bluuebunny/crossref_metadata_2025 huggingface dataset:
Room boundary absorption coefficient measurements in a small room
Authors: Hyde Jerald R.
Published: July 2012

During the renovation of an 1890s Victorian building, the author’s high ceiling office became entirely empty, the rectilinear boundaries consisting of wood, plaster, and glass surfaces. With a volume of 86 m3 (3030 ft3) the empty room had reverberation times (RT) ranging from 1 sec at low frequencies to over 2-1/2 sec at high frequencies. Boundary absorption coefficients were derived from RT data for the empty room’s surfaces with the greatest absorption occurring in the 125-Hz octave band. Two different (weight) carpets of approximately 8.5 m2 (92 ft2) were then added to the floor and their absorption values calculated. Absorption coefficient results will be presented along with a study of the derived coefficient values of each of the component surfaces. Similar ‘‘boundary only’’ results from an ‘‘empty’’ 500-seat theater will also be shown.
Pressure-amplitude reflection coefficients of active impedance tube terminations and their relationships to energy-related quantities of adjacent sound fields
Authors: Leishman Timothy W.
Published: July 2012

Active boundary surfaces intended to control reverberation or other characteristics of enclosed sound fields have often been investigated using impedance tubes. Unfortunately, the significance of pressure-amplitude reflection coefficients produced by these surfaces and their relationships to acoustic energy quantities in enclosed spaces has remained obscure. This paper accordingly presents a straightforward analysis of an actively terminated impedance tube to provide needed clarification. It demonstrates that increases in reflection coefficient moduli at the termination do not necessarily produce proportional increases in total enclosed energy in the tube or energy flux toward the enclosed field. Very large reflection coefficients (i.e., with moduli much greater than unity) produce both total enclosed acoustic energies and vector magnitudes of net active intensity approaching those present under an anechoic boundary condition. Large relative changes in total enclosed energy occur only when active termination reflection coefficient moduli roughly approach unity. Energy-related effects of actively produced reflection coefficients are generally frequency-dependent functions of distinct enclosed spaces and acoustic fields generated by primary sources in these spaces. Hence, correlations between reflection coefficient moduli and energy quantities of adjacent sound fields are not necessarily simple or consistent. They depend upon important physical properties of acoustic spaces, sources, and source arrangements.
Normal-incidence sound absorption measurement of a perforated panel using a sound-intensity technique: Theoretical versus experimental
Authors: Dimon Mohamad N. , Rahman Tharek A. , Said Ahmad K. , Ibrahim M. N. , Jaafar M. Y.
Published: July 2012

A direct-piercing carved-wood panel (DPCWP) is a form of wood carving that allows air to pass through the panel easily. In Malaysia, DPCWPs are available with various perforation ratios, patterns, and elements, and are typically used as part of a wall partition for an enclosed room. It helps in providing natural ventilation, besides it is believed to be able to act as a sound absorber. Circular perforated panels are the simplest form of DPCWP available. It was found out that normal-incidence sound-absorption performance of perforated panels can be measured reliably using a sound-intensity measurement technique. In this paper, normal-incidence sound-absorption measurement of a perfortated panel using fixed-point scanning will be discussed. Close correlations were obtained from 250 Hz to 4 kHz between theoretical and measured sound absorption. Factors contributing toward sound intensity measurement reliability, primarily through its sound quality indicators such as F1, F2, F3, and F4, and the effect of measurement distance will be thoroughly discussed. This finding suggests that the sound intensity measurement technique can be used to measure normal-incidence sound-absorption performance of DPCWP reliably.
Underwater temporary threshold shifts in pinnipeds: Tradeoffs between noise intensity and duration
Authors: Schusterman Ronald , Kastak David , Southall Brandon , Kastak Colleen
Published: July 2012

Temporary threshold shifts (TTSs) were obtained in one female California sea lion (Zalophus californianus), one male harbor seal (Phoca vitulina), and one female northern elephant seal (Mirounga angustirostris). Prior to noise exposure, base-line hearing thresholds were obtained at 2500 or 3530 Hz using behavioral techniques. During noise exposure, the subjects were stationed in an underwater noise field for either 20–25 or 50 total minutes. The noise field consisted of octave-band noise centered at 2500 Hz with exposure levels of either 65, 80, or 95 dB above the mean base-line thresholds [i.e., sensation level (SL)]. Postexposure thresholds were obtained immediately following noise exposure. The same testing and diving patterns were used in the absence of noise to control for the effects of diving. Hearing losses ranged from 0 to 28 dB, and there was substantial inter- and intraspecific variability in the amount of hearing loss following exposure to similar noise regimes. Recovery was also variable, ranging from minutes to hours, with complete recovery always occurring within 24 hours. We found threshold shifts of 5 dB at 65 dB SL and only marginal increases in TTS with increasing noise intensity. However, increasing noise duration with constant noise exposure levels yielded greater shifts.
Characterization of measures of reference acoustic cavitation (COMORAC)
Authors: Leighton Timothy G.
Published: July 2012

