bluuebunny/crossref_metadata_2025 huggingface dataset:
Vowel recognition using an articulatory representation
Authors: Richard G. , Lin Q. , Zussa F. , Sinder D. , Che C. , Flanagan J.
Published: October 2005

An alternate approach to speech recognition based on an articulatory representation of speech is proposed. Unlike traditional methods based on Fourier or cepstrum representations, the articulatory description of speech provides a compact parametrization linked to physiological properties. The expected results are robust speaker-independent speech recognition. In fact, physiologically related parameters should be useful for handling variability across speakers. In this work, a three-parameter articulatory representation is applied to vowel recognition. These parameters (location and size of the main constriction in the vocal tract and the ratio of lip length to mouth aperture) are estimated using a codebook search strategy. Before the recognition process, a pattern database is built using a corpus of ten repetitions of nine different vowels. Vector quantization is then applied to this corpus to obtain several representative articulatory vectors, or centroids, for each vowel. In the recognition stage, articulatory parameters of the incoming speech segments are estimated and compared to the centroids of the pattern database to arrive at a recognition decision. Initial results indicate strong potential for articulatory-based speech recognition. [Research supported by ARPA-DAST 63-93-C-0064.]
Coproduction, accent, and the tense/lax vowel contrast
Authors: Fletcher Janet M. , Harrington Jonathan M.
Published: October 2005

The kinematics of accented versus unaccented syllables was analyzed in a corpus of Australian English. It was found that unaccented productions of the long vowel /a:/ in the word ‘‘barb’’ show evidence of articulatory truncation. In other words, opening jaw movements into the long vowel are cut short by the jaw-raising gesture for the final /b/. Unaccented vowels were best modeled as more ‘‘coarticulated’’ or coproduced versions of accented vowels in this corpus. As part of the same experiment, the kinematics of the vowel contrast /a/ vs /a:/ was also examined. Previous studies of Australian English vowels note the acoustic similarity of the vowels in words like ‘‘cut’’ versus ‘‘cart.’’ While treated phonologically as part of the set of tense/lax contrasts in Australian English, it is perhaps more accurately described as a vowel quantity as opposed to vowel quality contrast. Evidence of articulatory truncation or coproduction was also found in three speakers’ productions of the first (short) vowel in accented versions of the two words ‘‘bub’’ and ‘‘barb.’’ The short vowel was best modeled as a co-produced version of the long vowel. However, there was also evidence of alternative articulatory strategies implying some movement or gesture-specific dynamics in addition to intergestural articulatory timing strategies.
An analysis of Norwegian vowels: What determines the topography of a vowel space?
Authors: Ziolkowski Michael S. , Lowenstein Joanna H. , Landahl Karen L. , Viechnicki Peter D. , McDorman Richard E.
Published: October 2005

Paucity of information on the acoustic structure of Norwegian and interest in comparing similarities and differences with its well-described neighbor, Swedish, led to an investigation of Norwegian vowels. A commutation set of single-word utterances was presented to 12 native speakers (4 male, 6 female, 2 children), yielding a corpus of 505 tokens. Spectrographic analysis guided measurement of each vowel’s first five formant frequencies both at a single point in steady state (single FFT) and throughout (overlapping FFTs) to exploit the varying fundamental frequency through the steady state, which affords a more accurate reading of the formants. Results indicate a pattern of formant convergences and attenuations in the range of the first four formants, a robust finding which falls between the cracks when using a standard F1/F2 technique for laying out vowel spaces. That such patterns characterize different vowel categories and dimensions (front–back, rounded–unrounded) opens discussion to more general questions of what determines vowel location in acoustic space [e.g., Lindblom (1986)]. The hypothesis that two languages with isomerous vowel categories will yield unique acoustic topographies when their systems are structured on different primatives/‘‘features’’ is discussed.
Dynamic information for vowel identity is formant-based, while steady-state information is based on spectral shape
Authors: Cummins Fred
Published: October 2005

