than the even-numbered harmonics. The entire bank of tones is then low-pass filtered. The lowest tone of such a scale is therefore heard as though its fundamental frequency were displaced up an octave. For each scale all possible (i.e., 132) ordered tone pairs were presented, and 15 subjects judged for each pair whether the second tone was higher or lower than the first. The data derived from these pairwise comparisons were subjected to Kruskal’s nonmetric multidimensional scaling (MDS). For both scales, two-dimensional plots yielded approximately circular configurations; Stress1 values for the two scales were 0.016 and 0.034. When the tones were presented in semitone steps, the impression of infinitely ascending and descending scales was obtained. These circular scales are demonstrated with sound examples.
What do we know about noise in hospitals
Authors: West James E. , Busch-Vishniac Ilene
Published: October 2013

Little is known about noise levels inside hospitals and its effect on healing, safety, staff, and doctors. Many independent studies of noise levels in a wide range of hospital venues in many countries have been reported in the literature authored mainly by physicians and nurses. The World Health Organization (WHO) has set guidelines for noise levels in hospitals, but none of the reported studies meet WHO guidelines. In most cases noise levels are more then 15 dB A-weighted higher then those specified by WHO guidelines. Since 1960 the average noise levels in hospitals has increased an average of 0.38 dB per year during daytime hours and 0.42 dB during the night. This talk reviews the state of the art on interior hospital noise control and the remaining challenging issues. Equivalent sound pressure levels as a function of location, frequency and time of day were measured in five different venues at the Johns Hopkins Hospital in Baltimore Maryland. Results of our measurements, which confirm the trends seen in prior studies, will be used to describe patterns of hospital interior noise and avenues ripe for further investigation.
Decentralized active feedback control approach for vibration and noise reduction through an aircraft fuselage
Authors: Mathur Gopal , Fuller Christopher R. , Carneal J.
Published: October 2013

Active noise control has been commonly implemented with fully coupled, feed-forward approach, which employs reference sensors on the fuselage/source and error microphones in the radiated field. Implementation limitations include: complexity, delay/causality, and use of microphone error sensors. An alternative approach of feedback control utilizing sensors located on each panel may overcome most of these problems. The sensors on each panel should estimate the sound radiation from the panel and also should de-couple the control from the neighbor actuator signals by primarily observing the control signals on the panel to which it is attached. With this sensing arrangement, multiple, independent single input single output feedback loops applied to each panel in conjunction with an actuator and sound radiation sensor can be utilized. Causality problems are overcome by utilizing feedback control approach with sensors located on the panel as feedback sensors. This paper will present results from laboratory tests, conducted on an aircraft fuselage, which showed that a multiple SISO feedback control approach can provide global reductions of broadband interior noise. These tests demonstrated that the actuator, sensor, and control hardware technology is mature and can be integrated into a reliable, compact system.
Stability conditions in decentralized active vibration control of a flexible plate
Authors: Micheau P. , Berry A.
Published: October 2013

This paper presents the analysis of decentralized active control of periodic panel vibration using multiple pairs combining PZT actuators and PVDF sensors distributed (not necessarily collocated) on the panel. Frequency-domain gradient and Newton-Raphson adaptation of decentralized control were analyzed, both in terms of performance and stability conditions. The stabilization of the closed loop by adjusting the convergence coefficient was especially investigated through an adjustable control effort term in the quadratic cost function. Various necessary or sufficient stability conditions derived from the transfer matrix were obtained and ranked from the most restrictive to the less restrictive condition. One of them, the strictly positive real condition of the transfer matrix, appears to be very useful. This stability condition is obtained when the open-loop system is dissipative. Simulation and experimental results are presented for a simply supported panel with 4 PZT-PVDF pairs distributed on the panel. The experimental results were obtained with a decentralized harmonic controller demonstrated equivalent to any narrow-band disturbance control methods. Decentralized vibration control is shown to be highly dependent of the actuator and sensor configurations, but can be as effective as a fully centralized control even when the transfer matrix is not diagonal-dominant.
Energy density active noise control in an earthmoving machine cab
Authors: Copley David C. , Faber Ben , Sommerfeldt Scott
Published: October 2013

Conventional active noise control (ANC) systems attempt to minimize squared pressure at an error sensor (or sensors) to achieve control, and often result in a relatively small zone of control. Considering a practical application in a vehicle, this approach is acceptable provided the operator’s head remains within the control zone. In the case of an earthmoving machine, an operator’s head regularly moves about the cab, either because of the motion of the machine during operation or as the operator moves about to perform various tasks. By minimizing energy density (ED), instead of squared-pressure, a potentially larger control zone may be achieved. Active control of the sound field within an earthmoving machine cab was attempted using the ED technique. The scope was limited to controlling the engine firing frequency tonal within the cab with the machine running, but in a static condition (engine idle). Frequency response and spatial results show the method achieved nearly global control within the cab and effectively reduced the A-weighted sound-pressure level by a few decibels, despite only reducing a single low frequency tone. In this sense, active control using ED has the potential to be more suitable to earthmoving machine applications than squared-pressure techniques.
Hydrofoil vibration and noise reduction with leading edge isolation
Authors: Brungart Timothy A. , Myer Eric C. , Capone Dean E. , Campbell Robert L.
Published: October 2013