This paper describes a coordinated experiment involving a number of UK centers, with the aim of comparing a range of systems which measure cavitational activity. Sensors have been designed at a number of universities to produce quantitative outputs based on sonochemical (Bath and Southampton), calorimetric (Coventry), electrochemical and luminescent (Southampton) measures. In addition, acoustic sensors have been produced (Guys and St. Thomas Hospital Trust, and the National Physical Laboratory). These are all deployed to monitor controlled cavitation events, ranging from single bubble phenomena to a reference cavitation bath (produced by NPL). Design of these cavitation systems has involved not only the characterization of the sound field and the vessel, but also the specification of some reference cavitation liquid (NPL and Southampton). Comparison of the resulting measures of activity allows the feasibility of a scale for cavitation to be investigated.
Control of inertial cavitation in shockwave lithotripsy
Authors: Coleman Andrew J. , Cahill Mark D.
Published: July 2012

The role of inertial cavitation in stone comminution and tissue damage during extracorporeal shock-wave lithotripsy (ESWL) became appreciated several years after the successful introduction of ESWL into routine clinical use in the early 1980s. It is only relatively recently, however, that attempts have been made to enhance or suppress the cavitation field in lithotripsy by adapting the acoustic field generated by the shock-wave source. The single-cycle acoustic pulses used in commercial ESWL generate a cavitation field in which the bubbles may remain in an expanded phase for many times the pulse duration. Some control of cavitation can be gained by timing an additional pulse from a second source to coincide, for example, with the bubbles expanded phase [M. R. Bailey, Tech. Rep. No. ARL-TR-97-1, Univ. of Texas, Austin (1997)]. This can generate an earlier and more violent bubble collapse. A single source generating multiple-cycle pulses can, similarly, provide a means of controlling cavitation activity in lithotripsy. This approach has been examined using an electromagnetic-type shock-wave source to generate high-amplitude, multicycle pulses in water. By tailoring the pressure waveform specifically to control cavitation, it may be possible to refine medical ultrasound applications, such as ESWL, where cavitation plays a role.
Nonlinear scatter from the ultrasound contrast agent Sonazoid: Theory and numerical simulations
Authors: Hoff Lars
Published: July 2012

A model for the contrast agent Sonazoid is presented. The model is based on a modified Rayleigh–Plesset equation, with the shell added as an incompressible viscoelastic solid. Different models for the shell’s nonlinear stress–strain relationship are discussed. Shell elasticity and viscosity were estimated from experiments, and the model was used to simulate bubble radius and scattered sound. Pulse-inversion imaging was simulated. The amplitude was increased from 20 to 500 kPa, giving scattered pulses that changed from inverted to time-shifted versions of each other. This effect was best seen in the cross correlation of the responses. The nonlinear response was strongest for frequencies below bubble resonance. Compared to unshelled bubbles, Sonazoid required higher drive amplitudes to respond nonlinearly. The Sonazoid bubbles responded similarly to unshelled bubbles of smaller diameter. A subharmonic response was found in a limited frequency band and only for diameters above 3 μm. An amplitude threshold was found around 500 kPa, depending on diameter and frequency. This threshold is higher than for unshelled bubbles. A chaotic oscillation pattern was found for some diameter–frequency combinations, in agreement with published results. For some situations where the cw results predicted a subharmonic mode, this mode was not obtained from finite-length pulses.
Interaction of shock waves with cavitation bubble: Application of Ho:YAG pulse laser irradiation for cerebral thrombolysis
Authors: Hosseini S. H. R. , Hirano Takayuki , Onodera Osamu , Takayama Kazuyoshi
Published: July 2012

This paper reports on the application of underwater shock waves and vapor cavities for cerebral thrombolysis. The energy source was a Q-switched Ho:YAG laser (Nippon Infrared Industries Co., Ltd.) with 91 and 140 mJ/pulse energy measured at the end of a 0.60-mm-diam glass optical fiber, pulse duration of 200 ns, and wavelength of 2100 nm. The whole sequences of the shock-wave propagation and growth of the cavitation bubbles from the end of the optical fiber were visualized by high-speed photography using an Imacon 468 camera (Hadland Photonics Ltd.). The shock-wave generation was associated with the laser breakdown in the water. The laser interaction produced a microplasma and heated the liquid in front of the fiber. The plasma drove spherical shock wave in water, followed by the formation of a high-temperature vapor cavity. Collapse of the cavity produced a secondary spherical shock wave in water. Successive generation and collapse of the bubbles were visualized. Pressure histories were measured by PVDF needle hydrophones. The underwater shock waves and the vapor cavities were successfully applied for disruption of artificial thrombosis. The result clearly shows potential extension of this method to precise medical treatment for revascularization in neurosurgery.
Comparison of techniques for measuring the acoustic properties of porous materials
Authors: Beamer C. Walter , Muehleisen Ralph T.
Published: July 2012

