bluuebunny/crossref_metadata_2025 huggingface dataset:
Utilizing acoustic suspended-sediment measurement techniques in laboratory flumes
Authors: Wren Daniel , Vadakapurapu Srikanth , Chambers James , Kuhnle Roger , Barkdoll Brian
Published: October 2013

Automated measurement of suspended sediments is crucial to the study of sediment transport. The short duration, high-intensity flows that are responsible for a large fraction of sediment movement are best observed by continuous monitoring systems. Acoustic systems are ideal for continuous monitoring and add the advantage of nonintrusively measuring through the water column. In the present work, a single-frequency acoustic system for measuring suspended-sediment concentration in fluvial environments is described. The equipment and procedures used in developing hardware and software for the acoustic technique in two sets of laboratory flume experiments will be presented. Both implicit and explicit methods were used to convert backscatter data into sediment concentrations. The implicit method yielded 39% error and the explicit, 20%.
Correlation study of predictive and descriptive metrics of speech intelligibility
Authors: Stefaniw Abigail , Shimizu Yasushi , Smith Dana
Published: October 2013

There exists a wide range of speech-intelligibility metrics, each of which is designed to encapsulate a different aspect of room acoustics that relates to speech intelligibility. This study reviews the different definitions of and correlations between various proposed speech intelligibility measures. Speech Intelligibility metrics can be grouped by two main uses: prediction of designed rooms and description of existing rooms. Two descriptive metrics still under investigation are Ease of Hearing and Acoustical Comfort. These are measured by a simple questionnaire, and their relationships with each other and with significant speech intelligibility metrics are explored. A variety of rooms are modeled and auralized in cooperation with a larger study, including classrooms, lecture halls, and offices. Auralized rooms are used to conveniently provide calculated metrics and cross-talk canceled auralizations for diagnostic and descriptive intelligibility tests. Rooms are modeled in CATT-Acoustic and auralized with a multi-channel speaker array in a hemi-anechoic chamber.
An analysis and retrofit of the acoustics at Image Creators Health and Beauty Salon
Authors: Ellis Donna
Published: October 2013

This paper discusses the analysis and retrofit of the acoustics in a high-volume beauty salon in Severna Park, MD. The major issues in what was designed to be a serene environment are reverberation times of 1–1.68 s in the mid- to upper-frequency range. Employee and customer complaints include heightened stress, vocal strain, headaches, and poor intelligibility. Existing analysis and acoustical retrofit solutions will be demonstrated.
Speech intelligibility in the community mosques of Dhaka City
Authors: Najmul Imam Sheikh Muhammad
Published: October 2013

A mosque facilitates a Muslim community through different religious activities like congregational prayers, recitation and theological education. Speech in a mosque usually generates through bare voice though sound amplification system is also applied. Since no musical instrument is used in any liturgy, a mosque involves only speech acoustics. The community mosques of Dhaka city, the densely populated capital of Bangladesh, are usually designed and constructed by common people inspired from religious virtues. Seeking consultancy for acoustical design is almost never done. As an obvious consequence, there is a common crisis of speech intelligibility in different mosques, except those saved for their smaller volume and other parameters generated by chance. In a very few cases, a trial and error method is applied to solve the problem. But in most of the cases, the problem remains unsolved, putting the devotees in endless sufferings. This paper identifies the type and magnitudes of the prevailing crisis of speech intelligibility of these community mosques through instrumental measurements and questionnaire survey. This paper is also intended to establish certain research rationale and hypothesis for further research, which will propose certain parameters in acoustical design for mosques of Dhaka city in particular and of Bangladesh in general.
Models of ancient sound vases
Authors: Bruel Per V.
Published: October 2013

Models were made of vases described by Vitruvius in Rome in about the year 70 A.D. and of sound vases (lydpotter) placed in Danish churches from 1100–1300 A.D. Measurements of vase’s resonant frequencies and damping (reradiation) verified that the model vases obeyed expected physical rules. It was concluded that the excellent acoustical quality of many ancient Greek and Roman theaters cannot be ascribed to the vases placed under their seats. This study also found that sound vases placed in Nordic churches could not have shortened the reverberation time because there are far too few of them. Moreover, they could not have covered a broad frequency range. It remains a mystery why vases were installed under the seats of ancient Greek theaters and why, 1000 years later, Danes placed vases in their churches.
Acoustics of Chinese traditional theatres
Authors: Wang J. Q.
Published: October 2013

Chinese traditional theatre is unique in the world as an architectural form. The Chinese opera evolved into maturity as early as the Song and Yuan Dynasties, 11th–14th centuries, and Chinese theatrical buildings developed accordingly. As the Chinese opera plays on the principle of imaginary actions, no realistic stage settings are required. But Chinese audiences have placed great demands on vocal performance since ancient times. Pavilion stages that are small in area, open on three sides, and thrusting into the audience area are commonly found in traditional theatres, both the courtyard type and auditorium type. The pavilion stage is backed with a wall and a low ceiling (flat or domed). The stage functions as a reflecting shell, which enhances the sound to the audience and provides self-support to the singer. Numerous theatres of this kind exist and function in good condition to the present time. Acoustical measurements show that the sound strength and clarity in audience areas is satisfactory in moderate size courtyard traditional theatres. [Work supported by NSF.]
An acoustical performance space in ancient India: The Rani Gumpha
Authors: Ault C. Thomas , Manthravadi Umashankar
Published: October 2013

