bluuebunny/crossref_metadata_2025 huggingface dataset:
Vibroacoustics in airplane design.
Authors: Davis Evan B.
Published: March 2010

Structural and structural-acoustic (vibroacoustic) tools are used to predict the future performance of systems in order to guide design trades and system optimization decisions. The key questions to be answered are (1) what needs to be known? (2) how well does it need to be known? and (3) how reliable are the tools that will be used to make the decisions?
Dealing with noise in automatic speech recognition.
Authors: O’Shaughnessy Douglas
Published: March 2010

While automatic speech recognition (ASR) can work very well for clean speech, recognition accuracy often degrades significantly when the speech signal is subject to corruption, as occurs in many communication channels. This paper will survey recent methods for handling various distortions in practical ASR. The problem is often presented as an issue of mismatch between the models that are created during prior training phases and unforeseen environmental acoustic conditions that occur during the normal test phase. As one can never anticipate all possible future conditions, ASR analysis must be able to adapt to a wide variety of distortions. Human listeners furnish a useful standard of comparison for ASR in that humans are much more flexible in handling unexpected acoustic distortions than current ASR is. Methods that adapt ASR features and models will be compared against ASR methods that enhance the noisy input speech. Other topics to be discussed will include estimation of noise and channel parameters, RASTA, and cepstral mean normalization. TRAP-TANDEM features Vector Taylor Series, joint speech and noise modeling, and advanced front-end feature extraction. Single-microphone versus multi-microphone approaches will also be discussed.
Speech enhancement beyond minimum mean squared error with perceptual noise shaping.
Authors: Kim Lae-Hoon , Kim Kyung-Tae , Hasegawa-Johnson Mark
Published: March 2010

Residual error signal after speech enhancement through linear filtering can be decomposed into two disjoint portions: speech signal distortion and background noise suppression. Speech is known to follow a super-Gaussian probabilistic distribution function (PDF) such as Laplacian, while background noise follows Gaussian PDF. Minimum mean squared error estimation requires only second order statistics not only for the noise but also for the speech. Therefore higher-order dependence of observed speech on the original speech may cause leakage of speech information into the error residual. This talk will formulate an optimization problem minimizing higher-order statistics (HOS) as well as energy of the signal distortion constrained by a limit on the maximum audibility of the residual noise. Note that due to the non-stationary nature of speech, we perform the speech enhancement in short overlapping frames. Minimizing HOS of the speech distortion ensures that the speech distortion includes only noise terms, with minimum leakage from the speech signal. The constraint on the residual noise margin prevents over-suppressing, which may result in unwanted speech distortion.
Estimating the size and spatial distribution of bubble clouds in an underwater acoustic test tank.
Authors: Holt Fred D. , Park J. Daniel , Culver R. Lee , Coles David , Leighton Timothy
Published: March 2010

The AB Wood Underwater Acoustic test tank at ISVR, University of Southampton, UK is outfitted with a Venturi-based apparatus for generating bubble clouds containing a large range of bubble sizes. Larger bubbles are allowed to rise out in a settling tank before the nearly opaque bubbly water is pumped into the acoustic test tank through a discharge manifold on the bottom. A series of acoustic attenuation measurements was made at AB Wood in July 2008 in order to estimate the size and spatial distribution of bubbles in the cloud. An acoustic projector transmitted 1-ms pure tones from 25 to 100 kHz, which were received at a co-linear three-element horizontal array. The receive hydrophones were spaced 0.5 m apart, with the center hydrophone placed directly over the bubble discharge location. Measurements were taken on-axis with the projector, and at three distances off-axis, in 12-in. increments. The attenuation measurements were used to estimate the size and spatial distribution of bubbles within the cloud. The bubble size data will be used to support a study of the effect of nearby bubbles on array performance degradation. [Work sponsored by the Office of Naval Research, Code 321.]
Array performance in a complex littoral environment.
Authors: Means Steven L. , Heitmeyer Richard M. , Wales Stephen C.
Published: March 2010

In August of 2007 a long (∼1-km), 500 phone linear array began collecting acoustic data in the waters (∼260 m in depth) approximately 12 km off the coast of Fort Lauderdale, FL. The array consisted of four, 125-phone segments deployed closely along a line running nearly east and west. Marine-band radar data were collected concurrently so that shipping in the region of the array could be tracked. The data considered in this analysis were obtained over the month of August and contains ∼19 days of measurements. Array performance is investigated by beamforming at a number of frequencies (up to ∼420 Hz) and apertures then determining cumulative distribution functions as a function of bearing and noise window statistics. The results are compared for day, night, weekday, and weekend measurements during which the local shipping varies significantly. Additionally, ship tracks obtained from the acoustic array are compared against those obtained from radar. [Work supported by ONR base funding at NRL.]
Experimental validation of Helmholtz equation least squares when the Nyquist spatial sampling requirement is violated.
Authors: Dziklinski Richard E. , Wu Sean F.
Published: March 2010