There is a large variety of methods for measuring the acoustic properties of porous materials. Of particular interest to many acoustics researchers are the characteristic impedance and propagating wave number of the porous materials. The standing wave impedance tube and two-microphone method of measuring those properties have both become standards. A number of extensions of the two-microphone method have been developed. Song and Bolton recently published a transfer matrix method utilizing four microphones [J. Acoust. Soc. Am. 107, 1131–1152]. Comparisons of the tradeoffs and errors inherent in the major methods for the measurement of the acoustical properties of porous materials are presented. [Work supported by the Office of Naval Research.]
Relationship between the diffraction constants, the reciprocity parameter, and the mutual radiation impedance of a pair of compact radiators: An improved Pritchard approximation
Authors: Baker Steven R. , Scandrett Clyde L.
Published: July 2012

By the principle of reciprocity, the mutual radiation impedance matrix of an acoustical array in a stationary fluid must be symmetric. However, use of the classical ‘‘Pritchard approximation’’ to compute array mutual (mechanical) radiation impedance (Zmut=j Re[Zself]e−jkd/kd;  ejωt assumed) [R. L. Pritchard, J. Acoust. Soc. Am. 32, 730–737 (1960)] leads to a matrix which is not symmetric for nonidentical radiators. Also, it is restricted to low frequencies (ka≪1). By a simple application of the principle of reciprocity, it is shown that the mutual mechanical radiation impedance of a pair of reasonably compact radiators in an otherwise unbounded stationary fluid is expressible in terms of their (complex) diffraction constants D1 and D2 and the (complex) spherical wave reciprocity parameter Js as Zmut=S1S2D1D2/Js, where S is the radiator surface area, Jsf=2d/jρf, d is the separation between radiator acoustic centers, ρ is the fluid density, and f is the frequency. (For mutual acoustical radiation impedance, simply drop the factors S1 and S2.) For spherical radiators of radius a, D(1+n=ejkan/jkan). Note, this newly derived form for Zmut is guaranteed to be reciprocal. Also, for small ka, it reduces to S1S2/Js, which is equivalent to the classical Pritchard approximation, corrected for nonidentical radiators.
Measurements of orifice impedance with grazing flow
Authors: Dickey Nolan S. , Selamet Ahmet , Ciray Mehmet S.
Published: July 2012

Perforated interfaces are commonly used in silencers for automotive applications. In these silencers, the acoustic behavior of the perforations, typically described in terms of a perforate impedance, can have a significant effect on silencer performance. The perforate impedance, in turn, is affected by the mean flow in the silencer. The focus of the present study is mean flow tangential to the perforate face (grazing flow), which is often predominant. In most cases, the perforate impedance cannot be determined analytically, and therefore experimental data and empirical models are necessary. Yet, experimental data suitable for use in models of perforated tube silencers are relatively scarce. The objective of the present investigation is to measure the impedance of perforated plates subjected to grazing flow. A description is given of the experimental apparatus, which has been designed for measurements with flow conditions representative of those in an automotive system. Data are presented for plates with square-edged circular orifices of varied dimensions. The results are reduced in terms of scaling parameters suitable for use in empirical perforate models.
Interactive exhibits illustrating wind instrument acoustics
Authors: Campbell D. Murray , Myers Arnold
Published: July 2012

The authors were recently involved in developing demonstration equipment for musical instrument museums. The aim of this project, funded by the European Union, was to provide hands-on exhibits which would allow the user to explore some of the basic science underlying the operation of string, wind, and percussion instruments. While it is fairly straightforward to devise exhibits in which the user can pluck a guitar string, strike a tubular bell, or bow a violin, considerations of hygiene and the requirement for skilled embouchure techniques make it impossible to expect members of the public to blow demonstration wind instruments. To overcome this limitation, exhibits have been constructed in which a clarinet and a trumpet are played using artificial mouths. The user can adjust a valve controlling the flow of air from a blower to the artificial mouth; a digital manometer monitors the mouth pressure. The note played can be changed by operating a piston on the trumpet, or a key on the clarinet. The signal from a microphone registering the sound output is fed to the sound card of a PC, and specially written software allows the user to examine the waveform and the frequency spectrum of the sound.
Shaping the experience in Experience Music Project: Striking a balance between entertaining and educating in a popular music museum
Authors: Fricke James , Weatherhead Andrea
Published: July 2012

After eight years of planning, the Experience Music Project opened in Seattle on June 23, 2000. The institution’s press materials state that: EMP invites visitors to participate in a total sensory experience: see rare artifacts and memorabilia, hear musicians tell their stories, or play an instrument and create your own music. Learning about music has never been so much fun. Does the experience live up to the hype? EMP’s opening exhibitions, activities, and public programs are described, public and critical reception is reviewed, and lessons learned in the first months of operation are shared. The presentation will focus on multimedia exhibit components and interactive exhibits, with special emphasis on the design, development, and objectives of the Sound Lab area, EMP’s hands-on activity and learning center.
Assessment of annoyance in a multisource environment
Authors: Gjestland Truls , Miedema H. M. E.
Published: July 2012

