bluuebunny/crossref_metadata_2025 huggingface dataset:
Time-averaged pressure drop produced by an abrupt change in a resonator’s cross section
Authors: Doller A. , Atchley Anthony A. , Waxler Roger
Published: July 2012

The behavior of steady, incompressible flows through constrictions, expansions, bends, and branches in pipes is very well documented and commonly used to design fluid handling systems over a wide range of Reynolds numbers, surface roughness, etc. However, the state of knowledge of high-amplitude acoustic flows in similar structures is much less mature, as demonstrated by recent developments in thermoacoustic devices [S. Backhaus and G. W. Swift, J. Acoust. Soc. Am. 107, 3148–3166 (2000)]. The research presented here, motivated by this lack of understanding, focuses on the nature of predominately reactive, high-amplitude acoustic fields in the vicinity of changes in resonator cross section. Oberst-style resonators [H. Oberst, Akust. Z. 5, 27–38 (1940)], consisting of two sections of straight brass pipe of different diameters and joined through either step-like or conical couplers, were constructed. The resonators are driven by a graphite piston at one end, and rigidly terminated at the other. The acoustic pressure is measured at four locations along the resonator. Of particular interest is the time-averaged pressure drop across the coupler section. Measurements of this pressure drop are reported as functions of drive amplitude for the different coupling configurations. [Work supported by the Office of Naval Research.]
Torsionally resonant toroidal standing-wave resonator
Authors: Diehl Scott R. , Garrett Steven L. , Friesen Milo , Kessinger Roy L. , Receveur Paul , Schrank Leonard
Published: July 2012

A toroidal resonator with a rigid barrier can be used to generate high-amplitude standing waves if the resonator is oscillated in a torsional mode about its central axis [S. Garrett, US Pat. No. 5,953,921 (Sept. 21, 1999)]. In the following, a 2-1/2-in diameter schedule-40 steel pipe is bent into a 13-in radius torus to form the resonator. The torus is then deformed along its cross section to detune harmonic overtones and suppress shock wave formation. The torsional drive force is provided by rigidly attaching the resonator to the housing of a modified Lynx Model T468 Direct-Drive Servo Motor [Kessinger et al., US Pat. No. 5,744,896 (April 28, 1998)]. The resonator/motor housing and shaft/rotor assemblies are made into a mechanical 2-DOF torsional oscillator by coupling their moments-of-inertia through an elastic restoring force. The torsional restoring force is provided by a quartet of semi-cylindrical stainless steel (17-7 PH) springs mounted between the resonator/housing and shaft/rotor assemblies. Measurements of modal anharmonicity and peak acoustic pressures at resonance will be reported and compared to DeltaE model results. [Work supported by the Office of Naval Research.]
Nostack thermoacoustics
Authors: Wakeland Ray Scott , Keolian Robert M.
Published: July 2012

The ‘‘stack’’ used in conventional standing-wave thermoacoustics depends on intrinsic thermodynamic irreversibilities for its operation. One approach to increasing efficiency is to eliminate the stack, retaining a small gap between heat exchangers in a standing wave. While a ‘‘nostack’’ device has a temperature span that is limited by the achievable pressure amplitude, it is expected to have greatly increased thermodynamic efficiency compared to a stack-based device with the same power and operating temperatures. Losses associated with flow through the heat exchangers, however, are expected to be higher in a nostack device. The standard theory of low-amplitude thermoacoustics does not apply to nostack devices, where the displacement amplitude is larger than the heat exchangers and the gap. As an alternative, an idealized thermodynamic model of nostack is combined with separate calculations of conduction loss and flow losses, including so-called ‘‘minor losses’’ arising from sudden changes in cross-sectional flow area. The results suggest that by positioning the heat exchangers very close to a pressure antinode to reduce flow velocity, efficiencies similar to Stirling-like thermoacoustic devices might be achieved with the nostack idea. [Work supported by the Office of Naval Research and the Pennsylvania Space Grant Consortium.]
Alternative-geometry traveling-wave thermoacoustic devices
Authors: Wilen Larry , Petculescu Gabriela
Published: July 2012

Ceperley has discussed the idea that an acoustic traveling wave passing through a regenerator executes a Stirling cycle [P. H. Ceperley, J. Acoust. Soc. Am. 77, 1239–1244 (1985)]. He also emphasized that for an acoustic Stirling device to be useful, the impedance must be high or else viscous losses will dominate. Backhaus and Swift recently found a way to produce a useful device with high impedance and traveling wave phasing using a toroidal geometry [S. Backhaus and G. W. Swift, J. Acoust. Soc. Am. 107, 3148–3166 (2000)]. We will discuss possible ways to realize these conditions with alternative geometries, and we will present some preliminary results for a refrigerator employing one such configuration. [Work funded by the Office of Naval Research.]
Effect of tonal duration on auditory evoked potentials as a function of age
Authors: Ostroff Jodi , McDonald Kelly , Alain Claude , Schneider Bruce
Published: July 2012