Recent vowel research has attempted to identify a canonical set of acoustic parameters which best supports vowel categorization. Other work has argued that the speaker-independent information specifying vowel identity is time-varying, rather than static. The present study examines the possibility that these two research issues are related in complex ways. Recurrent neural networks were trained to identify vowels based on one of two types of time series: either spectral-shape (PLP) representations or formant peak (F1, F2, and fundamental frequency) representations. Networks were trained using inputs that reproduced the dynamics of vowels excised from continuous speech. The trained networks were then tested with both static and time-varying vowel tokens. Those trained on formant information outperformed those trained on spectral shape information. However, when tested on stimuli lacking dynamic information, the formant-based networks suffered more from the absence of time-varying information than did the PLP-based networks. This suggests that time-varying and steady-state information for vowel identity may not share a single ‘‘best’’ representation. [Work supported by ONR.]
Spectral-envelope synthesis of vowels: Progress report
Authors: Miller James D. , Heidbreder Arnold F. , Lee Sungbok
Published: October 2005

Synthesizers based on vocal-tract models do not allow independent control of perceptually relevant characteristics of spectral envelopes. The goal is to develop a tool that will allow assessment of envelope characteristics in speech perception by both normally hearing and hearing-impaired listeners. Using LabVIEW (National Instruments, Inc.), a software synthesizer is being developed that is designed to allow systematic and independent control of these envelope characteristics: (1) the locations of up to five spectral peaks; (2) the locations of the minimums (valleys) between peaks; (3) the peak-to-valley depths in decibels; (4) the ratio of peak-to-valley bandwidths; and (5) the overall spectral shape imposed on the patterns of peaks and valleys. The resulting envelopes specify the component amplitudes of carriers consisting of sinusoids. The phases of the component sinusoids can also be individually specified. Additionally, so-called ‘‘autofunctions’’ adjust ‘‘nominal’’ values of the envelope variables in accordance with the pattern of peak locations in a manner designed to be consistent with natural speech. For example, a nominal peak-to-valley depth is increased or decreased based on the logarithmic separation between adjacent peaks. Synthetic vowels and the effects of manipulation of the variables will be demonstrated.
Parametric coating
Authors: Arabadzhi Vladimir V.
Published: October 2005

A control algorithm for the multilayer parametric coating is suggested. The frequency of layer parameter manipulations is much larger than the incident wave frequency and the total multilayer coating thickness is much less than the incident wavelength. This denotes the space-time locality of the damping system. The coating provides the boundary conditions of the acoustical blackbody at low frequencies for a surface of arbitrary form and wave dimensions. This case includes the incident waves absorption and the forward scattering without backward scattering. The algorithm does not require wave field measurements. It assigns the law of coating parameters to time changes only (instantaneously on the whole surface). Algorithm realization may be based on the electrorheological liquids which make fast transformations from the liquid state to the solid one and back due to the applied electric voltage at all usual temperatures. The results of numerical simulation are presented.
The local algorithms of autoresonant absorption of the energy of bending waves in elastic plates
Authors: Arabadzhi Vladimir V.
Published: October 2005

For the simplest model—an infinite elastic plate—three control algorithms (local in space and time) are studied by a normal point shift to achieve the maximum of absorbed power. They are: (a) the algorithm of half-return, (b) the algorithm of the random search for the maximum of the instantaneous absorbed power, (c) the continuous algorithm of the resonant absorption. These algorithms provide the exit to the trajectory of the resonant absorption during the time much less than the minimum time scale of the damped wave, i.e., knowing either its period, or its length. The considered algorithms differ in the necessary volume of the apriori information on the plate parameters and in the power of the ‘‘technological’’ high-frequency radiation caused by rapid manipulations with the boundary condition. The speed of response of sensors and final control elements is supposed to allow the formation of arbitrary kinematic characteristics of the boundary. The conditions for the effective operation of the algorithms in the case of plates with finite dimensions are formulated. The algorithms may be used to decrease the quality of mechanical systems made up of elastic plates.
Experimental results from four thermoacoustic cryocoolers
Authors: Hofler Thomas J. , Adeff Jay A.
Published: October 2005

