bluuebunny/crossref_metadata_2025 huggingface dataset:
Are there gas cavities in red blood cells?
Authors: Selivanovsky Dmitry A. , Didenkulov Igor N. , Kostina Olga V.
Published: July 2002

Many of marine single-cell organisms (phytoplankton) have gas cavities which allow them to keep their life cycle. Existence of gas cavities can essentially have an influence on acoustic and mechanical properties of cells. It seems reasonable to suppose that such cavities can also exist in erythrocites, life cycle of which is related to gas exchange. The present work was aimed on measurements of acoustomechanical properties of human red blood cells to reveal their gas cavities. The velocities of erythrocite sedimentation (VES) in natural conditions and under compression/decompression were measured. The VES was found to increase considerably under or after compression/decompression. The effect was observed both for blood from healthy and sick people. Special microscope observations of sedimentation process allowed findings that compression/decompression changes the natural orientation of erythrocites: after compression/decompression their main planes become vertical instead of horizontal for natural conditions. Such a phenomenon can be explained with the model of the red blood cell as a body with gas cavity. A compression/decompression changes the balance between centers of gravity and buoyancy making cells rotate and consequently to decrease the viscous force. [Work supported in part by RFBR, Russia.]
The acoustic system for investigation of the temporomandibular joint pathology
Authors: Lis Waldemar , Salamon Roman , Zienkiewicz Jozef
Published: July 2002

The temporomandibular joint is the most complicated joint from the anatomic standpoint. Diagnosing it is still a problem to be solved. Modern top quality devices do not provide a complete solution—the barrier here is the high price of a single examination. For this reason, new, cheap methods of diagnosing the temporomandibular joint are being sought. One of these methods is diagnosing on the basis of passive listening for acoustic signals emitted by the joint in motion. This paper presents the application of the FFT and wavelet method for the purpose of examining the acoustic signal analysis of the temporomandibular joint. The advantages and disadvantages of both methods, the Fourier method and wavelet method, are discussed. Finally, the results obtained by the Fourier analysis in time window and by a wavelet method are presented and compared.
A numerical and experimental investigation into the effects of cavity geometry on the production of cavity tones
Authors: Henderson Brenda , Navaz Homayun
Published: July 2002

The effect of the leading and trailing edge geometries on the production of tones associated with the flow of low-speed subsonic air over a cavity were investigated experimentally and numerically. The leading edge geometries considered in the study included an overhang (simulating car door gaps) and an overhang with delta tabs such as used to control jet noise. The trailing edge geometries used in the investigations included sloped and rounded impingement regions. The numerical results documented the periodic fluctuations of the transverse velocity, pressure, and density of the shear layer and the resulting cavity pressures. The periodic vortex behavior in the cavity mouth and impingement region was also studied numerically to predict possible configurations for sound suppression. Experimental investigations of the cavity sound-pressure levels were used to determine the validity of the numerical simulations and the predicted cavity configurations for sound suppression.
The powerful role of the Commanders Decision Aid (CDS) software and acoustic sensor to increasing ground combat vehicle survivability
Authors: Yannone Ronald M.
Published: July 2002

With the proliferation of diverse anti-tank guided missiles and top attack munitions, ground combat vehicles require the use of multispectral sensors. The issues that arise by adding sensors to these vehicles are the additional cost, size, weight, and power required. Even more critical is the ability of the sensor to provide timely, high-confidence, low-false alarm rate threat detection and classification information to the crew. Amidst a heavy signal clutter battlefield and multiple sensors aboard the vehicle, the concerns are information overload for the crew, being detected by enemy sensors, and quickly depleting limited countermeasure assets by responding to false alarms. The use of infrared and laser warning receivers (IRW, LWR) has been assessed to be very beneficial toward this aim, but not sufficient. Operations analysis has shown that with the addition of an acoustic sensor and decision aid software, crew survivability increases dramatically with low cost. The paper reviews the ground combat vehicle problem space, the data, the complementary data the IRW, LWR, and acoustic sensors provide, and how the Commander’s Decision Aid (CDA) software performs multispectral/multisensor fusion, threat classification, threat prioritization, countermeasures response management, and countermeasures effectiveness assessment via various scenario descriptions.
Preventative medical limits for chronic traffic noise exposure
Authors: Maschke Christian , Hecht Karl , Balzer Hans-Ulrich
Published: July 2002

Because of an expert’s report on the medical effects of noise on healthy adults, permissible values for mainly traffic noise have been estimated by the standard of knowledge. If the permissible values are exceeded, then preventative medical action is necessary. Below this value the probability of noise-induced health hazards is essentially zero. The effect due to noise as a health hazard is, besides the mechanical damage of the inner ear, a psycho-physiological deregulation which can be either indirectly due to the annoyance or directly caused by stress of the vegatative-hormonal system. Therefore, different permissible values for annoyance, the stress on the vegetative-hormonal system, and for the loss of hearing are suggested, for both continuous and maximum noise levels. In addition, the deregulation depends on the time of the acoustic exposure because the sensitivity to noise follows a 24-h cycle (circadian rhythm). It is therefore necessary to give personal permissible limits for the evening noise and the nocturnal noise.
Cadastre of the acoustic characteristics of the whole road network of the Brussels region
Authors: Clairbois Jean-Pierre , Houtave Peter , Koellmann Andreas , Mosdzianowski Gerhard
Published: July 2002