The annoyance caused by common community noise sources (road traffic noise, rail noise, aircraft noise, etc.) has been shown to be highly correlated with the energy-equivalent noise level, LEQ (or similar derivatives) from that source. In some cases LEQ is adjusted depending on the time of day (as in LDN) or depending on the nature of the source (e.g., impulsive noise). So-called dose-response curves showing the relationship between the noise level and the annoyance have been established for a number of different noise sources. This annoyance assessment method, however, is only valid for single noise sources. The authors present a method for assessment of annoyance in the presence of several noise sources. Each noise source is transformed into a common reference source by means of established dose-response curves, and then added on an energy basis.
What can classical and fuzzy concepts contribute to the analysis of masking effects in environmental noise surveys?
Authors: Botteldooren Dick , Verkeyn Andy , Lercher Peter
Published: July 2012

In laboratory research masking of one noise source by another is well studied. Field research based on noise surveys fails to show this effect clearly. Both the uncertainty in noise levels and other environmental variables and the fuzziness in annoyance contribute to the difficulty of the problem. Traditional statistical and fuzzy techniques were used to look for masking effects in a large environmental noise dataset gathered in Austria. The fuzzy analyses use a rule-based model that is constructed to predict noise annoyance. Specific attention is paid to rules that predict masking based on variables such as background noise level, distance to masker, direction of bedroom and living room windows, etc.
Railway construction in Hong Kong: How to make it work
Authors: Frommer Glenn H.
Published: July 2012

The Mass Transit Railway Corporation designs, constructs, and operates one of the world’s most intensively used railway networks with 2.3 million passengers daily on 70 km of track. New railway construction is often undertaken in densely populated urban environments with high-rise developments surrounding works sites. For the Lantau and Airport Railway, operational in 1998, the Corporation had to remove 1000 m3 of granite 7 m from a high-rise residential estate for the construction of Lai King Station. A lightweight noise enclosure was erected but not without significant noise and political impacts. However, the station was successfully completed on time and within budget. Current extensive modifications to Mei Foo Station 15 m from residential towers require a heavyweight noise enclosure to include vehicular emergency service access. The construction method was developed to minimize noise impacts. The skeleton of the enclosure is now in place and there have been no significant environmental problems. This presentation will detail the following: the analysis methods used in determining noise impacts; the structure and training employed within contracts to obtain compliance to the noise specification; and the manner in which the noise impacts are monitored and controlled.
Noise monitoring, control, and compliance practices at several construction sites in Southern California
Authors: Eilar Douglas K.
Published: July 2012

Noise protection for residential neighborhoods, commercial properties, and wildlife habitats near construction sites is achieved to varying degrees within a maze of local, state, and federal regulations. Standards for a given site typically include noise limits for public nuisance under the municipal ordinance, but a project may also be subject to more restrictive requirements emanating from conditions of approval from a discretionary permit and the environmental review process. Sometimes, goals or provisions of the municipality’s noise element to the general plan are a factor. Sometimes, only noise monitoring is required, for documentation or to determine if noise is a problem. For wildlife, federal or state agencies may have established limits applicable to habitats of certain sensitive, endangered, or threatened species, during nesting season. Noise limits for constructing a subway access in Los Angeles require measurement of maximum noise level (Lmax), while noise limits for grading a park in San Diego use hourly average sound level (Leq). Different limits apply to intermittent versus continuous noise, to different times of day, and to different land uses. Noise reduction may be attained by means such as sound-attenuation barriers, certification of equipment noise emission prior to use, or operational controls.
Maglev—A super fast train
Authors: Gharabegian Areg
Published: July 2012

Magnetic levitation (Maglev) is a technology where magnetic forces lift, propel, and guide a vehicle over a guideway. This configuration eliminates contact between vehicle and guideway and permits speeds of up to 300 mph. The Federal Railroad Administration is evaluating the feasibility of Maglev construction in seven cities. Parsons Engineering Science conducted noise and vibration studies for four of these cities. Use of magnetic levitation and propulsion minimizes noise from mechanical and moving parts; however, the benefit of low-noise emission diminishes as a vehicle operates at high speed. Aeroacoustic sources generally dominate noise levels at speeds of 120 mph or greater. High-speed Maglev passby is characterized by high-noise levels and brief duration, which may startle people who are close to the alignment. Maglev systems generate ground-borne vibration when a vehicle travels above the guideway due to the sudden on and off load of the vehicle and magnetic current. Maglev noise, vibration, and startling sources as well as impacts and mitigation measures will be presented. Available vibration data are based on German standards because there is a prototype Maglev train in operation in Germany. These standards and procedures that are used to calculate equivalent vibration levels in in./s will be presented.
Meanings of SVD and wave-vector filtering in the near-field acoustical holography using the inverse BEM
Authors: Ih Jeong-Guon , Kang Sung-Chon
Published: July 2012