Behavioral research has shown that temporal resolution decreases with age as evidenced by higher-gap-detection thresholds in older versus young adults with normal hearing. In the present study, we examined the neural correlates of the temporal resolution function in young, middle aged, and older subjects, using a brief Gaussian-shaped 2-kHz tone that increased by 2 ms in separate trial blocks. All stimuli elicited a negative potential that peaked at about 100-ms poststimulus (N1). The N1 amplitude increased linearly with increases in tonal duration. The growth function of the N1 amplitude was similar across the three age groups, although the slope of the function in older adults was shallower. Results suggest that the N1 response can resolve temporal information on the order of 2 ms. This electrophysiologic threshold parallels behavioral findings. The slower growth function of the N1 response in older adults may reflect a deficit in temporal processing. [Work supported by the Medical Research Council of Canada.]
Speech recognition under conditions of frequency-place expansion and compression
Authors: Baskent Deniz , Shannon Robert
Published: July 2012

The mapping of frequency information onto the correct cochlear place is critical for speech recognition. In cochlear implants, the cochlear tonotopic range represented by the electrode array is smaller than the acoustic frequency range used in the speech processor. While this condition utilizes a wide range of speech frequency information, it results in a compression of the tonotopic pattern of speech information delivered to the brain. An alternative approach is to take the core frequency range necessary for speech and expand its representation in the cochlea, like an ‘‘acoustic fovea.’’ This study examined the effect of linear frequency-place compression and expansion on speech intelligibility for various cochlear locations and number of spectral channels. These conditions were presented to normal-hearing listeners using a noise band vocoder. The cochlear tonotopic range was held constant by employing the same carrier bands for each condition, while the frequency range of the analysis bands was changed. For each condition, the result was compared to that of the perfect tonotopic match, where the carrier and the analysis bands were perfectly matched. Speech recognition in frequency-place expansion and compression was always equal to or poorer than the matched condition. [Work supported by NIDCD.]
Horizontal and vertical minimum audible angle: Effects of stimulus onset asynchrony and azimuth
Authors: Strybel Thomas Z. , Adachi Eishi , Jeon Simon
Published: July 2012

The effects of stimulus onset asynchrony (SOA, the onset-onset time difference) on the minimum audible angle (MAA) were measured for horizontal and vertical orientations and two azimuth locations. Each participant was tested in 16 conditions created by all combinations of four SOAs (25, 50, 100 and 400 ms), two orientations (horizontal and vertical), and two azimuth locations (0 and 90 deg). MAAs were measured with an adaptive procedure. The stimulus was high pass noise with a lower frequency cutoff of 4 kHz and amplitude of 55 dB A-weighted. The burst duration was 50 ms with a rise/decay time of less than 1 ms. As expected, horizontal MAAs were lowest at 0 deg and increased substantially at 90 deg; vertical MAAs were only minimally affected by azimuth. The effect of SOA was similar for both orientations and azimuths. In all conditions, the MAA decreased exponentially with SOA. The slope of the horizontal function at 0 deg was slightly steeper than the slopes of the remaining conditions.
Psychophysical tuning curves and filter shapes sharpen over time
Authors: Repovsch Jennifer L. , Bacon Sid P.
Published: July 2012

Psychophysical tuning curves (PTCs) measured in simultaneous masking usually sharpen as a short signal is moved from the onset to the temporal center of a longer duration masker. Filter shapes derived from notched-noise maskers have not consistently shown this effect. One possible explanation for this difference is that the PTC paradigm uses a fixed signal level, whereas filter shapes typically have been derived from results where the noise masker was fixed in level. In the present study, PTCs and filter shapes were measured with a signal fixed in level at 10 dB SL. The masker was either a pure tone (PTCs) or a noise with a spectral notch placed symmetrically or asymmetricaly about the 2-kHz signal frequency (filter shapes). The 20-ms signal was presented at the onset or temporal center of the 400-ms masker. For a given signal delay, the PTCs were substantially sharper than the filter shapes. Importantly, however, for all four subjects, the PTCs and the filter shapes sharpened on both the low- and high-frequency sides as the signal moved from the beginning to the temporal center of the masker. This sharpening was considerably greater for the filter shapes. [Work supported by NIDCD.]
Greek bilingual listeners perceive the tritone stimuli differently from speakers of English
Authors: Chalikia Magdalene H. , Norberg Angeline M. , Paterakis Lena
Published: July 2012

When listeners are presented with pairs of octave-complex tones related by a tritone interval (a half-octave), they hear the pattern as ascending or descending, according to an individual pitch class template. Deutsch (1991) has claimed that this template may be influenced by language. In order to test this hypothesis, data from Greek bilingual listeners were collected and compared with data from Texas, California, and the south of England. The results show significant differences in how Greek listeners hear the tritone stimuli, as compared to listeners in the other groups. There is also evidence that the Greek listeners may have developed two different pitch class templates, possibly representing the influence of English and the influence of Greek.
The perception of tritone stimuli by listeners in the Midwest
Authors: Haugen Meredith , Chalikia Magdalene H.
Published: July 2012