The Brussels Institute of the Environment (IBGE-BIM) took the initiative to start a global study assembling elements of its future noise planning. Road surface noise is an important element of these. A strong methodology has been decided in order to get an exhaustive database of the whole road network of the Brussels region (1800 km). The idea is to get an interactive tool in order to control the actual conditions of the road surfaces and their influence on the global road traffic noise, and also to be able to look at the different possible improvement scenarios. Establishing this database required not only to visit every road of the network, but also to assemble all relevant data for estimating the road and traffic conditions. The methodology and tools used for the work, the results, and a statistical analysis of the database are presented. This work has been completed by noise measurements (CPB and trailer methods) of the nine different kinds of road surfaces used in the Brussels region. A strategy of action is suggested and the maintenance of the database is started so that the evolution of the network can be continuously considered within the noise planning. [Work supported by IBGE-BIM.]
Opto-acoustic sounding of the atmospheric parameters
Authors: Shamanaeva Lyudmila G.
Published: July 2002

Experimental investigations of sound pulse generation accompanying the propagation of high-power pulsed laser radiation in the atmosphere were started at the IAO SB RAS in 1986. Based on these investigations, new opto-acoustic methods of sounding of the atmospheric temperature, wind velocity, relative humidity, and number density of micron fraction of atmospheric aerosols were suggested. A source of the acoustic signal in an opto-acoustic sounding system is a discrete laser spark made by focusing a CO2 laser beam into the atmosphere at distances up to 500 m. The number density of coarsely dispersed aerosols was determined from the number of pulses in the acoustic signal generated by the discrete laser spark. Results of opto-acoustic measurements of the number density of coarsely dispersed aerosols agree well with the microphysical model of aerosol atmosphere for Western Siberia. A threshold laser energy density resulting in the origin of local plasma formations is about 6−10 J /cm2. For lower laser energy densities, the acoustic radiation is generated due to laser-induced thermal expansion of the propagation medium. The measurable parameters are the effective laser beam radius, the coefficient of laser radiation absorption, and the total laser beam energy.
Acoustic sounding of fog and rain
Authors: Shamanaeva Sergei V. , Shamanaeva Lyudmila G.
Published: July 2002

The coefficients and phase functions of sound scattering by a single rigid spherical particle whose parameter Mie changes in a wide range have been calculated with the use of exact formulas of the Mie scattering theory. Analytical expressions are given for the dependence of sound attenuation on the parameters of fog and rain and acoustic frequency. The acoustic scattering cross section of a single particle has been derived. New methods of acoustic sounding of fog and rain have been suggested and theoretically analyzed. Experimental data on the transformation of raindrop size distribution have been obtained by processing of raw spectra of acoustic signals recorded in rain for 20 s and 1, 2, 3, 5, and 25 min with cw bistatic sodars operating at frequencies of 5 and 40 kHz. The bimodal character of the raindrop size spectra was established. The position of the second maximum in the raindrop size spectrum was shifted with time toward larger raindrop sizes, from 0.3 to 1 mm. The estimated rain intensity varied from 0.5 to 1.9 mm per hour. The obtained results demonstrate that high-frequency cw bistatic sodars are very promising for measurements of fog and rain.
Sonochemical synthesis of new materials
Authors: Suslick Kenneth S. , Dantsin Gennady , Ekhtiarzadeh Arash , Dhas Arul
Published: July 2002

High-intensity ultrasound has found new applications in the synthesis of unusual inorganic materials. The chemical effects of ultrasound originate from acoustic cavitation, which produces local transient conditions of ∼5000 K, ∼500 atm, with heating and cooling rates that exceed 1×1010 K/s. In cold liquids, ultrasound is able to drive reactions that normally occur only under extreme conditions. Examples include intercalation, activation of liquid–solid reactions, and synthesis of amorphous and nanophase materials. The sonochemical syntheses of nanophase metals, alloys, metal carbides, supported heterogeneous catalysts, and nano-colloids derives from the sonochemical decomposition of volatile organometallic precursors during cavitation, which produces clusters a few nm in diameter. Such nanostructured solids are active heterogeneous catalysts for various reactions. Most recently, we have discovered a new synthesis of nanometer-sized MoS2 and of transition metal colloids of iron, cobalt, and iron–cobalt alloy colloids. Sonication of molybdenum hexacarbonyl in the presence of sulfur produces a novel morphology of MoS2 with extremely high activity for catalytic hydrodesulfurization of thiophene. Stabilized iron, cobalt, and alloy colloids have also been prepared that are amorphous as initially prepared with particle sizes ∼5 nm as determined by TEM. Magnetic studies show that the colloids are superparamagnetic and function as useful ferrofluids.
Physics of acoustic-to-seismic coupling and detection of buried objects
Authors: Sabatier James M. , Xiang Ning
Published: July 2002

