bluuebunny/crossref_metadata_2025 huggingface dataset:
Determining the detection function of passive acoustic data loggers for porpoises using a large hydrophone array
Authors: Koblitz Jens C. , Brundiers Katharina , Kost Mario , Burt Louise , Thomas Len , MacAulay Jamie , Ljungqvist Cinthia T. , Mikkelsen Lonnie , Stilz Peter , Benke Harald
Published: May 2014

Click loggers such as C-PODs are an important tool to monitor the spatial distribution and seasonal occurrence of small odontocetes. To determine absolute density, information on the detection function, the detection probability as a function of distance, and derived from this, the effective detection radius (EDR), is needed. In this study a 15 channel hydrophone array, deployed next to 12 C-PODs, was used to localize porpoises and determine their geo-referenced swim paths using the ship’s GPS and motion sensors. The detection function of C-PODs was then computed using the distance between the animals and each C-POD. In addition to this, the acoustic detection function of C-PODs has been measured by playing back porpoise-like clicks using an omni-directional transducer. The EDR for these porpoise-like clicks with a source level of 168 dB re 1 μPa pp varied from 41 to 243 m. This variation seemed to be related to the sensitivity of the devices; however, season and water depth also seemed to have an influence on detectability.
Female North Atlantic right whales produce gunshot sounds
Authors: Gerstein Edmund R. , Trygonis Vailis , McCulloch Steve , Moir Jim , Kraus Scott
Published: May 2014

North Atlantic right whales (Eubalaena glacialis) produce loud, broadband, short duration sounds referred to as gunshots. The sounds have been hypothesized to function in a reproductive context, as sexual advertisement signals produced by solitary adult males to attract females and/or agonistic displays among males in surface active groups. This study provides evidence that gunshot sounds are also produced by adult females and examines the acoustics and behavioral contexts associated with these calls. Results from boat-based observational surveys investigating the early vocal ontogeny and behavior of right whales in the critical southeast calving habitat are presented for a subset of mothers who produced gunshots while in close proximity to their calves. Of 26 different isolated mother-calf pairs, gunshots were recorded from females of varied ages and maternal experience. The signals were recorded when calves separated from their mothers during curious approaches toward objects on the surface. While the spectral and temporal characteristics of female gunshots resemble those attributed to adult males, these calls were orders of magnitude quieter (Ő30 dB). Relatively quiet gunshots posed minimal risk of injury to nearby calves. The social and behavioral context suggests gunshots were associated with maternal communication and may also be indicators of stress and agitation.
Acoustic levitation of gels: A proof-of-concept for thromboelastography
Authors: Gruver Nate , Holt R. Glynn
Published: May 2014

Current thromboelastography in the clinic requires contact between the measurement apparatus and the blood being studied. An alternative technique employs levitation of a small droplet to limit contact with the blood sample to air alone. As has been demonstrated for Newtonian liquid drops, the measurement of static spatial location and sample deformation can be used to infer sample surface tension. In the current study, ultrasonic acoustic levitation was used to levitate viscoelastic samples. Gelatin was used as a stand-in for blood to establish the validity of the ultrasonic levitation technique on viscoelastic materials. Liquid data was first taken to benchmark the apparatus, then deformation/location studies were performed on set and setting gelatin gels. Relationships between gelling time, gel concentration, and gel firmness were demonstrated. The elastic modulus of gels was inferred from the data using an idealized model.
Improved simulations of diagnostic ultrasound with the fast nearfield method and time-space
Authors: Nariyoshi Pedro C. , McGough Robert J.
Published: May 2014

Diagnostic ultrasound simulations are presently under development for FOCUS (http://www.egr.msu.edu/~fultras-web). To reduce the computation time without increasing the numerical error, each signal in FOCUS is calculated once, stored, and then the effects of different time delays are calculated with cubic spline interpolation. This is much more efficient than calculating the same transient signal at a scatterer repeatedly for different values of the time delay. Initially, the interpolation results were obtained from uniformly sampled signals, and now the signal start and end times are also considered. This step reduces the error in the pulse-echo calculation without significantly increasing the computation time. Simulated B-mode images were evaluated in a cyst phantom with 100 000 scatterers using this approach. Images with 50 A-lines are simulated for a linear array with 192 elements, where the translating subaperture contains 64 elements. The resulting simulated images are compared to images obtained with the same configuration in Field II (http://field-ii.dk/). An error of approximately 1% is achieved in FOCUS with a sampling frequency of 30 MHz, where Field II requires a sampling frequency of 180 MHz to reach the same error. FOCUS also reduces the simulation time by a factor of six. [Supported in part by NIH Grant R01 EB012079.]
Super wideband quantitative ultrasound imaging for trabecular bone with novel wideband single crystal transducer and frequency sweep measurement
Authors: Lin Liangjun , Ambike Eesha , Sahul Raffi , Qin Yi-Xian
Published: May 2014