Previous numerical studies [Dziklinsky and Wu, J. Acoust. Soc. Am. (2009)] have shown that Helmholtz equation least squares (HELSs) enable one to violate the spatial Nyquist sampling frequency and stand-off distance requirements inherent in Fourier acoustics. A direct benefit of this severe under sampling using HELS is a significant saving in measurement and computational effort in locating acoustic point sources in practice without loss of the required spatial resolution. The presented paper aims at validating the previous numerical studies by conducting experiments on locating two incoherent point sources separated by a small distance of 6.25 mm via HELS. The acoustic pressures are measured by a 5 × 5 microphone array over a 50 × 50 mm square plane at varying stand-off distances with fixed microphone spacing of 12.5 mm. The considered source frequencies are well above the spatial Nyquist sampling frequency. Results show that HELS is capable of locating point sources when stand-off distance is 10 mm or less and SNR is 10 dB or higher. Similar results obtained by using planar Fourier acoustics are also presented for comparison purposes.
Implementation of sound ball with acoustic contrast control method.
Authors: Song Min-Ho , Kim Yang-Hann
Published: March 2010

It is well known that the problem of generating sound in the region of interest, by using finite number of speakers, is mathematically ill-posed. This problem can be well-posed; in other words, the way to drive the speakers to make desired sound field in the prescribed zone can be directly determined by using energy measure, which is called acoustic brightness, contrast control method. With the method, we can manuver sound ball or balls in space which can generate personal listening zone or virtual sound source. In this paper, a novel way that guides a way to design the speaker array in space to generate sound ball will be introduced. The signals between the zone of interest and the speakers are interpreted as vector spaces. The vector space interpretation certainly provides insight to design the arrays for acoustic brightness or contrast control. Theoretical formulation in vector space and experimental results of generating the sound ball will be introduced.
Using the vector sensors as receivers for underwater acoustic communications.
Authors: Yang T. C. , Zajić Alenka
Published: March 2010

A vector sensor package (VSP) generally consists of three orthogonally oriented sensors and an omni directional hydrophone, all packed in a small compact housing. Because of its small size, the VSP might be more useful than a hydrophone array. In contrast to the hydrophone array, which has a non-negligible vertical aperture and is difficult to deploy on an autonomous underwater vehicle (AUV), the VSP can be easily deployed on the AUV and used for underwater acoustic communications (UAC). However, the usefulness of the VSP depends on whether it provides the same spatial diversity as a hydrophone array. Hence, to address this question, this paper investigates the spatial correlation characteristics of the VSP and the bit error rates and/or output SNRs, based on at sea data, between the VSPs and the hydrophone array. The data were collected in May of 2009 on the New Jersey shelf. A hydrophone array and a VSP were deployed close to the ocean bottom and used for UACs. The source was towed at a slow speed, transmitting signals of various modulations at distances 0.5 to a few kilometers from the receivers. Initial results will be presented. [Work supported by the Office of Naval Research.]
An overview of underwater acoustic communication via particle velocity channels: Channel modeling and transceiver design.
Authors: Abdi Ali , Song Aijun , Badiey Mohsen
Published: March 2010

Over the past few decades, the scalar component of the acoustic field, i.e., the pressure channel, has been extensively used for underwater acoustic communication. In recent years, vector components of the acoustic field, such as the three components of acoustic particle velocity, are suggested for underwater communication. Consequently, one can use vector sensors for underwater communication. The small size of vector sensor arrays is an advantage, compared to pressure sensor arrays commonly used in underwater acoustic communication. This is because velocity channels can be measured at a single point in space. So, each vector sensor serves as a multi-channel device. This is particularly useful for compact underwater platforms, such as autonomous underwater vehicles (AUVs). Funded by the National Science Foundation, our research efforts focus on the research problems in two closely related categories: channel modeling and transceiver design. Channel modeling research aims at characterization of those aspects of acoustic particle velocity channels such as delay and Doppler spread, and transmission loss, which determine the communication system performance. Transceiver design addresses optimal use of vector sensors and particle velocity for data modulation and demodulation, equalization, synchronization, and coding. [Work supported by NSF.]
Speech privacy: The new 2010 architectural guidelines.
Authors: Sykes David , Cavanaugh William , Tocci Gregory
Published: March 2010