The Rani Gumpha, or Queen’s Cavern, was built by artist–king of Kalinga, Kharavela (ca. 200–100 B.C.). It is a rock cut structure, carved into Udayagiri hill. As in ancient Greek and Roman theaters, the entire performance space of the Rani Gumpa is backed by a decorated facade, and it is remarkably similar to Greek theaters of the Hellenistic period, having both an upper and lower level for playing. There are acoustical chambers behind each level as well as on either side, and a special ‘‘cantor’s chamber’’ stage left on the lower level. The effect on the voice is astonishing. This is a rock cut acoustical installation analogous to that described by Vitruvius in Book V, Chaps. 5 and 8, of his de Architectura, where he speaks of vessels placed in Greek and Roman theaters for the same purpose. We have created a computerized model of the Ranim Gumpha, using CATT Acoustic. We have taken acoustic measurements of the site, using Aurora Sofware package. Our results indicate that the Rani Gumpha is an acoustical performance site, sharing characteristics of the classical Greek and Roman theaters of approximately the same period.
A general spike coding model for natural echoes
Authors: Müller Rolf
Published: October 2013

Bats navigating in natural environments face a challenging task in identifying landmarks (e.g., vegetation) that are composed of many reflecting facets and hence generate random echo waveforms. The biological substrate for these tasks is a spike code. Informative code features were identified by a computational approach which encoded a natural stimulus ensemble (84800 echoes from four deciduous tree species) using a parsimonious model of spike generation. Interspike intervals spanning more than one cycle at the auditory bandpass filter’s center frequency proved convenient classification substrates because of the following properties: (a) almost certain presence in each echo representation; (b) simple probabilistic description (uncorrelated); (c) undemanding constraints on firing threshold locations and spike time resolution. An m-ary sequential probability ratio test using a first-order characterization of these intervals (number plus sample mean of duration and threshold location) demonstrated good classification performance (0.1% to 1% error probability at <10 expected echoes) as well as remarkable robustness against changes in the spike-model parameters. Distant-cycle intervals are therefore hypothesized to be a primal sketch building block analogous to visual edges, with the notable difference that they do not delineate deterministic shapes [Work supported by DFG, SFB 550 B6.]
Narrowband Phocoena-like clicks produced by a delphinid species
Authors: Lammers Marc O. , Au Whitlow W. L.
Published: October 2013

A distinction is traditionally made between the echolocation clicks of the whistling members of the family Delphinidae and those of nonwhistling smaller odontocetes, which include the family Phocoenidae and members of genus Cephalorhynchus and Kogia. The larger, whistling delphinids typically emit clicks that are short (40–70 μs) and broadband (30–60 kHz) with peak frequencies ranging from 40 to 130 kHz. Clicks of the smaller nonwhistling odontocetes are generally longer (>100 μs), more narrowband (15–25 kHz) with peak frequencies between 90 and 160 kHz. Here we report findings of long (∼135 μs), narrowband (10–25 kHz) clicks produced by a whistling species of delphinid, the Hawaiian spinner dolphin (Stenella longirostris). These clicks typically have peak frequencies between 90 and 100 kHz and predominantly occur in a doublet pattern with clicks consistently spaced 13 ms apart within a doublet and 23 ms between doublets. The vast majority of free-ranging spinner dolphin clicks conform to the more traditional delphinid form. Narrowband clicks appear to be produced rarely, having been observed on only 4 out of 25 recording sessions. It is presently not clear whether these clicks represent echo location or communication signals.
Click train encoding in a song bird: A psychometric function showing two mechanisms of pitch perception
Authors: Cynx Jeffrey
Published: October 2013

In humans, the pitch of click trains composed of pulses with the same and alternating polarity can vary depending on whether the pulse sequences are below 100 Hz or above 200 Hz. Below 100 Hz, the pitch is equal to the pulse rate regardless of polarity. Above 200 Hz, the pitch is determined by the fundamental frequency and the pattern of click polarity [J. L. Flanagan and N. Guttman, J. Acoust. Soc. Am. 32, 1308–1319 (1960)]. European starlings (Sturnus vulgaris), a species of songbird, were trained on an operant procedure with bipolar stimuli on a two tone discrimination, then tested with unipolar stimuli. We then built a psychometric function, especially covering the ambiguous region between 100 and 300 Hz, and the upper frequency limits.
Ultrasound mediated transdermal drug delivery
Authors: Tezel Ahmet , Sens Ashley , Mitragotri Samir
Published: October 2013