The experimental results from a thermoacoustic cryocooler project will be reported. Four different versions of the cryocooler were constructed and the coldest temperature achieved was 180 K. While this temperature result fell short of our goals, a number of interesting discoveries were made. One engine performed very much worse than the linear theory predicted, the pitfalls associated with compact and efficient acoustic resonators were discovered, and lower SWR standing waves were found to enhance engine performance. [Work supported by NRL and ONR.]
A model of the temperature discontinuities found between the elements of thermoacoustic engines
Authors: Brewster James R. , Raspet Richard
Published: October 2005

In experimental investigations of thermoacoustic engines, the temperature difference required to drive these devices at high amplitude has been found to be markedly higher than that predicted by linear theory. This discrepancy is due in part to a significant difference in temperature that has been observed between stack sections and their adjoining heat exchangers. It will be shown that the existence of a step in the longitudinal temperature profile is a finite-amplitude effect, not encompassed by the linear theory, and is essential if heat is to be transferred between elements of the engine. Physical insights obtained from a simple model of the heat transfer process based on the assumption that the working fluid is inviscid and incompressible will be presented. This will be followed by consideration of how the existence of viscosity and fluctuations in the density of the working fluid affect this model. [Work supported by the Office of Naval Research.]
Comparative study of heat exchangers for thermoacoustic devices
Authors: Mozurkewich George , Murrell Steven R.
Published: October 2005

Among the critical elements of a thermoacoustic device are its internal heat exchangers. This work quantifies the behavior of actual heat exchangers insitu in an operating thermoacoustic refrigerator. Each heat exchanger consisted of a specified arrangement of metal in contact both with oscillating gas adjacent to a thermoacoustic stack and also with water bearing tubes. Measured quantities were the temperature Ts of the adjacent end of the stack, the temperature Tw of the water flowing through the tubes, the change of water temperature δT between tube inlet and outlet, and the water flow rate. The heat-transfer rate Q was determined from the latter two quantities. The overall heat-transfer conductance G, defined by G=Q/(Ts−Tw), is determined by three quantities: the gas-to-metal temperature drop, the fin efficiency, and the metal-to-water temperature drop. Raw experimental results will be presented for several gas-side heat-exchanger geometries, including copper screen, reticulated aluminum foam, and bundled copper tubes. Where possible, comparisons will be made to simple theoretical expectations.
Resonator coiling in thermoacoustic engines
Authors: Olson Jeffrey R. , Swift Gregory W.
Published: October 2005

Coiling the resonator of a thermoacoustic engine is one way to try to minimize the engine’s size. However, flow in bent pipes is known to alter the fluid flow pattern because of centrifugal forces. Theory and measurements will be presented on the energy dissipation caused by oscillating flow in curved pipes. Measurements have been taken using free oscillations of liquids in U-tubes, and using a thermoacoustic engine with straight and bent resonators. [Work supported by the TTI program of the US Department of Energy, and by the Tektronix Corporation.]
Turbulent losses in thermoacoustic resonators
Authors: Gardner D. L. , Olson J. R. , Swift G. W.
Published: October 2005

Minimizing losses resulting from turbulent flow in thermoacoustic resonators while preserving compactness is of concern. Iguchi etal. [Bull. JSME 25, 1398 (1982)], using an extension of the Blasius turbulent friction factor, determined a formulation by which turbulent losses in pipes with oscillating flows could be predicted. This formulation is applied in a preliminary effort to predict acoustic power dissipation. These predictions are compared with acoustic power flow measurements made using a thermo- acoustic engine having a straight pipe. Additional losses are expected if the resonator is not straight. Measurements using an engine having corkscrew or mitre-jointed resonators are compared to the work of Olson etal. (manuscript in progress). [Work supported by DOE.]
Thermodynamic properties of helium–xenon mixtures for thermoacoustic refrigerators
Authors: Hurly John J. , Boyes Steven J. , Schmidt James W.
Published: October 2005