Current quantitative ultrasound (QUS) imaging technology for bone provides a unique method for evaluating both bone strength and density. The broadband ultrasound attenuation (BUA) has been widely accepted as a strong indicator for bone health status. Researchers have reported BUA data between 0.3 and 0.7 MHz have strong correlation with the bone density. Recently, a novel spiral-wrapped wideband ultrasound transducer fabricated from piezoelectric PMN-PT single crystal is developed by TRS. This novel transducer combines the piezoelectric single crystal material and use of wide-band resonance transducer to provide a bandwidth superior to commercial devices with the capacity for a high sensitivity. To evaluate its application in bone imaging, a trabecular bone plate (6.5 mm thick) was prepared. The TRS transducer emits customized chirp pulses through the bone plate. The bandwidth of the ultrasound pulses is 0.2 MHz, ranging from 0.2 to 3 MHz. Based on the attenuation of the received pulses, the frequency spectrum is created to analyze the attenuation characteristics of the ultrasound attenuation across the super wide bandwidth. This new transducer technology provides more information across a wider bandwidth than the conventional ultrasound transducer and can therefore give rise to new QUS modality to evaluate bone health status.
Modeling ultrasonic scattering from high-concentration cell pellet biophantoms using polydisperse structure functions
Authors: Han Aiguo , O’Brien William D.
Published: May 2014

Backscattering coefficient (BSC) has been used extensively to characterize tissue. In most cases, sparse scatterer concentrations are assumed. However, many types of tissues have dense scattering media. This study models the scattering of dense media. Structure functions (defined herein as the total BSC divided by incoherent BSC) are used to take into account the correlation among scatterers for dense media. Structure function models are developed for polydisperse scatterers. The models are applied to cell pellet biophantoms that are constructed by placing live cells of known concentration in a mixture of bovine plasma and thrombin to form a clot. The BSCs of the biophantoms were measured using single-element transducers over 11–105 MHz. Experimental structure functions were derived by comparing the BSCs of two cell concentrations, a lower concentration (volume fraction: <5%, incoherent scattering only) and a higher concentration (volume fraction: ~74%). The structure functions predicted by the models agreed with the experimental data. Fitting the models yielded cell radius estimates (Chinese hamster ovary cell: 6.9 microns, MAT cell: 7.1 microns, 4T1 cell: 8.3 microns) that were consistent with direct light microscope measures (Chinese hamster ovary: 6.7 microns, MAT: 7.3 microns, 4T1: 8.9 microns). [Work supported by NIH CA111289.]
Effect of fire and high temperatures on alarm signals
Authors: Abbasi Mustafa Z. , Wilson Preston S. , Ezekoye Ofodike A.
Published: May 2014

Firefighters use an acoustic alarm to recognize and locate other firefighters that need rescue. The alarm, codified under NFPA 1982 : Standard for Personal Alert Safety System (PASS), is typically implemented in firefighter’s SCBA (self-contained breathing apparatus) and is carried by a majority of firefighter in the United States. In the past, the standard specified certain frequency tones and other parameters and left implementation up to manufacturers, leading to an infinite number of possibilities that could satisfy the standard. However, there is a move to converge the standard to a single alarm sound. The research presented provides science-based guidance for the next generation of PASS signal. In the two previous ASA meetings, a number of experimental and numerical studies were presented regarding the effect of temperature stratification on room acoustics. The present work uses models developed under those studies to quantify the effect of various signal parameters (frequency ranges, time delay between successive alarms, temporal envelope etc.) on the signal heard by a firefighter. Understanding the effect of these parameters will allow us to formulate a signal more resistant to distortion caused by the fire. [Work supported by U.S. Department of Homeland Security Assistance to Firefighters Grants Program.]
Measures for noise reduction aboard ships in times of increasing comfort demands and new regulations
Authors: Seiler Robin D. , Holbach Gerd
Published: May 2014

Through the revision of the “Code of Noise Levels on Board Ships,” the International Maritime Organization has tightened its recommendations from 1984 by lowering the allowed maximum noise exposure levels on board ships. Hereby, the most significant change can be observed for cabins. To consider the effects of noise on health and comfort their noise level limits were reduced by 5 dB to 55 dB(A) equivalent continuous SPL. Another important alteration is that parts of the new code will be integrated into the SOLAS-Convention, and therefore, some of its standards will become mandatory worldwide. In order to meet the increasing demands, the focus has to be put on noise reduction measures in receiving rooms and along the sound propagation paths since the opportunity to use noise reduced devices or machines is not always given. This study gives an overview of the current noise situation on board of different types of ships. The efficiency of measures for noise reduction is discussed with focus on cabins and cabin-like receiving rooms. Especially, the role of airborne sound radiation from ship windows induced by structure-borne sound is investigated.
On the acoustic and aerodynamic performance of serrated airfoils
Authors: Liu Xiao , Azarpeyvand Mahdi , Joseph Phillip
Published: May 2014