A technique for reducing the vibration and noise from hydrofoils subject to unsteady hydrodynamic loads was demonstrated experimentally. Unsteady loads are generated when hydrofoils interact with approach-flow disturbances such as hull boundary layer turbulence or wakes from upstream rotors. Since the unsteady loads are known to be concentrated in the vicinity of the leading edge, a single stage vibration isolation mount was incorporated into a hydrofoil at its 20% chord location to inhibit the leading edge-generated unsteady loads from being transmitted to the remainder of the foil and any structures coupled to it. The hydrofoil was tested in a water tunnel facility with a wake generator placed upstream to produce the approach-flow disturbances. The reduction in the loading on the portion of the hydrofoil isolated from the leading edge was inferred from vibration measurements. Reductions of 5 to 10 dB were demonstrated.
Use of existing standards to measure sound power levels of powered hand tools—necessary revisions
Authors: Hayden Charles S. , Zechmann Edward
Published: October 2013

At recent NOISE-CON and Acoustical Society of America meetings, noise rating labeling was discussed as a way of manufacturers providing full disclosure information for their noise emitting products. The first step is to gather sound power level data from these products. Sound power level data should be gathered in accordance with existing ANSI and/or ISO standards. Some standards, such as ANSI 12.15, may not define true operational noise emissions[r1] and thus may provide inaccurate information when that information is used to choose a hearing protection device or used to make a purchasing decision. A number of standards were systematically combined by NIOSH researchers to provide the most accurate information on sound power levels of powered hand tools used in the construction industry. This presentation will detail some of the challenges of existing ANSI 12.15 (and draft ANSI 12.41) to measure sound power levels of electric (and pneumatic) powered hand tools.
Sound power measurement techniques for powered hand tools
Authors: Zechmann Edward L. , Hayden Charles
Published: October 2013

As part of a project to reduce noise induced hearing loss in the construction industry, NIOSH developed a database of sound power level measurements of electric powered hand tools typically used in the construction industry. The tool testing jigs and setups specified and illustrated in ANSI S12.15 were modified to accommodate the higher precision ten-microphone arrangement used in ISO 3744. ANSI S12.15 is sometimes vague regarding the tool testing jig design, so test jigs were designed to supplement existing specifications in the standard. In the course of the project, test jigs were designed, techniques were devised to improve repeatability of measurements, to reduce waste materials, to reduce measurement setup time, and to reduce data acquisition time. Several types of tools were tested including circular saws, grinders, screw drivers, drills, jig saws, reciprocating saws, miter saws, hammer drills, belt sanders, and impact wrenches. The test jig designs and measurement techniques may help others to save time, reduce waste material, and improve measurement repeatability. Additionally, a microphone was placed in the nominal hearing zone of the tool operator to acquire a time series to assess other sound metrics.
Measurement of noise from toys
Authors: Altkorn Robert , Milkovich Scott M. , Rider Gene
Published: October 2013

Noise from toys is an issue receiving increasing attention in the toy and consumer product safety communities. Concern over loud toys is motivated both by reports of increasing hearing loss among children (the U.S. CDC estimated in 2001 that 12.5% of U.S. children 6 to 19 years old have permanent or temporary noise induced threshold shift in one or both ears) and by technological advances enabling sound and noise producing toys of increased play value at lower and lower cost. Consumer watchdog groups such as PIRG routinely identify excessively loud toys in their yearly lists of most dangerous toys. In 2003 ASTM revised its toy safety standard (F963-03) to include A and C weighted sound pressure level measurements and specific play or use dependent measurement geometries. RAM Consulting measures noise from toys as part of a comprehensive product safety program. Sound measurement equipment, geometries, and procedures used at RAM for different types of toys will be discussed. Unusual problems in noise measurement will be considered, as will the appropriateness of A and C weighting for the youngest age groups.
Frequency and neighborhood effects on auditory perception of drug names in noise
Authors: Lambert B. L. , Lin S.-J. , Toh S. , Luce P. A. , McLennan C. T. , La Vigne R. , Fisher W. M. , Dickey L. W. , Senders J. W.
Published: October 2013

