bluuebunny/crossref_metadata_2025 huggingface dataset:
Low-frequency surface loss values obtained using the global attenuation model
Authors: Tattersall J. M. , Browning D. G. , Laplante R. F.
Published: October 2005

A series of propagation loss measurements over a single surface reflected path is analyzed using the pH-dependent global attenuation model. Values of surface loss for the frequency range 10–2000 Hz were obtained at low sea state conditions. The results for incident angles between 10° and 24° were found to be very small and in general agreement with the work of Adlington [J. Acoust. Soc. Am. 35, 1834–1835 (1963)]. A comparison is made to presently used surface loss models. [Work supported by NUSC.]
Collective oscillations in a bubble cloud
Authors: Yoon S. W. , Park K. J. , Crum L. A. , Lu N. Q. , Prosperetti A.
Published: October 2005

The literature contains substantial evidence that oceanic ambient noise is wind dependent over a broad frequency range [G. Wenz, J. Acoust. Soc. Am. 34, 1936 (1962)]. The nature of the source of low-frequency acoustic emissions is still unknown, although a correlation with breaking waves points toward the possibility, suggested by one of the authors [A. Prospererti, J. Acoust. Soc. Am. 84, 1042 (1988)], that the collective oscillations of bubble clouds may be involved. Studies, both experimental and theoretical, are reported on for the noise generated by a column of bubbles that is self excited into oscillation. By varying parameters such as column height, void fraction, size of bubbles, etc., the applicability of a theory that presumes the bubbles are undergoing collective oscillations can be critically challenged. The theory survives the test in all respects. This will lead to future studies on the more general problem of oceanic ambient noise. [Work supported by ONR and KOSEF (SWY).]
Observation of high-frequency ambient noise generated by capillary waves
Authors: Kolaini Ali , Roy Ronald A. , Crum Lawrence A.
Published: October 2005

In the absence of breaking gravity waves, capillary waves may contribute to the generation of ambient noise in the ocean. Surface profiles of capillary water waves, with surface tension as a restoring force, are picked downward in the troughs and relatively flat at the crests. At a limiting amplitude (given by H/λ≈0.73, where H and λ are the wave height and wavelength, respectively) the free surface in the trough folds onto itself, encapsulating an air bubble. By blowing air over a water-filled, Plexiglas tank, 6bubble-producing capillary waves can be generated in the laboratory. Underwater acoustic emissions from these bubbles were monitored and a visual record of their formation was established via a high-speed videotape. The initial findings of an experimental study of generation, size distribution, and acoustic emissions of bubbles produced by capillary water waves are presented. [Work supported by ONR.]
Acoustic.wave propagation in quasiperiodic, incommensurate, and random systems
Authors: Lu Jian Ping , Birman Joseph L
Published: October 2005

Acoustic-wave propagation in one-dimensional systems with quasiperiodic, incommensurate, and random modulation is studied [J.P. Lu and J.L. Bitman, Phys. Rev. B 38, 8067 (1988)]. In the short-wavelength limit it was found that if the initial pulse is narrow (with a spatial extension of a few lattice spacings), the pulse is localized in a quasiperiodic system, as in the case of a random system. This indicates that at short length scale a quasiperiodic system is similar to a random system. On the other hand, if the initial injected wave has a wavelength much larger than the lattice spacing, it is found that there is resonance for quasiperiodic and incommensurate systems when the wave vector satisfies the Bragg conditions. In this case the propagation appears to be diffusive rather than propagative; namely, the total energy of the initial wave does not propagate along the chain as it does otherwise, but is homogeneously distributed over the region of space where the wave front passed. The problem is solved analytically in the long-wavelength limit in terms of two-mode-coupling theory and the Fourier spectrum of the quasiperiodic systems. Analytical results are in full agreement with numerical simulations.
Mapping by means of nonspecular reflections
Authors: Davis Bryan R. , Hazony Dov , Mansour Joseph M.
Published: October 2005

Nonspecular reflections radiate equally in all directions according to surface and not the effective aperture. Hence inclined planes or grain boundaries would make a stronger contribution to the reflected signal. A scanning ultrasonic method is demonstrated taking advantage of this effect. A single transducer is used in the scanning in conjunction with a signal processing method to cancel the specular reflections. Experimental results are given showing significantly improved resolution. [Work supported by NIH.]
Imaging of cancellous structure of bone
Authors: Chandra K. , Thompson C.
Published: October 2005

Noninvasive quantitative measurements of density and structural changes in bone are vital to the identification and monitoring of osteoporotic conditions. Recent experimental studies have indicated the potential of ultrasonic techniques in measuring the mineral content of both cortical and cancellous regions of bone. Ultrasonic attenuation in cancellous bone is attributed primarily to scattering from the inhomogeneous trabecular structure, whereas absorptive effects are predominant in the more compact cortical bone and tissue. In this study an analysis of these relative effects with respect to the porosity and the constituents of the two regions will be performed. The development of a data-processing technique to determine the structural organization of the trabeculas will be discussed. Simulation studies will be performed to demonstrate the utility of this work in medical analysis.
Pseudo “geminates” in French
Authors: Del Negro A. S. , Marchal A.
Published: October 2005