This paper is concerned with the aerodynamic and aeroacoustic performance of airfoils with serrated trailing edges. Although a great deal of research has been directed toward the application of serrations for reducing the trailing-edge noise, the aerodynamic performance of such airfoils has received very little research attention. Sawtooth and slitted-sawtooth trailing edges with specific geometrical characteristics have been shown to be effective in reducing the trailing edge noise over a wide range of frequencies. It has, however, also been shown that they can alter the flow characteristics near the trailing edge, namely the boundary layer thickness and surface-pressure fluctuations, and the wake formation. To better understand the effects of serrations, we shall carry out various acoustic and wind tunnel tests for a NACA6512-10 airfoil with various sawtooth, slitted and slitted-sawtooth trailing edge profiles. Flow measurements are carried out using PIV, LDV and hot-wire anemometry and the steady and unsteady forces on the airfoil are obtained using a three-component force balance system. Results are presented for a wide range of Reynolds numbers and angles of attack. The results have shown that the use of sharp serrations can significantly change the aerodynamic performance and wake characteristics of the airfoil.
Human-computer music performance: A brief history and future prospects
Authors: Dannenberg Roger B.
Published: May 2014

Computer accompaniment began in the eighties as a technology to synchronize computers to live musicians by sensing, following, and adapting to expressive musical performances. The technology has progressed from systems where performances were modeled as sequences of discrete symbols, i.e., pitches, to modern systems that use continuous probabilistic models. Although score following techniques have been a common focus, computer accompaniment research has addressed many other interesting topics, including the musical adjustment of tempo, the problem of following an ensemble of musicians, and making systems more robust to unexpected mistakes by performers. Looking toward the future, we find that score following is only one of many ways musicians use to synchronize. Score following is appropriate when scores exist and describe the performance accurately, and where timing deviations are to be followed rather than ignored. In many cases, however, especially in popular music forms, tempo is rather steady, and performers improvise many of their parts. Traditional computer accompaniment techniques do not solve these important music performance scenarios. The term Human-Computer Music Performance (HCMP) has been introduced to cover a broader spectrum of problems and technologies where humans and computers perform music together, adding interesting new problems and directions for future research.
Automatic music accompaniment allowing errors and arbitrary repeats and jumps
Authors: Sagayama Shigeki , Nakamura Tomohiko , Nakamura Eita , Saito Yasuyuki , Kameoka Hirokazu
Published: May 2014

Automatic music accompaniment is considered to be particularly useful in exercises, rehearsals and personal enjoyment of concerto, chamber music, four-hand piano pieces, and left/right hand filled in to one-hand performances. As amateur musicians may make errors and want to correct them, or he/she may want to skip hard parts in the score, the system should allow errors as well as arbitrary repeats and jumps. Detecting such repeats/jumps, however, involves a large complexity of search for maximum likelihood transition from one onset timing to another in the entire score for every input event. We have developed several efficient algorithms to cope with this problem under practical assumptions used in an online automatic accompaniment system named “Eurydice.” In Eurydice for MIDI piano, the score of music piece is modeled by Hidden Markov Model (HMM) as we proposed for rhythm modeling in 1999 and the maximum likelihood score following is done to the polyphonic MIDI input to yield the accompanying MIDI output (e.g., orchestra sound). Another version of Eurydice accepts monaural audio signal input and accompanies to it. Trills, grace notes, arpeggio, and other issues are also discussed. Our video examples include concertos with MIDI piano and piano accompanied sonatas for acoustic clarinet.
Improvement of the measurement of the sound absorption using the reverberation chamber method
Authors: Vercammen Martijn , Lautenbach Margriet
Published: May 2014

The random incidence absorption coefficient is measured in a reverberation room according to ISO 354 or ASTM C423-09a. It is known that the inter laboratory accuracy under Reproducibility conditions of these results is still not very well. It is generally assumed that the limited diffusion properties of reverberation rooms, especially with a strongly sound absorbing sample, are the main reason for the bad reproducibility values for the sound absorption between laboratories. Reverberation rooms should be made much more diffuse to reduce the interlaboratory differences. However there are practical limitations in quantifying and improving the diffuse field conditions. The measured sound absorption still seems to be the most sensitive descriptor of the diffuse field conditions. A way to further reduce the inter-laboratory differences is the use of a reference absorber to qualify a room and to calibrate the results of a sound absorption measurement. In the presentation an overview will be given of the research performed and some suggestions for the new version of ISO 354 will be given.
When acoustically rated doors fail to perform as rated, who is responsible—Manufacturer or installer?
Authors: Hale Marlund E.
Published: May 2014

Acoustical doors are designed, manufactured, and sold by several companies in the United States. They are available in multiple styles and acoustical performance ratings. The doors are specified, selected, and purchased based on the published performance ratings provided by the manufacturers, which often have had their doors tested by NAVLAP accredited acoustical testing laboratories. Of course, it should be understood by the acoustical door specifier that lab-rated doors will rarely, if ever, perform as rated after field installation. This paper presents field performance test results for numerous acoustical doors that significantly failed even the lower expected field performance criteria. The acoustical doors were all tested in-situ after they were installed in several different venues by the manufacturer’s or vendor’s trained and/or certified acoustical door installers. Reasons for certain field-performance failures are discussed and specific remedies are recommended.
Evolution of the derivative skewness for high-amplitude sound propagation
Authors: Reichman Brent O. , Muhlestein Michael B. , Gee Kent L. , Neilsen Tracianne B. , Thomas Derek C.
Published: May 2014

