bluuebunny/crossref_metadata_2025 huggingface dataset:
Acoustical Society of America Silver Medal in Animal Bioacoustics
Authors: Fay Richard R.
Published: September 2012

The Silver Medal is presented to individuals, without age limitation, for contributions to the advancement of science, engineering, or human welfare through the application of acoustic principles, or through research accomplishment in acoustics.
Acoustical Society of America Silver Medal in Noise
Authors: Attenborough Keith
Published: September 2012

The Silver Medal is presented to individuals, without age limitation, for contributions to the advancement of science, engineering, or human welfare through the application of acoustic principles, or through research accomplishment in acoustics.
The consultant's risk is an invitation to academia—An exploration of the greatest successes in a design career thus far, and the research-based foundations that made them possible
Authors: Pfeiffer Scott D.
Published: September 2012

The path of discovery is common for both the academic and the consultant. The point of departure for the consultant is the decision which must be based on limited information. The resulting void in knowledge often invites research within the narrow scope necessary for academic certainty. Exploration of some past successes provides a roadmap for a closer relationship between academia and the consulting community. There are seminal papers that are universally used in bracketing design decisions. The strength of these is in their certainty, and the certainty comes from clear assumptions and limitations to the conditions of the studies. Too often, the consulting world levies criticism against ivory tower academia for these very limitations, without recognizing and respecting the power in concrete baby steps forward. Students are likewise ill-equipped to spend their energies designing concert halls, or full projects. It is precisely the accumulated experience of consulting and collaborating with architects, engineers of all kinds, and owners that allows for confidence when leaping into the gap between judgement and certainty. In honor of Knudsen's contributions to scientific exploration and education, we will dedicate ourselves to the betterment of our profession through real connections between academia and the consulting community.
Patient and staff perceptions of hospital noise
Authors: Shiers Nicola J. , Shield Bridget M. , Glanville Rosemary E.
Published: September 2012

A large scale survey of noise and acoustic conditions in a range of inpatient hospital wards has been undertaken in two major hospitals in the UK. The survey involved noise and acoustic surveys of occupied hospital wards, identification of noise sources and questionnaire surveys of nursing staff and patients. The surveys were carried out in a range of different ward types, including surgical and medical wards, and ward sizes. In total 25 patient bays were measured, varying in size from single rooms to large bays containing 12 beds. Questionnaire responses were received from 66 staff and 154 patients in the two hospitals. This paper will present the results of the questionnaire surveys relating to noise annoyance and disturbance among staff and patients. Factors which affect perceptions of noise will be examined including personal factors such as age, sex, and length of time working/staying in the hospital. The sources of noise which cause the most disturbance to staff and patients will also be discussed.
A different perspective on the ongoing noise problem in U.S. hospitals: Lessons learned from existing acute care facilities and their patients' quiet-at-night scores
Authors: Madaras Gary
Published: September 2012

Acute care hospitals that care for Medicare patients now participate in the Hospital Consumer Assessment of Healthcare Providers and Systems (HCAHPS) quality survey as part of The Hospital Value-Based Purchasing program implemented by the Centers for Medicare and Medicaid Services (CMS). One question on the 27-item survey asks inpatients to score “how often was the area around your room quiet at night” as `always', `usually', `sometimes' or `never'. Patients score the quietness question the lowest of all the quality metrics, responding only 58% of the time that the area around their room was always quiet at night (as compared to an average score of 72% for all other metrics). Results of the HCAHPS survey will affect market share and financial reimbursements from CMS. Hospitals are scrambling to reduce noise levels and increase HCAHPS scores. A study was conducted, asking leaders of hospitals to share their noise reduction stories. Leaders from 241 hospitals contributed their challenges, successes and lessons learned. This presentation will share the findings including an in-depth look at one of the participating hospitals. Further insight into the ongoing noise problem in hospitals will be gained via HCAHPS scores analysis and overnight noise audits recently conducted in existing hospitals.
Experience measuring underwater sounds from piling activities
Authors: Reyff James A.
Published: September 2012

Extensive acoustic monitoring of pile driving activities along the U.S. West Coast has occurred in recent years as response to concerns regarding the effects to aquatic species. Impact pile driving activities have been found to produce high amplitude sounds that have injured fish and harassed marine mammals. As a result, requirements to reduce sounds, restrict the amount of pile driving and monitor effects to the environment have been required. The monitoring requirements vary for each project depending on the strength of the sound sources and potential presence of sensitive aquatic species. This presentation describes our experiences measuring acoustic signals from pile driving activities for various construction projects. Some results from testing sound attenuation devices are also presented. The challenges associated with monitoring these sounds are described, which include the complexities of measuring highly dynamic sounds in an environment with varying background levels. This presentation also describes the analysis methods used to describe pile driving sounds and how they are used to assess potential impacts to aquatic species. Methods for reporting results on a real-time or daily basis are also described.
Attenuation of pile driving noise using a double walled sound shield
Authors: Reinhall Per G. , Dahl Peter H.
Published: September 2012