In January, speech privacy performance criteria were released in the 2010 Guidelines for the Design and Construction of Healthcare Facilities, which is accepted as code by ∼42 states and many federal, state, and municipal agencies. This is the first acceptance by regulatory authorities of speech privacy and will impact healthcare facilities across the United States. The criteria have also been adopted as the reference standard for two environmental quality credits in LEED HC and GGHCv2. In addition new 1.5 million dollar penalties took effect on Nov 30, 2009 for violations of the HIPAA Privacy Rule, the first serious penalties since the law was written in 1995. The new speech privacy criteria simplify enforcement by accepting as “equivalent” all four of the established measurement systems (articulation index, privacy index and sound transmission index, and speech intelligibility index), thereby leaving regulators, courts, and professionals with a choice. The developers are working on the next edition (2014) when they hope to introduce the fifth and newest measurement system, S/N(A), which provides specific metrics for both “confidential” and “secure” privacy. Acoustical professionals will need to assist healthcare organizations, regulatory authorities, judges, lawyers, and consumer groups to understand the new criteria.
Setting speech privacy criteria for closed rooms in terms of speech privacy class values.
Authors: Bradley John S. , Gover Bradford N.
Published: March 2010

The new ASTM E2638 standard defines speech privacy class (SPC) as the sum of the measured average noise level at the position of a potential eavesdropper outside the room and the measured level difference between a source room average and the transmitted levels at the same potential eavesdropper location. For a given situation, the likelihood of transmitted speech being audible or intelligible can be related to the probability of higher-speech levels occurring in the meeting room. Increasing speech privacy criteria can be defined in terms of increasing SPC values. For a particular meeting room speech level, there is an SPC value for which transmitted speech would be below the threshold of intelligibility or even below the threshold of audibility. One can therefore create a set of increasing SPC values corresponding to increasing speech privacy and for each SPC value, one can give the probability of transmitted speech being either audible or intelligible. This paper describes a new procedure that makes it possible to specify degrees of speech privacy for meeting rooms and offices in terms of the expected risk of a privacy lapse and varying from quite minimal to extremely high-speech privacy.
A primer on classroom acoustics.
Authors: Siebein Gary W. , Skelton Reece , Siebein Keely M. , Jones Chris P.
Published: March 2010

Research involving quantitative and qualitative evaluation of classroom activities has shown that speech perception and intelligibility in elementary, middle, and high schools can be measured, modeled, and simulated based on an impulse response-based theory. The theory combines the vocal production of the speaker, the hearing abilities of the listeners, the strength of the direct sound and early sound reflections from room surfaces, duration of longer term reverberation, and the level, type, information content, and frequency content of intruding sounds. Regression models relating measured intelligibility in classrooms to measured, modeled, and simulated sounds show model r2 > 0.90. A model relating speech perception score to the level, type, information content, and frequency content of typical classroom noise reaches r2 > 0.90 as well. The impulse response based measures are reduced to a series of architectural systems that can be implemented using alternate construction systems to meet budget requirements.
Assessing the potential intelligibility of assistive listening systems.
Authors: Mapp Peter
Published: March 2010

Approximately 14% of the general population suffer from a noticeable degree of hearing loss and would benefit from some form of hearing assistance or deaf aid. Recent DDA legislation and requirements mean that many more assistive listening systems are being installed, yet there is evidence to suggest that many of these systems fail to perform adequately and provide the benefit expected. There has also been a proliferation of classroom and lecture room “soundfield” systems, with much conflicting evidence as to their apparent effectiveness. This paper reports on the results of some trial acoustic performance testing of such systems. In particular, the effects of system microphone type, distance, and location are shown to have a significant effect on the resultant performance. The potential of using the sound transmission index and, in particular, STIPa for carrying out installation surveys has been investigated, and a number of practical problems are highlighted. The requirements for a suitable acoustic test source to mimic a human talker are discussed. The findings discussed in the paper are also relevant to the installation and testing of “soundfield systems.”
Ambient noise levels and reverberation times in Mississippi school rooms.
Authors: Goshorn Edward L. , Lucus Megan N. , Kemker Brett E.
Published: March 2010

Nine elementary school classrooms at three Mississippi public schools were selected at random for noise and reverberation time measures to monitor voluntary compliance with ANSI standard S12.60-2002 (Acoustical Performance Criteria, Design Requirements, and Guidelines for Schools). 1-h equivalent dBA noise levels and reverberation times (T60) were measured with SPECTRAPLUS Version 5.0 software. Measures were taken on separate days at each school in unoccupied classrooms with the HVAC system operating. For ambient noise measures, an Audix TR40 omnidirectional microphone was placed in a 12 in. stand on a student’s desk near the middle of the room and oriented toward the teacher’s desk at a 45 deg angle. For the reverberation time measure a 400 W loudspeaker (Yamaha BR15M) was placed on the teacher’s desk about 3 m from the microphone. Results showed that noise levels varied from 28 to 51 dBA with broad spectra containing peaks at 120 Hz and harmonics. Five of nine classrooms had noise levels that exceeded the ANSI recommended level of 35 dBA. Reverberation times varied from 0.21 to 0.62 s; only one classroom exceeded the recommended minimal reverberation time of 0.6 s. Acoustical modifications to reduce noise levels and reverberation times will be addressed.
Voice privacy associated with raised floor law office: A case study.
Authors: Pollock Christopher J. , Sparks Geoffrey
Published: March 2010