The skewness of the first time derivative of a pressure waveform has been used as an indicator of shocks and nonlinearity in both rocket and jet noise data [e.g., Gee et al., J. Acoust. Soc. Am. 133, EL88–EL93 (2013)]. The skewness is the third central moment of the probability density function and demonstrates asymmetry of the distribution, e.g., a positive skewness may indicate large, infrequently occurring values in the data. In the case of nonlinearly propagating noise, a positive derivative skewness signifies occasional instances of large positive slope and more instances of negative slope as shocks form [Shepherd et al., J. Acoust. Soc. Am. 130, EL8–EL13 (2011)]. In this paper, the evolution of the derivative skewness, and its interpretation, is considered analytically using key solutions of the Burgers equation. This paper complements a study by Muhlestein et al. [J. Acoust. Soc. Am. 134, 3981 (2013)] that used similar methods but with a different metric. An analysis is performed to investigate the effect of a finite sampling frequency and additive noise. Plane-wave tube experiments and numerical simulations are used to verify the analytic solutions and investigate derivative skewness in random noise waveforms. [Work supported by ONR.]
Spectral variations near a high-performance military aircraft
Authors: Neilsen Tracianne B. , Gee Kent L. , James Michael M.
Published: May 2014

Spectral characteristics of jet noise depend upon location relative to the nozzle axis. Studies of the spectral variation in the far field led to a two-source model of jet noise, in which fine-scale turbulent structures are primarily responsible for noise radiation to the nozzle sideline and large-scale turbulent structures produce the broad, dominant radiation lobe farther aft. Detailed noise measurements near an F-22A Raptor shed additional insights into this variation. An initial study [Neilsen et al., J. Acoust. Soc. Am. 133, 2116–2125] was performed with ground-based microphones in the mid-field. The similarity spectra associated with the large and fine-scale turbulent structures [Tam et al., AIAA paper 96–1716 (1996)] provide a reasonable representation of measured spectra at many locations. However, there are additional features that need further investigation. This paper explores the presence of a double peak in the spectra in the maximum radiation direction and a significant change in spectral shape at the farthest aft angles using data from large measurement planes (2 m × 23 m) located 4–6 jet nozzle diameters from the shear layer. The spatial variation of the spectra provides additional insight into ties between the similarity spectra and full-scale jet noise. [Work supported by ONR.]
Acoustic propagation over a complex site: A parametric study using a time-domain approach
Authors: Dragna Didier , Blanc-Benon Philippe
Published: May 2014

The influence of the ground characteristics and the meteorological conditions on the acoustic propagation of impulse signals above a complex site is studied. For that, numerical simulations using a finite-difference time-domain solver in curvilinear coordinates [Dragna et al., JASA 133(6), 3751–3763 (2013)] are performed. The reference site is a railway site in la Veuve near Reims, France, with a non-flat terrain and a mixed impedance ground, where outdoor measurements were performed in May 2010. Comparisons between the experimental data and the numerical results will be reported both in frequency domain and time domain. First, it will be shown that the numerical predictions are in a good agreement with the measured energy spectral densities and waveforms of the acoustic pressure. Second, the impacts of the variations of the ground surface impedances, of the topography and the wind direction will be analyzed.
Challenges in exploring the role of medial olivocochlear efferents in auditory tasks via otoacoustic emissions
Authors: Wojtczak Magdalena , Beim Jordan A. , Oxenham Andrew J.
Published: May 2014

A number of recent psychophysical studies have hypothesized that the activation of medial olivocochlear (MOC) efferents plays a significant role in forward masking. These hypotheses are based on general similarities between spectral and temporal characteristics exhibited by some psychophysical forward-masking results and by effects of efferent activation measured using physiological methods. In humans, noninvasive physiological measurements of otoacoustic emissions have been used to probe changes in cochlear responses due to MOC efferent activation. The aim of this study was to verify our earlier efferent-based hypothesis regarding the dependence of psychophysical forward masking of a 6-kHz probe on the phase curvature of harmonic-complex maskers. The ear-canal pressure for a continuous 6-kHz probe was measured in the presence and absence of Schroeder-phase complexes used as forward maskers in our previous psychophysical study. Changes in the ear-canal pressure were analyzed using methods for estimating the effects of efferent activation on stimulus frequency otoacoustic emissions under the assumption that changes in cochlear gain due to efferent activation will be reflected in changes in the magnitude and phase of the emission. Limitations and challenges in relating effects of feedback-based reflexes to psychophysical effects will be discussed. [Work supported by NIH grant R01DC010374.]
Tongue shape complexity for liquids in Parkinsonian speech
Authors: Whalen Doug H. , Dawson Katherine M. , Carl Micalle , Iskarous Khalil
Published: May 2014