Pile driving in water produces high sound levels in underwater environments. The associated pressures are known to produce deleterious effects on both fish and marine mammals. We present an evaluation of the effectiveness of surrounding the pile with a double walled sound shield to decrease impact pile driving noise. Four 32 m long, 76 cm diameter piles were driven 14 m into the sediment with a vibratory hammer. A double walled sound shield was then installed around the pile, and the pile was impact driven another 3 m while sound measurements were obtained. The last 0.3 m was driven with the sound shield removed, and data were collected for the untreated pile. The sound field obtained by finite element analysis is shown to agree well with measure data. The effectiveness of the sound shield is found to be limited by the fact that an upward moving Mach wave is produced in the sediment after the first reflection of the deformation wave against the bottom end of the pile. The sound reduction obtained through the use of the sound shield, as measured 10 meters away from the pile, is shown to be approximately 12dB dB re 1 μPa.
Transient analysis of sound radiated from a partially submerged cylindrical pile under impact
Authors: Shahab Shima , Hastings Mardi C.
Published: September 2012

Underwater noise generated by impact pile driving has potentially harmful effects on aquatic animals and their environment. In effort to predict sound radiation from piling activities, a structural acoustics finite-difference, time-domain (FDTD) model has been developed for transient analysis of a partially submerged cylindrical pile. Three coupled partial differential equations govern vibration of the pile wall and six partial differential equations govern its boundary conditions. The space-time gridding underlying the numerical computations controls selection of an appropriate time step while the physical geometry of the pile imposes an upper limit on the frequency bandwidth of wall oscillations and radiated sound. This bandwidth is inversely proportional to diameter for a cylindrical steel pile. The higher the frequency content in the dynamic response, the smaller the time step required in a transient analysis. So as diameter of the pile decreases, smaller time steps are required to capture the total bandwidth observed in field data. Results of correlations between radiated sound predicted by the FDTD model and acoustic field data from piles of different diameter are presented. [Work supported by the Georgia Institute of Technology and Oregon Department of Transportation through a subcontract from Portland State University.]
Barotrauma effects on fishes in response to impulsive pile driving stimuli
Authors: Casper Brandon M. , Halvorsen Michele B. , Carlson Thomas J. , Popper Arthur N.
Published: September 2012

We report on new results from controlled exposure studies of impulsive pile driving stimuli using the High Intensity Controlled Impedance Fluid Filled Wave Tube (HICI-FT). Following upon initial investigations focusing on injury thresholds and recovery from injuries in the Chinook salmon, experiments have been expanded to include lake sturgeon, Nile tilapia, hybrid striped bass, and hogchoker. Several key questions concerning pile driving exposure in fishes have been explored utilizing species with different types of swim bladders as well as a species without a swim bladder. Injury thresholds were evaluated in all species, with recovery from injuries measured in the hybrid striped bass. Other pile driving variables measured with the hybrid striped bass include difference in response between fish less than or greater than 2g as well as the minimum number of pile strikes needed for injuries to appear. A study to evaluate potential damage to inner ear hair cells was also conducted on hybrid striped bass as well as the Nile tilapia. These studies will be utilized to better understand, and possibly predict, the potential effects of pile driving exposure in fishes.
Sensor arrays for automated acoustic monitoring of bird behavior and diversity
Authors: Taylor Charles
Published: September 2012

There is growing interest in how to automate analysis of acoustic monitoring of bird vocalizations -- especially for monitoring bird behavior and biodiversity. I will review some of the main approaches to this problem and describe how this is being approached in our laboratory. We break the problem down to: event recognition; classification; localization; and analysis. These are not entirely independent. I will discuss some new approaches to these problems that seem to hold special promise.
Accurate localization over large areas with minimal arrays
Authors: Jones Douglas L. , Jones Aaron L. , Ratnam Rama
Published: September 2012

Passive terrestrial acoustic monitoring often requires accurate localization of acoustic sources over large areas. At least five microphones are required for unambiguous 3D relative-time-delay-based localization, but within what range can reasonable accuracy practically be obtained? An efficient new method for estimating localization error for any given array geometry and location allows rapid exploration of the expected accuracy for any given array geometry and region. The accuracy is proportional to the standard deviation of the relative-time-delay error and an array-geometry-and-source-location-specific term. Box-like arrays show high accuracy within the box boundaries, but a quasi-linear “discrete helical” array also shows excellent planar localization performance, over large squarish regions of the extent of the long axis of the array to either side of that axis, independent of the array length. Assuming a 1 kHz bandwidth acoustic source with an approximate “Rayleigh” correlation error of 1 ms, the analysis shows the planar localization error to be less than 2 m within that region. Field tests with a 60-m five-element discrete helical array and several recorded bird and mammal calls closely conformed to the analytical estimates and experimentally achieved sub-2-m accuracy within 60 m of the array.
A wireless acoustic sensor network for monitoring wildlife in remote locations
Authors: McKown Matthew W. , Lukac Martin , Borker Abraham , Tershy Bernie , Croll Don
Published: September 2012