The equation of state and the speed of sound have been measured for helium, xenon, and three helium–xenon mixtures in the temperature and pressure ranges of interest for designing thermoacoustic refrigerators. The results have been correlated with a virial equation of state and can be used to optimize the refrigerator designs. [Work supported by the Office of Naval Research.]
Radial wave refrigerator driven by a plane-wave prime mover
Authors: Arnott W. Patrick , Raspet Richard
Published: October 2005

Previous heat-driven thermoacoustic refrigerators have used a design that compromises the performance of both the prime mover sound source and the refrigerator. The prime mover and refrigerator were placed next to each other in the resonator, and neither could be placed at the optimal performance location; otherwise, the efficiency or output of the one placed well away from the optimal location would be low. A radial wave refrigerator in a wide cylindrical resonator driven by a plane-wave prime mover from a narrow resonator allows for a relatively compact design, and more importantly, for optimization of the performance of both elements. Results of numerical analysis for the radial wave refrigerator driven by a plane-wave prime mover will be presented. [Work supported by the Office of Naval Research.]
Optimization of thermoacoustic engine design variables for maximum performance
Authors: Minner Brian L. , Mongeau Luc , Braun James E.
Published: October 2005

Thermoacoustic engine prototype design typically proceeds based on an intuitive, trial and error approach. This study investigates the benefits of performing a systematic optimization of design parameters in a thermo- acoustic engine for given operational requirements. The design optimization seeks to minimize a cost function of performance using the simplex method. This method allows constraints to be readily implemented without need for gradient evaluations. Parameter space maps are generated for visualization of solution sensitivity. System analysis is performed with the assistance of DeltaE, a commercially available software tool which solves the 1-D lossy wave equation in resonator sections and Rott energy and wave equations in stack sections. The solution is therefore subject to the low-amplitude (linear) flow assumptions and conduction mode heat transfer assumptions in heat exchangers. The optimization and space mapping tools systematically write input decks, execute DeltaE, and evaluate results. Optimization of up to 13 geometric, fluid, and material properties has been explored, producing encouraging performance predictions. Application of this strategy to design modifications of documented prototypes and resulting benefits of systematic optimization will be illustrated. It is anticipated that the optimization scheme will be useful in enhancing performance of future thermoacoustic engine prototypes.
Statistical phase analysis—The phase behavior of complex structures
Authors: Lyon Richard H.
Published: October 2005

The magnitude and phase of a transfer function are often thought of as complementary or conjugate variables, and there may be special relationships between them. Statistical energy analysis (SEA) is a procedure for estimating the magnitude of a transfer function, not only of a single, directly excited structure, but of several structures joined together. In some situations, as in problems of machinery diagnostics and signal transmission in drill piping, the phase of the transfer function is important in determining system performance. If the structure is complex, a statistical estimate of the phase may be the best one can hope for, and may also be adequate. For this reason, an investigation has been done on the statistical properties of the phase of complex structures, first of directly excited structures, and, recently, of joined structures to see if some of the relatively simple results of SEA are reflected in statistical phase analysis (SPA). This paper will review the approach taken to understanding the phase in complex structures and some of the results thus far.
Diffuse energy propagation on heterogeneous plates: Structural acoustics radiative transfer
Authors: Turner Joseph A. , Weaver Richard L.
Published: October 2005