Parkinson’s disease (PD) is a neurological disorder characterized by the degeneration of dopaminergic neurons. Speech impairments in PD are characterized by slowed muscle activation, muscle rigidity, variable rate, and imprecise consonant articulation. Complex muscular synergies are necessary to coordinate tongue motion for linguistic purposes. Our previous work showed that people with PD had an altered rate of change in tongue shape during vowel to consonant transitions, but differences were small, perhaps due to the simplicity of the speech task. In order to test sentences, four PD participants and three older controls were imaged using ultrasound. They repeated sentences from the Rainbow Passage. Tongue shape complexity in liquids and adjacent vowels was assessed by their bending energy [Young et al., Info. Control 25(4), 357–370 (1974)]. Preliminary results show that bending energy was higher in liquids than in vowels, and higher in controls than PD speakers. Production of liquids typical requires a flexible tongue shape; these PD speakers show reduced flexibility that is nonetheless compensated sufficiently for the production of intelligible speech. Implications for speech motor control and for PD evaluation will be discussed.
Perceptual learning in the laboratory versus real-world conversational interaction
Authors: Casserly Elizabeth D. , Pisoni David B.
Published: May 2014

Understanding perceptual learning effects under novel acoustic circumstances, e.g., situations of hearing loss or cochlear implantation, constitutes a critical goal for research in the hearing sciences and for basic perceptual research surrounding spoken language use. These effects have primarily been studied in traditional laboratory settings using stationary subjects, pre-recorded materials, and a restricted set of potential subject responses. In the present series of experiments, we extended this paradigm to investigate perceptual learning in a situated, interactive, real-world context for spoken language use. Experiments 1 and 2 compared the learning achieved by normal-hearing subjects experiencing real-time cochlear implant acoustic simulation in either conversation or traditional feedback-based computer training. In experiment 1, we found that interactive conversational subjects achieved perceptual learning equal to that of laboratory-trained subjects for speech recognition in the quiet, but neither group generalized this learning to other domains. Experiment 2 replicated the learning findings for speech recognition in quiet and further demonstrated that subjects given active perceptual exposure were able to transfer their perceptual learning to a novel task, gaining significantly more benefit from the availability of semantic context in an isolated word recognition task than subjects who completed conventional laboratory-based training.
Passive ranging in underwater acoustic environment subject to spatial coherence loss
Authors: Ge Hongya , Kirsteins Ivars P.
Published: May 2014

In this work, a two-stage multi-rank solution for passive ranging is presented for acoustic sensing systems using multi-module towed hydrophone arrays operating in underwater environments subject to spatial coherence loss. The first stage of processing consists of adaptive beam-forming on the individual modular array level to improve the signal-to-noise ratio and at the same time to adaptively reduce the data dimensionality. The second stage of multi-rank filtering exploits the possible spatial coherence existing across the spatially distributed modular arrays to further improve the accuracy of passive ranging. The proposed solution reduces to either the well-known non-coherent solution under no spatial coherence, or the fully coherent solution under perfect spatial coherence. For large distributed arrays, the asymptotic approximation of the proposed solution has a simple beam-space interpretation. We conclude with a discussion of the estimator when the spatial coherence is unknown and its implications for the passive ranging system performance.
Bearing estimation from vector sensor intensity processing for autonomous underwater gliders
Authors: Smith Kevin B. , Kubisak Timothy , Upshaw James M. , Martin James S. , Trivett David , Traweek C. Michael
Published: May 2014

Data have been collected on acoustic vector sensors mounted on autonomous underwater gliders in the Monterey Bay during 2012–2013. In this work, we show results of intensity processing to estimate bearing to impulsive sources of interest. These sources included small explosive shots deployed by local fisherman, and humpback whale vocalizations. While the highly impulsive shot data produced unambiguous bearing estimations, the longer duration whale vocalizations showed a fairly wide spread in bearing. The causes of the ambiguity in bearing estimation are investigated in the context of the highly variable bathymetry of the Monterey Bay Canyon, as well as the coherent multipath interference in the longer duration calls.
Development of a standing-wave calibration apparatus for acoustic vector sensors
Authors: Lenhart Richard D. , Sagers Jason D. , Wilson Preston S.
Published: May 2014

An apparatus was developed to calibrate acoustic hydrophones and vector sensors between 25 and 2000 Hz. A standing-wave field is established inside a vertically oriented, water-filled, elastic-walled waveguide by a piston velocity source at the bottom and a pressure-release boundary condition at the air/water interface. A computer-controlled linear positioning system allows reference hydrophones and/or the device under test to be scanned through the water column while their acoustic response is measured. Some of the challenges of calibrating vector sensors in such an apparatus are discussed, including designing the waveguide to mitigate dispersion, mechanically isolating the apparatus from floor vibrations, understanding the impact of waveguide structural resonances on the acoustic field, and developing processing algorithms to calibrate vector sensors in a standing-wave field. Data from waveguide characterization experiments and calibration measurements will be presented. [Work supported by ARL IR&D.]
Modular construction in healthcare
Authors: Logsdon Edward , Seep Benjamin
Published: May 2014