Geminates are usually described as sequences of two identical articulations. They can be found in the same word and have, for a number of languages, a phonological status. They can also result from the concatenation of two homorganic consonants at word boundaries. This latter case has been explored for French stops to an acoustic and articulatory study. The important question, then, is to know whether geminated segments differ from long consonants. Ten speakers read ten times (five normal and five fast speech rate) 36 natural sentences of the following form: S1 S2 S3 (Co)V11≠ XV21(CF), where V1 = a; V2 = i,a,u; X = t,d,k,g,tt,dd,kk,gg,td,dt,kg,gk. Electropalatographic and airflow data were synchronously recorded from three speakers. Main results for stop geminates compared with corresponding single consonants are the following: (1) A “geminate” is not produced with greater linguo-palatal contact; (2) there is no significant duration difference; (3) for voiced consonants, the voicing is maintained throughout the closure phase; (4) there is no indication of a time varying force of articulation; and (5) there is no trace of any rearticulation process. A further perceptual study is needed to assess the respective roles of context and other acoustic cues in distinguishing single consonants from “geminates.”
The time course of labial gestures for sibilant articulations
Authors: Faber Alice
Published: October 2005

Simultaneous investigation of lip position and linguo-palatal contact patterns for sibilants reveals that [∫] differs from [s] not only in its more posterior constriction, but also in increased lip protusion; this lip position contrast is neutralized for sibilants flanked by rounded vowels [A. Faber, J. Acoust. Soc. Am. Suppl. 1 86, S113 (1989)]. That conclusion is based on palatographic and movement data from one Italian and one German speaker. The current study examines displacement and velocity curves for the upper lip for these and other speakers. Preliminary analysis indicates that, unlike /isi/ and /asa/, /usu/ has upper lip velocity peak coincident frication onset; this peak is smaller than that for [∫] in any vocalic context. These result, combined with the earlier finding of a linguo-palatal constriction for /usu/ anterior to that for /isi/ or /asa/, suggest that the articulatory target for /s/ varies according to context. The lack of contrast between /usu/ and /u∫u/in absolute lip displacement should not, therefore, be treated as a passive consequence of the lip position required for the flanking /u/'s, but rather as an active response to the articulatory demands imposed by that context. [Work supported by NIH Grant NS-00016.]
Protective laryngeal closure during swallowing
Authors: Hamlet Sandra L. , Carr Richard
Published: October 2005

This investigation was part of a general research effort to develop noninvasive methods for examining swallowing, which may serve as a supplement or alternative to conventional radiological techniques. The temporal onset of laryngeal closure during swallowing was monitored simultaneously with real-time ultrasonic scanning and electroglottography. Application of both techniques is complicated by extensive laryngeal excursions during deglutition. Transverse ultrasonic scans, although capable of showing anatomically clear vocal fold abduction and adduction activity, are especially sensitive to transducer position. In young adults, a sagittal placement of a linear array transducer yielded distinctive and consistent echo evidence of laryngeal closure, with temporal correspondence to an electroglottic signal feature indicative of the onset of sustained laryngeal closure in swallowing. The applications and limitations of these techniques for swallowing study are reviewed. [Work supported by NIH, CA 43838.]
Acoustic effects of smiling on the voice
Authors: Rekart Deborah M.
Published: October 2005

The utterance “How are you?” was produced by ten female speakers of American English in two conditions: smiling and not smiling. Spectrographic analysis revealed that smiling had no observable effect on the first two formant frequencies of the last stressed vowel [u]. However, cross sections of the vowel revealed a strong peak of intensity around 2500 Hz, which was identified as “singer's formant.” It is suggested that this formant is a result of laryngeal constriction in the aryepiglottic sphincter muscle above the vocal folds. A perception experiment showed that ten female listeners could distinguish significantly between “smiling” and “unsmiling” stimuli, and that they were equally confident about both types of judgments.
Computerized extraction of the tongue surface from sequences of ultrasound images
Authors: Unser Michael , Stone Maureen
Published: October 2005

An image-processing system has been developed for a Macintosh II personal computer. It is designed to process individual sagittal tongue sections that are digitized in real time and stored in standard TIFF format. The successive processing steps are (a) a prefilter (smoothing and vertical differentiation) for noise reduction and enhancement of the tissue-air interface in the surface region of the tongue, (b) a resampling of the sector of interest in polar coordinates, and (c) an extraction of border points by searching for an optimal radial path along the angular dimension. This latter task is performed very efficiently using dynamic programming, which has the following advantages. First, the procedure is very robust due to the use of a global criterion to guide the detection. Second, the allowable transitions. Finally, the method allows an optional specification of some ultrasound data will be presented.
Lip rounding and formant frequencies of the Nantong vowel system
Authors: Ao Benjamin
Published: October 2005

