bluuebunny/crossref_metadata_2025 huggingface dataset:
Measurements of room effects on digital simulations of a concert hall sound field
Authors: McAtee Patrick R. , Wang Lily M.
Published: October 2013

Digital signal processing is becoming more and more commonplace in the field of architectural acoustics. One way it has been utilized is to simulate the acoustics of a space within another one through convolution of that space’s digitized acoustic characteristics with a source signal. In the consumer market, Yamaha pioneered and leads this area, producing a full range of amplifiers with several multichannel auralizations built in. It is not possible to ensure that all users will tune their listening space to allow the auralization to perform its best. This raises questions about how well the auralization can perform in various acoustic environments, and what indicators there might be as to the quality of that performance. A Yamaha system and two sets of speakers were taken to more than a dozen spaces, including offices, classrooms, band rooms, and larger performance spaces. Measurements of each room’s acoustical characteristics were recorded and analyzed to see how the acoustic parameters changed when the digital simulation of a concert hall sound field was running. Comparisons of the frequency responses, reverberation times, and clarity indices will be presented. [Work supported by UNL College of Engineering Summer Undergraduate Engineering Research Experience Grant.]
Composition and performance as outgrowth of synthesis techniques
Authors: Boulanger Richard , Thompson Greg
Published: October 2013

New methods of controlling and interacting with synthesizers are increasingly available to the composer. Advances in input devices enable a large range of gestural parameters to be translated into musically-relevant data, which can then be used in synthesis environments like Csound and Max/MSP. This paper will examine such input devices, including the radio baton, and show how this technology may be combined with existing synthesis techniques to produce exciting new sounds, algorithms, and compositional works.
Integrated circuit technology in hearing aids
Authors: Armstrong Steve
Published: October 2013

In recent years, digital technology has enabled the provision of many new hearing aid features such as noise reduction, feedback suppression and environment classification. As silicon technology evolves, more and more features will be possible within the existing package size and power budget. This paper provides an overview of integrated circuit technology and its application to hearing aid design. The architecture of a digital hearing aid circuit is described in light of the system constraints. The talk will conclude with a brief discussion of expected technological advances and their impact on hearing aid design.
Observations of aeroacoustic modifications of a supersonic jet by using a spherical reflector
Authors: Seto Kunisato , Islam Md. Tawhidul Khan
Published: October 2013

Jet screech was eliminated by placing a spherical reflector at the nozzle exit of an underexpanded supersonic jet. The placement of the reflector minimized the sound pressure and this muted sound did not excite the unstable disturbance at the exit of nozzle and the loop of feedback mechanism disappeared, thus the generation of jet screech was cancelled. The proposed method was very effective in reducing overall sound pressure in the upstream region of the nozzle exit. Therefore, it could be a promising countermeasure against acoustic fatigue to protect the fuselage of an aircraft by incorporating it into a streamline form. The flow characteristic of the jet for the proposed system was observed by the Schlieren apparatus with a high speed video camera. A slit path was cut to the reflector for visualizing the jet properly. The shock structure of the jet was slightly modified and became more stable. [The research was supported by a grant from JSPS of the government of Japan.]
High-frequency, high-power ultrasonic chemical reactors
Authors: Hoffmann Michael , Lesko Timothy , Colussi Agustin
Published: October 2013

A novel high-frequency (612 kHz), high-power (4 kW), pilot-plant scale sonochemical reactor was developed and used to study the degradation of organic chemical pollutants in aqueous solutions. The degradation rates of trichloroethylene, dichloromethane, and phenol were found to exceed those of similar frequency, small-scale bench reactors by factors ranging from 2.5 to 7. In addition, there is linear dependence between the observed sonolytic rate constants and the applied power density. The addition of ozone during sonication did not affect the first-order degradation rate constants for phenol degradation compared to the linear combination of sonication and ozonation. However, enhancement in the degradation rates of the total organic carbon (TOC) were observed. The enhanced reactivity of sonolysis coupled with ozonation is due to the sonolytic formation of hydrogen peroxide in water, which in turn reacts with ozone to form a highly reactive ozonide intermediate, dihydrogen trioxide, that reacts in a similar fashion to hydroxyl radical. However, its lifetime in aqueous solution is found to be substantially longer, and thus it is more likely to react with refractory organic compound fragments.
Fluid–structure interaction in a physical model of the human cochlea
Authors: Wittbrodt Michael J. , Steele Charles R. , Puria Sunil
Published: October 2013