Healthcare facilities are utilizing modular constructions where elements like the patient restroom or headwall are built off-site and then shipped to the project where they are then installed. The modular assemblies are constructed under tight quality control and the manufacturers suggest savings in labor, shortened schedules, and improved architectural and acoustical performance. Modular patient restroom assemblies were used in the construction of a new major Colorado hospital with 360 private patient rooms. This includes the restrooms used in the labor and delivery areas of the hospital. Acoustical plus and minuses with the use of the modular patient restrooms will be discussed along with recommendations to maintain sound isolation between the spaces. This includes detailing during design and modifications needed to address issues in the field.
The implication of door undercut in patient room to corridor speech privacy
Authors: Tocci Gregory C.
Published: May 2014

Un-gasketted corridor door undercuts and un-gasketted head, hinge, and lockset jambs compromise the STCc rating of corridor wall/door assemblies. However, health care infection control policies often do not permit gasket systems on many doors. Though loss of sound isolation is obvious, this paper specifically characterizes the loss of speech privacy between patient rooms and corridors with doors not provided with undercut drop seals and jamb gaskets. The work draws upon that of Kim and An, and characterizes speech privacy conditions using the articulation index (AI) and its compliment the privacy index (PI).
Integrated design experience and post-occupancy acoustic performance of medical office building of the future
Authors: Miller-Klein Erik
Published: May 2014

This case study discusses the experiences working within this integrated design team with architects, engineers, and contractors from day one, which included mock-ups and physical models of proposed systems. This project was completed in 2013, and was designed and evaluated compared to the 2010 Facilities Guidelines Institute Guidelines for Design and Construction of Health Care Facilities. During construction, we evaluated some acoustic construction defects and addressed these impacts, and completed a full acoustic evaluation of the space prior to occupancy. This building was a paradigm shift for the doctors and nurses, and required additional testing and analysis to interpret some of the feedback from users about the acoustic function of the spaces.
Trends of the acoustic condition in an intensive care unit based on a long-term measurement
Authors: Park Munhum , Vos Piet , Kohlrausch Armin , Oldenbeuving Annemarie W.
Published: May 2014

Noise levels in hospitals, especially in intensive care units (ICUs), are often very high, potentially influencing the patients’ well-being and recovery processes, where the undesirable acoustic environment is also considered to be one of the risk factors contributing to ICU delirium. In the current study, a continuous measurement was taken for 3 months in 8 single-bed patient rooms in an ICU, of which the results were analyzed in synchrony with the admission of 106 patients. On average, the A-weighted energy-equivalent sound pressure level (LAeq) in patient rooms varied significantly with the time of day (p < 0.001), but was not dependent on the day of week (p = 0.448). Furthermore, analysis of noise levels in occupied versus unoccupied rooms indicated the dominance of room-internal sources in the former and room-external sources in the latter periods. During the first four days of patients’ ICU stay, the acoustic condition improved slightly from day 1 to day 2, but the noise level rebounded from day 2, most likely in relation to the various phases of treatment and recovery. Between-patient variability was found to be significant, which may be an important aspect to consider when comparing the acoustic conditions in an environment occupied by different groups of patients.
Study to optimize speech clarity in a hospital pediatric trauma room, using newly patented tuning tube and a custom nonwoven fabric
Authors: Schnitta Bonnie
Published: May 2014

There are several acoustic requirements in order to optimize the healing environment for the patients in a trauma room, as well as increase medical staff concentration and clarity of speech within the room. This is especially true in a pediatric setting. First, there is the requirement that the reverberation time of the room must be reduced in order to assist in hearing/speech clarity while adhering to clean room standards. Secondly, there needs to be an increase in the signal to noise ratio (SNR). A greater SNR assists in hearing/speech clarity; the lower reverberation time also assists in preventing the various intrusive mechanical sounds from becoming amplified and further reducing the SNR. In addition to these two standard room requirements, there is also a need for the reduction of lower frequency sounds within a room, such as sounds typical of mechanical equipment. Since standard products used to absorb sound have more absorption in speech frequencies, there is a need for products that have greater absorption in lower frequencies. This paper presents background on two SoundSense patented products that were used in a study for improved conditions and outcomes in a hospital pediatric trauma room.
Aircraft dose-response research in National Park backcountry areas
Authors: Rapoza Amanda , Lewis Kristin , Aaron Hastings , Lee Cynthia
Published: May 2014