The tritone stimuli [Deutsch (1986)], consist of two tones, each with octave-related harmonics. The tones are separated from each other by a tritone (half-octave) interval. The tones are presented successively, and listeners decide whether or not the second tone in the pair is perceived as ascending or descending, relative to the first one. Listeners tend to hear the tritone pattern as ascending or descending, according to an individual pitch class template, which Deutsch (1991) claims may be influenced by language or English dialect. Some similarities have been found among people from different areas of the U.S., suggesting a canonical manner of perceiving the tritone stimuli, probably propagated by the media [Ragozzine and Deutsch (1994)]. The present study tested the media exposure hypothesis, by presenting tritone stimuli to listeners who grew up in the Midwest. Results show that Midwesterners show a different perceptual pattern relative to that of listeners from Texas and the south of England, but the same pattern with that heard by listeners from California. Spectral envelope effects were also examined, and suggest that the perceptual patterns found under high and low envelopes are similar to those found for Californians, but different from those found with listeners from Texas.
Lamb waves scattering by inhomogeneities in elastic waveguides
Authors: Gorodetskaya Natalya S. , Grinchenko Victor T.
Published: July 2012

Different types of conjunctions of elements with various mechanical properties are widely used in engineering practice. Such conjunctions strongly affected the process of acoustic energy transmission in constructions. To study the influence of the physical and geometrical discontinuities in conjunctions on the wave propagation process the composite waveguides have been considered. The method of the boundary problem solution taking into account local singularities of stress is presented. The quantitative data for characteristics of transmitted and reflected waves at the conjunction are given in a wide band of frequencies. At relatively low frequencies the estimations of energy flows by beam model are correct. When the frequency increases, the wave field near conjunction becomes more complicated. As a result the ratio between transmitted and reflected energy becomes a sharply changing function of frequency even in the domain when only one propagating wave exists. This phenomenon is caused by strong excitation of evanescent waves. Excitation of these waves was due to strong mismatch between the form of the incident wave and first transmitted and reflected waves. At the frequency when transmitted energy was minimum the mismatch was maximum. At the same frequency the maximum of normal stresses on the conjunction has been found.
Thai monophthongs classification using CDHMM
Authors: Maneenoi Ekkarit , Jitapunkul Somchai , Ahkuputra Visarut , Luksaneeyanawin Sudaporn
Published: July 2012

This paper presents Thai monophthongal vowels recognition. The Thai monophthongs were qualitatively recognized by the 3-state left-to-right continuous density hidden Markov model. The 18 monophthongs are qualitatively 9 different vowels, each of which has two members, short and long. The LPC cepstral coefficients were used and the temporal cepstral derivative was additionally utilized to compare efficiency of the additional feature with the single feature. Qualitative recognition means that short and long vowel pairs were categorized in the same model. Thai polysyllabic words were used in this research. The database consists of 2100 training phonemes from 30 speakers and 1378 testing phonemes from a different group of 20 speakers, respectively. The highest recognition rate of the single feature obtained from 18-order LPC cepstral coefficients is 86.983 percent, while the recognition rate of the 16-order LPC cepstral coefficients plus temporal derivative is 94.580 percent. The results indicate that all the LPC cepstral coefficients associated with temporal derivative have better recognition accuracy than those of LPC cepstral coefficients. It is concluded that the additional temporal derivative can improve recognition rate. The misclassification is analyzed and it is concluded that this resulted from excessively overlapped distributions of vowels in the low- and back vowel groups, respectively.
Measurement and visualization of speech quality with VIPER
Authors: Mundt Harald , Daniel Peter
Published: July 2012

In this presentation the new VIPER speech quality measurement (VSQM) will be presented. Audible differences between two versions of a sound can be visually inspected in VIPER through the help of auditory distance spectrograms. The objective instrumental measures provided by VIPER will be validated with the results of listening experiments on speech quality (MOS) and compared with the performance of other speech quality measures (PAMS, TOSQA, MNB, PSQM+, PSQM). The comparison is based on the ITU-T Series P. supplement 23 database. The database has been developed in order to characterize the performance of the ITU-T speech codec G.729. Therefore, a wide range of different speech codes, in noisy and clean conditions, in various tandem conditions, with bit and frame errors of various intensity, was tested for different languages (English, French, Japanese). In order to quantify the assessment performances, the linear correlation coefficient and the standard deviation based on the mapped objective data and the subjective data are used.
Ray dynamics in the AET experiment
Authors: Brown Michael G. , Colosi John A. , Virovlyansky Anatoly L. , Zaslavsky George M. , Tomsovic Steven , Wolfson Michael A.
Published: July 2012

A ray-based wave field description is employed in the analysis of measurements made during the November 1994 Acoustic Engineering Test (the AET experiment). In this experiment phase-coded pulse-like signals with 75-Hz center frequency and 37.5-Hz bandwidth were transmitted near the sound channel axis in the eastern North Pacific Ocean. The resulting acoustic signals were recorded on a moored vertical receiving array at a range of 3252 km. In our analysis both mesoscale and internal-wave-induced sound speed perturbations are taken into account. Much of this analysis exploits results that relate to the subject of ray chaos; these results follow from the Hamiltonian structure of the ray equations. It is argued that all of the important features of the measured AET wave fields are consistent with a ray-based wave field description in which ray trajectories are predominantly chaotic. [Work supported by ONR.]
Miniature wildlife telemetry transmitter equipped with a microphone
Authors: Pater Larry , Cochran William , Swenson George
Published: July 2012