Airborne acoustic waves coupled into the surface of the ground excite Biot type I and II compressional and shear waves. If a mine-like target or other inhomogeneity is present below the surface, the ground surface vibrational velocity will show distinct changes due to reflection and scattering of these waves. Sound waves with a wavelength comparable to the object size are suitable for recognizing geometrical shapes of targets, while true wave-like acoustic scattering phenomena can be observed with a shorter acoustic wavelength. In this paper, a review of porous material physics relevant to mine detection will be presented. Recent development in the acoustic technology for mine detection will be reported. Taking advantage of a noncontact measurement technique, the surface vibrational velocity is detected with a laser Doppler vibrometer. [This work is supported by U.S. Army Communications-Electronics Command.]
About Biot’s theory and the acoustic propagation in aerogels
Authors: Forest Luc , Gibiat Vincent , Woignier Thierry
Published: July 2002

Although aerogels are now well known for their very particular acoustical behavior (very low speed of sound, very low acoustical impedance), no theoretical model has been proposed to describe both velocity and absorption. Since aerogels are porous media constituted by an amorphous silica skeletal and air-filled pores, it seems interesting to study the possible application of the current reference theory of propagation in elastic porous media, developed in the 1950s by Biot. Biot has proposed a semiphenomenological theory in which the average motion of both solid and fluid parts is studied separately. Then he introduces in Lagrange’s equations the energies of two interpenetrating ‘‘effective media,’’ considering each phase, solid and fluid, as homogeneous. Viscous losses are taken into account from Poiseuille’s model. The prediction concerning the velocities in the ultrasonic range are shown accurate and a simple rheological model derived from this theory is defined. Concerning the attenuation, theoretical results and experimental data are carefully compared in the frequency range (0.8–8 MHz). A qualitative agreement for the low-density samples is obtained and it will be shown that the agreement could become quantitative if a dynamic permeability higher than the static one is taken into account.
Surface waves above thin porous layers and periodic structures
Authors: Lauriks Walter , Kelders Luc , Allard Jean François
Published: July 2002

Airborne surface waves above thin air-saturated porous layers and periodic structures have been studied in the low-ultrasonic frequency domain. These waves were observed performing two different kinds of experiments. Because surface waves are related to a pole in the reflection coefficient, we adapted a setup based on near-field acoustical holography to the frequency range of interest. In this way, it was possible to measure the reflection coefficient of the porous layer as a function of the angle of incidence. The existence of a surface wave was observed for different layer thickness. Second, the velocity of the inhomogeneous waves has been determined directly by time-of-flight measurements of ultrasonic bursts, by phase velocity measurements with a sine signal, and from interference patterns of standing waves. The results are compared to predictions using several models. The reflection coefficient above the reticulated polyurethane foams was predicted by an equivalent fluid model, the frame being motionless at the frequencies considered here. For the calculations of the velocity above rectangular- and triangular-groove gratings, we adapted models developed for electromagnetic waves above these structures to acoustics.
The eigenray method for rapidly estimating refraction effects in a linear profile atmosphere
Authors: White Michael J.
Published: July 2002

Eigenray solutions to sound propagation in an atmosphere with a linear sound-speed profile offer a convenient technique to estimate the effects of refraction. Eigenrays represent the trajectories of wave fronts that depart from the source and reach a given receiver. In a linear profile, the rays are arcs of circles, and over flat ground with perfect reflection, the paths can be constructed from a series of hops. Improvements to the eigenray technique are proposed that match the exact solution for pressure and phase in the unbounded linear profile. For reflection, the choice of a correct branch in the expression for divergence is necessary so that adjacent receivers with different numbers of eigenrays report the same pressure. Extension of the technique to lend estimates for some more complex situations is straightforward, although it fails to offer an advantage near caustics and focal regions.
Sound propagation near the ground in a turbulent atmosphere
Authors: Ostashev V. E. , Goedecke G. H.
Published: July 2002

For many geometries of sound propagation in an atmosphere, the sound-pressure field is a sum of the direct wave from the source to the receiver and that reflected from the ground. The resulting field is significantly affected by atmospheric turbulence. A theory is presented that gives an analytical formula for the mean-square sound pressure in an anisotropic turbulent atmosphere with temperature and wind velocity fluctuations. This formula contains a ‘‘turbulence’’ factor T which describes the reduction of interference maxima and minima due to atmospheric turbulence. For the important particular case of isotropic turbulence, T is expressed in terms of the coherence function of the direct wave from the source to the receiver. The turbulence factor T and the mean-square sound pressure are calculated and compared for Kolmogorov, Gaussian, and von Karman spectra of temperature and wind velocity fluctuations. Furthermore, the relative contributions to the mean-square sound pressure due to temperature and wind velocity fluctuations are compared. [This material is based upon work supported by the U.S. Army Research Office under Contract No. DAA G55-98-1-0463.]
Forgetting pitch and loudness
Authors: Clément Sylvain , Demany Laurent , Semal Catherine
Published: July 2002