Nantong, a Chinese dialect spoken in the northern Yangtze Delta, has six high vowels: [i], [y], [Ɯ], [u], and two others that are like [i] and [y] produced with strong laminal frication (represented as [ȝ] and [ȝw], respectively). This paper examines the lip position and formant frequencies of these and five other vowels in order to characterize the Nantong vowel space. Three native speakers (two males and one female) were videotaped, producing each of the 11 vowels preceded by each of the phonotactically possible consonants. Measurements of lip position similar to those used in Linker [“A cross-linguistic study of lip position in vowels,” UCLA Working Papers in Phoneties 51, 1–35 (1982)] were taken from the recorded video images. Preliminary results show that the three pairs of the nonback high and midvowels [i/y], [ȝ/ȝw], and [e/ə] have similar F2 frequencies, and therefore cannot be represented with F1 and F2. They also show that the first vowel in each pair has a higher F3 than the second one. An improved representation of the vowel space is thus obtained by plotting F1 against F2′, as weighted average of F2 and F3 calculated under the same principle as discussed in Bladon and Fant [“A two-formant model and the cardinal vowels,” R. Inst. Tech., Speech Trans. Lab., Stockholm, Q. Prog. Stat. Rep. 1 (1978)]. Finally, it is demonstrated that a fairly good correlation exists between lip rounding and F3 lowering with most of the vowels investigated.
Nonlinearity and phonetic segmentation
Authors: Marchal A. , Nguyen-Trong N.
Published: October 2005

ESPRIT II basic research action “ACCOR” aims at investigating the articulatory-acoustic correlations in coarticulatory processes in seven European languages (English, French, German, Italian, Irish, Spanish, and Swedish). In order to allow for cross-language comparisons, it is particularly important that partners in the project adopt a common methodology, i.e., standardized investigation tools and normalized measurement procedures at specified locations in the speech signals. The physiologic and acoustic database first needs to be segmented and labeled according to principles that do not preclude any theorical intrepretation. The usual phonetic discretization at segment boundaries that implicitly considers coarticulation as a phonological feature spreading process is rejected. On the contrary, a nonlinear annotation of the articulatory and acoustic events has been adopted, based on the evidence provided by the different channels of information: acoustic sound wave, airflow traces, linguo-palatal contact patterns, jaw and lips movement, etc. From a theoretical point of view, this approach has proven very productive and has given for the data a clear picture of coproduction processes, of the timing relationships among different submotor system activities, and of the dynamic properties of the articulatory gestures. It furthermore provides a sound basis for distinguishing between universal regularities and language-specific constraints. This nonlinear procedure enables a unified interpretation of contradicting results obtained from different scholarly oriented segmentation operations.
Electromagnetic articulography as a tool in the study of lingual coarticulation
Authors: Hoole Philip , Gfoerer Stefan
Published: October 2005

Two recent papers [Schönle et al., Biomedizinische Technik 34, 126–130 (1989) and Shao et al., J. Acoust. Soc. Am. Suppl. 1 86, S115 (1989)] have evaluated a commercially available electromagnetic system for articulatory measurements, the articulograph AG-100. The present investigation includes some complementary methodological studies followed by an analysis of vowel-to-vowel coarticulation in German speakers. Within the first area, discussion focuses on the problems encountered and the solutions chosen in adapting the system for large-scale data collection, relevant topics including sample rates, noise, extension of the standard calibration procedures, detection of corrupted data by means of appropriate control tasks, and synchronization with audio recordings. Preliminary work in the second area suggested that the spatial magnitude of vocalic carryover effects in VCV sequences exceeded that of anticipatory effects at the midpoint of the intervening consonants. This will be reviewed in the light of two recent recordings (totaling some 1500 logatomes of the form /bV1CV2/) using three lingual transducers, and one each on upper and lower incisors. Tongue-jaw interactions, as well as the problem of defining analysis points in lingual trajectories, will be discussed. [Work supported by ESPRIT/BRA.]
A simple model of consonant-vowel phasing
Authors: Hochberg Judith G.
Published: October 2005

A consistent phasing relationship was found between movements of the lower lip and the tongue body in the nonsense words [′pipƜpip], [pipƜ′pip], [′bibƜbib], and [bibƜ′bib]. Data came from two native English speakers who were tape recorded while an x-ray microbeam tracked their articulatory movements. In an alternative model of phasing [C. P. Browman and L. Goldstein, Haskins Labs. Stat. Rep. on Speech Res., SR-92, 1–30], vocalic (V) gestures are seen as sequentially covering the entire duration of a continuous utterance (i.e., each vowel's offset coincides with the next V's onset), and consonantal (C) gestures are phased with respect to this vocalic background. In the model proposed here, the sequential view of gestures is extended to consonants, and C and V are phased with respect to each other. Specifically, each C gesture begins when the immediately previous V gesture reaches its articulatory target. Likewise, each V gesture begins at the articulatory target of the ongoing C gesture. [Work supported by DOE Contract W-7405-ENG-36.]
Labial position and acoustics of Korean and English high vowels
Authors: Jun Sun-Ah
Published: October 2005