Understanding the mammalian cochlea requires an understanding of the complex fluid structure interaction of an elastic partition separating two fluid channels. Using a combination of microfabrication and macrofabrication technologies, a passive physical model was developed. Compared to most MEMS devices the elastic partition is large. The width is tapered from 100 to 500 μ over the 36-mm length. Orthotropic properties are achieved with 9000 discrete aluminum fibers supported by either 1 or 5 μ of a polyimide thin film. Two fluid channels are macromachined from plastic and filled with saline. A magnet-coil system excites the fluid channel. The model demonstrates a traveling wave which peaks at a characteristic place. Normalized responses show gains of 2.5 and 3 at 29 and 23 mm from the basal end with phase lags of 3 pi and 5 pi for 8 and 18 kHz, respectively. Calculations using the WKB asymptotic approximation confirm the general character of the responses measured. The presence of fluid provides an efficient means of transporting the wave energy to a characteristic place on the elastic partition followed by a sharp roll-off in response. [Work supported in part by grants DC03085 and DC05454 from the NIDCD of NIH.]
Sensors at small scales for applications in fluid structure interaction problems
Authors: Varadan Vasundara V.
Published: October 2013

This talk will present an overview of the state of the art in the development of sensors at the nano and micro scale that are particularly suited for the study of small scale effects in fluid structure interaction problems. The parameters of interest pertain to pressure, shear stress, thermal effects, material surface modifications, and sensors and devices that play a role in microfluidics for applications in materials analysis on a chip as well as biomedical uses. In several applications wireless telemetry of data is a necessity and special challenges arise if devices are immersed in a liquid. Power sources for such devices as well as the telemetry system is also a research issue. Passive sensors such as remotely excited rf surface acoustic wave sensors are also of great interest. Real time correlation of data from several sensors measuring either the same or different parameters is also needed to provide parametric data for adaptive computer models that start with incomplete system models but rely on real time experimental data to evolve the computation. Active collaboration is needed between researchers working on device design and development and those studying fluid–structure interaction problems either experimentally or numerically.
Aspects of acoustics in MEMS devices
Authors: Dohner Jeffrey , Jenkins Mark , Walsh Timothy
Published: October 2013

In this talk we will present an overview of aspects of structural acoustics in MEMS devices at Sandia. Recent results concerning viscous wave motion in a rotational micromechanical system will be presented. In addition, experimental approaches for the characterization of acoustic effects in MEMS devices will be discussed. We will also present an overview of massively parallel numerical simulation capabilities for large-scale and small-scale (MEMS) structural acoustic analysis. Since large numbers of degrees of freedom are typically present in structural acoustic analysis, massively parallel computations are essential in solving practical application problems. Two formulations for the fluid will be considered: a standard linear velocity potential formulation, and a nonlinear wave formulation. The applications of the two formulations will be discussed. A parallelization scheme will be presented that allows for arbitrary decomposition of the wet interface. Finally, numerical results of application problems will be presented. [Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company for the United States Department of Energy’s National Nuclear Security Administration under Contract DE-AC04-94AL85000.]
An acoustic and electroglottographic study of V[glottal stop]V in two indigenous American languages
Authors: Esposito Christina , Scarborough Rebecca
Published: October 2013

Both Pima, a Uto-Aztecan language spoken in Arizona, and Santa Ana del Valle Zapotec (SADVZ), an Otomanguean language spoken in Oaxaca, Mexico, have sequences of two vowels separated by an intervening glottal stop. In both languages, this V?V sequence becomes reduced in certain occurrences, with the perceptual effect of the loss of /?/ in Pima and the loss of V2 in SADVZ. The purpose of this study is to provide an acoustic and electroglottographic (EGG) description of these sequences in both full and reduced forms, prompted by varying speech rate. Two acoustic measures of phonation type (H1–H2, H1–A3) and two EGG measures (OQ and peak closing velocity) were made for each vowel at the midpoints and adjacent to /?/. For Pima, an issue of interest is what properties of the /V?V/ sequences (when V1=V2) allow them to be distinguished from phonemic long vowels in the reduced forms where /?/ is lost. It is hypothesized that /?/ will be preserved as vowel glottalization. For SADVZ, an important question is what property of V?(V) (where V2 is devoiced), V?, and creaky vowels allow them to be distinguished from each other in reduced forms, given that they are all characterized by glottalization.
The Davis addendum to the Tomatis effect
Authors: Davis-Kalugin Dorinne S.
Published: October 2013

The relationship of the ear and voice is defined in three laws, known as the Tomatis effect. Specifically, these laws state: (1) The voice only contains the harmonics that the ear can hear. (2) If you give the possibility to the ear to correctly hear the distorted frequencies of sound that are not well heard, these are immediately and unconsciously restored into the voice. (3) The imposed audition sufficiently maintained over time results in permanently modifying the audition and phonation. Using a time domain frequency analysis of the voice, the spontaneous otoacoustic emissions from the ear were evaluated and compared with a frequency analysis obtained through voice analysis. One hundred percent correlation between the stressed frequencies of the ear and voice was noted. An addendum to the Tomatis Effect describes these effects. First, the ear emits the same stressed frequencies that are emitted by the voice. Second, when complementary or supplementary frequencies of stressed frequencies are introduced via sound vibration to the ear, vocal patterns regain coherence.
Low-frequency passive performance of a towed volumetric array during maneuvers
Authors: Dietz Jerrold , Edgerton James , Newhall Bruce , Arvelo Juan , Frazier Catherine
Published: October 2013