Short-term memory for pitch and loudness was investigated in discrimination experiments using a 2I-2AFC paradigm with feedback. The two stimuli presented in each trial were separated by a variable delay (D); they consisted of pure tones, a series of resolved harmonics, or series of unresolved harmonics mixed with lowpass noise. A roving procedure was employed in order to minimize the influence of context coding [N. I. Durlach and L. D. Braida, J. Acoust. Soc. Am. 46, 372–383 (1969)]. During an initial training phase, frequency and intensity discrimination thresholds [P(C)=0.80] were measured with an adaptive staircase method while D was fixed at 0.5 s. The corresponding physical differences (in cents or dB) were then constantly presented at four values of D: 0.5, 2, 5, and 10 s. In the case of intensity discrimination, d′ markedly decreased when D increased from 0.5 to 2 s, but was not further reduced when D was longer. In the case of frequency discrimination, the decline of d′ as a function of D was significantly less abrupt. Similar decline functions were observed for 50- and 500-ms pure tones. These results support the idea that pitch and loudness are processed in separate modules of auditory memory.
Further studies of auditory decruitment and a visual analog
Authors: Canévet Georges , Regal Xavier , Sauvage Olivier , Teghtsoonian Robert , Teghtsoonian Martha
Published: July 2002

A tone continuously decreasing in amplitude from moderate to weak levels will, at any point in the sweep, have a loudness increasingly lower than an equally intense tone presented alone. This accelerated loss in loudness has been called decruitment [Canévet and Scharf, J. Acoust. Soc. Am. 88, 2136 (1990)] and interpreted in part as an adaptation effect. For a 1-kHz tone, the amount of decruitment increases with the duration of the sweep and becomes asymptotic at about 20 s; a phenomenon similar to decruitment can be observed for circles continuously shrinking in size [Teghtsoonian et al., P & P, 1998, submitted]. Further studies, in which tone frequency and sensation level are varied, show that (a) at 4 kHz, the degree of decruitment increases with sweep duration for a longer period (over 50 s) and achieves a higher value than obtained with a 1-kHz tone, and (b) sensation level has little effect on either measure. These findings for loudness are not easily interpreted in terms of simple adaptation but may be consistent with a form of adaptation characterized as ‘‘medium-term.’’ A study confirming the accelerated shrinkage of a continuously decreasing circle is also reported and the problem this creates for adaptation-based interpretations of loudness decruitment is noted.
Effect of time distribution of energy on loudness evaluation
Authors: Meunier Sabine , Susini Patrick , Regal Xavier
Published: July 2002

Most work on loudness have been done on stationary sounds. However, environmental sounds are usually temporally variable, and memory effects could be important in loudness evaluation of long-lasting dynamic sounds. The loudness of one-minute sounds containing a local dominating peak of energy was measured. The sounds differed only by the temporal position of the peak. The influence of peak location on the global loudness judgment was evaluated. The global loudness was first evaluated using magnitude estimation. Contrary to expectations, mean estimations were the same for all sounds regardless of peak distribution. In a second experiment, subjects had to judge the loudness, using cross-modal matching. They matched the size of a circle on a computer screen with the loudness of the sound. At the end of the signal, a global estimation was also made using the same cross-modal matching paradigm. This global estimation was made either just after the sound or after a pause of one minute. During the pause, the subject had to perform a distracting task. Relations between global and continuous judgments are discussed. The study can help to design a model of the loudness of temporally variable sounds.
Modeling the role of masker-correlation uncertainty in binaural masking experiments
Authors: Breebaart Jeroen , Kohlrausch Armin
Published: July 2002

Recently, a new approach to modeling binaural interaction was described [Breebaart et al., J. Acoust. Soc. Am. 103, 2844–2845 (1998)]. This model is based on a subtractive mechanism and is sensitive to interaural time differences as well as interaural intensity differences. In order to extend this model to masking data for partially correlated noise maskers, the following experimental findings have to be considered. (a) For broadband maskers with correlations < 0.95, the power ratio between signal and masker difference intensity (i.e., masker intensity at the output of the subtractive mechanism) is constant. (b) In broadband conditions, frozen- and running-noise maskers lead to the same thresholds, indicating that masker correlation uncertainty does not influence detectability of the signal. (c) For narrow-band running-noise maskers, the masker correlation uncertainty is the dominant factor to explain signal thresholds. Result (a) can be implemented by applying a logarithmic compression to the output of the substractive mechanism and adding an internal noise with a constant rms value. With this modification, the model is capable of describing the differences between frozen- and running-noise maskers as listed under (b) and (c). [Work supported by the Dutch Organisation for Scientific Research (NWO).]
Adults’ perception and production of the English vowel /i/
Authors: Frieda Elaina
Published: July 2002