In the conformal near-field acoustical holography (NAH), using the boundary element method (BEM), the vibroacoustic information on the source surface can be indirectly reconstructed by utilizing the measured field pressure and the inverse transfer matrix. The involved vibroacoustic transfer matrix is generally ill conditioned and the reconstruction process should include the singular value decomposition (SVD) in order to solve the problem in the inverse procedure. The accuracy of the reconstructed field is deteriorated substantially due to the ill conditioning of the transfer matrix and the inevitable measurement noise of field pressure related to the nonpropagating wave components. In this study, the computational processes of SVD and wave-vector filtering in the BEM-based NAH are discussed and their physical meanings are investigated through a simulation example. The vibroacoustic transfer matrix decomposed by SVD permits an effective regularization of the source field: This is possible because the involved information in the transfer matrix can be separated into the radiation efficiency and the wave modes at the source and surface fields. In particular, it is clearly shown that the restored source image can be improved dramatically by adopting the wave-vector filter that suppresses the nonpropagating wave components appropriately that cause the deterioration of the reconstruction accuracy.
Characterizing mechanical system integrity using structural surface intensity
Authors: Banks Jeffrey C. , Hambric Stephen A.
Published: July 2012

Many structural intensity measurements have been made on simple beam and plate-like structures to determine source strengths and transmission paths. When analyzing more complex structures it is often difficult to compute the intensity throughout the depth of an element. Using a method developed by Pavic [G. Pavic, J. Sound Vib. 115, 405–422 (1987)], the structural surface intensity (SSI) is computed on a gearbox housing using an array of accelerometers and strain gauges. The focus of this research is to use SSI as a machinery fault indicator, with the objective of developing a method that is more sensitive than other conventional diagnostic methods. Experimental data were taken on a gearbox from the Mechanical Diagnostic Test Bed (MDTB) at the Penn State Applied Research Laboratory as the gearbox was run to failure. The changes in energy flow are analyzed and characterized to provide criteria for fault detection. Analysis of the data indicates that significant changes in structural surface intensity occur as geartooth faults develop and that SSI can be more sensitive than other traditional indicators. [This research was supported by the Multidisciplinary University Research Initiative for Integrated Predictive Diagnostics (Grant No. N00014-95-1-0461) sponsored by the Office of Naval Research.]
Discharge acoustic signal detection in insulating oil using the optical fiber Sagnac interferometer
Authors: Lee Jongkil , Lee June-ho , Kim Sang-joon
Published: July 2012

In this paper, an optical fiber sensor (OF sensor) utilizing the principal of the Sagnac interferometer was proposed to detect the discharge acoustic signals which generated from a needle-sphere electrode system in insulating oil. The performance of the OF sensor was checked by a sinusoidal calibration signal generated by a PZT actuator at 198 kHz. The detected discharge signals consisted of the acoustic signal and electrical noise. The noise signal could be removed by a digital low-pass filter. It was demonstrated that the OF sensor in this research had a possibility to detect the discharge acoustic signals in the power apparatus.
A crack localization system based on the spatio-temporal gradient method
Authors: Teramoto Kenbu
Published: July 2012

For several decades, nondestructive tests, including x rays, gamma rays, radar, infrared thermography, and acoustic methods have been used not only for concrete structures but for other types of materials. Acoustic methods are the oldest and most widely used nondestructive testing. They are based on the propagation, and in some cases reflection, of elastic waves in solids or over their boundary surfaces. A well-known example is striking an object with a hammer and listening to variations in the ‘‘ringing’’ sound to detect the presence of internal voids, external cracks, or other defects. Usually, there are three techniques based on acoustic nondestructive tests sorted into the wave-velocity method, resonance methods, and echo methods. This paper proposes a fourth method with spatio-temporal analysis, which has two processes, as follows. In the observation, the resulting surface wave, its partial derivatives for x, y, and t, are calculated at several points. In the detection, the rank of the short-duration covariance matrix of time-series vector f [=(f fx fy ft)T] classifies the situation of the surface-wave field. Consequently, the proposed method can provide the wave front and the location of the cracks as the singularity in the sound field.
Usage of Wigner–Ville distribution for vibroacoustical forced oscillation diagnostics of cracks
Authors: Gelman Leonid M. , Adamenko Denis A.
Published: July 2012

For diagnostics of fatigue cracks using vibration and noise, the new low-frequency vibroacoustical method of forced oscillations with nonstationary excitation is considered. The usage of an advanced time-frequency signal-processing technique based on Wigner–Ville distribution is proposed and developed to improve the effectiveness of diagnostics. The simulation results are presented.
Effects of oscillation of a mechanical hemilarynx model on mean transglottal pressures and flows
Authors: Alipour Fariborz , Scherer Ronald C.
Published: July 2012