A miniature microphone was integrated into a telemetry transmitter package with a total weight of 1.2 grams (operating life of 7 days) or 2.0 grams (21-day life). To obtain meaningful acoustical information, the radio transmitter is continuous transmission, rather than the pulsed type typically used for wildlife telemetry. It is sensitive enough to pick up bird songs at a distance of over 30 m and small airplane engine sounds at several kilometers. This device is useful for remote monitoring in inaccessible locations and to avoid the intrusive impact of direct observation by humans. It can be used to document acoustical environment and auditory stimuli and to monitor vocalizations and behavior of the animal on which the transmitter package is mounted. Applications include studying behavior and responses to disturbance. The transmitter has been successfully used to monitor bird calls and wing-beat patterns during various types of activity, including foraging and nighttime migration flights.
Use of a radio microphone array to study banded-wren song interactions at the neighborhood level
Authors: Burt John M.
Published: July 2012

An array of distributed microphones was used to locate and identify singing banded wrens in Santa Rosa National Park, Costa Rica. Wrens were recorded both during natural singing interactions and during song playback experiments. The array consisted of 11 weatherproofed radio-microphones distributed among neighborhoods of up to seven banded-wren territories, with a centrally located radio receiver/recording station. Audio from the radio receivers was stored to a laptop computer using a multichannel data-acquisition card and custom recording software. Singing birds were located after recording using software developed at the Cornell Lab of Ornithology’s Bioacoustics Research Program. The system’s durability and flexibility enabled several different array configurations to be tested at two field sites under a range of recording conditions. Preliminary results suggest that this system is a powerful and flexible tool for studying the dynamics of vocal interactions across entire neighborhoods of singing birds.
Remote infrared acoustically triggered video monitoring unit
Authors: Ambrose Robert , Donaldson Michael , Lavallee Timothy , Andersen Troy
Published: July 2012

A remotely operable, infrared system for recording digital video and audio information immediately before, during, and after an acoustical event was developed. The primary application of this system to date has been the recording and documentation of effects of noise on wildlife, including Peregrine falcons (Falco peregrinus), Mexican spotted owls (Strix occidentalis lucida), and brown pelicans (Pelecanus occidentalis). The system triggers, records, and stores digital video and audio data on an IBM compatible computer running win9x. Serial communication with a Larson Davis sound-level meter allows a field video camera to store video and audible sound data on the computer. The need for field crew collection of bioacoustical effects data at sites with video acquisition systems is minimized. The video information reduces observation or interpretation bias in the data collection procedures. The systems can be maintained from remote locations using cellular modem technology and can be operated without being visited for extended periods. It is low powered and can be operated by a system of batteries and solar panels for indefinite field deployment. With the correct lens the system is capable of seeing in complete darkness up to 25 ft or as far away as 200 ft in the daytime.
Programmable DSP datalogger for animal bioacoustics monitoring
Authors: Mann David A. , Tucker Timothy J.
Published: July 2012

Two hardware modules for animal bioacoustics monitoring based on the Analog Devices Sharc DSP are described. The RP2 Real-Time Processor connects to a PC via the USB port and can be used for signal detection and direct logging to disk. The SD2 Smart Datalogger is a battery-powered digital datalogger. The RP2 has two channels of A/D with 100-kHz bandwidth, two channels of D/A with 200-kHz bandwidth, eight digital inputs, eight digital outputs, and up to 64 MB RAM. The SD2 Smart Datalogger has two channels of A/D and D/A with a 25-kHz bandwidth on each channel, two digital I/O channels, and up to 64 MB RAM. The datalogger weighs 2 ounces and its dimensions are 5.6×7.6×1.8 cm3. DSP programming for both devices is accomplished through the use of a drag-and-drop interface for configuring detection circuits using a library of over 120 DSP components including digital filters, signal detectors, and memory operations. The use of the RP2 for detecting and recording animal sounds in the field will be described where sounds in given frequency bands are detected, time-stamped, and saved to memory or hard disk. [Work supported by NIH.]
The development of a compact instrument for the measurement of biological sea noise
Authors: Duncan Alec J. , Cato Douglas H. , Thomas Frank , McCauley Robert D.
Published: July 2012

This paper describes a compact, low-power instrument that has been developed to monitor biological sound sources and other sea noise over extended periods in remote locations. The instrument is based on a low power microcontroller and was designed to provide flexibility in specifying sampling rates and sampling schedules so that the utilization of battery power and disk space could be optimized for any given application. In its basic configuration the signals from two hydrophones are sampled and stored on a 12-GByte hard disk drive. Multiple drives can be installed if greater capacity is required. The electronics fits inside a 100-mm i.d. underwater housing resulting in a package that is easy to transport and deploy. Further details of the instrument design will be given, together with the results of deployments off the Western Australian coast where it has been used to monitor the passage of migrating humback whales.
Horizontal refraction modal tomography (HRMT) for ocean front and ocean current monitoring
Authors: Shang E. C. , Wang Y. Y.
Published: July 2012