The Federal Aviation Administration and National Park Service conducted joint research to better understand visitor response to noise from commercial air tour operations over units of the National Park System. Dose-response research in National Parks was conducted during the 1990’s at heavily visited, frontcountry sites. To expand this work, aircraft dose-response measurements were recently performed at seven backcountry sites in four National Parks. These sites provided both day and overnight hiking and camping opportunities, with visits ranging from one hour to several days. The sampling approach included side-by-side use of three survey instruments, enabling the evaluation of multiple response variables (annoyance, interference with natural quiet, and acceptability) and comparison of audio clip and in situ dose-response, along with the effects of wording and question order. The evaluation of visits longer than previously studied necessitated methodological enhancements including the use of global positioning system based tracking of visitor locations. In total, over 4600 visitor surveys and 50 days of simultaneous acoustic data were collected. This paper, the first of two on this research, describes the research methods and visitor surveys and presents summary results of collected data.
Interaction noise reduction for a counter-rotating fan by slitted trailing-edge of the forward rotor
Authors: Wang Chen , Huang Lixi
Published: May 2014

A counter-rotating configuration can decrease the size and weight of fans by eliminating stators and increase the efficiency by recovery of the swirl velocity losses. However, that potential is not fully harnessed due to perhaps the issue of noise. This study explores one idea of passive noise reduction for a small axial-flow counter-rotating fan (120 mm in diameter) by the introduction of slitted trailing-edge for the forward rotor. The fan is designed with simple velocity triangle analyses which are checked by 3D steady-flow numerical simulation and experimental measurements of aerodynamic performance. The aerodynamic consequence and the acoustic benefit of such slit geometry are investigated experimentally when the separation distance between the forward and aft rotor is 4 mm. The results show that there is a reduction of total pressure compared with the baseline fan (without slit) at the same rotational speeds, but this is easily compensated for by slightly raising the rotational speeds. A reduction of about 5 dB in overall noise is achieved for the same aerodynamic output in all directions around the fan center. The spectral comparison at the fan inlet indicates that the most prominent interaction noise peaks are suppressed greatly by such trailing edge slits.
The flow-induced sound of a wall-mounted finite airfoil
Authors: Moreau Danielle , Doolan Con J.
Published: May 2014

In this study, the aeroacoustic behavior of a wall-mounted finite airfoil is experimentally investigated. Compared to a semi-infinite or two-dimensional airfoil where end effects are not considered, a wall-mounted finite airfoil is more realistic, especially for applications such as wind turbine blades attached to a hub, submarine hydrofoils mounted to a hull, or stators connected to a hub or outer wall. Acoustic and aerodynamic measurements have been taken in an anechoic wind tunnel with single microphones, multiple acoustic beamforming arrays, and hot-wire anemometry. These measurements are used to examine changes in flow topology and radiated noise as a function of Reynolds number and airfoil aspect ratio. Additionally, the data gives insight into the influence of flow at the airfoil tip and wall junction on noise production.
Focused ultrasonic pulsed source for non-contact measurements in air
Authors: Cohen Tenoudji Frederic , Busquet Dominique , Mourey Jean François
Published: May 2014

Ultrasonic spark sources have qualities propitious to non-destructive testing of materials in air. They are energetic, and they generate a short acoustic pulse which bandwidth extends from a few hundred Hertz to several hundred kilohertz. It is shown here that by focusing the cylindrically symmetric wavefront generated by the spark with an elliptical mirror, it is possible to concentrate the acoustic energy on the focal line image of the spark. This technique provides a powerful virtual source of small dimension, which may be localized on the surface of the material to be inspected. The performance of this source for non-contact inspection in transmission of composite materials is evaluated by measurements on test samples. The lateral spatial resolution and the high frequency limitation of this technique are determined.
Energy flux streamlines versus acoustic rays for modeling an acoustic lens: Energy flow inside and in the focal region for a carbon dioxide filled spherical balloon in air
Authors: Dean Cleon E. , Braselton James P.
Published: May 2014

As an extension of recently published experimental work [Dean and Parker, “A ray model of sound focusing with a balloon lens: An experiment for high school students,” J. Acoust. Soc. Am. 131, 2459–2462 (2012)], a comparison of ray acoustics and wave analysis via energy flux streamlines [Chapman, “Using streamlines to visualize acoustic energy flow across boundaries,” J. Acoust. Soc. Am. 124, 48–56 (2008)] as a means of visualizing the sound field for a positive acoustic lens in the form of a carbon dioxide filled spherical balloon in air is made. The sound field is expanded in the usual Legendre polynomials and spherical Bessel functions [Anderson, “Sound scattering from a fluid sphere,” J. Acoust. Soc. Am. 22, 426–431 (1950)], and the energy flux vectors at points throughout the regions of interest are calculated [Adin Mann III, et al., “Instantaneous and time-averaged energy transfer in acoustic fields,” J. Acoust. Soc. Am. 82, 17–30 (1987)]. Then, energy flux streamlines are plotted using Mathematica routines for comparison with conventional acoustical rays, both inside and outside the balloon. Particular attention is paid to the focal region.
Auditory evoked responses to perceived quality of vocoded speech
Authors: Tan Chin-Tuan , Glassman Elizabeth , Oh Samuel , Wang WenJie , Martin Brett , Neuman Arlene , Svirsky Mario
Published: May 2014