Seabirds are the most threatened marine group with nearly 28% of extant species considered at risk of extinction. Managers and researchers face considerable financial and logistical challenges when designing programs to monitor the status of any of the 97 species listed as critically endangered, endangered, or vulnerable by the IUCN. These challenges are exacerbated by the fact that these birds breed in isolated/inaccessible locations, many have cryptic nest sites, and most return to colonies only at night. Acoustic sensors are an effective tool for monitoring the presence, distribution, and relative abundance of rare and elusive seabirds. We have developed new, cellphone-based wireless acoustic sensors that 1) are comparable to state-of-the-art sensors, 2) are affordable (~US$500.00 per hectare), 3) can sample continuously over months, 4) can telemeter data from remote locations via a cellular, microwave, or satellite link, and 5) can be reprogrammed remotely. To date we have deployed our wireless acoustic sensor networks to monitor seabirds of conservation concern including - Ashy Storm-petrel, Oceanodroma homochroa, on Southeast Farallon Island (CA), Tristram’s Storm-petrel, O. tristrami, on Tern Island (French Frigate Shoals), as well as Newell’s Shearwater, Puffinus newelli, and Hawaiian Petrel, Pterodroma sandwichensis, at the Upper Limahuli Preserve (Kaua’i, HI).
A template-based automatic bird phrase classification in noisy environments using limited training data
Authors: Kaewtip Kantapon , Williams Lance , Tan Lee N. , Kossan George , Alwan Abeer , Taylor Charles
Published: September 2012

Bird Songs typically comprise a sequence of smaller units, termed phrases, separated from one another by longer pauses; songs are thought to assist in mate attraction and territory defense. Studies of bird song would often be helped by automated phrase classification. Past classification studies usually employed techniques from speech recognition, such as MFCC feature extraction and HMMs. Problems with these methods include degradation from background noise, and often require a large amount of training data. We present a novel approach to robust bird phrase classification using template-based techniques. One (or more) template is assigned to each phrase with its specific information, such as prominent time-frequency components. In our trials with 1022 phrases from Cassin’s Vireo (Vireo cassinii) that had been hand-identified into 32 distinct classes, far fewer few examples per class were required for training in some cases only 1 to 4 examples for 84.95%-90.27% accuracy. The choice of distance metrics was crucial for such systems. We found that weighted 2D convolution is a robust distance metric for our task.. We also studied phrase patterns using Multi-Dimensional Scaling, a discriminative feature for phrase patterns that are very similar
Separating anthropogenic from natural sound in a park setting
Authors: Gillette John , Kemball Jeremy , Schomer Paul
Published: September 2012

This paper is a continuation of a study with the National Park Service to detect and separate natural and anthropogenic sound in a park setting. Last year, an algorithm was written to detect anthropogenic tones, because virtually all anthropogenic sound contains tones less than one 1KHz. By comparing each frequency to the surrounding third octave band, the algorithm detects almost all anthropogenic sounds. However, this method does not work for jet aircraft, because of their broad band sound when flying at altitude, not tones. This year, an algorithm was developed to detect jet aircraft, by comparing natural and anthropogenic sound over time as opposed to over frequency. The algorithm finds average equivalent sound level (LEQ) over a day and then removes anomalous peaks from the original sound recording. The program then subtracts the LEQ from the entire file, and the remaining sound is marked as probable jet aircraft sound. If the sound is present for a long enough duration, it is recorded as a jet sound.
Effects of encapsulation damping on frequency dependent subharmonic threshold for contrast microbubbles
Authors: Katiyar Amit , Sarkar Kausik
Published: September 2012

The frequency of minimum threshold for subharmonic generation from contrast microbubbles is investigated here. Increased damping—either due to the small radius or the encapsulation—is shown to shift the minimum threshold away from twice the resonance frequency. Free bubbles as well as four different models of the contrast agent encapsulation are investigated varying the surface dilatational viscosity. Encapsulation properties are determined using measured attenuation data for a commercial contrast agent. For sufficiently small damping, models predict two minima for the threshold curve—one at twice the resonance frequency being lower than the other at resonance frequency—in accord with the classical analytical result. However, increased damping damps the bubble response more at twice the resonance than at resonance, leading to a flattening of the threshold curve and a gradual shift of the absolute minimum from twice the resonance frequency towards the resonance frequency. The deviation from the classical result stems from the fact that the perturbation analysis employed to obtain it assumes small damping, not always applicable for contrast microbubbles (Supported by NSF CBET-0651912, CBET-1033256, DMR-1005283).
Pulse duration dependence of cavitation emissions and loss of echogenicity from ultrasound contrast agents insonified by Doppler pulses
Authors: Radhakrishnan Kirthi , Haworth Kevin J. , Kopechek Jonathan A. , Huang Bin , Huang Shaoling , McPherson David D. , Holland Christy K.
Published: September 2012