This paper examines and contrasts the labial configuration and formant frequencies of Korean and English high vowels. Korean has three high vowels, /i, i, u/, and English has four,/i, ɪ, ᴜ, u/. The lip gestures and formant frequencies were compared within each language and across language to determine whether the idea of maximal dispersion [Liljencrants and Lindblom, 1972] can account for the formant frequencies and also be extended to account for the labial configurations. Three male speakers of each language produced each vowel in four different contexts with five repetitions. The production of each word was videotaped and the sound wave simultaneously recorded. The lip configurations were assessed using measurements similar to those in Linker [UCLA Working Papers in Phonetics 56 (1982)]. Formant frequencies were measured using an LPC formant tracker. Preliminary results suggest that Korean high vowels can be grouped into two categories, /i, i/ vs /u/, on the basis of measurements of lip position. The English vowels similarly can be grouped into three categories, /i, ɪ/ vs /ᴜ/ vs /u/. For the vowel /u/, Korean and English used different degrees of lip protrusion and, for the vowel /i/, they differed in the relationship between the horizontal width and the vertical opening. The acoustic spaces of Korean and English high vowels both support the dispersion theory in covering the same amount of the vowel space, although Korean high vowels all had lower F2 values.
Variability of motor strategies
Authors: Gentil Michèle
Published: October 2005

The activity patterns of the mandibular and labial muscle systems, respectively, were investigated for the purpose of determining whether the functions of the jaw and lips are based on a set of universal neuromotor rules. In the first experiment, intramuscular wire electrodes were placed into the eight muscles of the jaw. The activity of these muscles was recorded along with the displacement of the jaw in two-dimensional space, from three American subjects, during the production of speech at different rates. In the second experiment, intramuscular wire electrodes were placed into seven perioral muscles. EMG activity was recorded along with two-dimensional upper and lower lip movements from three French subjects during labial closure associated with speech production. Results indicated that different individuals use individual motor strategies for the production of the jaw and lip movements, and that the same motor objective can be accomplished by the nervous system in many different ways.
The influence of orthographic information on the identification of an auditory speech event
Authors: Layer Jody K. , Pasture Richard E. , Rettberg Ellen
Published: October 2005

It has been shown that the identification of an auditory or visual speech event can be influenced by information from the other modality when the information is perceived to arise from the same event. Employing a selective attention task, Logan et al. (1990) demonstrated an influence of an auditory speech event on the identification of orthographic characters over a range of stimulus onset differences. The current research investigates the influence of orthographic information on the identification of the initial phoneme of an auditory speech event. The stimuli were nonword CVC syllables. The stimuli were edited natural speech and orthographic representations of these stimuli plus a set that was neutral with respect to the auditory set. A range of stimulus onset differences was employed. The results show that when the auditory and visual information agree, there is faster responding for the identification of the initial auditory phoneme. When the information is discrepent, responding is slowed. These results do not support a qualitative change in perception with differing information in the two modalities. Implications for the nature of cross-modal integration and speech event processing will be discussed.
Exploring the basis of the “McGurk effect”: Can perceivers combine information from a female face and a male voice?
Authors: Green Kerry P. , Stevens Erica B. , Kuhl Patricia K. , Meltzoff Andrew M.
Published: October 2005

In the “McGurk” effect, observers typically report the illusory syllable /da/ when they hear the auditory syllable /ba/ presented in synchrony with a video display of a talker saying /ga/. In such experiments, there is usually congruence between the two modalities in that the same talker produces both the auditory and the visual signals. In the experiments reported here, the effect of reducing the congruence between the two modalities on the magnitude of the McGurk effect was examined. This was accomplished by dubbing a male talker's voice onto a video tape containing a female talker's face, and a female talker's voice onto a video tape containing a male talker's voice. These “cross-dubbed” video tapes were compared to normal video tapes in which the male talker's voice was dubbed onto a male talker's face, and the female talker's voice was dubbed onto a female talker's face. The results show that even though there was clear incompatibility in the talker characteristics between the auditory and visual signals for the cross-dubbed stimuli, there was little difference in the magnitude of the effect compared to the normal stimuli. These results indicate that the mechanism for integrating speech information from the two modalities is not sensitive to certain incompatibilities, even when they are perceptually apparent. [Work supported by NIH.]
Cross-modal semantic priming of neighbors of multisyllabic words
Authors: Luce Paul A. , Cluff Michael S.
Published: October 2005