Presentation and discussion of the acoustical transmission and voice privacy issues associated with raised floor office fit out construction. Many new LEED office fit out projects are using raised floor constructions for future flexibilty and use of underfloor plenum for HVAC systems and/or technology cable plant. Issues of user expectations of privacy versus capabilities of the system are becoming more common. Case study office fit out was completed with raised floor and the extent of voice transmission due to various construction conditions limited voice privacy and created noise disruption from offices, workrooms, and conference rooms. Case study involves a law office where privacy concerns are heightened due to sensitive discussions. Measurements of noise isolation and privacy were made both before and after modifications, and results will be presented and discussed and conclusions for practitioners will be discussed.
Determining the spatial distribution of an Antarctic top predator using passive acoustics.
Authors: Constantinou Nadine E. , Rogers Tracey L. , Laffan Shawn W. , Warton David I.
Published: March 2010

The leopard seal (Hydrurga leptonyx) is one of four species of ice seals in Antarctica with each species occupying a distinct position in the Antarctic sea-ice ecosystem. Ice seals offer a potential source of information about ecosystem interactions and environmental variability integrated over a variety of spatial and temporal scales. During the austral spring and summer, leopard seals move within the pack ice to breed. Acoustic surveying is necessary to assess their distributions as male leopard seals vocalize underwater as part of their breeding display. During the 1999/2000 austral summer, the relative abundance of adult male leopard seals was determined using underwater passive acoustic point-transect surveys. The abundance data were combined with environmental data in a geographical information system, and a model was developed to determine what factors of the environment are correlated with their abundance and distribution. The model with the best predictive power showed a trend of increased abundance toward the pack ice edge. These regions are associated with areas of increased foraging potential suggesting that the distribution of leopard seals off Eastern Antarctica is influenced, in part, by increased availability of prey.
Are passive acoustics an appropriate method to accurately represent a soniferous Atlantic croaker (Micropogonias undulatus) population?
Authors: Krahforst Cecilia S. , Luczkovich Joseph J. , Sprague Mark W.
Published: March 2010

It was observed that the fundamental frequency of Atlantic croaker sounds is inversely correlated with the length of the fish. We used fundamental frequency as a method to estimate the average length of the croaker population at any given time. Croaker were collected using an otter trawl and simultaneously counted and measured acoustically with a 200-kHz split-beam echosounder at two sites within the Pamlico Sound estuary, NC from June to November 2008. Passive acoustic recorders [long-term acoustic recording system (LARS) recordings 10-s wave files < 10 kHz at 15-min intervals] were deployed near each trawling site to obtain in-situ recordings of croaker over the same period. Based on captive fish recordings, a linear regression analysis related total length to fundamental frequency, where TL = 305.323 mm−(0.270 Hz−1)f0(r2 = 0.84). This equation was then used to estimate croaker lengths from LARS recordings. Lengths of fish collected in the trawls, compared with the estimate from the passive LARS recordings and the echosounder surveys, were significantly smaller (P > 0.0001). Thus suggests that size-selectivity of the trawl underestimates the average size of fish and that acoustic methods (active and passive) provide a more accurate size estimate for croaker populations.
A parallel algorithm for high-intensity focused ultrasound simulation.
Authors: Soneson Joshua E.
Published: March 2010

The Khokhlov–Zabolotskaya–Kuznetsov (KZK) equation serves as today’s workhorse for the modeling and simulation of high-intensity focused ultrasound. This approximation of the full nonlinear wave equation allows serial algorithms to compute the pressure distribution produced by circular transducers usually in several hours on a modern workstation. However, more complicated transducer geometries preclude axisymmetric modeling, and extending into the third spatial dimension requires significantly more computational power, making serial algorithms intractable. This presentation details a parallel implementation of a combination time and frequency domain algorithm for rapid solution of the KZK equation. A split step method is used in which the linear terms in KZK are solved in the frequency domain and the nonlinear term is solved in the time domain. In the frequency domain, each harmonic may be computed independently, so this task is distributed over the available processors. In the time domain, the transverse spatial domain may be partitioned and distributed for independent solution of the nonlinear term. Near-linear scaling (acceleration vs number of processors) using this algorithm is demonstrated.
Modeling of high-frequency ultrasound contrast agents.
Authors: Allen John , Cugnet Fanny , Mamou Jonathan , Lee Paul , Chitnis Parag , Ketterling Jeff
Published: March 2010