The present experiment examined the link between the perception and production of the English vowel /i/. Thirty-five male subjects produced the vowel /i/ in the following two conditions: first, subjects produced ‘‘casual’’ or citation speech; second, subjects produced exaggerated (hyperarticulated) speech. Subjects then completed a perceptual experiment employing a method of adjustment procedure which enabled them to select their own preferred or ideal exemplar for /i/. Subjects’ vowel productions were measured with LPC analysis for the following parameters: F0, F1, F2, and duration. The perceptual data were averaged for each subject to determine their preferred F1 and F2 dimensions. Comparing the two speech samples yielded predicted results in that the hyperarticulated speech was more extreme and fronted within the vowel space than the citation speech. Analyses also revealed a negative correlation between subjects’ citation speech and their perceptual data, reflecting a tendency for the perceptual data to be higher and more fronted in the vowel space than citation speech. The production data were converted to bark difference scores for F1−F0 (vowel height) and F2−F1 (front–back dimension). These values were compared to subjects’ perceptual data and demonstrated that the hyperarticulated speech was more similar to the perceptual data than citation speech.a) Formerly at Dept. of Psych., Univ. of Alabama, Birmingham, AL.
Perceptual properties of English fricatives
Authors: Jongman Allard , Spence Michelle , Wang Yue , Kim Brian , Schenck Diana
Published: July 2002

A series of experiments was conducted to determine the properties that contribute to fricative perception. Listeners’ identification of English fricatives based on fricative-vowel syllables and on isolated fricative noise portions reveals the perceptual salience of each fricative and the extent to which fricative-to-vowel transitions contribute to identification. Two further experiments specifically address perception of the nonsibilant fricatives, which, it has been claimed, may be based more on semantic or facial factors. One experiment investigates how a semantically matching or mismatching precursor affects perception of minimal pairs (e.g., fin-thin). A second experiment determines the extent to which auditory and/or visual information each contribute to fricative perception. Moreover, regression of these perceptual data on acoustic measurements, including noise duration, amplitude, relative amplitude, spectral peak location, spectral moments, and locus equations [see Jongman et al., J. Acoust. Soc. Am. 103, 3086A (1998)], indicates which acoustic properties play a significant role in fricative perception. [Work supported by NIH.]
Spheres for calibrating high-frequency broadband echo sounders
Authors: Foote Kenneth G. , Francis David T. I. , Furset Hilde , Hobaek Halvor
Published: July 2002

The notion of standard-sphere broadband calibration [Dragonette et al., J. Acoust. Soc. Am. 69, 1186 (1981)] is being realized for a new echo sounding system that spans the seven-octave range 25 kHz to 3.2 MHz. Spheres formed of tungsten carbide with 6% cobalt binder, with 10- and 20-mm diameters, have been measured in the laboratory to determine their backscattering spectra over the approximate frequency ranges 0.85–1.3 MHz and 2.9–3.6 MHz. This allows exploration of the wave number radius (ka) product over the nominal ranges 18–28, 36–56, 61–75, and 122–150. Comparison with theoretical expectation, as derived from the standard modal solution using published values for the material properties, is quite good. Confidence in the computations thus enables favorable regions of the backscattering spectra to be sought and exploited in choosing optimal diameters, as has earlier been the case with spheres for calibrating resonant transducers. In the course of checking computations, it was discovered that two independently developed numerical codes yield values for the backscattering cross section that agree to within 1 part in 10 000 to better than one part in 1 000 000 for ka of the order of 100. [Partial support of the EU through RTD Contract No. MAS3-CT95-0031 is acknowledged.]
Experience with a new ANSI standard for measuring the real-ear attenuation (REAT) of hearing protectors (S12.6-1997)
Authors: Berger Elliott H. , Kieper Ronald W. , Peyton Donald L.
Published: July 2002

It has become increasingly apparent during the past 20 years that laboratory-measured values of hearing protector attenuation obtained in conformance with ANSI standards (S3.19-1974, S12.6-1984) bore little correspondence to those obtained by workers in actual occupational settings. The development of a new standard, ANSI S12.6-1997, Methods for Measuring the Real-Ear Attenuation of Hearing Protectors, addressed this problem. The new standard includes both experimenter-supervised fit and subject-fit methods. The latter method, designated as method B, requires the use of audiometrically experienced subjects who are naɪ̈ve in the use of hearing protection. This method is intended to approximate the upper limits to the attenuation that can be expected for groups of occupational users. It yields mean attenuation values, more so for earplugs than earmuffs, that are substantially lower, and standard deviation values that are higher than previously found using ANSI standards. This paper will describe the new S12.6, present method-B test data, compare and contrast the standard to the existing related ISO standard (4869-1:1990), and review the results of ongoing studies designed to evaluate aspects and assumptions of the Method-B protocol. The problems inherent in obtaining and utilizing test panels of inexperienced hearing protection wearers, as well as observations gleaned from working with those subjects for in excess of 30 evaluations, will also be examined.
Realization of an auralization software based on echograms calculated by a sound ray technique
Authors: Archambeau Dominique A.
Published: July 2002