Low-frequency sonophoresis (LFS) is a noninvasive method of transdermal drug delivery and diagnostics. In this method, a short application of ultrasound is used to permeabilize skin for a prolonged period of time. During this period, ultrasonically permeabilized skin may be used as a permeable interface to the body. This interface may be used for the extraction of analytes or the delivery of drugs. Our main objective in this study is to understand the mechanisms of skin permeability due to LFS. Although the principal mechanism of LFS is known to be cavitation, little is known about how cavitation does actually enhance skin permeability. We are specifically interested in understanding the interactions of cavitation bubbles with the skin surface. We are also interested in assessing the structural alterations in the skin induced by ultrasound. We hypothesize that ultrasound generates defects that are responsible for the enhanced delivery of large hydrophilic solutes such as proteins (e.g., insulin). In this study we sought to determine the dependence of LFS transport pathways on ultrasound parameters such as application frequency and energy density.
Ultrasound-enhanced gene transfer: Comparison of contrast agents and ultrasound modalities in vitro and in vivo
Authors: Pislaru Sorin V. , Rajiv Gulati , Pislaru Cristina , Kinnick Randall R. , Singh Ripudamanjit , Greenleaf James F. , Simari Robert D.
Published: October 2013

Ultrasound (US) enhancement of plasmid-based gene transfer is an emerging technique. Our hypothesis was that two contrast agents (Optison and PESDA), and two US exposure modalities (dedicated continuous wave system and diagnostic scanner) may have different effects. Luciferase plasmid with or without contrast agent was added to vascular smooth muscle cells and endothelial cells, followed by US exposure. Luciferase activity was measured 24 h later. US exposure consistently induced higher transfection rates than all controls. PESDA was superior to Optison in both cell lines. In vitro, continuous wave and diagnostic US were not significantly different. In vivo, Lux and PESDA were injected into skeletal muscles of rats (IM or intra-arterial) followed or not by US exposure. In separate animals, adenovirus encoding for luciferase was injected IM and was not followed by US exposure. Gene transfer efficacy was 8–10 fold higher with US and PESDA than with plasmid alone, but 2 fold lower than with adenovirus. However, as opposed to adenovirus, US-enhanced plasmid gene transfer was highly localized to the injected muscle, with no expression at distal sites. Our results support the hypothesis that contrast agents and exposure modalities are not equivalent with regard to gene transfer efficacy.
Bubbles, membranes and molecules: sequence of events from sonication to intracellular delivery
Authors: Prausnitz Mark R. , Kamaev Pavel P. , Schlicher Robyn K. , Zarnitsyn Vladimir G.
Published: October 2013

To elucidate mechanisms and control bioeffects for ultrasound-mediated drug and gene delivery, we carried out an experimental study to quantitatively measure the effects of ultrasound and other physical parameters on the sequence of events leading from sonication to drug and gene delivery. Using a Coulter counter, the number and size distribution of bubbles was measured as a function of ultrasound pressure and time, and found to decrease as a function of acoustic energy exposure. The effects of these bubbles on cells were measured by electron and confocal microscopy, which indicated that cavitation created cell membrane defects that could be actively repaired and permitted the intracellular transport of molecules. Using flow cytometry, levels of molecular uptake and cell viability were quantified over a broad range of conditions and correlated with acoustic energy, the ratio of cells-to-cavitation nuclei and the size distribution of bubbles. Finally, levels of gene expression were quantified as a function of acoustic and other parameters and related to cavitation bubble dynamics. By examining each of the steps, rather than only measuring endpoints, we can understand and ultimately control the process by which ultrasound delivers drugs and genes into cells.
Shock induced jetting of micron sized bubbles
Authors: Ohl Claus-Dieter , Ikink Roy , Lohse Detlef , Prosperetti Andrea
Published: October 2013

Gas bubbles having a radius between 10 μm and 100 μm and rising freely in water when being subjected to a shock front exhibit a liquid jetting phenomenon. The jet points in the direction of the propagating shock wave. A linear relationship between the jet length and the bubble radius is found and a lower bound of the averaged velocity of the liquid jet can be estimated to be between 50 m/s and 300 m/s increasing linearly for larger bubbles. In a later stage the jet breaks up and releases micron sized bubbles. In the course of shock wave mediated cell permeabilization this observation suggests a microinjection mechanism responsible for cell transfection when minute gas bubbles are present and exposed together with cells to shock waves.
Quantification and optimization of transfection efficiency and cell viability by acoustic cavitation
Authors: Zarnitsyn Vladimir G. , Prausnitz Mark R.
Published: October 2013