It has been pointed out by Voronovich and Shang [IEEE J. Ocean. Eng. 24, 224–231 (1999)], that the HRMT has the ability of reducing the mode-coupling effect. In this paper, two examples of the application of HRMT in strong mode-coupling environment are discussed: (1) Polar front, and (2) transverse current in Fram Strait. In both cases, strong mode coupling takes place for the used frequency and mode number. Due to the modal phase difference is measured by two close paths, the mode-coupling effect can be significantly reduced. The results of the retrieved frontal parameters and the transverse component of the current based on adiabatic theory are pretty good even without any iteration. For the Polar front, the horizontal refraction angle is estimated. The parameters that can be retrieved by using HRMT are: the normal direction of the front, the center location of the front, and the sound speed profile difference of the two water masses. The interaction of those acoustically estimated parameters with satellite remote sensing is discussed. [Work supported by NOAA and ONR.]
A comparison of acoustic and TOPEX/POSEIDON altimetric data in the Kuroshio Extension region during summer 1997
Authors: Yuan Gang , Mitsudera Humio , Nakano Iwao , Fujimori Hidetoshi , Yoshikawa Yasushi , Nakamura Toshiaki
Published: July 2012

Approximately two months of data from a five-transceiver acoustic tomography array in the Kuroshio Extension (KE) in the summer of 1997 are used for comparing with the TOPEX/POSEIDON (T/P) altimeter measurements. The acoustic data show that travel time (TT) variations are very consistent with contemporaneous variations of sea surface height anomalies (SSHA) as in the T/P in the KE front region, but have significant differences in the KE recirculation region. This difference is assumed to be due to the fact that the altimeter might not pick up the signal associated with the variations occurring below the seasonal thermocline. The inversions from a new approach show that the temperature in the surface layer (0–100 m) had been warming up 1.0 °C  during the experimental period, but cooling down about 0.2 °C in the subsurface layer (100–1500 m). This temperature warming up in the surface layer derived from acoustic data is excellent, consistent with the steric height change determined from net heat flux data of the NCEP/NCAR. Zonal range and depth averaged (barotropic) westward-flowing current velocity determined from reciprocal acoustic TTs in the recirculation region is about 5 cm/s; it is comparable with the surface geostrophic current velocity determined from the SSHA of the T/P. Acoustic tomography complements the altimetry.
The multiple source feedback of supersonic jet screech, II: Space-time diagrams and the standing wave puzzle elucidated
Authors: Powell Alan
Published: July 2012

Space-time diagrams for defined phases of the periodic instability wave and the feedback sound waves from the resultant equivalent point sources provide a simple physical picture of the multiple source feedback process, illustrated for cases of perfect reinforcement when φ=1, and for p=1/2 and for μ=±1/2 when φ≠1. They also provide a simple interpretation of the nature of the (sometimes necessary) approximation. The intersections of the maxima of the instability and sound waves form ‘‘partial standing waves’’ with maxima LSW=s/φ apart, involving one complete cycle of the instability and sound wave. This provides a simple explanation of the puzzling standing waves observed by Westley and Woolley (1975), Rice and Taghavi (1992), and by Panda (1996, 1997), it having been speculated that they may indicate, or be fundamentally associated with, the actual sound sources. Rather, n′s≡(N+μ+ν)s=(N+p+ν)LSW showing, for ν=0, that (N+p) standing waves (cycles) must fit in the nozzle-to-source distance, closely analogous to the N’th stage of (high-speed) edge tones. Then both μ and p can be estimated from such experimental data.
Hydrodynamic lift and drag fluctuations of a sphere—empirical model
Authors: Wang J. , Lauchle G. C. , Howe M. S.
Published: July 2012

An empirical model is developed to estimate the unsteady lift and drag induced on a spherical body subjected to a steady, uniform flow. A wind tunnel is used to measure the statistics of the surface pressure fluctuations on a sphere under subcritical Reynolds number conditions. The measurement results are incorporated into the model for predicting the unsteady force induced on the sphere. The model is based on a separable assumption of the cross-power spectral densities of the surface pressure fluctuations. This assumption is shown to be a proper engineering approximation except in low-frequency ranges. The model functions are obtained using least mean-square curve fits of the data. Tow tank experiments are performed, where the flow-induced unsteady side force and drag are measured independently of each other on spheres configured as acoustic velocity hydrophones. The empirical model and the tow tank measurements are in very good agreement with each other and also with a simplified vortex ring model presented in the accompanying paper. The predicted forces are used to determine the flow-induced noise on underwater inertial sensors subjected to a steady, uniform flow. [Work supported by ONR Code 321 SS.]
Boom cars: Noise pollution at its worst
Authors: Raichel Daniel R.
Published: July 2012