The propagation of diffuse energy on an unwetted heterogeneous plate is examined using a diagrammatic approach. The heterogeneities are assumed to lightly couple the membrane and flexural waves. The energy propagation is formulated in terms of the Bethe–Salpeter equation. This equation is further reduced to a radiative transfer equation in limit that the attenuations per wave number are small, i.e., when the heterogeneities are weak. This approach allows the diffuse energy propagation to be calculated as a function of space, time, and propagation direction. Solutions of the derived radiative transfer equation are presented for the simple case of attached heterogeneities in the form of delta-correlated springs excited by an extensional point source launched in a single direction. The results show the evolution and mode conversion of the extensional, shear, and flexural energy densities across the plate as a function of time. A similar approach is expected to apply to the more complicated case of submerged complex structures. [Work supported by ONR.]
Scattering from complex elastic structures
Authors: Photiadis Douglas M.
Published: October 2005

The scattering cross section of elastic structures is modified in a nontrivial fashion by the presence of effectively random internal structure. The locus of the highlights in frequency-angle space can often be modeled reasonably by considering the behavior of the associated average structure, but the influence of the internal structure on the levels of the scattering cross section cannot be determined in this way. In terms of the development of effective scattering models, the mean Green’s function does not contain enough information in this context and higher-order averages are required, at a minimum the mean intensity 〈GG*〉. The perturbative computation of such quantities is relatively well understood for a medium which is uniform, but for the structures of most interest, those whose properties on average vary spatially, the problem is much more difficult. The theoretical approach to the solution in this case will be discussed, and the approximate results obtained will be compared with the results from direct Monte Carlo simulations.
Waves in random media: Coherent and fluctuating parts, energy distribution
Authors: Rybak Samuil A.
Published: October 2005

Waves in media with fluctuating parameters are described with the help of a Green’s function method. For the average field, the integral Dyson equation is formulated and its solution is obtained by means of the Bourret approximation. The average field (coherent part) decays exponentially with distance from the point source while the fluctuations grow. The Bethe–Salpeter equations are formulated for the average energy distribution. The ‘‘ladder’’ approximation then gives a system of transport integral equations which resemble heat transport equations. For the validity of the theory some threshold level of dissipation in the medium is necessary. The distribution of the fluctuations of the parameters is taken to be Gaussian. The solutions for energy distribution have an exponential decay with the index proportional to the root of the dissipation coefficient of the medium. In waveguides with fluctuating parameters the wave modes are coupled and both the coherent parts of these modes and the energy distributions are not independent. The energy fluxes become equal for traveling normal waves. Elastic plates with fluctuating parameters are examples of such waveguides for coupled longitudinal and flexural waves. Verification of the theory was made with the help of direct calculations for some simple models.
Ultrasonic band gaps in aggregates of sintered aluminum beads
Authors: Turner Joseph A. , Weaver Richard L.
Published: October 2005

An experimental examination of the transmission power spectrum of a block of sintered aluminum beads is discussed. Periodic structures such as these have complicated dispersion curves that contain stop bands and pass bands. Thus the power transmission spectrum for the agglomeration of sintered beads is strikingly different than that for a solid aluminum block. The positions of the observed band gaps are shown to agree with theoretical predictions. The width of the bands is directly related to the sintering level and the corresponding coupling between beads. Unlike previous one-dimensional work, the medium considered here is three dimensional. Also, the rare modes that may lie in the band gaps or those near the edges of the bands are expected to localize. Therefore, this sintered bead structure is a promising candidate for the discovery of localizing ultrasound. [Work supported by NSF.]
Diffuse wave energy transport in multicoupled, one-dimensional Anderson localizing systems
Authors: Weaver R. L. , Burkhardt John
Published: October 2005