Careful determination of stable and inertial cavitation thresholds of UCAs exposed to pulsed ultrasound is required for their safe use in diagnostic and therapeutic applications. Echogenic liposomes and Definity® were diluted in porcine plasma and pumped through a physiological flow phantom. UCAs were insonified with pulsed Doppler ultrasound at three pulse durations (3.33 µs, 5.83 µs and 8.33 µs) over a range of peak rarefactional pressure amplitudes (0.06-1.9 MPa). A 10-MHz focused passive cavitation detector (PCD) was used to record cavitation emissions. PCD signals and B-mode images of UCAs and degassed water were acquired during insonation. Thresholds of stable and inertial cavitation, and loss of echogenicity were determined by piecewise linear fits of the cavitation powers and mean gray scale values, respectively. The stable cavitation thresholds were found to be lower than the inertial cavitation thresholds at each pulse duration setting. The thresholds of loss of echogenicity and stable and inertial cavitation were found to be dependent on pulse duration. The relationship between loss of echogenicity and cavitation emissions will be discussed in the context of using onscreen echogenicity to indirectly monitor cavitation during ultrasound-mediated therapy with UCAs. [Supported by NIH R01 HL059586.]
Acoustic emissions associated with ultrasound-induced rupture of ex vivo blood vessels
Authors: Hoerig Cameron L. , Serrone Joseph C. , Burgess Mark T. , Zuccarello Mario , Mast T. Douglas
Published: September 2012

Occlusion of blood vessels using high-intensity focused ultrasound (HIFU) is a potential treatment for arteriovenous malformations and other neurovascular disorders. However, HIFU-induced vessel occlusion can cause vessel rupture resulting in hemorrhage. Possible rupture mechanisms include mechanical effects of acoustic cavitation and hyperthermia of the vessel wall. To investigate the mechanism of vessel rupture and assess the possibility of rupture prediction from acoustic emissions, HIFU exposures were performed on 18 ex vivo porcine femoral arteries with simultaneous passive cavitation detection. Vessels were insonified by a 3.3 MHz focused source with spatial-peak, temporal-peak focal intensity 1728-2791 W/cm2 and a 50% duty cycle for durations up to 5 minutes. Time-dependent acoustic emissions were recorded by an unfocused passive cavitation detector and quantified within low-frequency (10-30 kHz), broadband (0.3-1.1 MHz), and subharmonic (1.65 MHz) bands. Vessel rupture was detected by inline metering of saline flow, recorded throughout each treatment. Rupture prediction tests, using receiver operating characteristic curve analysis, found subharmonic emissions to be most predictive. These results suggest that acoustic cavitation plays an important role in HIFU-induced vessel rupture. In HIFU treatments for vessel occlusion, passive monitoring of acoustic emissions may be useful in avoiding hemorrhage.
Ethanol injection induced cavitation and heating in tissue exposed to high intensity focused ultrasound
Authors: Chen Chong , Liu Yunbo , Maruvada Subha , Myers Matthew , Khismatullin Damir
Published: September 2012

High Intensity Focused Ultrasound (HIFU) can ablate tumors located deep in the body through highly localized energy deposition and tissue heating at the target location. The volume of a HIFU-induced thermal lesion can be increased in the presence of cavitation. This study explores the effect of ethanol injection on cavitation and heating in tissue-mimicking phantoms and bovine liver tissues exposed to HIFU. The HIFU transducer (0.825 MHz) operated at seven acoustic power levels ranging from 1.3 W to 26.8 W. The cavitation events were quantified by B-mode ultrasound imaging, needle hydrophone measurements, and passive cavitation detection (PCD). Temperature in or near the focal zone was measured by thermocouples embedded in the samples. The onset of inertial cavitation in ethanol-treated phantoms and bovine liver tissues occurred at a lower power level than in the untreated samples (control). The cavitation occurrence in turn resulted in a sudden rise of temperature in ethanol-treated samples at a lower acoustic power than that in control. The results of this work indicate that the use of percutaneous ethanol injection prior to HIFU exposure may improve the HIFU therapeutic efficiency.
Measurements of resonance frequencies and damping of large encapsulated bubbles in a closed, water-filled tank
Authors: Lee Kevin M. , McNeese Andrew R. , Tseng Laura M. , Wochner Mark S. , Wilson Preston S.
Published: September 2012