Previous studies have shown that ultrasound-mediated cavitation can introduce large numbers of biological macromolecules, such as DNA, into cells. However, optimization of ultrasound conditions is complicated because elevated levels of cavitation increase uptake of molecules, but also decrease cell viability. The goal of this study was to optimize DNA transfection by identifying acoustic and physical conditions that promote DNA uptake without excessive viability loss. To achieve this, suspensions of DU145 prostate cancer cells were sonicated at 24 and 500 kHz in the presence of plasmid encoding green fluorescent protein (GFP) over a range of pressures, exposure times, cell concentrations, media composition, and nucleation site (Optison) concentration. Expression of GFP and cell viability were independently measured by flow cytometry one day after sonication. We found that above a threshold value, transfection increased, went through a maximum and then decreased with increasing pressure, exposure time, and energy exposure. Cell concentration, media composition, and nucleation site concentration also affected transfection levels and were adjusted to optimize DNA expression. Although exact conditions identified in this study may not be optimal in other biological scenarios, we believe the trends observed here can broadly guide optimization of transfection.
Characterization of ultrasound-mediated cellular effects
Authors: Schlicher Robyn K. , Desai Monali , Prausnitz Mark R. , Apkarian Robert P.
Published: October 2013

Ultrasound can temporarily make cells and tissue more permeable, an effect that could be used for enhanced and targeted drug delivery. Increased permeability is believed to involve creation of transient disruptions in cell membranes. This study seeks to characterize these disruptions and the mechanisms by which they are created, reseal and permit intracellular transport. To achieve this, DU145 prostate cancer cells were exposed to 24 kHz ultrasound with 0.1 s pulse length and 10% duty cycle for 2 s total exposure at pressures from 0.36 to 0.89 MPa. Disruptions were estimated to be at least 50 nm in diameter with lifetimes of 1–2 min using a range of fluorescent molecules with known molecular radii studied using flow cytometry. Cell morphological effects were examined using scanning electron, transmission electron, and laser scanning confocal microscopies after rapid fixation (within seconds after exposure). Images indicate that cell death from ultrasound exposure occurs due to a combination of apoptosis, necrosis and mechanical fragmentation and uptake may occur through physical disruptions in cell membrane structure. Using red blood cell ghosts and ATP-depleted prostate cancer cells, it was found that molecular uptake into viable cells requires active cellular processes which infers that cell recovery is an energy-dependent process.
Measurement of cavitation bubble lifetime and size distribution and its correlation with bioeffects
Authors: Kamaev Pavel , Prausnitz Mark
Published: October 2013

Ultrasound-induced disruption of cell membranes can be used to deliver drugs and genes into cells. Because ultrasound bioeffects are governed by cavitation, measurement and control of cavitation bubble lifetime and size distribution should afford greater control over ultrasound’s effects on cells. In this study, 500 kHz ultrasound was focused onto suspensions of albumin-stabilized gas bubbles (Optison) either with or without DU145 prostate cancer cells bathed in calcein. Bubble size and lifetime were determined by Coulter counting, while uptake of calcein and cell viability (i.e., bioeffects) were quantified by flow cytometry. We found that the lifetime and size of Optison bubbles decreased with increasing acoustic energy exposure. Moreover, bioeffects were shown to correlate well with disappearance of bubbles. For example, cell viability remained above 90% until approximately 75% of bubbles were destroyed; viability then dropped dramatically as more bubbles disappeared. Additionally, Optison solutions presonicated to destroy all detectable bubbles also caused significant bioeffects. These observations suggest that bioeffects were caused by the cavitation dynamics of free, short-lived, and/or very small daughter bubbles liberated from albumin-stabilized Optison parent bubbles. Regulation of bubble size distribution, possibly by presonication of Optison solutions, could provide a means to optimize high uptake and cell viability.
Nonlinear behavior of encapsulated bubbles relevant to ultrasound mediated gene transfection applications
Authors: Wu Junru , Pepe Jason , Dewitt William
Published: October 2013

Ultrasound contrast agents (UCA) have been widely used therapeutic applications in medical research and clinical practice. Recently, UCA have been shown to be effective in vitro in ultrasound mediated sonoporation and gene transfection and treating vascular thrombosis. The possible primary reasons proposed for the therapeutic applications of UCA are acoustic cavitation [W. J. Greenleaf et al., Ultrasound Med. Biol. 24, 587–595 (1998)] and acoustic microstreaming surrounding acoustically driven UCA [J. Wu, Ultrasound Med. Biol. 28, 125–129 (2002)]. Our study has shown that low frequency (0.6 MHz) is more effective than high frequency (2 MHz) in effects related to the acoustic cavitation, and the opposite is true for the microstreaming due to the nonlinear oscillation behavior of encapsulated bubbles of UCA.
Issues concerning international comparison of free-field calibrations of acoustical standards
Authors: Nedzelnitsky Victor
Published: October 2013