High-frequency applications of ultrasound contrast agents continue to develop with their increasing use for imaging intravascular locations as well as dermal and ocular tissue. However, conventional ultrasound contrast agents were originally designed for traditionally lower diagnostic frequencies. The optimal contrast agent design and related acoustic forcing methods for high-frequency applications are important topics of on-going research. In this respect,ultrasound contrast agent models are reviewed and, in particular, the role of the shell is highlighted for novel high-frequency applications. Shell material and related stability issues are discussed in terms of the constitutive equation assumptions. The concept of auto-resonance, which may be achieved by a slowly varying forcing frequency, is introduced as a method for enhancing the subharmonic response of free or bound agents. The phase locking characteristics of auto-resonance are analyzed using an empirical mode decomposition of the scattered signal. This provides the intrinsic mode functions from which the associated instantaneous frequencies and phases can be determined. The Shannon entropy and the variance of the phase are used to quantify the behavior. Comparisons of the numerical results are made with current experimental data. [Support from NIH-EB006372 and NIH-2G12-RR003016121.]
Modeling of nonlinear shock wave propagation and thermal effects in high-intensity focused ultrasound fields.
Authors: Khokhlova Vera A. , Bessonova Olga V. , Averiyanov Mikhail V. , Soneson Joshua E. , Cleveland Robin O.
Published: March 2010

Numerical simulations based on the Khokhlov–Zabolotskaya-type equation are currently used to characterize therapeutic high-intensity focused ultrasound fields in water and to predict bioeffects in tissue. Here results from three different algorithms that differ in calculating the nonlinear term in the equation are presented. Shock capturing schemes of Godunov type, exact implicit solution with further extrapolation of the waveform over a uniform temporal grid, and direct modeling in the frequency domain are tested. In the case of weak nonlinearity, all schemes give essentially the same solution. However, at high peak pressures around 50 MPa and strong shocks developed in the focal region, the predictions of acoustic variables and heat deposition become sensitive to the algorithm employed. The parameters of the schemes, such as number of harmonics or temporal samples and the inclusion of artificial absorption that provides consistent results, are discussed. It is shown that the spectral and Godunov-type approaches require about 6 points and implicit time domain approach needs more than 50 points in the shock to be accurate. In all schemes artificial absorption should be employed to obtain acceptable accuracy with fewer points per cycle. [Work supported by the NIH EB007643, ISTC 3691, RFBR 09-02-01530, and NSF 0835795 grants.]
Generalization of the iterative nonlinear contrast source method to realistic, nonlinear biomedical tissue.
Authors: Verweij Martin D.
Published: March 2010

Originally, the iterative nonlinear contrast source (INCS) method has been developed to compute the nonlinear, wide-angle, pulsed ultrasound field in a homogeneous and lossless medium. The method considers the nonlinear term of the lossless Westervelt equation as a distributed contrast source in a linear background medium. The full nonlinear wave field follows from the Neumann iterative solution of the resulting integral equation. Each iteration step involves the spatiotemporal convolution of the background Green’s function with an estimate of the contrast source. Appropriate filtering provides accurate field predictions for a discretization approaching two points per smallest wavelength or period. The current paper first discusses the theoretical generalization of the original contrast source approach, e.g., to include tissue attenuation or inhomogeneity. Next, computational results are presented that show the directional independence (even for the nonlinear distortion) and the wide-angle performance of the original INCS method. Finally, results are presented for extensions that can deal with power law losses or inhomogeneity in the wave speed. The wide-angle capability and the versatility of the contrast source approach demonstrate that the INCS method is well-suited for modeling the various aspects of realistic biomedical tissue behavior. [Work supported by STW and NCF.]
Transducer models in the ultrasound simulation program FIELD II and their accuracy.
Authors: Jensen J. A. , Bk D.
Published: March 2010

The FIELD II simulation program can be used for simulating any kind of linear ultrasound fields. The program is capable of describing multi-element transducers used with any kind of excitation, apodization, and focusing. The program has been widely used in both academia and by commercial ultrasound companies for investigation novel transducer geometries and advanced linear imaging schemes. The program models transducer geometries using a division of the transducer elements into either rectangles, triangles, or bounding lines. The precision of the simulation and the simulation time is intimately linked through the choice of the fundamental elements. The rectangular elements use a far-field approximation, whereas the two other methods use the full analytic solution, leading to a higher precision at the price of a slower simulation time. The talk will describe the different compromises and solutions to obtain a fast simulation and still attain a high precision including a newly developed semi-analytic solution for a convex surface elements.
Estimating construction noise using the Environmental Science Research Institutes geographic information systems program.
Authors: Noel Scott
Published: March 2010