Among the different auralization implementations yet devised, a completely computerized auralization technique, in which the acoustics of the room to be treated is simulated by a sound ray tracing algorithm, was realized. The major difficulty closely linked with this process was to convert the set of temporal energy distributions (one per frequency band), issued from the ray tracing software, into pressure echograms or impulse responses, so that the phase information had to be reintroduced. The various stages were conducted according to an earlier investigation of this problem [R. Heinz, Entwicklung und beurteilung von computergestützten methoden zur binauralen raumsimulation (Verlag Shaker, Aachen, 1994)]. Several methods able to derive the binaural room impulse responses from the corresponding monaural impulse response were then studied. These binaural impulse responses were next convolved with any vocal or musical anechoic signal yielding the signal as it could be heard or auralized in the real room. The convolutions were conducted in the frequency domain using the fast Fourier transform algorithm. This auralization program was finally tested on various acoustical spaces and a subjective study was then carried out to compare real sound signals and the corresponding auralized ones.
Combination of monaural and binaural noise suppression algorithms and its use for the hearing impaired
Authors: Marzinzik Mark , Wittkop Thomas , Kollmeier Birger
Published: July 2002

A single-channel noise suppression algorithm based on the Ephraim–Malah suppression scheme [Y. Ephraim and D. Malah, IEEE Trans. Acoust. Speech Signal Process. 32, 1109–1121 (1984)] was tested with hearing-impaired subjects for different noise conditions. Significant benefits could be demonstrated for hearing-impaired subjects regarding reductions in listener fatigue and in the mental effort needed to listen to speech in noise over longer periods of time. However, an improvement of speech reception thresholds measured with the Göttingen sentence test could not be shown. Hence, a combination of the single-channel noise suppression scheme with the directional filter binaural noise reduction algorithm [T. Wittkop and V. Hohmann, this conference] is investigated. While the directional filter is assumed to suppress distinct noise sources, as, for example, jammer talkers that are not located in the desired direction, the monaural noise suppression algorithm reduces the diffuse stationary noise floor. Different combination strategies are being studied and evaluated with hearing-impaired subjects with regard to speech intelligibility, ease of listening, and subjective quality. The benefits as well as the shortcomings of the combined noise suppression algorithms for hearing-impaired subjects will be described and discussed. Implications for future developments will be drawn.
Help or hindrance: How violation of different assimilation rules affects spoken-language processing
Authors: Weber Andrea
Published: July 2002

Recent phoneme detection studies showed that spoken-language processing is inhibited by violation of obligatory assimilation [e.g., Otake et al. (1996)]. A phoneme detection experiment was designed to replicate this effect with German fricative assimilation. German fricative assimilation is progressive and applies within syllables. The velar fricative [x] occurs after back vowels, the palatal fricative [ç] after front vowels. In contrast to previous findings, listeners detected [x] faster when violation occurred. A second experiment explored whether these results are due to the tested assimilation applying within syllables, whereas earlier experiments tested assimilation across syllables. Again, listeners detected [x] faster when the assimilation rule was violated across a syllable boundary. The discrepancy with the earlier results might be due to the German fricative assimilation rule being progressive, while earlier experiments tested regressive assimilation. A third experiment tested German place assimilation for nasals. Regressive place assimilation in German is obligatory within syllables. A velar stop /k/ specifies the place for the preceding nasal /ŋ/. This time listeners detected the target phoneme /k/ more slowly when the assimilation was violated. The results show that whereas violation of regressive assimilation inhibits processing, violation of progressive assimilation speeds up processing.
A phonological interpretation of the ‘‘Gussenhoven–Rietveld Effect’’
Authors: Jannedy Stefanie , Beckman Mary E.
Published: July 2002

Dutch listeners rate the perceived prominence of the second fundamental frequency (F0) peak (P2) to increase as the first peak (P1) increases and decreases in F0 while P2 is held constant. This Gussenhoven–Rietveld effect was replicated with English listeners [Ladd et al. (1994)]. They interpret the positive correlation between the frequency of P1 and the perceived prominence of P2 as a function of the pitch range. Gussenhoven and Rietveld (1997) attribute this effect to parsing P1 and P2 as occurring in a single phrase, signaled by the intonation contour between the peaks. It is proposed that listeners parse the intonation phrase internal F0 peaks as relational to each other and as good or bad instances of phonological accent categories: An F0 contour with a lower P1 and a higher P2 can be interpreted as an H* L+H* sequence, with the realization of the L+H* as not prominent for this category. A flat-shaped F0 contour with P1 and P2 roughly equal can be interpreted as an H* accent on both peaks. A higher P1 interpolating onto a lower P2 can be interpreted as a rather prominent instance of a downstepped H* accent on P2. This explanation assumes a phonological interpretation of intonation contours.
Propagation of an ultrasonic impulse in porous media having a rigid frame
Authors: Fellah Zine el Abidine , Aknine Achour , Castagnède Bernard , Depollier Claude
Published: July 2002