The present experiment was designed to test the principle of delayed commitment in spoken word recognition by using a cross-modal priming paradigm. Subjects were asked to made a lexical decision on visually presented targets that were preceded by auditory primes. These auditory primes consisted of spondees (words containing two individual lexical items) that had second syllables with at least two meanings. For example, the second syllable of “baseball” could refer to either a round object for throwing or to a formal dance. Targets were words that were either related to the alternate meaning of the prime's second syllable or were unrelated. For example, after hearing “logjam,” subjects were presented with either “JELLY,” which is related to an alternate meaning of “jam,” or “BOMB,” which is unrelated to either meaning of “jam.” Evidence of priming in the related condition suggests that multiple candidates for recognition remain activated until well after the word's isolation point, contrary to the predictions of cohort theory. However, consistent with the neighborhood activation model, these results demonstrate that word recognition operates by a principle of delayed commitment.
Similarity neighborhoods of spoken two syllable words: Retroactive effects on multiple activation
Authors: Cluff Michael S. , Luce Paul A.
Published: October 2005

This research examined the recognition of two-syllable spoken words and the means by which the auditory word recognition system deals with ambiguous stimulus information. The perceptual identification of two-syllable words comprised of two monosyllabic words (spondees) was examined. Individual syllables within a spundee were characterized as either “easy” or “hard” depending on the neighborhood characteristics of the syllable. An “easy” syllable was defined as a high-frequency word in a sparse neighborhood of low-frequency words, whereas a “hard” syllable was a low-frequency word in a high-density, high-frequency neighborhood. Neighborhood structure was found to have a strong effect on identification. In particular, identification performance for spondees with a hard—easy syllable pattern was higher than for spondees with an easy-hard syllable pattern, indicating a primarily retroactive pattern of influence in spoken word recognition. These results strongly suggest that spoken word recognition involves multiple activation and delayed commitment, thus ensuring accurate and efficient recognition.
Hemispheric differences in spoken word recognition
Authors: Auer Edward T. , Luce A.
Published: October 2005

Previous research on visual word recognition has demonstrated differences in the manner that the left and right hemispheres process lexically ambiguous words [Burgess and Simpson, Brain Language 33, 86–103 (1988)]. The present study evaluated these findings for spoken word recognition. Lexically ambiguous primes (e.g., BANK) were presented binaurally. A target word was then presented monaurally to the left or right ear for a speeded lexical decision response (i.e., WORD-NON-WORD). Target words were either (1) related to the dominant meaning of the ambiguous prime (BANK-MONEY), (2) related to the subordinate meaning of the prime (BANK-RIVER), or (3) unrelated to the prime. Priming of dominant meanings produced more facilitation than priming of subordinate meanings regardless of ear of presentation. In addition, a right-ear advantage was observed for words but not for non-words. Implications of these results for models of spoken word recognition will be discussed.
An inexpensive wide-bandwidth hydrophone for lithotripsy research
Authors: Everbach E. Carr
Published: October 2005

Probing the acoustic field of extracorporeal lithotripters places severe demands upon conventional hydrophones. “Needle” hydrophones, while better able than “membrane” hydrophones to withstand the cavitation-related damage inherent in lithotripter measurements, nevertheless lack their superior high-frequency response. Even the most popular of membrane hydrophones, however, do not have sufficient sensitivity at high frequencies to resolve the rapid risetimes (1–10 ns) of waveforms that may occur at a lithotripter focus. To overcome these limitations, a membrane-type hydrophone has been developed that costs hundreds (not thousands) of dollars and has disposable active elements that can be replaced easily when damaged. These elements, of 9-μm-thick PVDF film, incorporate an electrode pattern that assures identical sensitivity from one element to the next, obviating the need for recalibration after replacement of the element. Furthermore, on-board conditioning electronics increase the effective bandwidth of the hydrophone to almost 100 MHz (five times that of Marconi membrane hydrophones) and provide clipping of the undesirable electromagnetically induced transients of spark-discharge lithotripters. [Work supported by the F. V. Hunt Postdoctoral Fellowship of the Acoustical Society of America and the National Institutes of Health through U.S.P.H.S. Grant No. DK39796.]
An acoustic intensity probe for underwater measurements
Authors: Segota Jeff , Hughes W. Jack
Published: October 2005

An intensity probe was designed and built for underwater use. Two sensors were built from 550-μm-thick voided PVDF and mounted on the opposite sides of a 12-in.-thick neoprene rubber spacer to provide a known separation distance. A FET-like preamplifier was mounted as close as possible to each of the hydrophones to minimize the coupling loss due to the low capacitance of the small PVDF pieces. The unit was then placed into a shielded plastic tube filled with castor oil and sealed for waterproofing. Over a frequency test range of 1–20 kHz, the sensor channels free-field voltage sensitivities were reasonably flat at about − 210 dB re: 1V/μPa and their patterns were omnidirectional. The probe performance was evaluated by amplitude and phase calibration, diffraction testing, and active intensity measurements of a bandlimited noise source using the FFT method [Fahy, Sound Intensity (Elsevier, New York, 1989), pp. 127–132].
High-frequency air-coupled transducers
Authors: Bao Xiaoqi , Varadan Vasundara V. , Varadan Vijay K.
Published: October 2005