For a large towed volumetric array, array element deformations significantly degrade system performance both during tow-ship maneuvers as well as during straight tows. Using a least squares fit for the shape estimation sensors we can generate accurate array shapes that allow us to maintain signal gain through array maneuvers. Array signal gain was calculated throughout maneuvers and is observed against measures of the array distortion. These calculations are compared for a linear, planar and volumetric array. We will discuss the experimental results in addition to environmental modeling to determine the best achievable gains. [This work was supported by the Defense Advanced Research Project Agency (DARPA) under the Robust Passive Sonar (RPS) project.]
Measuring sediment density and velocity gradients in the transition layer
Authors: Holland Charles W. , Dettmer Jan , Dosso Stan E.
Published: October 2013

The geoacoustic properties of marine sediments, e.g., bulk density and compressional velocity, commonly exhibit large variations in depth near the water–sediment interface. This layer, termed the transition layer, is typically of O(10−1−100) m in thickness. Depth variations within the transition layer may have important implications for understanding and modeling acoustic interaction with the seabed, including propagation and reverberation. In addition, the depth variations may contain significant clues about the underlying depositional or erosional processes. Characteristics of the transition layer can be measured directly (e.g., coring) or remotely. Remote measurements have the advantage of sampling without disturbing the sediment properties; they also have the potential to be orders of magnitude faster and less expensive than direct methods. It is shown that broadband seabed reflection data can be exploited to remotely obtain the depth-dependent density and velocity in the transition layer to high accuracy. Mid-shelf seabed reflection measurements in the Italian littoral are exploited to obtain transition layer properties. These properties agree with direct (i.e., core) measurements within the uncertainty estimates. A slight but discernable bias between the two methods may be due to compaction during core sampling. [Work supported by ONR and NATO Undersea Research Centre.]
Frechet-derivative calculations of the environmental sensitivity of the arrival structure in shallow water
Authors: Sarkar Jit , Cornuelle Bruce , Roux Philippe , Kuperman W. A.
Published: October 2013

The expected sensitivity of a high-resolution tomographic inversion of a 10-km slice of shallow water has been studied. Parabolic equation calculations of the Frechet derivative of simulated data at 10-km range for measured sound-speed profiles were made. The computations are based on using an existing 29-element transmitter array together with a 32-element receive array separated by 10 km. The frequency bandwidth was 3.4 kHz. The Fourier syntheses of these results produce a sensitivity map for each temporal segment of the arrival structure.
Coupled vibration of a fluid-filled and submerged vascular tube with internal transitional/ turbulent flow due to a constriction
Authors: Yazicioglu Yigit , Royston Thomas J. , Spohnholtz Todd , Martin Bryn , Loth Francis
Published: October 2013

The vibration of a thin-walled cylindrical, compliant viscoelastic tube with internal flow and an axisymmetric constriction that results in transitional/turbulent fluid flow is studied theoretically and experimentally. Vibration of the tube is considered with internal fluid-coupling only and with coupling to internal flowing fluid and external stagnant fluid. The theoretical analysis includes the adaptation of a model for turbulence in the internal fluid and its vibratory excitation of and interaction with the tube wall. Theoretical predictions are compared with experimental measurements conducted on a flow model system using laser Doppler vibrometry to measure tube vibration and miniature hydrophones to measure fluid pressure. This study is relevant to and may provide further insight into vascular diagnostics via noninvasive acoustic measurements. [Research support: NIH EB002511 and HL55296, and Whitaker Foundation BME RG 01-0198.]
Minimization of the vibration transmission through the propeller-shafting system in a submarine
Authors: Dylejko Paul , Kessissoglou Nicole
Published: October 2013

Ships and submarines are efficient sources of underwater radiated noise. In the low-frequency range, the main sources of ship vibration and noise are the working machinery such as the diesel engines, gearboxes and generators, and the propeller/propulsion system. Rotation of the propeller results in discrete tonals at the blade passing frequency and its harmonics. In addition, in the case of a submarine, hydrodynamic forces acting on the propeller due to the fluctuating pressure field are transmitted through the propeller-shaft and thrust bearings, resulting in axial excitation of the submarine hull. A hydraulic dynamic absorber, also known as a resonant changer, is used to minimize the vibration transmission through the propeller-shafting system, in order to prevent excitation of the hull axial resonances. The present work is concerned with minimizing the vibration transmission to the hull by optimizing the virtual spring, mass, and damper parameters associated with the resonant changer in a submarine. The dynamic response of the propeller-shafting system, including the propeller shaft, thrust bearing, thrust block foundation, and resonant changer, are characterized using four pole parameters.
Contrastive backward effects of nonspeech tones on speech perception
Authors: Wade Travis , Holt Lori L.
Published: October 2013