The ultimate goal of this work is to accurately predict the resonance frequencies of large (on the order of 10 cm radius) tethered encapsulated bubbles used in an underwater noise abatement system, and also to investigate ways to enhance the system’s efficacy over the use of air-filled bubbles alone. Toward that end, a closed water-filled tank was developed for the purpose of measuring the resonance frequency and damping of single large tethered encapsulated bubbles. The tank was designed to be operated in the long wavelength limit for frequencies below the lowest tank resonance, which was chosen to be 500 Hz, using the method described be Leighton, et al. [J. Acoust. Soc. Am. 112, 1366--1376 (2002)]. Individual bubble resonance frequencies and Q-factors were measured for encapsulated bubbles of various sizes. The effects of the encapsulating material and wall thickness were investigated, along with the effects of alternative fill gases and internal heat transfer materials. Experimental results are compared with an existing predictive model [J. Acoust. Soc. Am. 97, 1510--1521 (1995)] of bubble resonance and damping. [Work supported by Shell Global Solutions.]
Acoustic radiation from a point excited multi-layered finite plate
Authors: Hayek Sabih I. , Boisvert Jeffrey E.
Published: September 2012

The acoustic radiation from a finite rectangular composite plate is evaluated using eigenfunctions obtained through the use of three-dimensional equations of elasticity. The composite plate is made of perfectly bonded finite plates of identical lateral dimensions and of different thicknesses. The plate is free of shear stresses and is pinned on the in-plane displacements on all its boundaries and is baffled by an infinite rigid plane. The multi-layered plate is in contact with a different fluid medium on each of its two surfaces. The solution for the vibration response due to normal and shear surface forces is found in terms of the composite plate eigenfunctions that include heavy acoustic loading. The displacement vector field throughout the thickness of the plate is computed as well as the resultant near- and far-field radiated acoustic pressures for various ratios of thickness to plate dimensions over a broad frequency range. Initial results focus on a bilaminar plate. [Work supported by the ASEE Summer Faculty Research Program.]
Radiation loading on multi-panel plates
Authors: Vendhan Chiruvai P. , Suresh Poosarla V. , Bhattacharyya Subrata K.
Published: September 2012

Fluid-structure interaction problems involving the harmonic vibration of plates may be analyzed by employing an assumed modes approach. The associated hydrodynamic problem may be solved employing boundary element or finite element (FE) methods. An infinitely long multi-panel plate, having uniform spans and vibrating in contact with a fluid is considered here. A typical single span panel of the multi-panel system is set in a rigid baffle and the semi-infinite fluid domain over it is truncated. A FE model for the Helmholtz equation is employed over this domain, and suitable dampers are used on the truncation boundary to impose the radiation boundary condition. The FE solution is used to set up an eigenfunction expansion of the acoustic field outside the FE domain. Such an approach has originally been developed for exterior acoustic problems [C.P. Vendhan and C. Prabavathi, J. Vib. and Acoust., 118, 1996, 575-582]. The pressure field on the single panel and the infinite baffle is used to obtain the modal radiation loading in the form of added mass and radiation damping matrices of the multi-panel system, employing reciprocity and linear superposition. The method has been validated for an infinite plate example and illustrated using two and three panel systems.
Free-wave propagation relationships of second-order and fourth-order periodic systems
Authors: Hull Andrew J.
Published: September 2012

This talk develops an analytical expression for the determinant of two diagonally-indexed, full matrices when they are zero. These matrices originate from second- and fourth-order periodic system theory. The partial differential equations of these systems are solved using a series solution and are converted into closed-form analytical expressions. The denominators of these expressions are zero when free-wave propagation is present, and these denominators are equated to the determinants of the system matrices derived from a second analytical method. This process develops a relationship between frequency and wavenumber that is explicit for free-wave propagation in these systems. Two examples are included to illustrate this relationship.
Human body rhythms motion analogy in music sound
Authors: Ekimov Alexander
Published: September 2012

The universal algorithm developed for searching periodic and quasiperiodic rhythms in different type of signals [JASA 129(3)] was applied for a processing a few musical sound files and the results were reported on the ASA and other conferences and published in the POMA 14 (2011) article. Originally this algorithm was developed for finding human body motion rhythms in signals of different security systems. A preliminary conclusion from usage of this algorithm for a few music sound files founded rhythms in music files corresponded to rhythms of human regular body mechanical motion. Its appears that the musicians body parts motions, due to playing music can be found in rhythms of the playing music, which create an impression for the audience. These rhythms in analyzed music sound files are corresponding to mechanical human body movements due to walking or running also. More music file (including vocal) analysis with this rhythm algorithm and the results corresponding to rhythms of the human body motion are presented. This work was supported by the National Center for Physical Acoustics (NCPA) of the University of Mississippi.
Using resonance to study the deterioration of the pulse percept in jittered sequences
Authors: Velasco Marc J. , Large Edward W.
Published: September 2012