One of the common uses of vocoded speech is to simulate what speech would sound like when it is processed via a cochlear implant. However, listeners with normal hearing may perceive vocoded speech differently depending on the carrier signals (noise or tone) or channel bandwidths. In this study, we attempted to determine how physiological measures correlate with the quality ratings of vocoded speech that varied in carrier signal and channel bandwidth. Eleven NH subjects rated the perceived sound quality of a spoken sentence processed with noise and tone vocoders (22-channel analysis/synthesis filterbank) whose channels were broadened and narrowed by different Q factors. Each subject was instructed to rate sound quality on a 10 point scale where “10” indicates “clean” and “1” represents “very-distorted”. Quality ratings for six different combinations of carrier and Q factor were very consistent across listeners. Auditory evoked potentials (MMN) were obtained from three NH listeners. Vowel stimuli processed through the vocoders with variations in the Q value were used as stimuli. Changes in N1 latency were observed to correlate with the perceived quality ratings of the vocoded speech. [This study was supported by NIH-K25-DC010834 (PI: Tan), PSC-CUNY (PI: Martin), NIH-R01-DC011329 (PI: Neuman and Svirsky), and NIH-R01-DC003937 (PI: Svirsky).]
The precedence effect: Exploring the build-up of echo thresholds in cochlear-implant listeners
Authors: Thakkar Tanvi D. , Brown Andrew D. , Jones Heath G. , Kan Alan , Litovsky Ruth Y.
Published: May 2014

In reverberant environments, listeners rely on early arriving spatial cues to accurately localize sound sources, a phenomenon known as the precedence effect (PE). In deaf individuals fitted with bilateral cochlear implants (BiCIs), this effect is diminished, ostensibly due to the fact that clinical processers do not preserve binaural cues. We have recently demonstrated that BiCI listeners do exhibit aspects of the PE similar to normal-hearing (NH) listeners when binaural stimulation is restored using synchronized research devices. Here, we consider whether BiCI users also demonstrate an aspect of the PE known as “buildup”—enhancement of the PE after a repeated stimulus. BiCI users with demonstrated sensitivity to interaural time differences (ITDs) were tested using dichotic electrical pulses (±500µs ITD in opposing “lead” and “lag” pulse pairs, with lead-lag delays of 1–64 ms). On each trial, listeners indicated (1) whether one or two locations were perceived (to assess “fusion”) and (2) the location perceived (or, given two locations, the “left-most” location perceived, to assess “localization dominance”). Preliminary results indicate that ‘buildup’ may be atypical in BiCI users, who have experienced years of acoustic deprivation. Lack of adaptation to redundant stimuli may temper the extent of benefit from restored binaural inputs in reverberant environments.
Modulation masking attributes of narrowband and low-noise noise forward maskers in normal-hearing and hearing-impaired listeners
Authors: Svec Adam , Nelson Peggy B. , Dubno Judy
Published: May 2014

Savel and Bacon (2003) measured detection thresholds for a 4000 Hz pure-tone signal in the presence of a narrowband noise (NBN) or a low-noise noise (LNN) simultaneous masker. The authors asserted that fluctuations in the envelope of the NBN were likely responsible for its increased masking effectiveness. Because modulation detection interference (MDI) is larger for hearing-impaired (HI) than normal-hearing (NH) listeners using modulated simultaneous maskers (e.g., Lorenzi et al., 1997) and forward maskers (e.g., Koopman et al., 2008), we measured detection thresholds for NH and HI listeners for pure tones in the presence of either NBN or LNN forward maskers that were either 1-ERB wide or 1/3-ERB wide. Based on previous MDI findings (Koopman et al., 2008), we predicted larger differences in masked thresholds for the NBN and LNN conditions for HI than NH listeners. These results for detection thresholds for pure-tone signals have implications for interpreting differences in modulated forward masking for NH and HI listeners. [Work supported by grants from NIH/NIDCD.]
Optimizing masker phase effects for use in a portable hearing screening tool
Authors: Hoglund Evelyn M. , Feth Lawrence L. , Oh Yonghee , Klyn Niall
Published: May 2014

The current study is a continuation of work toward development of a preclinical indicator for noise induced hearing loss. Masked threshold differences produced by Schroeder-phase maskers have been demonstrated with long duration tones at different frequencies (1, 2, and 4 kHz) as well as with IEEE sentences (Summers and Leek, 1998) for normal hearing listeners, but these differences are not found for hearing impaired listeners. Similar results are also found for repeated short duration tone bursts and greater differences occur with systematically changed tone burst frequencies (Hoglund et al., 2012). Using the enhanced channel model (Oh, 2013), threshold differences are predicted, and the Schroeder-phase masker characteristics are adjusted to maximize the difference. This leads to a greater range of masker phase effect differences between the positive and negative Schroeder-phase maskers, and should allow greater sensitivity to preclinical hearing threshold changes. These optimized maskers were also applied to a digit triplets test designed for telephone hearing screening (Watson et al., 2012). Testing with both the digit triplets and the short duration tone bursts are compared for ease of use and portability, as well as sensitivity to small changes in post-exposure thresholds. [Work supported by the Office of Naval Research.]