Nonspeech stimuli influence phonetic categorization, but effects observed so far have been limited to precursors’ influence on perception of following sounds. However, both preceding and following speech affect phonetic categorization. This asymmetry in nonspeech and speech effects raises questions about whether general auditory processes play a role in context-dependent speech perception. Here, experiments test whether the asymmetry stems from methodological issues rather than genuine mechanistic limitations. To determine whether backward effects of nonspeech on speech may be achieved when listeners are sufficiently encouraged to incorporate later-occurring acoustic events, a series of experiments examined perception of CVC words with [da]–[ga] series onsets followed by embedded tones and one of two possible final consonants. When the final consonant was required for word identification, subjects showed clear contrastive effects; more [d]-initial words were heard with higher-frequency tones approximating a [g] third formant location, and vice versa. More limited effects were observed when subjects identified only the initial consonant and when no final consonant was present. Results are discussed with respect to a contrastive mechanism not speech specific but operating at a relatively high level, taking into account spectral patterns occurring over extended periods before and after a target event. [Work supported by NIH.]
The role of multimodal sensory feedback in the perceptual learning of speech under a novel acoustic transformation
Authors: Webster Kevin T. , Lachs Lorin
Published: October 2013

This experiment examined spoken word recognition during and after perceptual learning of an unusual acoustic transformation of speech. Previous research has found that adults and children receive more benefit from cochlear implants when auditory information is effectively integrated with visual lipreading information. Because cochlear implant users have little, if any, preoperative experience with auditory information, these findings suggest that perceivers are able to capitalize on already-obtained lipreading skills in order to effectively learn to perceive new acoustic information about speech. This may be due to the fact that auditory and visual speech are lawfully related to the same physical event, a spoken utterance. Alternatively, it is possible that the addition of any relevant stimulus, regardless of its lawful relations with auditory speech, will aid in the process of learning how to deal with new perceptual information. To test these hypotheses, normal-hearing participants were trained with three different conditions of perceptual input while learning to perceive frequency-inverted speech: auditory-alone, auditory with orthographic visual stimulation, and auditory with visual information about the lips and face. The results of this study showed interesting patterns of perceptual learning and are discussed in terms of their implication for current theories of perceptual integration.
Vowel discrimination in early bilinguals: Evidence of phonetic reorganization
Authors: Hojen Anders , Flege James E.
Published: October 2013

The issue of whether new categories may be established for vowels found in a second language (L2) but not the native language (L1) remains controversial. The present study compared the discrimination of English vowels by native English speakers, early Spanish-English bilinguals, and Spanish monolinguals (n=20 each). Vowels in the control contrast (/i/-/u/) were likely to be heard as two distinct Spanish vowels by Spanish speakers, whereas the vowels in three test contrasts (/eI/-/I/, /α/-/Λ/, /o■/-/■/ were likely to be heard as a single Spanish vowel. To avoid the ceiling effects often seen in cross-language vowel discrimination research, within-trial F0 variation was introduced into the categorial AXB test used here. The 64 trials testing each contrast were presented in two randomized blocks differing in interstimulus interval (0 vs. 1000 ms). All three groups obtained high scores for the control contrast (means=88% to 98% correct), but only the Spanish monolinguals obtained low (<65%) scores for the three test contrasts. All early bilinguals showed significantly above-chance performance (p<0.01 by binomial probability), but only three Spanish monolinguals did so. The results are interpreted to mean that the early bilinguals established new categories for English vowels. [Work supported by NIH.]
Performance of a multichannel time-reversal receiver design in a highly reverberative environment
Authors: Candy James V. , Guidry Brian , Robbins Christopher , Poggio Andrew , Chambers David , Meyer Alan
Published: October 2013

The development of multichannel time-reversal (T/R) communications in a highly reverberative environment was discussed previously [Candy et al., J. Acoust. Soc. Am. Suppl. 115, 2467 (2004)]. This paper focuses on the development and performance of a 1-bit receiver in the multichannel case. Here, we discuss the performance of a suite of multichannel TR 1-bit receiver realizations, similar to the multichannel case, using an acoustic 8-element T/R array and a set of client stations. The performance of these processors on both simulated and experimental data is discussed in detail. The experiment is provided by a stairwell between two floors of a noisy building. The stairwell is populated with obstructions (pipes, rails, wall, etc.) and a 90-deg landing—clearly a highly reverberative environment. It is shown that the 1-bit multichannel receivers perform quite well when compared to their full-dynamic-range 16-bit counterparts, and are able to reliably extract the transmitted code from the noisy measurements.
Experimental testing of broadband decomposition of the time reversal operator (DORT) in shallow water
Authors: Fromm David M. , Gaumond Charles F. , Menis Richard , Calvo David C. , Lingevitch Joseph F. , Edelmann Geoff F. , Kim Elisabeth
Published: October 2013