Studies of pulse perception in rhythms often ask what periodicity describes the pulse, e.g., tempo identification. In studies of pulse attribution, irregular rhythmic sequences are rated for the degree to which a pulse percept is elicited, if at all. Here, we investigate how a resonance approach to pulse perception may explain the reduction in pulse attribution ratings for jittered sequences while also predicting perceived tempo. We use a signal processing approach to predict perceptual ratings and behavioral performance measures (i.e., tapping data). Measures of resonance are evaluated using both FFT and a network of neural oscillators. The stimuli were isochronous sequences modified with varying levels of pseudorandom Kolakoski jitter. In separate blocks, participants were asked to provide pulse attribution judgments and to tap at the pulse rate. As levels of jitter increased, pulse attribution ratings decreased and participants tapped periodically at the mean sequence rate. At certain high levels of jitter, pulse attribution ratings increased and participants entrained at a new tapping rate. Resonance measures account for both mean tapping rate and pulse attribution ratings, suggesting that these two behavioral measures may be different aspects of the same resonant phenomenon.
Cross-cultural concepts and approaches in musical rhythm
Authors: Krishnamurthy Rohan
Published: September 2012

Western (written, notated) and Indian (oral, unnotated) systems of musical rhythm will be analyzed from theoretical and performance perspectives. Rhythmic concepts and parameters such as meter and tala (rhythmic cycles with constant duration and tempo), tuplet and nadai subdivisions of an underlying pulse, and accelerando (gradual accelerations in musical tempo) and decelerando (gradual decelerations in musical tempo) will be defined in a cross-cultural context. These systems of understanding temporal flow have wide-ranging implications on musical form, style and aesthetics, and artistic freedom. The corporeal or physical dimension of musical rhythm, resulting from instrumental techniques, vocalizations of rhythms, and physical systems of constructing and maintaining temporal flow such as tala visualizations and ensemble conducting, will also be considered. The presentation will include live, interactive musical demonstrations and will be followed by a performance on the mridangam, the primary percussion instrument from South India.
Essex experimental study: The impact of reverberation time on working classrooms
Authors: Canning David , James Adrian , Shields Bridget M.
Published: September 2012

There has been considerable debate regarding the value of adding acoustic treatment to refurbished classrooms. Is there any demonstrable benefit in reducing reverberation time in secondary schools to below 0.8s? This study aimed to examine the impact of reverberation time on working classrooms. Four similar classrooms with RT > 0.9s were selected for the study. Three rooms were treated with visually similar acoustically absorbent materials to reduce the RT to between 0.3 and 0.8s, the fourth room being left as a control. Over a period of six months the treatments were changed so that all class/teacher combinations experienced the different acoustic environments, while remaining blind to the condition. Ten teachers and 400 children including 17 hearing impaired children were involved in the study. Extensive objective and qualitative (interview and questionnaire) data were collected throughout the project. Analysis of the impact of room acoustics on classroom noise was conductedblind to the acoustic condition. Results demonstrate that RT has a significant impact on classroom noise levels and occupant behaviour. Reductionof reverberation time from 0.8 to 0.4s brought a reduction of 9 dB in LA90 as against the expected 3dB reduction. Qualitative data supports the beneficial impact on the classroom experience.
Effects of noise in high schools on pupils' perceptions and performance
Authors: Dockrell Julie E. , Connolly Daniel , Mydlarz Charles , Conetta Robert , Shield Bridget M. , Cox Trevor J.
Published: September 2012

A recent project has investigated acoustical conditions in secondary (high) schools, and examined the effects of a poor acoustic environment on teaching and learning of 11- to 16-year-olds. Around 2600 pupils from suburban secondary schools in England responded to an online questionnaire concerning the acoustic environment in their schools. The questionnaire data highlighted the differential effects of noise reported by more vulnerable learners. A repeated measures experimental study involving 572 pupils examined reading performance under two different classroom noise simulations. Results revealed a complex pattern reflecting noise levels, time of testing and measure of reading performance used. Reading text while exposed to classroom noise of 70 dB resulted in quicker reading but less accuracy in measures of reading comprehension compared with performance in 50 dB. The data further suggested that the pupils were not processing the text as deeply as was evident from their reduced lexical learning. There were also interactions with time of testing highlighting the importance of examining the effects of chronic exposure in addition to single session experimental testing. The test results show that capturing the effects of noise on pupils’ learning in realistic classroom environments raises a number of methodological and analytical problems.
Classroom acoustics and beyond: Soundscapes of school days
Authors: Crukley Jeff
Published: September 2012

Moving beyond traditional measures of classroom acoustics, in this presentation I propose a novel approach that addresses the dynamic nature of the school-day soundscape. In addition to noise floor and reverberation measures, I suggest that the use of dosimetry and observation of children's acoustic environments and situations can provide a more realistic representation of children's listening needs and the contexts of potential challenges. Cohorts of daycare, elementary, and high school students were shadowed by a researcher wearing a dosimeter and recording observational data. Detailed tracings of the sound levels, the types and sources of sounds, and classifications of the acoustic situations will be presented. Results demonstrated a wide range of listening environments, goals, and situations across all three cohorts of students. Sample recordings from the school day soundscapes will be presented. The implications of these results for how we think about and study classroom acoustics will be discussed.
Ongoing developments in classroom acoustic theory and practice in 2012, and reports on efforts to implement good classroom acoustics
Authors: Brown Pamela , Crouse Mary
Published: September 2012