The sound propagation in porous materials having a rigid frame filled by air, is well described by the equivalent fluid model where the interactions between fluid and structure are taken into account in the dynamic tortuosity α(ω) and in the dynamic compressibility β(ω) defined by the basic equations ρα(ω)(∂〈v〉/∂t)=−∇〈p〉, (β(ω)/Ka)(∂〈p〉/∂t)=−∇〈v〉. In the domain of the low-frequency approximation, the behavior of these response factors leads to a wave equation with a dissipative term due to the viscous effects. For high frequencies, a porous material becomes a dispersive medium in which the phase and group velocities are functions of frequency; in such a material a transient pulse changes its shape by spreading. A theoretical model of the sound propagation in a dispersive porous material is presented. This problem is posed in the time domain for an ultrasonic pulse in a slab of porous material. A method is proposed for computing the sound field in the medium. This allows one to deduce the transmission and reflection coefficients which are dependent only on the physical parameters of the medium (but not of the incident wave), which is important for inverse problems. The spreading of the transient pulse is calculated for various porous media and compared to experimental data.
Minimizing the sound power radiated by a cube as a function of the size of constrained layer damping patches
Authors: Kruger Daniel H. , Mann J. Adin
Published: July 2002

In cases where a structure’s excitation cannot be altered, the sound radiation from the structure must be minimized by modifying the structure within given design constraints. In this work small modifications of an existing structure are considered, rather than a complete design of complex material geometries and properties, or active control methods. Sound power radiated by a cube as a function of normal surface velocity was written using the boundary element method (BEM) [K. A. Cunefare and G. H. Koopman, J. Vib. Acoust. 113, 387–394 (1991)]. The normal surface velocity of a square plate was measured using a laser vibrometer. The plate was measured with no damping and with eight areas of constrained layer damping material. A cube was simulated by placing various combinations of measured plate velocity distributions on the sides of the cube. In this case, the BEM power function was minimized using a finite difference modification of the gradient method and by the method of simulated annealing. Sound power of the cube was reduced by as much as 8 dB while applying constrained layer damping material to only 0.93% of the cube’s surface area when one side of the cube was vibrating. The sound power radiated by the cube was reduced by 7.8 dB by covering just 4.06% of the total surface area of the cube when all six sides of the cube were vibrating.
Psychometric functions for discrimination of two-component complex tones in listeners with normal hearing and listeners with hearing loss
Authors: Arehart Kathryn Hoberg , Rosengard Peninah Fine
Published: July 2002

This study compared the ability of 5 listeners with normal hearing and 12 listeners with moderate to moderately severe sensorineural hearing loss to discriminate complementary two-component complex tones (TCCTs). The TCCTs consist of two pure tone components (f1 and f2) which differ in frequency by Δf (Hz) and in level by ΔL (dB). In one of the complementary tones, the level of the component f1 is greater than the level of component f2 by the increment ΔL; in the other tone, the level of component f2 exceeds that of component f1 by ΔL. Five stimulus conditions were included in this study: fc=1000 Hz, ΔL=3 dB; fc=1000 Hz, ΔL=1 dB; fc=2000 Hz, ΔL=3 dB; fc=2000 Hz, ΔL=1 dB; and fc=4000 Hz, ΔL=3 dB. In listeners with normal hearing, discrimination of complementary TCCTs (with a fixed ΔL and a variable Δf) is described by an inverted U-shaped psychometric function in which discrimination improves as Δf increases, is (nearly) perfect for a range of Δf’s, and then decreases again as Δf increases. In contrast, group psychometric functions for listeners with hearing loss are shifted to the right such that above chance performance occurs at larger values of Δf than in listeners with normal hearing. Group psychometric functions for listeners with hearing loss do not show a decrease in performance at the largest values of Δf included in this study. Decreased TCCT discrimination is evident when listeners with hearing loss are compared to listeners with normal hearing at both equal SPLs and at equal sensation levels. In both groups of listeners, TCCT discrimination is significantly worse at high center frequencies. Results from normal-hearing listeners are generally consistent with a temporal model of TCCT discrimination. Listeners with hearing loss may have deficits in using phase locking in the TCCT discrimination task and so may rely more on place cues in TCCT discrimination.
Counteracting moment device for reduction of earthquake-induced excursions of multi-level buildings
Authors: Nagaya Kosuke , Fukushima Toshiyuki , Kosugi Yasuhiro
Published: July 2002