Results are shown from the application of DORT to at-sea data taken in an area south of Hudson Canyon off the New Jersey coast during Spring 2004. A vertical source/receiver array with 64 hydrophones spanning the water column of 100-m depth was operated in 500-Hz bands between 500 and 3500 Hz. Sets of four, five, or six beams were transmitted at small angles from horizontal and the response from an echo repeater was recorded on 64 channels. The resulting data were analyzed using broadband DORT. Specific transmissions were used to quantify the degradation of coherence due to temporal variability of the source/receiver, environment, and echo repeater. The isolation in the singular vectors of the echo repeater using sets of independent source beams is comparable to that from the coherence tests. The singular spectrum of the noise field is compared with the expected results from that of a random matrix. Backpropagation images based on at-sea data and propagation using in situ XBT measurements are shown. [Work supported by ONR.]
Parametric synthetic interferometric sonar for bottom and subbottom imaging and mapping
Authors: Zakharia Manell E. , Hibral Sidonie , Pollet Claire , Rigaud Emmanuel
Published: October 2013

Parametric sonar and synthetic aperture processing are commonly viewed as competing solutions for the detection of buried objects. In the framework of the SITAR project (EC funded project for the detection and characterization of buried waste in the Baltic Sea), both techniques are used concurrently in order to get the best resolution for both bottom and subbottom images. The primary frequency of the prototype is around 100 kHz, leading to a secondary one ranging from 10 to 20 kHz. The difference in penetration will be used to discriminate proud from buried targets. Two lines of receiving arrays, were used in order to provide SAS interferometric mapping. Six SAS images were thus obtained from the same spot, at the same time and with comparable resolution (two high frequency images and a low frequency one for both top and bottom arrays). Three maps were then obtained by applying interferometric processing to data issued from each frequency range. The paper will compare the images and maps obtained in the three frequency ranges and correlate a target’s elevation (or burial) to its reflectivity.
RoomWeaver and Digitract: Two digital waveguide mesh acoustic modeling reseach tools
Authors: Murphy Damian T. , Beeson Mark J. , Mullen Jack , Howard David M.
Published: October 2013

RoomWeaver is a digital waveguide mesh (DWM) development environment for virtual acoustic spaces. Scripting is used to define room geometry, object, surface and material properties, together with source and receiver parameters. Different mesh types and topologies are accommodated through a user-extensible plug-in architecture with the selected DWM grown to fit the defined room at simulation run-time. Visualization options allow mesh behavior and wave propagation to be observed in 2D or 3D. Excitation signals can be selected accordingly and resultant room impulse responses can be obtained in mono, stereo, binaural or surround formats. Digitract is a speech synthesis research tool that uses 1D and 2D digital waveguide models to simulate the human vocal tract. 1D simulation is already well established and Digitract allows direct comparison with 2D DWM models that offer improved control over formant bandwidths and greater naturalness in synthesized speech. Mesh types and topology can be defined together with reflection values at lip, glottis, and, in the 2D case, inner wall boundaries. Vibrato and pitch-slide can be introduced to the input and dipthongs and tripthongs can also be synthesized. 3D graphical feedback illustrates the behavior of the acoustic pressure waves present within the tract model.
Perceptual grouping of musical sequences: Pitch and timing as competing cues
Authors: Hamaoui Kamil , Deutsch Diana
Published: October 2013

A series of experiments was conducted that explored the roles of pitch and timing cues on perceptual grouping of musical patterns, in which tones were presented at rates slower than those giving rise to stream segregation. Sequences of 12 tones were constructed in which a pitch cue (size of pitch distance between adjacent tones) and a temporal cue (size of temporal gap between adjacent tones) were set in opposition to each other. Either the pitch cue suggested groupings of three and the temporal cue suggested groupings of four, or vice versa. Listeners judged for each sequence whether they heard groupings of three or four tones. When the sequences traversed a semitone scale, grouping judgments were made on the basis of timing in a remarkably fine-grained fashion, and the effects of timing were related in an orderly fashion to the size of pitch distance cue employed. However, when the sequences possessed a hierarchical pitch structure, grouping on the basis of pitch dominated judgments instead. The effect of hierarchical pitch structure was substantial, even when compared with control sequences in which parameters such as interval size and contour were held constant. Implications of these findings for music perception and performance are discussed.
Classroom acoustics and ANSI S12.60: A British perspective
Authors: Mapp Peter A.
Published: October 2013

At the same time that ANSI S12.60 was being developed, UK recommendations for classroom acoustics were also being drawn up (Building Bulletin BB 93). The resulting standards turned out to require similar goals and set very similar criteria (e.g., 0.6 s RT). The British document however, also set a criterion for intelligibility of 0.6 STI for open-plan classrooms and teaching areas. Apart from making some general comparisons between the standards, the paper looks at the practicality of measuring STI in classrooms. The practical problems of making measurements under occupied conditions as well as the influence that the sound source itself can have on the measurements are discussed. An empirical relationship between STI and the reverberation time of a classroom is established which may be of use to designers. The effects of source directivity on the resultant STI are discussed and measurement data are presented that compare different loudspeaker types including omnidirectional (dodecahedral array), single-cone units, and head/mouth simulators.
Blue and fin whales in the Southern California Bight: Using long-term acoustic records and acoustic recording tags
Authors: Oleson Erin M. , Calambokidis John , Wiggins Sean M. , Hildebrand John A.
Published: October 2013