This study introduces a mechanical model of the larynx for investigating the aerodynamics of phonation. The model mimics the hemilarynx. The tracheal inlet section was rectangular (2.5 cm by 2 cm). The vocal fold was fabricated from hard plastic with an attached oscillating plunger. A speaker assembly and audio amplifier drove the plunger, mimicking one-dimensional vocal fold motion toward a flat wall. The glottal shape was rectangular. The glottal diameter was well specified or dynamically followed with a laser system. The air was sucked through the channel using a vacuum with controlled speed. Frequency and amplitude of the glottis were varied. The mean pressure and mean flow data were recorded. For steady flow conditions, the glottal gap ranged from 0.4 to 2.5 mm. The pressure coefficient for steady flow had a range of 3.1–1.3 for Reynolds numbers between 500 and 5000. For oscillation conditions: (a) the frequency was varied from 75 to 150 Hz while the amplitude was held (almost) constant; and (b) the amplitude was varied for a fixed frequency of 100 Hz. The results indicate that oscillation amplitude has a strong effect on the flow resistance of the glottis. [Work supported by NIDCD Grant No. R01 DC03566.]
Parameters for a first-order Kelvin model of laryngeal muscles
Authors: Hunter Eric J. , Titze Ingo
Published: July 2012

Because the intrinsic muscles of the larynx determine vocal fold posturing in phonation, a model of vocal fold posturing requires data from the passive and active viscoelastic properties of these intrinsic muscles. Using reported one-dimensional active (twitch and tetanus) and passive muscle (step elongation and relaxation) measures from fresh excised canine laryngeal muscles, one-dimensional first-order Kelvin model parameters were obtained. Obtaining these parameters was accomplished through optimization, where force-elongation patterns predicted by the model were compared to measured muscular passive cyclic force-elongation patterns. These parameters are reported along with the design for the Kelvin model. The results of this study, which will be integrated into a larger finite-element posturing model, become the first step in predicting the vocal fold configurations needed for phonation.
Phonetic targets as the link between speech production and speech perception
Authors: Xu Yi , Wang Emily Q.
Published: July 2012

We argue in this paper that the coherence between speech perception and production, which the motor theory maintains, lies in the common knowledge about speech production shared by the speaker and the listener. More specifically, we propose that abstract phonemic units are associated with phonetic targets that are articulatorily operable. These targets, however, are usually not fully achieved in speech production. Rather, they are often only approximated by different degrees under the limitation of various articulatory constraints. The process of speech production, therefore, is one in which various phonetic targets are being continuously approximated. As evidence, we will demonstrate with recent acoustic data how lexical tones in Mandarin are implemented through continuous approximation under specific articulatory constraints, how these constraints bring about extensive variations in the F0 contours, and how, despite the variations, tonal targets maintain their integrity in connected speech. We will then further argue that listeners, being also speakers themselves, should be able to discover the intended targets by noting the consistency the speaker manages to achieve despite the articulatory constraints. In other words, listeners hear not just what the speakers do, but more importantly, what they intend to do: We listen to hear what is being said.
Perception of speaker characteristics with long and short samples
Authors: Payri Blas G.
Published: July 2012

In this article, the perception of speaker’s characteristics is compared using long and short samples. The sound material was an Italian read sentence (seicento-cinquantotto) and the last two syllables ‘‘to’’ from this sentence. Twenty healthy Italian native speakers (10 females, 10 males) read the sentence, with the same recording conditions. In the first experiment, the listeners performed a free categorization of the syllables and then of the sentences. Then, the listeners were asked to give qualifiers to describe the classes they had made. The aim was to obtain the main criteria for the description of long samples (sentences) and short samples (isolated syllables). For the sentences, the gender and prosody criteria were more frequently used by listeners, whereas the pitch and voice quality were preferred to classify the syllables. In the second experiment, listeners rated the same samples as previously, along predefined axes (age, gender, breath, liveliness, etc.). The ratings were compared with acoustic measures. The results show that the ratings for the whole sentence, and for the extracted syllables, can be significantly different, leading to the conclusion that, within a sentence, there are significant local variations of the perceived voice quality and speaker characteristics as gender and age.
The effects of speech rate and listening experience on the intelligibility of synthesized speech
Authors: McCole Carol , Bell-Berti Fredericka
Published: July 2012

Some persons with severe communication disorders are only able to communicate effectively using speech synthesizers, although even the most intelligible synthesis systems (e.g., DynaVox-DECTalk) have limitations. Listener success has been reported to vary with listener age, listener experience with synthesized speech, speech rate, and the presence of pauses between words. This series of experiments has examined the effects of listener age and experience, and speech rate and interword pauses on the perception of synthesized speech. Eighty IEEE-Harvard Sentences were presented to four groups of 12 listeners each [children (9–11 years), teens (14–16 years), young adults (20–25 years), and adults (38–45 years)], in two experiments. In the first experiment (40 sentences) speech rate was varied (105, 135, 165, and 195 wpm); in the second experiment (40 sentences), 7–12 days later, interword pauses occurred in half the sentences. Conditions were counterbalanced; no sentence was presented twice. Preliminary results indicate little effect of speech rate but a substantial effect of experience for the children: they improved substantially through experiment 1; the improvement carried over into experiment 2. Parallel results will be presented for all age groups. [Work supported by St. Johns University and New York City Board of Education, Technology Solutions, District 75.]
Spatial and temporal variation of large- and small-scale seafloor roughness
Authors: Briggs Kevin B.
Published: July 2012