The spatial and time domain evolution of energy density in a multicoupled, one-dimensional disordered system is investigated. Scaling theory predictions are presented for both localization lengths and rates of diffuse transport. Scaling arguments suggest that localization lengths equal πρDo, where ρ is the modal density per unit length and Do is the bare diffusivity. Additionally, the rate of diffuse energy transport over a distance L is found to scale as ρL. These predictions are compared with the behavior of a numerical model for an Anderson localizing system. The system modeled is a cylindrical membrane disordered by the introduction of a random foundation of springs. [Work supported by ONR.]
The relation between identification and discrimination of vowels by young normal-hearing and elderly hearing-impaired listeners
Authors: Coughlin Maureen P. , Kewley-Port Diane , Humes Larry E.
Published: October 2005

Four young normal-hearing (YNH) and four elderly hearing-impaired subjects (EHI) with moderate sloping sensori-neural hearing losses participated in vowel-identification and formant-discrimination tasks. To examine the relationship between vowel-identification and formant-discrimination abilities in conditions differing in audibility, signals were presented at two levels (70 and 95 dB SPL). Four mid-vowels (/I/, /e/, /ε/, and /æ/) were chosen as the target signals for both tasks. Identification performance for the YNH subjects was near ceiling performance. The EHI subjects averaged 80% for the 95 dB and 69% for the 70 dB SPL presentation level, although individual subject variability was high. Equivalent discrimination performance in the F1 region (ΔF threshold approximately 30 Hz) was observed for all four vowels, between groups and across levels. In the F2 region the EHI subjects’ thresholds were elevated compared to the YNH subjects at both levels, even when the formants appeared to be fully audible (at 95 dB SPL). Correlational analyses suggested that vowel identification was partially predicted by reduced ability to discriminate spectral differences in the F2 region (at higher frequencies) as well as the subjects’ hearing loss. [Work supported by NIH and NIA.]
Identification of natural and synthesized vowels produced by children and adults: Effects of fundamental frequency variation
Authors: Katz William F. , Assmann Peter F. , Jenouri Kathleen M.
Published: October 2005

Fundamental frequency (F0) and formant frequencies (F1–F4) were measured for vowels from /hVd/ words produced by 10 men, 10 women, and 30 children (ages 3, 5, 7). For all age groups, intrinsic F (IF0) differences were present, i.e., high (open) vowels had higher F0’s than low vowels. However, there was increased F0 variability for younger children. Theoretically, the vocal tract transfer function is less precisely defined in the vowel spectrum when F0 is high. Therefore, time-varying changes in F0 could help delineate the shape of the transfer function. Also, IF0 might help specify vowel identity. To determine the perceptual consequences of F0 variation, natural and synthesized versions of a subset of the vowels were presented to listeners for identification. Although the natural vowels were identified more accurately than the synthesized vowels, there was no reduction in accuracy when the natural F0 contour was held constant over the time course of the vowel. Moreover, accuracy was not reduced when IF0 differences were eliminated by synthesizing each vowel with the speaker’s average F0. These results suggest that F0 variation does not play a prominent role in vowel identification for isolated syllables produced by children and adults. [Work supported by Texas Advanced Research Program.]
Identification of natural and synthesized vowels produced by children and adults: Effects of formant frequency variation
Authors: Assmann Peter F. , Katz William F. , Jenouri Kathleen M. , Hamilton Phillip W.
Published: October 2005

To examine developmental patterns in the production and perception of American English vowels, recordings were made of 12 /hVd/ words from 10 men, 10 women, and 30 children (ages 3, 5, 7). Fundamental frequency (F0) and formant center frequencies (F1–F4) were estimated and a subset of the measurements served as input to a cascade formant synthesizer. Natural and synthesized vowels were presented to adult listeners for identification. Overall, natural tokens were identified more accurately than synthesized versions. Performance was significantly lower when time-varying changes in either F1 or F2 were replaced by constant values drawn from the vowel nucleus. A further drop in accuracy resulted when all formants (F1−F4) and F0 were ‘‘flattened,’’ consistent with findings of Hillenbrand [J. Acoust. Soc. Am. 97, 3245(A) (1995)]. These findings highlight the perceptual importance of time-varying changes in vowel spectra. It has been suggested that time-varying changes in the formants can improve the intelligibility of vowels whose spectral envelopes are sparsely sampled by harmonics of the source spectrum. Although the vowels produced by children were generally less well identified, there was no evidence of an increased contribution of formant frequency dynamics with decreasing age. [Work supported by Texas Advanced Research Program.]
Creation of a children’s speech database
Authors: Miller James D. , Lee Sungbok , Uchanski Rosalie M. , Heidbreder Arnold F. , Richman Barbara B. , Tadlock John
Published: October 2005