Blue and fin whales have been the subject of acoustic investigation for decades, but recent advances in technology, including acoustic tags, autonomous recorders, computer automated signal detectors, and genetic sex-identification allow us to examine fine scale patterns in acoustic behavior. Northeast Pacific blue whales are known to produce at least five separate call types, and North Pacific fin whales at least three. Since August 2000, we have been acoustically monitoring blue and fin whales in the Southern California Bight using acoustic recording packages (ARPs), acoustic recording tags, and through genetic sampling of vocal whales. There are patterns of occurrence of particular call types with nonacoustic behaviors, and sex-biases exist in the production of certain calls. Acoustic sampling from several sites in the region indicates there are significant changes in the detection of various call types both within and between years, and among sites. Hourly detection patterns also vary, potentially serving as an indicator of feeding activity. An understanding of the temporal and spatial patterns of occurrence of individual call types, and the behavior associated with each, will lead to more efficient methods to monitor habitat, distribution, and abundance of these species.
Sound-quality analysis of sewing machines
Authors: Chatterley James J. , Boone Andrew J. , Blotter Jonathan D. , Sommerfeldt Scott D. , Lago Thomas L.
Published: October 2013

Sound quality has become an important factor in consumer product development. Sound quality analysis procedure and results for six sewing machines ranging from entry level to professional grade machines will be presented. The focus of the study was to determine what consumers feel constitutes a pleasant sounding sewing machine and what structural modifications can be made to produce those sounds. The procedure consisted of forming small (15 person) then large (50 person) jury-based tests. These tests consisted of listening to various sound bytes and ranking the sounds as well as indicating why sounds are appealing or unappealing. The sound bytes were from actual sewing machines as well as computer generated sounds and modified machine sounds, which were constructed such that the spectral features most important in achieving a desirable product from an acoustic perspective could be statistically determined. The procedures and analysis of the jury testing results will be presented and discussed. This paper presents sound localization scans, indicating machine sound hot spots and possible sources for undesired sounds. In conclusion proposed modifications to machine structure to alter machine sound signature into a more sensory pleasant sound will also be presented.
End correction for an open pipe from measured resonance frequencies
Authors: Ludwigsen Daniel O. , Dilworth Brandon J.
Published: October 2013

As briefly noted in freshman physics textbooks, resonance in open-ended pipes depends on an effective length that is greater than the actual length of the tube. The additional end correction varies with the termination at the open end. By measuring several peak frequencies in a response function (pressure in the pipe over source excitation), we have calculated the end correction for open ends of PVC tubes of varying diameters with several flanges of increasing size. Temperature effects were carefully controlled, and resonance frequencies recorded to within 0.01 Hz. Averaged results are in agreement with literature and theoretical expectations, but anomalies and unexpected results will also be presented.
Measurements of the acoustics of the kalimba
Authors: Ludwigsen Daniel O.
Published: October 2013

The kalimba is an idiophone (self-sounding instrument) of African origin, specifically a standardized type of mbira manufactured with modern facilities by Hugh Tracey. The sound production is somewhat similar to a small glockenspiel, but the free ends of the metal keys are plucked rather than simply-supported struck bars. The body of the kalimba, however, more resembles a guitar with a central sound hole in the top plate. There are additionally two smaller holes in the back plate, which a player can use to create vibrato effects with rapid covering and uncovering with fingertips. Spectral information and modal analysis are used to investigate the dynamics of sound production of the kalimba, and are compared with such measurements in the literature for guitar and mallet instruments. These measurements will inform future modeling efforts to better understand the dynamics of the instrument.
Drumstick ‘‘Pitching’’—A modal analysis approach
Authors: Bissinger George
Published: October 2013

‘‘Pitching’’ drumsticks by ear is too time intensive for a manufacturing process that generates many millions of drumsticks each year. Yet, it is a sought-after attribute that is worth implementing if some pitching technique can be made compatible with typical manufacturing rates. Drumstick pitch is normally determined by our evaluation of the sound produced by the nonharmonic vibrations when it is held and struck against a hard surface. Vibration analysis performed on drumsticks in a free–free support fixture provided normal mode results for over 100 solid wood and wood+plastic tip drumsticks. Modal analysis measurements up to 5 kHz were made parallel and perpendicular to the plane of the grain at 17 points along the length of a few drumsticks. A small sample of four drumsticks, pitch-matched by ear for comparison with these vibration analysis predictions, indicated a promising solution to the problem of real-time pitch matching. Even though the usual problems were encountered—orthotropic, small knots, kinked or twisted grain, density variations (dimensional consistency was within 0.1% but mass varied over 40%), and stiffness variations—the least sensitive to these problems was the lowest bending mode near 0.4 kHz, now the basis for automated pitch matching by a major manufacturer.
Multiphonic model of split pressure-phase modes using the finite-element-method
Authors: Rolf Bader
Published: October 2013