Primary free-field calibrations of laboratory standard microphones by the reciprocity method establish these microphones as reference standard devices for calibrating working standard microphones, other measuring microphones, and practical instruments such as sound level meters and personal sound exposure meters (noise dosimeters). These primary, secondary, and other calibrations are indispensable to the support of regulatory requirements, standards, and product characterization and quality control procedures important for industry, commerce, health, and safety. International Electrotechnical Commission (IEC) Technical Committee 29 Electroacoustics produces international documentary standards, including standards for primary and secondary free-field calibration and measurement procedures and their critically important application to practical instruments. This paper addresses some issues concerning calibrations, standards activities, and the international key comparison of primary free-field calibrations of IEC-type LS2 laboratory standard microphones that is being planned by the Consultative Committee for Acoustics, Ultrasound, and Vibration (CCAUV) of the International Committee for Weights and Measures (CIPM). This comparison will include free-field calibrations by the reciprocity method at participating major national metrology laboratories throughout the world.
A BIPM/CIPM key comparison on microphone calibration—defining the state of the art
Authors: Barham Richard G.
Published: October 2013

The formation of the Consultative Committee on Acoustics, Ultrasound and Vibration (CCAUV) now gives acoustical quantities the same status as more established metrics like mass or voltage. The principle work of CCAUV is to establish degrees of equivalence between member states of the Metre Convention. This is achieved through key comparisons and subsequent regional comparison. For sound-in-air, the subject of this key comparison is most appropriately the calibration of laboratory standard microphones. The first such project considered the pressure calibration of IEC type LS1P microphones in the frequency range from 63 Hz to 8 kHz. Twelve national laboratories took part in the key comparison, piloted by the UK’s National Physical Laboratory. The project has now been completed. The results for the measured pressure sensitivity level have a standard deviation of around 0.02 dB at frequencies below 1 kHz, rising to a maximum of 0.04 dB at 8 kHz. The mean of these results normalized to 0 dB at each frequency is considered as the key comparison reference value (KCRV) and the standard deviation provides an estimate of its standard uncertainty. The KCRV then defines the datum which enables the performance of all laboratories to be related.
The influence of standards on acoustic transducer design and calibration
Authors: Rasmussen Gunnar
Published: October 2013

The Western Electric 640AA microphone set the standard for measurement microphones and influenced their development for many decades. It has made its mark on 1−1/2−1/4−1/8 in. microphones. It has also had an influence on calibration techniques and calibrators. Developments in microphones—calibration and standards will be discussed. The microphone is an important part of a sound level meter and of the complete measurement setup. In particular, measurements in the outdoor environment are greatly influenced by the requirements set by sound level meter standards.
Validity of acoustic reference standards
Authors: Frederiksen E.
Published: October 2013

Today, acoustic calibrations and associated uncertainties are hot topics. Countries all over the world establish new calibration facilities and coordinate their efforts to make sure that they can calibrate correctly and have their results internationally accepted. This work goes on within accreditation, between National Calibration Institutes, and within standardization. The working groups of the technical committee IEC/TC29, which today make essentially all acoustic instrument and calibration standards, thus expand existing standards with detailed test procedures and related uncertainty requirements. The new requirements are partly associated with the primary pressure and free-field calibration of Reference Standards performed by National Calibration Institutes, and partly with the testing of instruments in Calibration Service Centers, which are the main users of the references. This paper deals with calibration of Reference Standards, which generally needs to be analyzed and elaborated in connection with the ongoing international work. Thousands of microphone and pistonphone calibration results of the Danish Primary Laboratory of Acoustics have been analyzed. Resulting data including uncertainty, reproducibility, and repeatability will be presented. The data are based on calibrations performed over several decades and covering the range from 20 Hz to 25 kHz.
ISO standardization to ensure traceability of vibration and shock acceleration measurements
Authors: von Martens Hans-Jürgen
Published: October 2013

Traceability to the International System of Units (SI) is increasingly demanded for vibration and shock measurements as specified in international standards, recommendations, and regulations to ensure product quality, health, and safety. Hierarchies of measurement standards have been established and are operated at the National Metrology Institutes (NMIs) as well as accredited and nonaccredited calibration laboratories. To meet the increasing demands, a revision of the ISO 5347 series, renumbered to ISO 16063, started in 1995 (ISO TC 108). Improved and new standard methods for vibration and shock calibration have been specified at the different traceability levels. For primary vibration calibration by laser interferometry at the NMI level, ISO 16063-11:1999 has extended the frequency range (0,4 Hz–10 kHz) and included absolute-phase shift measurement. ISO 16063-13:2001 provides interferometric primary shock calibration (100 m/s2–100000 m/s2). For vibration and shock calibration at lower levels, parts 21 and 22 of ISO 16063 provide upgraded comparison methods. ISO standards for the calibration of angular transducers by laser interferometry (part 15) and by comparison (part 23) are under development. Using the methods specified, national standards and calibration equipment have been developed for calibration laboratories, offering many new and improved calibration and measurement capabilities and thus international traceability.
On the uncertainties of accelerometer calibration by laser interferometry
Authors: Silva-Pineda Guillermo
Published: October 2013