Seafloor microtopography, measured at subcentimeter resolution over scales up to a meter or more by underwater stereo photogrammetry, was periodically characterized during the SAX99 high-frequency acoustic backscattering experiment. Analog 35-mm stereo photographs of seafloor roughness were digitized at 2- to 5-mm intervals from film transparencies with a stereo comparator capable of 1-mm-scale lateral precision and submillimeter-scale vertical accuracy. Relative seafloor height profiles were used to estimate roughness power spectra, which are parametrized as slopes and intercepts of regressions fit to the roughness power spectra. The composite roughness model developed by Applied Physics Laboratory–University of Washington requires these two spectral parameters to determine the contribution of the seafloor roughness to the overall backscattering strength. Data from two locations over 31 days in the experimental area off Ft. Walton Beach, FL in 19-m water depth are presented in order to demonstrate the relationship between seafloor roughness morphology at subcentimeter to meter scales and model parameters predicting high-frequency acoustic scattering. Model predictions are generated from the measured geoacoustic properties of the rippled, medium sand seafloor and the range of roughness parameters that varied temporally and spatially during the experiment. [Work supported by ONR.]
Quantification of Darcy’s coefficient of permeability in siliciclastic marine sands using image analysis and effective medium theory modeling
Authors: Reed Allen H. , Lavoie Dawn
Published: July 2012

Darcy’s coefficient of permeability (Dcp) and porosity strongly influence the behavior of sound in unconsolidated sediments at high frequencies, therefore it is important to assess physical property values in sediments undisturbed by coring and subsequent handling. The objective of this study was to determine Dcp and porosity of siliciclastic marine sands from Ft. Walton Beach, FL that were embedded in situ using a polyester casting resin. For comparison, direct measurements of Dcp were made with an in situ falling head permeameter and porosity was determined by water weight loss. Modeling Dcp entailed quantifying pore dimensions and pore connectivity in the resin-embedded medium from two-dimensional scanning electron microscopy images using standard image analysis techniques. The value of Dcp is estimated from average, or ‘‘effective,’’ pore characteristics using an effective medium theory technique. Dcp of the samples in both vertical and horizontal directions averaged 1.9×10-3±1.3×10-3 and porosity averaged 0.44±0.04. The modeled and measured Dcp values are comparable, whereas modeled porosity was slightly higher than measured porosity. From these data we conclude that estimating Dcp and porosity from in situ embedded sands results in values of physical properties close to those in the undisturbed state. [Work funded by ONR and NRL.]
Estimation of seafloor roughness using ROV-mounted lasers
Authors: McCurley Brett K. , Piper James N. , Chotiros Nicholas P.
Published: July 2012

The method employs lasers mounted on the remotely operated vehicle (ROV). Using a cylindrical lens to spread a laser beam into a fan and viewing the intersection of the laser fan with the water-sediment interface, it is possible to obtain a profile of the sediment. As the ROV advances, a bathymetric profile of the sediment may be constructed using successive profile snap shots. Data were collected at the Sediment Acoustics Experiment (SAX99) and processed to produce sediment surface profiles. [Work supported by the Office of Naval Research, Ocean Acoustics.]
Mechanisms for biological modification of seabed: Direct acoustic observations
Authors: Holliday D. V. , Greenlaw C. F. , McGehee D. E.
Published: July 2012

Surface roughness and volume heterogeneity have both been implicated in the anomalous penetration of high-frequency sound into the ocean bottom. These physical characteristics of the seabed are dynamic properties of the bottom environment, with changes driven by both biotic and abiotic forces. Species that use the bottom for shelter from visual predators can change surface roughness at the time of emergence and re-entry. Acoustic observations of the movement of marine endo- and epibenthic organisms between the seabed and the water column will be used to illustrate the potential for these behaviors to modify the bottom. This behavior can also be the source of some of the dynamic volume heterogeneity that characterizes the seabed. The maintenance of burrows by animals is a known source of changes in both surface roughness and volume heterogeneity. At one study site fish appeared to anticipate the behavior of the plankton, foraging on lower trophic levels near, in, and on the seabed. This behavior can also modify surface roughness at the bottom-water column interface. [Research supported by ONR.]
Ultrasonic studies on the effect of water content on compressional wave velocity in beach sand
Authors: Chamuel Jacques R.
Published: July 2012