The generation of multiphonic sounds in blown musical instruments is modeled by an eigenvalue finite-element-method (FEM) calculation. A common technique for the production of multiphonic tones is the use of complex sound-hole closing techniques, where more than one overtone spectrum appears, with fundamental frequencies being in inharmonic relations. Eigenfrequencies of a tube with both ends open are compared to eigenfrequencies of a tube with at least one sound hole open. It shows up that the tube with one open sound hole leads to additional eigenfrequencies in the tube for each node number. This is because of two possibilities of pressure curves within the tube for each node number, the pressure right and left of the hole being in phase or in opposite phase. The frequencies of equal phase form a new overtone structure which is harmonic within itself and so forms a new tone, a multiphonic. So the multiphonic model is in agreement with the Backus formula of multiphonic sounds as a combination of the tubes fundamental and multiples of the frequency difference of the zero node mode components.
Influence of control structure and sound reproduction on the intelligibility of speech in headsets with active noise reduction
Authors: Brammer Anthony J. , Peterson Donald R. , Cherniack Martin G. , Gullapalli Subhash
Published: October 2013

A primary requirement for a communication headet is to maintain speech intelligibility under all conditions of use. For headsets equipped with active noise reduction (ANR), the performance of the control system may influence the communication signal reaching the ear. Conversely, the communication signal may perturb the operation of the ANR system. The interaction between the communication and control signals will depend primarily on the control structure, and the electro-acoustic transfer function of the earphone and drive electronics of the communication channel. The effect on speech intelligibility will be described using the speech transmission index, for circumaural headsets employing feedback control with a fixed filter and analog signal processing, an approach commonly used in commercial devices, and one employing adaptive, digital feed-forward control. In each case, the active control systems attempt to control low-frequency noise, as the passive attenuation of the earmuff enclosing the ear substantially reduces noise at frequencies above 500 Hz. Results will be discussed for different environmental noise spectra, and speech-to-noise ratios.
An objective method for measuring the attenuation of hearing protection devices using otoacoustic emissions
Authors: Knaus Darin A. , Dietz Anthony J. , Musiek Frank E.
Published: October 2013

An objective human subject test technique for measuring the attenuation performance of hearing protection devices is presented. The technique is similar to the real-ear attenuation at threshold (REAT) technique, except distortion product otoacoustic emission (DPOAE) measurements in the ear canal replace the standard audiometric threshold measurements. The primary advantages of the new technique are that the measurement is objective, relatively fast, and can be applied at supra-threshold sound levels. Microphone in real ear (MIRE) data is also available from the DPOAE probe in the ear canal. Disadvantages are the restricted frequency range in which DPOAE signals may be reliably recorded (2–5 kHz) and the need for an in-ear probe. Attenuation data for a set of earmuffs was measured on a pool of seven subjects using DPOAE, MIRE, and threshold methods. The DPOAE and threshold measurements were in agreement, validating the DPOAE method. The MIRE data were significantly higher than the DPOAE or threshold data. The difference in the attenuation levels represents sound reaching the cochlea that is bypassing the ear canal. This difference was smaller for measurements of the attenuation performance of a helmet, which provides increased shielding from bypass transmission paths through the head.
Acoustic levitation in the field of analytical, physical, and atmospheric chemistry
Authors: Tuckermann Rudolf
Published: October 2013

In this contribution an overview of fundamentals, possibilities, and applications of acoustic levitation in the field of analytical, physical, and atmospheric chemistry investigated by Neidhart and co-workers since the 1990s will be given. Started with sample preparation procedures in acoustically levitated drops, e.g., analytical enrichment, liquid–liquid extraction, and acid-base titration [E. Welter and B. Neidhart, Fresenius J. Anal. Chem. 357, 345–350 (1997); R. Eberhard and B. Neidhart, ibid. 365, 475–479 (1999); O. Rohling, C. Weitkamp, and B. Neidhart, ibid. 368, 125–129 (2000)], the work has been continued in evaporation processes of liquids [R. Tuckermann, S. Bauerecker, and B. Neidhart, Analytical Bioanal. Chem. 372, 122–127 (2002)], crystallization, and freezing processes in acoustically levitated drops, formation and characterization of monomolecular films on the surface of levitated drops, formation and growth of particles [S. Bauerecker and B. Neidhart, J. Chem. Phys. 109(10), 3709–3712 (1998); Science 282, 2211–2212 (1998)] and trapping of heavy gases [R. Tuckermann, B. Neidhart, E. G. Lierke, and S. Bauerecker, Chem. Phys. Lett. 363, 249–354 (2002)] in stationary ultrasonic fields. Examples and results of these investigations will be presented.
Acoustically assisted phase-separation processes
Authors: Feke Donald
Published: October 2013