Depending on both measurement standards and measurement methods, derived quantities such as acceleration are traceable to the basic quantities in the International System of Units, SI. The uncertainty of measurement is often related to the length of the traceability chain up to the standards of reference quantities and the accuracy of the methods used in every calibration step. The traceability chart of the experimental arrangements can be used to visualize the different uncertainty levels and their relationships from the application of measurement to the standards of basic quantities in the SI. For the case of accelerometer calibration, experimental results of the fringe-counting method using a Michelson interferometer, which has standards traceable to basic units of length and time, are shown. Also, the physical principles and the alignment of the laser interferometer are discussed, and how the measurement accuracy can be improved. The classical approach of the uncertainty budget, based on a first-order Taylor series approximation, for the sensitivity calibration of an accelerometer is compared with a model based on higher-order terms in the Taylor series approximation. Some concluding remarks obtained from the comparison of these two approaches are given.
High-frequency acceleration comparison among NIST, CENAM, and INMETRO
Authors: Ripper Gustavo P. , Payne Beverly F. , Silva-Pineda Guillermo
Published: October 2013

This paper presents the results obtained in an international laboratory comparison among NIST/USA, CENAM/Mexico, and INMETRO/Brazil. This acceleration comparison was focused on the calibration of the charge sensitivity of a single-ended standard accelerometer in the frequency range from 3 kHz to 10 kHz. The measurements were carried out by laser interferometry in accordance with the standard ISO 16063-11:1999 and with a preagreed protocol. This comparison supplements the former comparison SIM.AUV.V-K1, which covered the frequency range from 50 Hz to 5 kHz.
Charge amplifier calibration comparison among NIST, CENAM, and INMETRO
Authors: Ripper Gustavo P. , Payne Beverly F. , Silva-Pineda Guillermo
Published: October 2013

This paper presents the results obtained in an international laboratory comparison among NIST/USA, CENAM/Mexico and INMETRO/Brazil which was focused on the electric calibration of a charge amplifier B & K model 2626 from 50 Hz to 5 kHz. One of the main concerns of this comparison was to conclude all measurements within the period of 1 month, in order to minimize the influence of long-term temporal instabilities. Each participating laboratory carried out the measurements in accordance with a calibration protocol, which was established to avoid the effect of additional sources of uncertainty. The results are compared with the ones obtained during the former comparison SIM.AUV.V-K1 and the conclusions are presented.
Animations and auralizations for noise control education
Authors: Muehleisen Ralph T.
Published: October 2013

For students just starting out in acoustics, some basic concepts can be terribly difficult to understand. Ideas like plane, spherical, travelling, standing, and evanescent waves are easily described mathematically but can be difficult to understand physically. The use of animation to show the particle motion, velocity, and/or pressure fields associated with these wave motions helps to solidify the understanding of the basic physics. In noise control, students often have problems conceiving the effects of reverberation on acoustic signals and the perceived noise reduction from various acoustic treatments. These acoustic effects can be simulated through the use of auralization. Animations and auralizations developed using MATLAB, CATT Acoustics, and Cooledit for a senior level architectural engineering undergraduate classes in building noise control and acoustical room design will be presented.
Acoustics workshops for teachers in elementary schools and in secondary school science classes
Authors: Hansen Uwe J.
Published: October 2013

A number of acoustics workshops have been conducted throughout the US with support from ASA technical initiative and education funds. Emphasis in elementary schools is on using music to introduce science concepts. Concepts discussed include wave properties such as wavelength, frequency, propagation speed, and standing waves. The idea of resonance is experienced musically and physically, and the relationship between whole number frequency multiples and the musical harmonic series is developed. Computer programs such as cool-edit are used extensively in secondary teacher workshops to experience frequency analysis, frequency synthesis, and resonances in open and closed tubes. Workshop teaching approaches for these topics will be illustrated in this presentation.
Computer simulations enhance experimental demonstrations in the underwater acoustics and sonar course
Authors: Korman Murray S.
Published: October 2013

Underwater acoustics and sonar (SP411) is a 3 hour course that is offered to midshipmen in their senior year. Typically, general science and oceanography majors, totaling 110 students/yr, enroll. Since this course is offered without a lab, the ‘‘in class’’ experience has been enhanced with the development (over many years) of our demo carts and computer workstations which surround the classroom. In a studio classroom atmosphere, students perform a variety of experiments in small groups. How can scientific visualizations best develop learning of complex interactions? Two examples are presented. PC–IMAT (personal curriculum interactive multisensor analysis training) simulations of multielement array steering support the theory and enhance the experiments that are performed in class such as the two-element array. Mathematica simulations involving the programming and animation of a point source in a rigid–rigid infinite parallel wave guide are used to stress the method of images, superposition, group and phase velocity and far-field modal pattern that is observed as a function of depth and source frequency. Later, students have fun using a ripple tank with an eye dropper to generate a point source between two adjustable parallel boundaries, and their understanding of ‘‘underwater sound’’ is greatly enhanced.
Experiences on Science, Technology and Society (ScTS) in teaching environmental noise
Authors: Paulin Pablo Roberto Lizana , Redondo Jose de Jesus Negrete , Rizo Elena Romero
Published: October 2013