High-frequency air-coupled ultrasonic transducers are used in industrial applications for detecting or ranging with high resolution. The improvement of the coupling between PZT and air is of importance for the transducer performance. Unfortunately, it is difficult to find a material with proper acoustical impedance and small attenuation at high frequency for matching layers. Theoretical analysis and experimental investigation showed that a layer made of a material with an impedance close to that of water is able to improve this matching significantly. Three air-coupled transducers at frequency ranges of 0.5 to 2.0 MHz were fabricated. Reasonable sensitivities and bandwidth were obtained. The variation of performances of the transducers with the thickness of the layer were investigated theoretically and experimentally.
Digital-to-analog conversion of acoustic signals
Authors: Morgan M. Scott , Bolen Lee
Published: October 2005

This paper describes the theory, construction, and operation of a transducer that is capable of transmitting an analog acoustic signal when driven by a digital input signal. The digital signal drives a capacitive dielectric transducer whose active surface area is proportional to the magnitude of the digital signal. The output of the transducer contains the original analog signal in addition to higher frequency Fourier components that result from the sampling process. The unwanted additional signal is attenuated when the transducer output is fed into an acoustic low-pass filter whose response is determined by using electrical circuit analysis techniques. Results indicate that this system is useful for signals that have an upper frequency limit that does not exceed 8 kHz.
Heterogeneity of ambient noise distributions of natural origin
Authors: Silvati Laura , Fidell Sanford , Harrison Robin
Published: October 2005

Although much less is known about ambient noise distributions in park and wilderness areas than in populated areas, ambient noise levels of natural origin are often believed to be uniformly low in absolute level and spatially homogeneous. Initial field measurements made for purposes related to Public Law 100-91 reveal considerable spatial and temporal heterogeneity of ambient noise environments of natural origin. Means and variances of one-third octave band measurements of acoustic energy of natural ambient levels made at a number of remote sites are compared with one another and with urban spectral distributions.
Relative masking effectiveness of self-noise and ambient noise distributions in outdoor recreational settings
Authors: Fidell Sanford , Silvati Laura , Pearsons Karl , Harrison Robin
Published: October 2005

The audibility of man-made noise intrusions in park and wilderness environments is determined not only by masking of natural origin, but also by the self-noise of outdoor recreationists. The relative influences of self-noise and ambient noise on the audibility of aircraft noise, a matter of central concern for aircraft overflight management for purposes of Public Law 100-91, thus vary with the activity and location of outdoor recreationists. Comparisons of spectral distributions of acoustic energy from fixed and at-ear microphone locations document large differences between estimates of masking based on place-oriented rather than visitor-oriented acoustic measurements in outdoor recreational settings.
LSVOCN: A pulse-propagation model for a linear, space-variant ocean
Authors: Ziomek Lawrence J.
Published: October 2005

A full-wave, pulse-propagation model for three-dimensional wave propagation in a Pekeris waveguide based on linear systems theory is presented. The randomly rough ocean surface and bottom are accounted for via coherent (average) reflection coefficients. Attenuation due to absorption in all three fluid media is included. Transmit and receive planar arrays with beam steering can be simulated and, as a result, vertical arrays and a single, omnidirectional point source are automatically included. A built-in signal generator can simulate arbitrary amplitude and angle-modulated carriers. Outputs from this model include plots of the magnitude and phase of the ocean surface and bottom reflection coefficients, the complex acoustic field across the receive array. Because of its highly modular structure, the model can also be used to generate pulse-propagation solutions using any time-harmonic solution such as normal mode theory or the parabolic equation method. Preliminary computer simulation results are presented. [Work supported by ONR, Code 11250A, and the Naval Postgraduate school.]
Acoustic tomographic measurement of oceanic advective heat flux
Authors: Barock R. Timothy , Chiu Ching-Sang , Miller James H. , Clancy R. Michael , Lynch James F.
Published: October 2005

Acoustic tomography is assessed as a means of measuring the seasonal oceanic advective heat transport into the Barents Sea from the Norwegian Sea. The assessment is made by using seasonal climatological data to simulate the regional temperature and current fields in the computer. Inversion of the synthetic acoustic travel time data gives the reconstructed ocean fields from which the advective heat flux is estimated. Resolution and variance analyses of several array geometries are performed in an effort to determine an optimal configuration for a given number of moored transceivers. Furthermore, the acoustic technique is compared to conventional methods.
Experimental studies of sound propagation using a scaled marine geoacoustic model
Authors: Hundley Allen , Glegg Stewart A. L.
Published: October 2005

This paper will describe a sound propagation experiment with a scaled shallow-water geoacoustic model. This two-layer seafloor model has dimensions 1.2×2.5 m and is composed of an epoxy layer 5.8-cm thick overlying a concrete basement. With a water depth of 15 cm, this model represents a shallow-water marine environment where the surficiai sediment possesses enough rigidity to transmit shear waves. This experiment concentrates upon the pressure magnitude as a function of depth in the water column using a fixed cw source with frequencies between 8 and 30 kHz. These pressure-depth shapes are compared with the effective depth theory of Chapman et al. [J. Acoust. Soc. Am. 85, 648–653 (1989)]. [Work supported by ONR.]
Objective and subjective measures of noise quality in buildings
Authors: Kingsbury Howard F.
Published: October 2005