Theoretical results by Bachrach and Nur [Geophysics 63(4), 1225–1233 (1998)] indicate that the compressional wave velocity in wet sand decreases from 1700 to 250 m/s as the moisture content is decreased by 1% from saturation based on the Biot-Gassmann theory low-frequency limit. New quantitative experimental results from beach sand (280 μm average grain size) are presented. Experimental results from wet sand ‘‘half-space’’ are compared with small wet sand samples. The sand moisture content was continuously measured from the weight of a mechanically balanced fixture holding ultrasonic transducers and the wet sand sample. Preliminary quantitative experimental results from the mechanically balanced wet sand show that the compressional wave velocity remained near 1650 m/s in the 100–500 kHz frequency range as the moisture content was decreased by more than 35% from saturation (typical drained sand is only about 5% from saturation). Beach sand, being angular with flat grain areas, may need to be modeled as platelets with large contact areas rather than spherical grains with point contact.
Effects of echo variability in geoacoustic sediment characterization
Authors: Sternlicht Daniel D. , de Moustier Christian P.
Published: July 2012

The variability in shape and amplitude of bottom echoes affects the resolution of geoacoustic parameter estimation techniques that match measured bottom-echo envelopes with envelope models derived from incoherent acoustic backscatter theory at the sediment–water interface and in the sediment volume. Following earlier echo envelope matching work carried out with data collected at 10–100 kHz in San Diego Bay [Sternlicht and de Moustier, J. Acoust. Soc. Am. 105, 1206 (1999)], coarse- and fine-grain substrates are identified by estimates of their mean grain size (Mφ) and of the strength (w2) of their power-law roughness spectrum describing the spatial statistics of the interface. Statistics of the (Mφ, w2) estimates are combined with those from Monte Carlo simulations, based on the data covariance matrices, to demonstrate that in sandy substrates, echo variability has little effect on estimates of w2, and a pronounced effect on estimates of Mφ. The reverse pattern is observed for fine-grain substrates. However, the parameter estimation technique used introduces a degree of correlation between Mφ and w2, which is especially large for sand substrates. These observations are consistent with nature, where relief spectra of coarser sediments contain more energy than those of fine-grain substrates. [Work supported by ONR.]
Three-dimensional localization of diving sperm whales using a short-aperture towed horizontal array
Authors: Thode Aaron M. , Mellinger David K. , Stienessen Sarah , Martinez Anthony , Mullin Keith D.
Published: July 2012

Three-dimensional sperm whale localizations are typically obtained via recording their ‘‘clicks’’ on widely distributed hydrophones. Here, an alternative 3D localization method is investigated, using data collected by an 8-m aperture, five-element horizontal towed array deployed from the NOAA ship Gordon Gunter in the Gulf of Mexico, as part of a recent sperm whale pilot study. During the night of 3 July 2000, the Gunter towed the array at a steady 1-kn speed and 60-m depth through a pod of sperm whales, in 1000-m-deep water. During that time, surface and bottom reflections from a single sperm whale click were often recorded. By measuring the bearings and relative arrival times of the direct arrival and reflections, the whale location, array depth, and array tilt could be computed. The latter results were checked against measurements obtained from a time-depth recorder attached to the array. Assuming that the speed of the ship remained fixed and the prevailing currents did not change, subsequent positions could then be obtained using only a surface reflection. This method may provide a convenient way for observing dive profiles of animals within a few kilometers of a survey ship. [Work supported by Minerals Management Service, National Marine Fisheries Service, and ONR.]
Planning for a pilot census of marine life in the Gulf of Maine: The role of acoustics
Authors: Foote Kenneth G.
Published: July 2012

Preparations are being made for a pilot census of marine life in the Gulf of Maine ecosystem. The role of acoustics as a rapid, remote sensing tool is elaborated. Potential target organisms for acoustic surveying range from mesozooplankton and macrozooplankton to fish and cetaceans. A number of methodological problems must be addressed. These are illustrated for the echo integration method as applied to a stock of Atlantic herring (Clupea harengus) [J. Acoust. Soc. Am. 105, 995 (1999)]. Particular problems of determining target strength and compensating for possible behavioral effects are also general to the method. [Work supported by the Alfred P. Sloan Foundation.]
Acoustic identification of female Steller sea lions
Authors: Campbell Gregory S. , Gisner Robert , Helweg David A.
Published: July 2012

Steller sea lions (Eumetopias jubatus) breed and rear their young in coastal rookeries dispersed along the northern tier of the North Pacific. Population densities are high and no allomaternal behavior occurs, providing strong selection pressure for mother–pup recognition processes. Mothers and pups establish and maintain contact with individually distinctive vocalizations. Our objective is to understand the acoustic features that serve to identify individual females, and develop a ruggedized computer system to perform acoustic recognition of females in the field. We have cataloged almost 2000 contact calls from 46 females in 1998 and 25 in 1999. Each female is visually identified by marking patterns, which provides the ground truth for acoustic identification. Acoustic properties of the calls were measured and presented to several statistical classifiers. Representations of the calls had to be robust with respect to acoustical variability introduced by motivational changes as the mother and pup regained proximity. The calls, classifiers, and results of generalization tests will be described, and a concept for the field system will be discussed. [Research supported by ONR Research Opportunities for Program Officers award N00014-00-1-0114 to R. H. DeFran, Cetacean Behavior Laboratory, SDSU.]