A vibration-control mechanism for beams and columns was presented in our previous report in which the earthquake force was transformed into a vibration-control force by using a gear train mechanism. In our previous report, however, only the principle of transforming the earthquake force into the control force was presented; the discussion for real structures and the design method were not presented. The present article provides a theoretical analysis of the column which is used in multi-layered buildings. Experimental tests were carried out for a model of multi-layered buildings in the frequency range of a principal earthquake wave. Theoretical results are compared to the experimental data. The optimal design of the control mechanism, which is of importance in the column design, is presented. Numerical calculations are carried out for the optimal design. It is shown that vibrations of the column involving the mechanism are suppressed remarkably. The optimal design method and the analytical results are applicable to the design of the column.
Sound propagation over a large wedge: A comparison between the geometrical theory of diffraction and the parabolic equation
Authors: Robertson J. S.
Published: July 2002

Low-frequency propagation over wedges, hills, and barriers is an important problem with many applications. Two different propagation models (the geometrical theory of diffraction and the parabolic equation) are used to compare the sound field generated by a steady single-frequency source in front of, over, and behind a large, rigid, V-shaped wedge. Predictions along the boundary made with both models at several frequencies are compared and found to be in excellent agreement. The results provide additional evidence that the parabolic equation is able to account accurately for propagation effects caused by terrain irregularities.
Active control of multiple tones in an enclosure
Authors: Sampath A. , Balachandran B.
Published: July 2002

In this paper, analytical and experimental investigations into active control of multiple tones in a three-dimensional enclosure are presented. The frequency range of the disturbance is chosen to encompass one or more structural and/or enclosure resonances. Distributed piezoceramic actuators and distributed polyvinylidene fluoride (PVDF) sensors are mounted on one of the enclosure boundaries. Acoustic sensors are used inside and outside the enclosure. An analytical formulation based on a state-space model is developed for local vibration control on an enclosure boundary and/or local noise control inside the enclosure for bandlimited disturbances. The error sensor signals are minimized by using digital feedforward control schemes based on filtered-U gradient descent algorithms. Analytical predictions from the current work are found to compare well with the results obtained in our previous experimental investigations. The current efforts are relevant to sound fields such as those enclosed in rotorcraft cabins.
Comments on “A field survey on the annoyance caused by sounds from large firearms and road traffic” [J. Acoust. Soc. Am. 104, 2890–2902 (1998)]
Authors: Schomer Paul D.
Published: July 2002

Buchta and Vos [J. Acoust. Soc. Am. 104, 2890–2902 (1998)] have recently analyzed one set of blast-sound attitudinal survey data. From this survey, they conclude that annoyance increases less rapidly with level for high-energy impulsive sounds than it does for conventional sounds like road traffic noise, a result that is at odds with a significant number of research results. This paper discusses the analysis by Buchta and Vos and points to several areas in their analysis that might cause their results to depart from the results found by others. Specifically, it appears that the communities in their study exhibit abnormally high levels of annoyance to noise. Also, the great majority of the data that they analyze are below the threshold at which people in the community will notice these sounds. These factors may account for the results found.
Using vocal identifiers of individuality in research
Authors: Gisiner Robert
Published: July 2002

Many animals use vocal cues for individual recognition to mediate interactions between parents and offspring, between mates or between territorial neighbors. These cues or other features of vocalizations with no apparent social role can also be used by researchers to identify individuals or estimate the gender, age, size or other features of the vocalizing individual. In order to establish the reliability of the vocal cue the researcher must first have access to a pool of individuals of known identity, or gender, size, etc. Simple statistical measures such as the within and between measures of variance from an ANOVA can provide a quantitative measure of the potential utility of a vocalization as an identifier. Sorting of individuals can often be accomplished with a discriminant function analysis using relatively few features (three to five may be all that are needed), but more often a simple neural network classifier can achieve comparable classification results without preselecting acoustic features for sampling. Field application of a trained classifier can greatly aid research requiring rapid identification of individuals when visual identification is difficult or impossible.
Impulse response characterization of composite materials and structures for design and manufacturing
Authors: Gibson Ronald F.
Published: July 2002

Impulse response testing may be used for fast and efficient characterization of both the elastic and viscoelastic properties as well as the structural integrity of composite materials and structures. Impulsive excitation is used to induce vibrations in the structure and modal frequencies and damping factors are extracted from the response using frequency domain and/or time domain techniques. The use of measured modal frequencies in the solution to the inverse problem for composite beams or plates yields the elastic constants for the composite. A variation on this method yields the spatial distribution of fibers in the composite. For certain configurations, the damping has been found to be a good indicator of interlaminar fracture toughness of a composite. Adhesively bonded composite structures having various flaws and defects have also been tested using this method, and both frequencies and damping factors have been found to vary from those of the ‘‘good’’ structures. PC-based virtual instrumentation software has been developed for data acquisition and analysis, and the method has also been used to test full scale composite automotive vehicle components as well as small laboratory samples. The long range goal of the research is the development of rapid, inexpensive screening tests for composite components.