Many objective measures of the acceptability of sound in buildings have been proposed over the years, e.g., dbA, NC, PNC, NCB, RC. Most of these have been related to speech interference and general occupant acceptability, Few have dealt with the more nebulous topic of sound quality, although loudness and its converse, annoyance, have been attempts in this direction. Unanswered at this time are questions such as what indeed is “rumble,” or why does electronically generated masking noise, even when carefully controlled, frequently sound “artificial” or harsh? This paper will present a critique of the historical development of objective measures and their application to the built environment.
Air-conditioner noise and noise quality
Authors: Kuwano Sonoko , Namba Seiichiro , Kinoshita Kanjiro
Published: October 2005

Most people would agree that air conditioners should be as quiet as possible. However, it can be shown that air-conditioner noise can have a positive effect in that it can mask other, more unwanted, noises. It is, therefore, desirable that the noise produced by air conditioners should be as acceptable as possible. A series of experiments was conducted using simulated air-conditioner noise to investigate the loudness and sound qualitites of air-conditioner noise and to examine the appropriateness of applying ISO 532B to air-conditioner noise.
Analysis of an L-shaped plate structure subjected to acoustic excitation using mobility power flow (MPF)
Authors: Cuschieri J. M.
Published: October 2005

In previous work on the structural response analysis using a mobility power flow (MPF) approach, the type of excitation considered on the structure consisted of a direct type of excitation, independent of the response of the structure. No coupling existed between the excitation and the structural response, such that these can be treated independently. This is not the case with acoustic excitation because of the scattered pressure component, which makes the excitation dependent on the response of the structure. In this paper, the MPF approach for the analysis of the response of a structure is extended to deal with this couple problem. Following the same approach as in previous work, the technique is demonstrated by considering the case of an L-shaped plate structure subjected on one side to an incident airborne acoustic wave. The interaction between the structure and the acoustic fluid is represented by corrected structure mobility functions. Also, from the scattered pressure component, a value for the radiated acoustical power from the plate structure is computed. [Work supported by NASA Langley Research Center.
Proposed “Military Handbook” for dynamic data acquisition and analysis: An invitation to review
Authors: Himelblau Harry , Wise James H. , Piersol Allan G. , Grundvig Max R.
Published: October 2005

A draft “Military Handbook” has been prepared under the sponsorship of the Space Division, U.S. Air Force, and is presently being distributed throughout the U.S. for review by the aerospace community. This comprehensive document provides recommended guidelines for the acquisition and analysis of structural dynamics and aeroacoustic data, and is intended to reduce the errors and variability commonly found in flight, ground, and laboratory dynamic test measurements. In addition to the usual variety of measurement problems encountered in the definition of dynamic loads, the development of design and test criteria, and the analysis of failures, special emphasis is given to certain state-of-the-art topics, such as pyroshock data acquisition and nonstationary random data analysis. Those involved in the data process are invited to review and critique the draft handbook. The review period is intended to close by September 1990.
Measuring vibrational power flow through a rubber isolation mount
Authors: Kendig R. P.
Published: October 2005

This paper presents a method for measuring vibration power flow through rubber isolation mounts. The approach uses previously determined input and transfer inertances that characterize the mount and appropriately scaled cross-spectral functions from two axially oriented accelerometers. Theory and experimental results are presented. Results of calibration tests show that the magnitude and direction for vibrational power flow across an isolation mount can be determined. The technique is significant because it can be used to validate statistical energy analysis (SEA) predictions, to evaluate the effectiveness of vibration isolation systems, and to monitor vibrational sources or transmission paths in complex machinery.
Experimental evaluation of chain noise
Authors: Stone Wesley A. , Trethewey Martin W. , Wang K. W.
Published: October 2005

Chains are commonly used in automotive powertrains for their reliability and durability. However, chain drives can be noisy, and thus a fundamental understanding is needed. One of the fundamental sources of this noise is the impact of the chain roller on the sprocket teeth. To investigate the mechanism behind this impact, an experimental apparatus has been designed, constructed, and tested. The test stand is composed of a high-speed stepper motor (6000 rpm) driving a two-sprocket chain drive with a simple flywheel at the output. The signal from a strain gauge instrumented on one sprocket tooth is extracted by means of a slip ring. This instrumentation will be used to conduct a parametric study to examine the relationship between impact and various system parameters, such as chain tension and speed. [Work supported by General Motors Corporation.]
Interaction of bending wave vibrations and fluid flow in a thin layer
Authors: Akay Adnan , Xu Zhaoshun , VanAntwerp Mary , Ingard K. Uno
Published: October 2005