ArcGIS is a series of Geographic Information Systems (GIS) programs and tools developed by the Environmental Science Reaserch Institue (ESRI). ArcGIS has many tools built in, however, no tools to extimate construction noise levels for either point sources or for a project construction footprint. PYTHON is a programming language that is becoming the preferred programming language for ESRI programs. Parsons Brinckerhoff, Inc. has modified the buffer tool in ArcGIS to estimate noise levels from a variety of construction equipment. The tool allows the user to choose what typical construction equipment will be used on their project. The tool then creates a noise contour showing what noise levels could be expected at certain distances from the project area or point source. The tool is useful for estimating construction noise at various distances to sensitive receptors. The tool also helps in graphics creation to aid in summarizing noise impacts. Parsons Brinckerhoff, Inc. has used this tool on transportation projects but it is applicable to other projects as well.
Proactive regulation engenders creative innovation: Quieting the jack hammer.
Authors: Zwerling Eric , Shamoon Charles , Szulecki Stephen
Published: March 2010

In 2002, the New York City Department of Environmental Protection undertook to completely revise the city’s Noise Code; it went into effect in 2007. The Mayor’s Office made the reduction in construction noise a priority. Incentives were provided for the application of best management practices and the use of quieter equipment. DEP staff proposed the development of a remediation strategy for pneumatic pavement breakers. Working with KeySpan Energy (now National Grid), they approached Zo-Air Company, an industrial tool distributor, who developed the “No Racket Jacket.” The key to developing a successful engineered solution is understanding the noise source. Most of the noise emissions from a pavement breaker come from internal components, not the tool bit hitting the pavement. Enclosing the source significantly reduces the noise emissions. The jacket al.so serves to insulate the operator from the exhaust air of pneumatic units, and the oil often spewed onto their legs. This paper discusses the development process which included four prototypes, and the results, with data from source sound level measurements and operator dosimetry. Three scenarios were tested: unremediated pneumatic hammer, pneumatic hammer with the “No Racket Jacket,” and an electric pavement breaker.
Noise control evaluation for a concrete batch plant.
Authors: O’Neal Robert D.
Published: March 2010

As a result of neighborhood complaints, an Administrative Consent Order was issued to a concrete batch plant for violating the Massachusetts noise policy. The fact that the batch plant had been in business long before the residential subdivision was built did not factor in the State’s decision. A detailed noise control study was conducted for the facility. All mobile and stationary sources of noise were measured in addition to measurements at the receiving property. The major sources included mixer trucks receiving concrete and prepping their load, concrete trucks climbing a hill, batch plant dust collector fans, and bulk cement truck deliveries. The measurements were analyzed, and a series of noise control measures was evaluated and recommended, some of which were implemented by the facility. Several rounds of controls and associated sound level testing were conducted to determine if the batch plant met the State noise requirements, and compliance was eventually achieved. This paper will discuss the key sources of noise at the facility and the techniques used to reduce noise at the source.
German information technology-equipment noise categorization concept: Study on several data projectors.
Authors: Feneberg Gregor
Published: March 2010

An investigation project tendered by the German Federal Institute for Occupational Safety and Health (BAuA), with a planned duration of 1 1/2 years, has recently been awarded to Mueller-BBM. The existing concept of the quality classification of household appliances, where the energy efficiency categories A–F each represents a determined range of power consumption, is to be transferred to a system for the categorization of IT-equipment with regard to its noise emission. Currently it is almost impossible for a layperson to compare noise declarations provided by manufacturers even though there are standardized and very detailed specifications in ISO 9296 for the measurement and declaration of the noise emission of IT-equipment. One of the central issues of the project is the consolidation of existing procedures for noise emission measurements on IT-equipment with consideration of the impact of psychoacoustic parameters. A categorization proposal based on ISO 7779 will be presented. In order to check the neccessity of additional psychoacoustic metrics like tonality and transient loudness, 11 data projectors were measured according to the BAuA proposal. In addition, the annoyance of the operational noise was evaluated by a panel test. The results will be compared and contrasted with the current ISO/ECMA standard measurements.
Development of schemes to gauge the annoyance of time-varying sound.
Authors: Rafaelof Menachem
Published: March 2010

Hard disk drives (HDDs) nowadays have use in many diverse applications. Examples include various types of consumer electronic devices that operate in extremely quiet environments and personal computers that integrate the HDD and other peripherals within the display very close to the user. Higher exposure to the HDD sound, either due to the lack of masking sound or close proximity to the user, require establishment of a scheme to identify features within the sound to decide on its acceptability. This paper describes an effort aimed at developing a scheme for identification of attention-grabbing or annoying features within time-varying sound that would point to its unacceptability by a typical user. In this first part, sample sounds were examined based on their perceived strength (loudness), duration, repetition rate, and higher order statistics to acceptability based on a jury study.
Aero-acoustic simulations of small scale electronic cooling blowers.
Authors: Gullbrand Jessica , Beltman Willem M
Published: March 2010