The separation and recovery of micron- to millimeter-sized secondary phases suspended in liquids is of fundamental importance in a variety of chemical, biochemical, and materials processing applications. These secondary phases can be solid particles, immiscible liquid droplets, or gas bubbles. In our laboratory, we have developed a separation technique in which the application of acoustic radiation pressure enables the phase separation within meshes having pore size up to 100 times the size of the secondary phase being retained. For the case of droplets and bubbles, the transport and coalescence induced by the acoustic radiation forces augments the separation efficiency. As a means to understand the fundamental physics of this process, we have developed both micro- and macro-scale models of the behavior of dispersed phases in our laboratory-scale acoustic devices and have performed experiments to validate these models. Micro-scale models predict the motion of individual dispersoids in response to the applied acoustic and flow fields, while the macro-scale models predict overall collection dynamics and breakthrough times. Generally, the correspondence between model predictions and experimental observation is excellent. These models thus reveal the fundamental physics that underlies the enhancement of the separation process by the acoustic radiation pressure.
Optical detection of the response of liquid jets to internal modulated ultrasonic radiation pressure
Authors: Lonzaga Joel B. , Osterhourdt Curtis F. , Thiessen David B. , Marston Philip L.
Published: October 2013

A liquid jet in air is an acoustic waveguide having a cutoff frequency inversely proportional to the jet diameter. Ultrasound applied to the jet supply liquid can propagate down the jet when the carrier frequency is near-to or above the cutoff frequency. The jet response to the internal acoustic radiation pressure of amplitude modulated ultrasound was monitored along the jet using an optical pseudo-extinction method. The jet profile oscillates at the frequency of the radiation pressure modulation and, where the response is small, the amplitude was found to increase in proportion to the square of the acoustic pressure amplitude as previously demonstrated for oscillating drops [P. L. Marston and R. E. Apfel, J. Acoust. Soc. Am. 67, 27–37 (1980)]. Small amplitude deformations initially grow approximately exponentially with axial distance along the jet. Modulated radiation pressure can be used to stimulate large amplitude deformations and the breakup of the jet into drops. [Work supported by NASA.]
Use of a slightly curved reflector to enhance an airborne ultrasonic standing wave in a semi-infinite rectangular channel
Authors: Anderson Michael , Cluff Andrew , Lemmon E. Clark , Putnam Gabriel
Published: October 2013

One way to separate small particles from a moving air stream is to pass the stream through an intense ultrasonic standing wave. If the standing wave propagates perpendicular to the fluid flow direction, acoustic radiation pressure will move the particles to specific locations in the stream, where they can be collected at the stream outlet. Of primary importance is to achieve very high pressure amplitude in the standing wave, in spite of the presence of openings for fluid flow. In this presentation, the use of a slightly curved reflector within a flow channel to increase the amplitude of an ultrasonic standing wave is discussed. A finite element analysis was used to predict the amplitude of the standing wave that would be excited in a semi-infinite channel. A perfectly matched layer was used to account for the semi-infinite geometry. The finite element analysis showed that a significant gain in amplification within the channel could be achieved with a surprisingly small amount of reflector curvature. Experiments show that much of this gain can be obtained in practice.
Global foreign accent in English sentences produced by native Spanish learners of English: A 5-year longitudinal study
Authors: Imai Satomi , Flege James E. , Wayland Ratree , Talla Surya P.
Published: October 2013

Second language acquisition theorists posit that the performance of adult second language (L2) learners improves up to a certain point but may then fossilize, that is, show little further improvement. However, few empirical studies have tested for changes in L2 production by individual adult L2 learners over an extended period of time. In the present study, sentences produced by adult native Spanish (NS) learners of English over a 5-year period will be evaluated for changes in pronunciation. Fifteen NS adults (mean age=34 years when first tested) who had lived in Birmingham, AL and three native English (NE) controls produced four English sentences at 6-month intervals for 5 years. NE listeners will rate the sentences for foreign accent. One-way repeated measures ANOVAs will be carried out to determine if individual NS participants, or the group as a whole, became less foreign-accented over the study interval. Individual differences in demographic variables that might have affected degree of foreign accent (e.g., age of arrival in the U.S., chronological age of testing, percent English and Spanish use, family status) will be discussed in relation to any improvement in L2 production. [Work supported by NIH.]
Perception of multimodal time differences in virtual environments
Authors: Begault Durand R. , Wenzel Elizabeth M.
Published: October 2013

Presentation of multimodal information with a virtual environment human interface can enable teleoperation of remote tools, sensors, and vehicles for space applications. However, the performance advantages of providing multimodal information can be potentially reduced by intermodal timing asynchronies between different rendering systems (system–system asynchrony). Additionally, asynchronies between the rendering system and proprioceptive, vestibular, and kinesthetic cues that are produced by the actions of the human user can also be problematic (human-system asynchrony). Preliminary data on tolerable asynchrony for audio-haptic interfaces for virtual environments is presented, along with data relevant to perceptually acceptable update rates and latency to minimize computational and perceptual artifacts within virtual auditory displays. [Work supported by the Human Measurement and Performance Project within NASA’s Airspace Systems Program.]