The behavior of fluid flow in a thin layer between a vibrating beam and a flat surface is investigated. It is shown that distinctly different flow patterns are generated in the layer by the bending waves with a corresponding damping of the beam vibrations. A simple analysis is presented to illustrate the damping effects of fluid motion in a thin layer in the presence of free edges. Corresponding experiments show the motion of the fluid in the layer. [Work supported by NSF and ONR.]
Natural vibration of cylindrical shell elastically closed by a circular plate with general boundary conditions
Authors: Cheng L. , Nicolas J.
Published: October 2005

This work considers the natural frequencies and mode shapes of a circular cylindrical shell elastically coupled to a vibrating plate at one end. Translation and rotation springs are introduced at the edges of the shell, the plate, and their interface. A variational approach is adopted by using the normal modes of a simply supported shell and the polynomial basis for the shell and plate, respectively. This model has the advantage of being very general for different combinations of springs, enabling one to simulate both the classical and complicated edge conditions encountered in practice. It can also be easily extended to vibroacoustic problems. Numerical results are presented related to the natural frequencies of the shell and the plate with various edge conditions. Wherever possible, the results obtained are compared with the existing values in the literature and very good agreement is shown to exist [S. Azimi, J. Sound Vib. 120(1), 19–35 (1988)]. Then, several results are given for the case in which the shell is rigidly connected to the plate, showing the coupling phenomena between two subsystems, comparison with the finite element method more significant. The numerical method used is based on a finite element method for structural vibrations and a boundary element method for radiation in air. The key parameters presented for this comparison are the quadratic velocity, the radiation factor, and the overall sound power.
Vibroacoustic modelization of planar semicomplex structures—A comparison between analytical and numerical approaches
Authors: Nicolas J. , Berry A. , Wynendaele H.
Published: October 2005

Among the various methods used to simulate the vibroacoustic behavior of structures, the “analytical” and the “numerical” approaches are probably the most powerful. Analytical methods are defined as methods using a discretization of the solution. Numerical methods are defined as methods using a discretization of the governing equations (in differential, integral, or variational form), and they are used for complex structures. Interesting and meaningful comparisons between these two approaches have been made possible because the analytical method has been generalized to the case of planar semicomplex structures. “Semicomplex” means that the plate has any type of boundary conditions, has added masses and stiffeners, and has any type of excitation forces or moment. This has been done by choosing an appropriate basis [Berry et al., J. Acoust. Soc. Am. Suppl. 1 85, S131 (1989)] of the modal expansion. These developments allow us to study structures that are no longer of the “academic type” (a plate simply supported with one single force in the middle), making the comparison with the finite element method more significant. The numerical method used is based on a finite element method for structural vibrations and a boudary element method for radiation in air. The key parameters presented for this comparison are the quadratic velocity, the radiation factor, and the overall sound power.
On the dynamic response of flexible structures coupled through viscous fluid layers
Authors: Tan Chin-An
Published: October 2005

The dynamic response of planar flexible structures that are coupled to each other through viscous fluid layer forces is considered. The fluid-structural interaction can occur over a partial or over the complete span of the structures. The linear vibration of the coupled system is analyzed in the frequency domain using the Green's function method. Interactions between the structural response and the fluid layer are described by the impedance function. The impedance function depends on the structural response, the frequency of the coupled system response, and the spatial location of the fluid layers. As an illustrative example for the proposed method, the vibration response of two stringlike structures (second-order problem) that are placed very close to each other and separated by a fluid layer is studied. The fluid is assumed to be incompressible, and the impedance function is given in a recent publication [C. A. Tan and C. D. Mote, Jr., ASME J. Tribology (to appear)]. The frequency response of this coupled system under different excitation forces is examined.
Computer simulation of a trumpet
Authors: Strong William J.
Published: October 2005

In an effort to generate realistic trumpet mouthpiece pressure waveforms, a player-trumpet model was created that consisted of the player's lungs, the player's airway, the player's upper lip, and the trumpet. The player's lungs were modeled as a constant pressure source. The player's airway (from lungs to lips) was modeled as a resistance of 20 acoustic ω (cgs). The player's lip was modeled as a swinging-sliding door having 1 deg of rotational freedom and one degree of translational freedom. The trumpet was modeled in terms of its pressure response to a volume-flow impulse. Equations were solved iteratively to give (1) lip opening as a dynamic function of the forces and torques acting on the lip, (2) volume flow as a function of lip opening and the pressure difference across the lips, and (3) mouthpiece pressure as a convolution of volume flow with trumpet impulse response. Waveforms were calculated and displayed for the lip-opening area, the volume flow through the lips, and the pressure in the mouthpiece. The lip-opening area and mouthpiece pressure waveforms were realistic when compared to experimental waveforms in the literature. However, there are still too few experimental data to constrain the model in terms of lip closure time and total air flow on sustained notes. Simulation data will be presented and compared with experimental data. [The work to be reported was carried out while the author was on leave at IRCAM in Paris. René Caussé supplied player and trumpet data and Duanne Dudley supplied trumpet impulse data.]