The noise emission of small radial blowers is important for the cooling of notebook systems. It has been demonstrated that airflow simulations for these radial blowers can be performed to predict the blower performance, even in the presence of inlet restrictions. The current paper presents an extension of this work to include predictions of the radiated acoustic noise. The calculated blower flow field is used as an input for a second stage aero-acoustic prediction. This paper outlines two methods. The first method uses a free field approach based on the Ffowcs-Williams and Hawkings analogy. The second approach constructs a rotating fan source, the magnitude of which is determined by integrating the pressure across a number of blade segments. The radiated field is then determined in a boundary element calculation, both for a free field and in the presence of the fan enclosure. Results for both methods are presented and compared to experimental data.
Passive noise control methods applied to a household icemaker.
Authors: Ruhala Richard
Published: March 2010

Two icemakers were provided to the engineering program at the University of Southern Indiana for educational testing and development. Three students worked sequentially over 1 year to quantify and localize the noise sources using sound pressure and sound intensity methods, and then implement various design modifications in order to reduce the overall sound power by a goal of 3 dBA. Noise reduction was achieved during some machine operating cycles, although the overall noise reduction goal was not obtained. The students did learn one important finding in noise control engineering: that reducing the noise of a well developed and quiet product is a difficult task that requires expertise in noise assessment and control. This paper will also focus on findings from these studies that are pertinent to the development of quieter refrigerators, freezers, and icemakers.
Overview of aircraft en-route noise prediction.
Authors: He Bill (Hua) , Boeker Eric
Published: March 2010

Community noise near airports is a major aviation noise concern, prompting the development of various modeling tools to predict the noise changes due to airport expansion and fleet changes. Once aircraft leave the terminal area and reach high altitudes, the aircraft noise received on the ground is assumed to be insignificant relative to urban ambient noise and is often neglected. However, this might not be the case, under either of the following conditions: (1) when aircraft fly over areas with very low ambient noise levels, such as in wildness areas, or (2) when an aircraft is powered by advanced propulsion systems that produces high noise levels. There is an increasing need to address both of these issues. Over the past 2 decades, some limited noise modeling capabilities and related research have begun to quantify the high-altitude aircraft noise or “en-route” noise. The purpose of this paper is to review and summarize related noise prediction research conducted through direct technical exchange with researchers, some simple data analysis as well as through a literature review. The authors will draw on experience in developing current aircraft community noise tools and formulate key future research questions and options.
Flanking paths associated with exposed roof decks in condominiums.
Authors: Kwolkoski Jeff
Published: March 2010

An award winning residential/commercial condominium project featured two-story loft condominiums with an industrial look. The building was constructed with steel structure, exposed concrete on metal deck floors, and an exposed metal deck roof. Condominiums were separated by gypsum board on metal stud walls. A number of owners in the building complained of poor sound isolation from adjacent units. Field tests showed that sound isolation of the walls fell below expectations for the design. Subsequent investigation showed that a variety of structureborne and airborne flanking paths contributed to poor sound isolation. Improving sound isolation required a combination of conventional and creative methods.
A method for determining the force spectrum produced by mechanical equipment.
Authors: Gorton Andrew , Papadimos Chris
Published: March 2010

Currently there is no standardized method for determining the force spectrum produced by a piece of mechanical equipment. This information is useful for conducting detailed vibration analysis in buildings, specifying proper vibration isolation for mechanical equipment, and comparing mechanical equipment vibration performance. This paper presents a method for estimating the force spectrum for a piece of mechanical equipment supported on spring isolators. The force spectrum is calculated from the measured vibration response of the sprung mass and the frequency response function of the system. For validation, this procedure was used to determine the force spectrum of a 21 500 CFM air handling unit externally mounted on nominally 1-in. static deflection spring isolators. The calculated force spectrum was then used as a force input to a finite element model of a mass-spring-damper system with the same properties as the sprung air handler. The predicted results compare favorably with the measured vibration response and tend to support that this is a viable method for characterizing the force produced by mechanical equipment.
Surface integration method used on semi-solid surface for fan noise prediction.
Authors: Shin Yoon-Shik , Bolton J. Stuart
Published: March 2010

As a continuation of previous work, the Ffowc-Williams and Hawkings model was applied to an axial fan that was operated under unfavorable inflow condition. A thin aluminum foam screen that is used as a treatment for disturbed inflow condition was included as a noise source in computational aeroacoustic simulation. The incompressible URANS model was used for the CFD simulation and the inflow foam was modeled as a homogeneous porous zone with permeability and inertial resistance factors found experimentally. Since the homogeneous porous zone defined in this way does not have a solid structure that could be used as a dipole noise source, the control surface integration method was applied to the surface of the homogeneous porous zone: i.e., to a surface right between the normal fluid zone and the porous zone. The unsteady pressure data on the control surface under the incompressible assumption was treated as representing pressure fluctuations on a semi-solid surface rather than as a representation of acoustic sources within the volume surrounded by the control surface.
Disastrous decisions: Costs to natural quiet of Grand Canyon National Park.
Authors: Hingson Dickson J.
Published: March 2010