The ScTS (Science, Technology and Society) is a new work field for a critical and interdisciplinary way to evaluate the social dimension of science and technology with regard to the social and environmental effects, in this case of environmental noise contamination. This new way to see science promotes reflection and modification of personal and professional values. Teams were organized to research the environmental noise impact on society and the human being. Then discussions were carried out in order to prepare classroom presentations. After the presentations and proposals, further discussion and conclusions about the problem were made, getting the students involved in the possible solutions. (To be presented in Spanish.)
Didactic toy for teaching the Fourier principle
Authors: Medina-Villanueva Miguel , Medina-Tamez Victor , Medina-Tamez Javier , Garcia-Mederez Adrian
Published: October 2013

The mathematical tool of Fourier analysis is used in many areas like vibrations, communications, optics, electronics, etc. The understanding of this subject sometimes causes frustration in students. The main purpose of this presentation is to propose a didactic toy that calculates the harmonic magnitudes through the discrete values of analog periodic signals. This device shows the rotative vectors in a physical way that makes the principle of Fourier understandable.
Using computers to overcome math-phobia in an introductory course in musical acoustics
Authors: Piacsek Andrew A.
Published: October 2013

In recent years, the desktop computer has acquired the signal processing and visualization capabilities once obtained only with expensive specialized equipment. With the appropriate A/D card and software, a PC can behave like an oscilloscope, a real-time signal analyzer, a function generator, and a synthesizer, with both audio and visual outputs. In addition, the computer can be used to visualize specific wave behavior, such as superposition and standing waves, refraction, dispersion, etc. These capabilities make the computer an invaluable tool to teach basic acoustic principles to students with very poor math skills. In this paper I describe my approach to teaching the introductory-level Physics of Musical Sound at Central Washington University, in which very few science students enroll. Emphasis is placed on how vizualization with computers can help students appreciate and apply quantitative methods for analyzing sound.
Lab experiment using physical models of the human vocal tract for high-school students
Authors: Maeda Eri , Arai Takayuki , Saika Noriko , Murahara Yuji
Published: October 2013

Recently, the development of educational tools for acoustics has become popular in Japan. We believe that physical models of the human vocal tract are particularly useful for teaching acoustics. Formerly we proposed three models of the vocal tract corresponding to the Japanese vowels, /i/, /e/, /a/, /o/, and /u/. We presented cylindrical, nasalized, and plate type models. The models were made of transparent acrylic resin, enabling the configurations of the oral cavity to be seen from the outside of the model. In this presentation, we will discuss the results of a lab experiment in which we used these tools to teach the mechanism of vowel production to high-school students who had just finished studying basic acoustics. By manipulating the plates in the plate type model, students were able to simulate constrictions at nodes and antinodes, and they were able to hear the shift in formant frequencies. The exercise helped students to understand vowel production. We received positive feedback from those who participated in the experiment.
Musical appreciation
Authors: Medina Maria del Consuelo
Published: October 2013

Pre-school listening to music is the principal way that leads to the appreciation of music that later facilitates knowledge and pleasure in the history of music. At the prescholastic age it is a very important aspect of education, and reasons and suggestions will be given. The activities must be brief, the teachers of music can at the most develop the activity every five minutes, leaving time for rest or expansion. Another suitable way to bring the child to music is through stories, which please all children; let them go to an unreal and fantastic world and listen to a story or an exciting adventure. The story then, should be brief, simple, with action, with familiar characters, but with some mystery; some repetitive element; and an ending both surprising and happy. It is preferable to include small folkloric tales from the universal repertoire, with works of simple and clear structure.
Recent advances in active control of aircraft cabin noise
Authors: Mathur Gopal , Fuller Christopher
Published: October 2013

Active noise control techniques can provide significant reductions in aircraft interior noise levels without the structural modifications or weight penalties usually associated with passive techniques, particularly for low frequency noise. Our main objective in this presentation is to give a review of active control methods and their applications to aircraft cabin noise reduction with an emphasis on recent advances and challenges facing the noise control engineer in the practical application of these techniques. The active noise control method using secondary acoustic sources, e.g., loudspeakers, as control sources for tonal noise reduction is first discussed with results from an active noise control flight test demonstration. An innovative approach of applying control forces directly to the fuselage structure using piezoelectric actuators, known as active structural acoustic control (ASAC), to control cabin noise is then presented. Experimental results from laboratory ASAC tests conducted on a full-scale fuselage and from flight tests on a helicopter will be discussed. Finally, a hybrid active/passive noise control approach for achieving significant broadband noise reduction will be discussed. Experimental results of control of broadband noise transmission through an aircraft structure will be presented.
Interior noise control through tuned loudspeaker absorption
Authors: Clark Robert L. , McEver Mark A.
Published: October 2013