Boom cars, sometimes referred to as ‘‘boomers,’’ are vehicles that have stereo sound equipment installed specifically to generate exceedingly loud sound levels. Because the market is so lucrative, particularly among automobile owners under 30 years of age, manufacturers aggressively engage in promotion of ultra-high-power amplifiers, auxiliary bass drivers, midrange drivers, tweeters, crossovers, etc. Loudness competitions are held; and levels as high as 170 dB have been reported. Most advertising emphasizes loudness—for example, a TV spot shows a van’s sound system shattering store windows as it speeds down a street. In addition to an extremely high probability of hearing loss, those exposed to the excessive vibration inside a boomer’s interior may experience other sorts of physiological trauma, this in addition to annoying the surrounding neighborhood with excruciatingly high sound levels. The phenomenon of boom cars compares to that of tobacco addiction—a danger to vehicle occupants and a nuisance to ‘‘secondary’’ listeners. Countermeasures against such public nuisances include: (1) enactment and diligent enforcement of municipal laws specifying limits on discernable sound levels, (2) education in secondary schools on the dangers of excessive noise levels, and (3) public criticism of manufacturers’ promotional efforts that emphasize extremely high sound power.
Noise control in buildings—A noise-control class for architectural engineers
Authors: Muehleisen Ralph T.
Published: July 2012

As public awareness of noise control grows and the public tolerance for noise diminishes, interest in building noise control is increasing. Since noise control is better applied as an integral part of the building design, rather than as an afterthought, building designers need to be educated in the basics of noise control. To this end a new class entitled Noise Control in Buildings has been developed for architectural engineering majors at the University of Colorado (CU). The class is a senior-level/graduate-level design class that introduces the basics of acoustics and noise control as applied to building design. In the class students learn from lecture, homework, guest lecturers from industry, field trips, experimental sessions, and projects. A discussion of the class content and teaching method is provided.
The 1-day public symposium as a format for acoustics dissemination
Authors: Ternstrom Sten
Published: July 2012

The 1-day public seminar or symposium is a combined education and dissemination format that has been successfully applied by the Music Acoustics group at KTH in Stockholm, about once a year for the past 25 years. Such a seminar is typically structured as a full morning and afternoon of scheduled, invited lectures on a particular theme, followed by a public evening concert or other performance that corresponds to the theme. One or two international guests are keynote speakers, while the bulk of the program is contributed by leading Scandinavian researchers, teachers, and performers. The target style for the presentations is that of an introduction or overview for the interested and motivated but nonexpert academic. The topics are chosen for their expected public appeal, from ongoing or recent research activities in music acoustics and voice acoustics. Recent topics have included ‘‘Music and motion,’’ ‘‘Real-time biofeedback in voice therapy and pedagogy,’’ and ‘‘Randomness and noise in music.’’ Attendance usually ranges from 70 to 200. When possible the lectures are also published in book form, complete with sound examples. Aspects of content, public relations, and the financing of such symposia are discussed.
‘‘Sound’’ science and technical education for sixth graders: A practical approach
Authors: Alter Harry , Evans Rebecca
Published: July 2012

Following the renovation of the Granville Middle School Cafeteria in Granville, OH it was noticed by students and faculty that noise levels during lunch period had dramatically increased. As a result, speech became unintelligible and eating became both unenjoyable and uncomfortable. The resident sixth-grade science teacher with the assistance of a local acoustical engineer saw the opportunity to teach the sixth-grade science class about acoustics and to get the children directly involved in solving the school’s cafeteria noise problem. The class met on a weekly basis to learn about sound and its influences on the school environment. Ultimately, the students would build a single microphone impedance tube and test the sound absorption characteristics of various materials. From their investigation they would design and install an acoustical wall treatment system to reduce reverberant noise levels in the school’s cafeteria. Acoustical measurements of the cafeteria were taken before and after treatment to compare the student’s calculations and final work. The paper also outlines the comprehensive effort involved from securing local grant monies to technical discussions and photographs of the children’s work.
Application of modal analysis and synthesis of reed and pipe to numerical simulations of a clarinet
Authors: Facchinetti Matteo , Boutillon Xavier , Constantinescu Andrei
Published: July 2012

A finite-element model of a complete clarinet is proposed in order to simulate the acoustical dynamics of the instrument. Following the work of Pinard and Laine on isolated reeds [unpublished reports of the Ecole Polytechnique], modal analysis of clarinet reeds performed with holographic interferometry has been compared with modal synthesis derived from the FEM. In this linear model, the reed is considered alone first, then coupled to the mouthpiece, and finally to the mouthpiece and the barrel. The good agreement between the two approaches makes the mixed solid-acoustical FEM usable in a numerical simulation of the whole clarinet. The rest of the pipe is modeled by lumped mechanical elements whose parameters are fitted with measurements of the acoustical input impedance. Eigenmodes of the complete system—reed, mouthpiece, barrel, pipe—are computed and damping is subsequently attributed to each mode. The evolution of the system subject to nonlinear boundary conditions—incoming airflow, one-sided contact of the reed against the curved lay of the mouthpiece—is computed in the time domain: at each time step, external forces and internal variables are projected onto the modal basis and the evolution of each modal amplitude is integrated. Findings of the simulations will be discussed.
Wireless surface acoustic wave ice sensor
Authors: Jose K. A. , Gangadharan S. , Varadan V. V. , Varadan V. K.
Published: July 2012