We live in a time of increasingly loud competing sounds and hearing loss is the number one disability in the world. Diverse populations of school children are especially vulnerable. The result is a degradation of the child’s academic achievement. New classrooms, built everyday, often incorporate acoustical barriers which limit students’ achievements. Overcoming these barriers involves funding constraints, construction timelines and lack of support which requires advocacy from parents, school boards, and design teams. This advocacy should include the ANSI Classroom Acoustics standards and an acoustical assessment of existing classrooms. Complex classroom acoustics challenges may include reduction of noise radiated by HVAC systems, improved acoustic treatment of external walls to minimize exterior noise and acoustic design of walls between adjacent noisy classrooms. Next steps for schools should be to retain an architect and/or an acoustical engineer for remodels and new school construction who are well versed in acoustics for educational settings and noise control. A booklet covering these issues, and designed as a practical guide for educators not versed in acoustics, is in preparation by the Acoustical Society of America.
Creation of an architects' companion booklet for ANSI 12.60 American National Classroom Acoustics Standard
Authors: Woolworth David S. , Phinney Peter
Published: September 2012

This paper outlines the process of collaboration between an architect and acoustician to produce a document that translates the fundamental objectives and ideas of ANSI 12.60 from the semi-archaic language of an acoustics standard to a simple, useful reference for all stripes of architects. Included will be the paradigm of the approach, definition of scope presented, order of presentation, and methods of presentation.
Coherent ambient infrasound recorded by the International Monitoring System
Authors: Matoza Robin S. , Landes Matthieu , Le Pichon Alexis , Ceranna Lars , Brown David
Published: September 2012

Ambient noise recorded by the International Monitoring System (IMS) infrasound network includes incoherent wind noise and coherent infrasonic signals; both affect detection of signals of interest. We present summary statistics of coherent infrasound recorded by the IMS network. We have performed systematic broadband (0.01-5 Hz) array processing of the IMS historical dataset (39 stations from 2005 to 2010) using an implementation of the Progressive Multi-Channel Correlation (PMCC) algorithm in log-frequency space. From these results, we estimate multi-year 10th, 50th, and 90th percentiles of the rms pressure of coherent signals in 15 frequency bands for each station. We compare the resulting coherent noise models in the 15 frequency bands with raw power spectral density noise models, which inherently include both incoherent and coherent noise. We show that IMS arrays consistently record coherent ambient infrasound across the broad frequency range from 0.01 to 5 Hz when wind-noise levels permit. Multi-year averaging of PMCC detection bulletins emphasizes continuous signals such as oceanic microbaroms, as well as persistent transient signals such as repetitive volcanic, surf, or anthropogenic activity (e.g., mining or industrial activity).
The variability in infrasound observations from stratospheric returns
Authors: Evers Läslo , Smets Pieter
Published: September 2012

Long range infrasound propagation depends on the wind and temperature around the stratopause (alt. 50 km). There is a seasonal change in the wind direction around the equinoxes. In summer, the wind and temperature structure of the stratosphere is stable. In winter, however, planetary waves in the troposphere can travel into the stratosphere and disturb the mean flow. This mean flow is most pronounced in the stratospheric surf zone from 20N (20S) to 60N (60S). One of the most dramatic events in the stratosphere is a Sudden Stratospheric Warming (SSW) during the winter. These occur every winter on the Northern Hemisphere as minor Warmings with a major SSW each other year. SSWs have a strong influence on infrasound propagation due to the large change in temperature and possible reversal of the wind. Therefore, SSWs are important to consider in relation to, e.g., regional and global monitoring with infrasound for verification purposes or other strategic deployments. In this presentation, the detectability of infrasound will be considered as a function of the state of the stratosphere. Variations in strength of the circumpolar vortex (around the stratopause) and temperature changes will give rise to specific propagation conditions which can often not be foreseen.
Anomalous transmission of infrasound through air-water and air-ground interfaces
Authors: Godin Oleg A.
Published: September 2012

Sound speed and especially mass density exhibit large relative changes at gas-liquid and gas-solid interfaces. Sound transmission through an interface with a strong impedance contrast is normally very weak. However, diffraction effects can lead to the phenomenon of anomalous transparency of gas-liquid or gas-solid interfaces, where most of the acoustic power generated by a compact, low-frequency source located within the liquid or within the solid is radiated into the gas. Contrary to the conventional wisdom based on ray-theoretical predictions and observations at higher frequencies, infrasonic energy from compact waterborne and underground sources can be effectively transmitted into air. This paper reviews the theory and emerging experimental evidence of the anomalous transparency. Physical mechanisms responsible for enhanced sound transmission at low frequencies are discussed. The phenomenon of anomalous transparency can have significant implications, in particular, for localization of buried objects and for acoustic monitoring, detection, and classification of powerful underwater and underground explosions for the purposes of the Comprehensive Nuclear-Test-Ban Treaty.
Exploiting correlation in wind noise for enhanced detection of transient acoustic signals
Authors: Frazier William G.
Published: September 2012