Drug name confusions occur when drugs whose names look or sound alike (e.g., Celebrex/Cerebyx) are confused by clinicians and patients. Our project examines effects of frequency and similarity on auditory perception of drug names. Luce’s Neighborhood Activation Model is the theoretical framework. Frequency information was taken from national prescribing frequency databases. Spoken drug names were transcribed to ARPAbet. Similarity neighborhoods were calculated based on phoneme edit distance using phoneme-to-phoneme confusion probabilities as substitution costs. The confusability of each name was estimated using Luce’s frequency-weighted neighborhood probability rule (FWNPR). One hundred brand and one hundred generic drug names, stratified by FWNPR, were recorded. Low and high frequency sounds were filtered out to mimic telephone bandwidth. Names were used as stimuli in a perceptual identification experiment. Participants heard the drug names, at three different signal-to-noise ratios, against a background of 20-speaker babble. Participants were then shown the 200 names and asked to pronounce them and rate their familiarity. Data have been collected from 66 pharmacists. These data are being scored. Additional data will be collected from 50 physicians, 50 nurses, and 50 lay people. Results will be used to refine the theory and to build screening tools for drug companies and regulators.
Curing the noise epidemic
Authors: Mazer Susan
Published: October 2013

The argument is made that design does not stop when the fixed architectural and acoustical components are in place. Spaces live and breathe with the people who reside in them. Research and examples are presented that show that noise, auditory clutter, thrives on itself in hospitals. Application of the Lombard reflex studies fit into the hospital setting, but do not offer solutions as to how one might reduce the impact. In addition, the basis for looking at the noise component as a physical as well cultural dynamic will be addressed. Whether the result of the wrong conversation in the wrong place or the right conversation in an unfortunate place, talk mixed with sounds of technology is shown to cause its own symptoms. From heightened anxiety and stress to medical errors, staff burnout, or HIPAA violations, the case is made that noise is pandemic in hospitals and demands financial and operational investment. An explanation of how to reduce noise by design of the dynamic environment - equipment, technology, staff protocols is also provided.
Noise in neonatal intensive care units (NICUs) and its effect on high risk newborns
Authors: Lasky Robert E. , Williams Amber L. , van Drongelen Wim , Gray Lincoln C.
Published: October 2013

We conducted sound surveys in a large state of the art NICU with six separate rooms devoted to the sickest babies requiring the most intensive care (Level III) and six rooms devoted to babies requiring special but less intensive care (Level II). Each room was capable of caring for up to 8 babies. Additionally, there were 8 individual Isolation rooms. We used Larson Davis Spark■ 703+ dosimeters to record 21 week long sound surveys, seven in each type of room. The American Academy of Pediatrics (1997) has recommended that sound levels in NICUs should never exceed 45 dB(A). That recommendation was exceeded 73.6% of the time in Level II, 92.1% of the time in Isolation, and 96.6% of the time in Level III. Sound levels were lowest in the Level II rooms especially for the softest sounds recorded (L90 and L70). Level III rooms were noisiest except for the noisiest decile of sound (L10). Isolation rooms were noisiest at the highest sound levels (probably because of their reverberant construction materials and enclosed space). Autocorrelation functions were calculated identifying periodic components in all three rooms at about 12 and 24 hrs. Periodic variations were very small compared to random sound variations.
Superluminal and negative group velocity of ultrasonic waves in microsphere suspensions
Authors: Mobley Joel
Published: October 2013

For acoustic propagation in a sufficiently dispersive medium, it is possible for the group velocity to exceed the vacuum speed of light and even become negative. In this talk a physically realizable suspension of elastic spheres in water is described that can support such abnormal (i.e., superluminal/negative) acoustic group velocities at moderate solids concentrations. The relative importance of single versus multiple scattering descriptions of these suspensions at volume fractions that can support abnormal velocities is discussed. The physical relevance of the group velocity concept to pulse propagation is also illustrated. Conditions under which superluminal/negative group velocities can be observed as the speed of a peak in the envelope of an acoustic pulse in the low-megahertz ultrasound band are identified. Waveforms derived from propagation simulations are used to demonstrate how superluminal/negative group velocities could be directly observed experimentally.
A low-pressure technique for measuring the nonlinearity parameter B/A of small volume liquids
Authors: Davies Jevon , Prenzlow Bjorn , Tapson Jonathan
Published: October 2013

The acoustic nonlinearity parameter B/A is important for characterizing acoustic propagation in fluids. Recent studies have shown that B/A may be used to investigate biological tissue composition and provide insight into the molecular behavior of fluids. Such methods require a means of measuring B/A noninvasively using small sample volumes. This paper describes a variation of the isentropic phase method, which makes use of high-Q resonant modes found within a liquid-filled piezoelectric cavity resonator. B/A is measured indirectly by observing the resultant change in velocity occurring with a low-pressure (20 kPa) sinusoidal variation, performed under isothermal and steady-state conditions. It is shown that a high-frequency pressure oscillation is all that is needed for reliable B/A measurements, and these can be performed on sample volumes of less than 700 μl. Furthermore, measurements can be performed continuously once steady-state conditions have been achieved. Values for B/A are provided for three liquids, namely FC43, FC75, and water, with a consistency error of less than 1%.