Ice formation on an aircraft can cause serious safety problems, and hence, there is a real need for ice detection and monitoring on aircrafts. It is well known that acoustic wave devices offer a simple and inexpensive technique for a number of sensing applications. In this paper, we present a wireless ice detection and monitoring system using a surface acoustic wave (SAW) device utilizing shear horizontal (SH) waves as the sensing mechanism. The SAW device is designed and fabricated on a quartz substrate. Silicon dioxide is then deposited to serve as a guiding layer for SH waves. The acoustic wave concentrated in the guiding layer is highly sensitive to surface perturbations. The experimental setup used to measure the effect of ice formation is by an oscillator setup. The SAW device is designed to oscillate at a particular frequency and any fractional change in wave velocity due to surface perturbations leads to a change in oscillation frequency. It is observed that phase transformation from water to ice causes a shift in oscillator frequency of 2 MHz. The ice sensor can be operated wirelessly by connecting the SAW sensor to a stand-alone oscillator and the oscillator can communicate with a remote monitoring system using a microstrip antenna.
Extracting vowel characteristics from smoothed spectra
Authors: Lienard Jean-Sylvain , Di Benedetto Maria-Gabriella
Published: July 2012

The object of this study was to define vowel spectral features by means of a spectral representation making no specific reference to formants and fundamental frequency, though preserving vowel identity and extralinguistic factors such as effort and gender. This investigation complements the analysis in Lienard and Di Benedetto [J. Acoust. Soc. Am. 106, 411–422 (1999)] which used manually measured formants of the same data. The database consisted of isolated French vowels, uttered by male and female speakers, with different vocal efforts. The analysis was carried out by selecting one segment along the vowel corresponding to a joint maximum of stability and level. A spectral envelope, based on prominent spectral peaks selected by a frequency-domain masking function, was computed. The frequency axis was Bark-transformed. The envelope was then decomposed by successive smoothings (cepstral filtering). The output was a representation where vowels are characterized by the presence or absence of energy concentration at different frequency locations (‘‘spectral bumps’’). Spectral bumps, although related to formants, do not correspond to formants themselves; rather, they reflect an integrated information similar to what might be used by the perceptual system.
Two independent sonar signal generators in the bottlenose dolphin: Physiologic evidence and implications
Authors: Cranford Ted W. , Elsberry Wesley R. , Blackwood Diane J. , Carr Jennifer A. , Kamolnick Tricia , Todd Mark , Van Bonn William G. , Carder Donald A. , Ridgway Sam H. , Bozlinski Devon M. , Decker Emily C.
Published: July 2012

Some indirect evidence exists for multiple sonar signal generators in odontocetes. Direct evidence was collected from two bottlenose dolphins by simultaneously measuring and digitizing internal nasal cavity pressure, nasal tissue motion, and acoustic pressure. Small catheters measured pneumatic pressure changes at the same depth within each bony nasal passage. A high-speed video endoscopy system revealed tissue motion at both pairs of phonic lips while two hydrophones measured acoustic pressure during biosonar target discrimination. The records clearly demonstrate that acoustic pulses can be generated at the phonic lips on the left and right sides, independently or simultaneously. We have only seen the left phonic lips generate whistles. Air pressure in the bony nasal passages rises and falls together, even if the activity patterns at the two pairs of phonic lips are different. Increasing pulse repetition rate or sound pressure level, and whistle production, are all normally accompanied by increasing nasal air pressure. Whistle production apparently requires greater nasal air pressure than does pulse generation. Discovering multiple sonar sources in a dolphin’s head should cause us to reinterpret previous findings and re-evaluate physiologic limits on pulse repetition rate, signal bandwidth, frequency composition, and projection beam geometry. [Work sponsored by Office of Naval Research.]
High-frequency auditory filter shapes in an Atlantic bottlenose dolphin
Authors: Lemonds David W. , Au Whitlow W. L. , Nachtigall Paul E. , Roitblat Herbert L. , Vlachos Stephanie A.
Published: July 2012

High-frequency auditory filter shapes were calculated for a 20-year-old female Atlantic bottlenose dolphin (Tursiops truncatus). Thresholds were determined for tones of 40, 60, 80, and 100 kHz masked by notched noise. Auditory filter shapes were determined by fitting the integral of the roex(p,r) filter shape to the functions relating masked tonal threshold to notch width. Filter shapes were found to be approximately symmetric at the moderate noise level used. Equivalent rectangular bandwidths of the auditory filters ranged from 16% of center frequency at 40 kHz to 11% of center frequency at 100 kHz. There was very little change in the bandwidths of the filters between 60 and 100 kHz, indicating that relative tuning sharpness increases as a function of frequency in this range. Efficiency of processing after the periphery was found to be maximal at 40 and 60 kHz (better than 12-dB SNR) and to decrease gradually above 60 kHz. The efficiency estimates allowed for the reanalysis of critical ratio data collected previously for the same animal; the bandwidth estimates from the present and earlier study were found to be in good agreement.
Three-dimensional imaging of sand transport processes over wave ripples
Authors: Traykovski Peter , Irish James D. , Hay Alex E.
Published: July 2012