In this work we describe the development and application of an interior noise control approach based on active loudspeaker tuning for sound absorption. Loudspeakers are tuned to minimize global sound pressure at specific acoustic modes through diaphragm velocity feedback. An experimental model of the acoustic space used for controller design is obtained through system identification. H2 optimal controllers are designed to minimize a performance microphone output by feeding back the tuned loudspeaker diaphragm velocity. By sensing speaker velocity rather than far-field sound pressure, the loudspeaker is actively tuned to minimize reflected sound at specific acoustic modes and therefore reduce the global pressure field. Experimental results, obtained from an acoustic enclosure modeled after a rocket fairing, are used to demonstrate the effectiveness of the tuned loudspeaker at global attenuation. Details of the design procedure and experimental applications are discussed.
An in-flight study of cabin buzz-saw noise
Authors: Reed David , Uellenberg Stefan , Davis Evan
Published: October 2013

This paper examines the characteristics of multiple-pure-tone noise generated by high-speed turbofans under conditions of supersonic fan tip speeds, especially as it is observed in an aircraft passenger cabin. This phenomenon, also known as buzz-saw noise, is an important noise source in commercial airplane passenger cabins and has proved to be difficult to treat with sound-absorbing materials. Recent flight test experiments by The Boeing Company have demonstrated extraordinary success in suppressing cabin buzz-saw noise by strategic placement of engine inlet acoustic linings. The observed behavior is explained by a propagation and radiation model, which is validated by in-flight measurements made with a phased microphone array mounted on the fuselage skin of a Boeing 777. A structural acoustic model is also offered to explain the different transmission characteristics of buzz-saw noise and turbulent boundary layer excitation. Correlation length scales measured on the fuselage surface for these two noise sources are key inputs to the structural model.
Structural acoustic modeling of aircraft fuselage structures
Authors: Buehrle Ralph , Klos Jacob , Robinson Jay , Grosveld Ferdinand
Published: October 2013

Recent studies at NASA Langley Research Center have examined the development and validation of finite element and boundary element modeling techniques for the prediction of structural acoustic response of aircraft fuselage structures. The goal of this work is to provide increased confidence in the modeling techniques so that interior noise criteria can be incorporated early in the design process. These efforts have focused on the development and validation of high-fidelity physics-based numerical models for structural acoustic predictions into the kilohertz region. Finite element models were developed based on the geometric and material properties of the aircraft fuselage structures. Experimental modal analysis and point force frequency response functions were used to validate and refine the finite element models. Once validated, the finite element predictions of the velocity response were used as boundary condition input for boundary element predictions of the radiated sound power. Experiments in the Structural Acoustic Loads and transmission (SALT) Facility at NASA Langley were used to validate the acoustic predictions. Numerical and experimental results will be presented for conventional aluminum rib and stringer-stiffened aircraft structures, a honey comb composite sidewall panel, and damped acrylic windows. Numerical predictions were in good agreement with the experimental data.
New analysis methods for the calculation of interior noise
Authors: Bliss Donald B. , Franzoni Linda P.
Published: October 2013

Recently developed analysis methods applicable to the prediction of aircraft interior noise are described. Analytical-numerical matching (ANM) and Local-global homogenization (LGH) are methods for the low- to mid-frequency range. Energy-intensity boundary elements are applicable for high frequencies. ANM is a method that replaces the effect of structural discontinuities (ribs, stringers, attachments) with dynamically equivalent smooth force distributions, thereby removing the need for high-resolution numerics in the overall computational problem. LGH, which applies for periodic and quasiperiodic structures, provides a means to solve directly for the long wavelength spatial content of the structure. This part of the structural motion is strongly coupled most to the interior sound field. Energy-intensity boundary elements provide a very efficient means to predict high-frequency broadband sound fields in a fundamentally correct manner. Current research on this boundary element method involves its extension to handle coupling with structural surfaces vibrating at high frequency. The strengths and limitations of each of the above methods is discussed in the context of the interior noise problem. Innovative methods for the reduction of interior noise, as suggested by these approaches, are also mentioned.
A prototype spherical array for interior noise investigations
Authors: Williams Earl G. , Houston Brian H. , Herdic Peter C.
Published: October 2013

A spherical array of radius 0.2 m with 18 uniformly distributed microphone elements on a spherical surface has been constructed. Using the theory of nearfield acoustical holography the instantaneous pressure, velocity, and intensity fields are reconstructed throughout a volume of 0.6 m radius centered at the array origin in the frequency range of 0–600 Hz. Since the measurements are instantaneous the array is intended to be used to measure distributed sources that need not be coherent or stationary, ideally suited for source identification in the interior of an in-flight aircraft, an automobile or in interior spaces in naval vessels. Preliminary experiments with a loudspeaker demonstrate the accuracy of the volume-field reconstruction of the instantaneous fields. This array is a prototype of an array with many more elements which will have a wider frequency range and finer spatial resolution. [Work supported by NASA and ONR.]