Noisy intrusions from air tour rides and other aircraft increasingly, adversely affect highly significant areas of the Grand Canyon National Park. These continue in the heart of the park, even though Theodore Roosevelt told us to “do nothing to mar its grandeur.” Preserving the Canyon’s numinous aura requires maintaining its emblematic silence. The requisite policy would be to severely restrict aircraft noise. Belated efforts for an aggressive noise policy began here soon after 1965 airport completion near the Park. Hard won Congressional mandates for restoration of natural quiet were nonetheless frustrated by an accelerating aircraft boom fed by still more bad decisions, FAA stonewalling/bullying, and industry selfishness. The NPS/FAA environmental outcome—being finalized now, under a “change” administration—is coming into focus via a detailed EIS under public comment. The still unmet national direction to curb this noisy, commercial park “take-over” illustrates serial failures in group decision-making. A “road map” of contributing reasons for a veritable acoustic/soundscape “collapse” here gains strength from insights in Jared Diamond’s recent book “Collapse”:, i.e., failures to anticipate, to perceive, and to behave or obey. To right these wrongs, the concerned public must assertively guide the current Administration’s implementation of substantial, enduring restoration of the Park’s natural quiet.
Batchelor’s fourth order velocity correlation.
Authors: Seiner John M.
Published: March 2010

The Lighthill theory for aerodynamic noise relates far field sound pressure to complex fourth order two point two-time space-time velocity correlations. The Mani–Gliebe–Balsa (MGB) jet noise prediction code follows Lighthill’s theory in the development of its algorithm. Since fourth order turbulence correlations are not modeled in the MGBs flow solver, it is necessary to resort to some form of approximation. The MGB invokes Batchelor’s fourth order decomposition, which is exact for homogeneous and isotropic turbulence. For anistropic flow, like that of a jet, it is not known what the error is in adopting Batchelor’s isotropic decomposition. The question here is can stereo particle image velocimetry (SPIV) provide a means to establish the error incurred with adoption of this decomposition. In an attempt to define the penalty for adopting the Batchelor’s decomposition, a simple 2×94; diameter laboratory jet was operated at ambient temperatures at Mach 0.85. SPIV measurements were acquired of the fourth order two-point space correlation and all of the other second order correlations. A comparison was made to numerical plume simulations with an advanced numerical flow solver running in the RANS mode. This paper provides an explanation for observed variations between measured and predicted jet noise.
A multiphysics model of hearing aid vibroacoustics using finite elements.
Authors: Burns Thomas , Tourtelotte Dave
Published: March 2010

Electromagnetic balanced armature receivers [Hunt, Electroacoustics, Chap. 7] are used exclusively to generate acoustic output in hearing aids. These transducers are much more efficient than electrodynamic transducers and are capable of delivering upward of 140 dB of sound pressure to person. In an effort to maximize system gain in a hearing aid, vibroacoustical feedback paths originating from the receiver are modeled using finite elements. Given an electrical excitation, the electromagnetic-mechanical force on the armature is solved as a function of frequency. The force on this armature vibrates an internal diaphragm, which generates acoustic output while vibrating the entire hearing aid. Assuming that there are no acoustical leaks in the design, vibroacoustical coupling limits the usable gain of the aid. Using commercially available software, the fluid is modeled with full Navier–Stokes elements and is coupled to all structural boundaries. The armature is “kicked” with the aforementioned force, and spectral analysis is used to study mechanical transmissibility within and vibroacoustic reradiation around the hearing aid.
SALINAS: A massively parallel finite element code for structural dynamics and acoustics analysis.
Authors: Rouse Jerry W. , Walsh Timothy F. , Reese Garth M.
Published: March 2010

This talk shall present an overview of SALINAS, a massively parallel finite element code for structural dynamics and acoustics analysis that is being developed at Sandia National Laboratories. SALINAS allows for prediction of both the time and frequency domain responses of complex structural, acoustic, and fully coupled structural acoustic systems having millions of degrees of freedom. An overview of SALINAS capabilities shall be presented including development history, solver and element types, quadratic eigenanalysis and frequency response, direct frequency response, nonlinear acoustics, implicit transient dynamic analysis, and infinite elements with focus given to structural acoustics capabilities. The application of SALINAS to structural acoustics problems shall also be presented as well as future directions of research for the development of the code.