Wind noise presents significant difficulties when trying to detect transient acoustic signals. The most common approach to enhancing signal detection when the signal-to-noise ratio is low due to wind noise is to utilize mechanical windscreens, large number of widely spaced microphones or a combination of both. Results from recent experimental investigations and algorithm developments are presented that demonstrate a alternative method for improving detection of transients that utilizes only a few closely spaced microphones and a unique processing technique that explicitly exploits the correlation among wind noise induced pressure fluctuations.
Uncertainty associated with in-situ frequency-response estimation by reference-sensor comparison at infrasound monitoring sites
Authors: Gabrielson Thomas B.
Published: September 2012

In-situ measurement of the frequency-response of infrasound array elements has proven to be a useful tool in the assessment of element performance. In order to transition to a true calibration process, the uncertainties inherent in the method must be determined. It is critically important to distinguish between bias errors and random errors and to recognize that the ambient pressure fluctuations are typically not stationary in a statistical sense. The time evolution of the cross-spectrum is particularly useful for identifying non-stationary behavior and for isolating high-quality data intervals. Three important cases are tractable: high coherence between the reference sensor and the infrasound element; low-to-moderate coherence resulting from uncorrelated noise in one channel; and moderate coherence resulting from uncorrelated noise in both channels. For a fixed number of averages, the confidence limits for the frequency-response estimate are often considerably tighter than the corresponding limits for the estimated spectral densities.
Links between mismatch negativity responses and speech intelligibility in noise
Authors: Koerner Tess K. , Zhang Yang , Nelson Peggy
Published: September 2012

Research has shown that the amplitude and latency of neural responses to passive mismatch negativity (MMN) tasks are affected by noise (Billings et al., 2010). Further studies have revealed that informational masking noise results in decreased P3 amplitude and increased P3 latency, which correlates with decreased discrimination abilities and reaction time (Bennett et al., 2012). This study aims to further investigate neural processing of speech in differing types of noise by attempting to correlate MMN neural responses to consonant and vowel stimuli with results from behavioral sentence recognition tasks. Preliminary behavioral data indicate that noise conditions significantly compromise the perception of consonant change in an oddball discrimination task. Noise appears to have less of an effect on the perception of vowel change. The MMN data are being collected for the detection of consonant change and vowel change in different noise conditions. The results will be examined to address how well the pre-attentive MMN measures at the phonemic level can predict speech intelligibility at the sentence level using the same noise conditions.
Effect of broadband contralateral noise on distortion product otoacoustic emissions and psychophysical tuning curves
Authors: Wicher Andrzej
Published: September 2012

The main purpose of this work was to describe an influence of contralateral stimulation (CS) on distortion products otoacoustic emissions (DPOAEs) and psychophysical tuning curves (PTCs). The fast method for determining PTCs was used in the study. DPOAEs and PTCs were measured in two modes: in the presence or absence of CS. The CS was a broadband noise at a level of 50 SPL. The primary tones with frequencies f1 and f2, (f2/f1 = 1.21) were presented at levels of L1 = 60 dB SPL, and L2 = 50 dB SPL. A pulsed sinusoidal signal at a sensation level (SL) of 10 dB was used in the measurements of the PTC. The signal frequency was 1 or 2 kHz. Ten normal-hearing subjects participated in this study. The CS caused a decrease in the level of the DPOAEs (suppression effect) in 90% of cases, in the whole frequency range of f2 (i.e. from 845 to 6200 Hz). The maximum suppression of the DPOAE level occurs for the f2 frequency from 1 to 2 kHz. For both signal frequencies the CS significantly reduces the sharpness of the PTCs. The CS has a significant effect on decreasing the quality factor (Q10) of PTCs.
Effects of listener bias on auditory acuity for aircraft in real-world ambient environments
Authors: Davis Matthew J. , Feth Lawrence L. , Spottswood Michael , Hall John
Published: September 2012

Hoglund et al. (2010) investigated the ability of listeners to detect the presence of aircraft masked by ongoing ambient sounds using a two interval forced choice (2IFC) procedure. They found that the signal-to-noise ratio required for target detection varied across the different types of ambient environments. Recordings of helicopters in flight were used as target signals and maskers were recorded in rural, suburban and urban locations. Their goal was to better approximate real-world conditions. The goal of the current study is to extend those results to include factors that may bias the listener under more realistic conditions. The 2IFC procedure is designed to minimize listener bias; however, real-world listening conditions are more typically one interval situations. The frequency of occurrence of aircraft over-flights and the costs of errors and rewards for correct responses may substantially affect some estimates of listener sensitivity. Work reported here investigated the influence of apriori probability of target occurrence and manipulation of the pay-off matrix on the acuity measures reported by Hoglund, et al., using the same target sounds and environmental maskers. Psychometric functions shifted by ~18 dB as frequency of targets varied from 20% to 80%. ROC curves display the influence of pay-off manipulations.