While the interactions between bedforms, suspended sediment transport and the forcing hydrodynamics are inherently three dimensional, most observations have been either point samples as a function of time, or 1-D vertical imaging systems. Recently, acoustic imaging systems have been designed to make 2-D maps of either bedform plan view topography (rotary fan beam sonars) or suspended sand concentration and bedform profiles (rotary pencil beam sonars). In the winter of 1999–2000, Woods Hole and Dalhousie investigators combined several of these 1- and 2-D systems to produce a data set on the 3-D structure of the suspended sand concentration field and its relation to the seafloor topography and forcing hydrodynamics. The data revealed that although the wave orbital scale ripples can be quite 2-D at times (i.e., long crested), the suspended sediment has considerable structure in the along-crest direction. The bedforms were observed to migrate in the onshore direction, and clouds of suspended sand were observed to be re-suspended in the lee of a ripple crest and then were advected back and forth over the crest.
Design characteristics of nineteenth century American-made brass instruments
Authors: Birkemeier Richard P.
Published: July 2012

The brass band was arguably the most popular form of entertainment for most American citizens in the nineteenth century. This ensemble flourished in nearly every town and eventually led directly to the development of jazz, the basis for all American popular music in the twentieth century. American brass instrument design underwent significant changes in a relatively short period of time during the second half of the nineteenth century. These design changes resulted in noticeable variations in instrumental timbre, changes that clearly had an effect on the music written for wind bands during this period. This presentation will feature two complete sets of nineteenth century brass band instruments, one from the Civil War era and one from the end of the century. They will be analyzed from the following perspectives: design specifications of bore, bell shape, valve configuration and mouthpiece design; weight and thickness of metal; and instrument timbre as demonstrated in live performance. It is hoped that the comparison of design characteristics followed by the actual sounds of the instruments will offer insights into this most important of relationships for the musician.
The measurement of impulse noise protection by earmuffs with the use of various sound sources
Authors: Zera Jan
Published: July 2012

Impulse attenuation of 23 hearing protectors from various manufacturers was determined by the transmission-loss method. Impulses were generated by a foil blaster, a starter gun, or by hitting a steel plate with a hammer. Peak levels of the impulses ranged from 130 to 160 dB. The measurements were carried out using an artificial test fixture (ISO/TR 4869-3:1989), and a KEMAR manikin. Peak sound pressure level of acoustic impulses was measured with two microphones, one of which was placed under the earmuff and the other one outside the earmuff. The best agreement between impulse attenuation and the protectors’ M, L, and SNR parameters was found when the foil blaster was used as a sound source. The results also show that the attenuation measured for impulses is usually smaller than the H, M, L, and SNR values given in the product data specification. [Work supported by the Polish Committee for Scientific Research Grant No. SPR 03.7.21.]
The ‘‘noisy’’ speech chain
Authors: Alwan Abeer
Published: July 2012

Kenneth Stevens’ seminal contributions to the field of acoustic phonetics are far reaching and have important implications for modeling normal and disordered speech production and perception. His studies of the relations between underlying discrete linguistic features and the analog worlds of articulation, sound, and hearing have influenced a generation of speech researchers, including myself. Our studies of speech perception in noise are inspired by the work of Ken and his colleagues on uncovering the acoustic and perceptual correlates of linguistic features. I will report on experiments which examined acoustic and perceptual (in noise) cues for the place of articulation and voicing features for syllable-initial plosive and fricative consonants. Results are analyzed in terms of voicing, vowel context, manner of articulation, place of articulation, shape of the noise masker, and gender of the talker. One of the interesting findings is that certain attributes which cue a feature acoustically and perceptually in quiet conditions (such as the VOT for the feature voicing) do not correlate well with the perceptual robustness of the feature in noise.
Overview of blind signal separation, part II: Structures and applications
Authors: Torkkola Kari
Published: July 2012

The focus of this talk is a class of blind signal separation procedures, blind separation of convolutive mixing of signals. The emphasis is on acoustic signals and methods applicable thereof, and their capabilities and limitations. At least two possible taxonomies of separation methods are possible. These are based on how to parametrize the separating structure, and on the criteria used for separation. The former will be the emphasis of the presentation. Different criteria to solve the problem are only briefly touched upon. Possible application areas are enumerated, especially in acoustics. Two exemplary areas are audio signal enhancement in the presence of disturbing noise, and machine vibration analysis. Some issues on why it is not straightforward to move blind separation techniques into real world applications are elaborated. Limitations in the audio setup are discussed that make unconstrained BSS an extremely hard (if indeed solvable) problem. Some further questions are posed and directions for further research are presented.