Speech was recorded from a large number of children ages 5 through 18 years inclusive, at a custom installation at the St. Louis Science Center. Two separate sets of recordings were made: (1) using a high-fidelity microphone, and (2) using one of five telephone handsets. To date, 415 and 456 children have been recorded for each data set, respectively. Microphone recordings are two repetitions of 15 American English vowels in /stop/-V-/stop/ words embedded in a carrier sentence. Five additional English sentences were also recorded twice each. The vocabulary for the telephone recordings included (1) 25 commands (e.g., delete, new name) spoken twice each, (2) six telephone numbers, and (3) spontaneous answers to eight questions. Exact distributions of the number of talkers of each age and sex will be presented. The recording environment, procedures, and real-time digitization equipment will be described and illustrated. [Work supported by Technology Resources, Inc. and Central Institute for the Deaf.]
Animal and computational models of development of graded vowel categories
Authors: Lotto Andrew J. , Kluender Keith R. , Holt Lori L.
Published: October 2005

Some acoustic instances of phonetic segments are phonemically more compelling than others, and studies involving human infants and monkeys suggest that experience plays a critical role in modifying the manner in which subjects respond to between and within phonetic category differences. In this study, eight European starlings (Sturnusvulgaris) were trained to discriminate vowel tokens drawn from stylized distributions either of the Engish vowel categories /i/ and /I/, or of the Swedish vowel categories /y/ and /I/. Following training, responses to novel stimuli drawn from these distributions indicated that starlings’ responses generalized with facility to novel category examples. Multiple linear regression analyses revealed that responses could be well predicted on the bases of F1 and F2 values and distributional characteristics of experienced vowel sounds. Responses manifested a graded structure about the central ‘‘prototypical’’ vowel of the training category. Starling response rates (/i-I/birds) corresponded closely to adult human judgments of ‘‘goodness’’ for the English vowel sounds. Finally, a simple linear association network model trained with vowels drawn from the training set captured 95% of the variance in birds’ response rates for novel vowel tokens. [Work supported by NIDCD and NSF.]
Study of quantal theory of vowel production using area function and articulatory models
Authors: Ananthapadmanabha T. V. , Sundara Megha
Published: October 2005

Quantal theory of Stevens [J. Phonetics 17, 3–45 (1989)] states that there appear to be ranges of the articulatory parameter for which there is very little change in the acoustic parameter and other ranges where the acoustic parameter is more sensitive to changes in articulation. This result has been arrived at using a three- or four-tube model and coupled resonator theory. In this paper, the above experiment is replicated using a more realistic frequency domain method for calculating the formant frequencies for a given area function which include the effect of yielding walls and radiation impedance. Further, the quantal theory of vowel production is studied using Steven’s and Mermelstein’s articulatory models. Nomograms have been generated for these models. The acoustic and perceptual effects of perturbing articulatory parameters centered around the target values for selected vowels are studied. Preliminary experiments show that (a) the so-called areas of stability (broad F2 maximum, F3 minimum) are, in fact, most sensitive for articulatory changes and (b) for a given change in articulation, while F2 is insensitive, F1 and/or F3 are highly sensitive. In view of these findings, the quantal theory may have to be restated.
Acoustic bottom penetration in a shallow water site from a parametric projector
Authors: Chotiros Nicholas P. , Mautner Adrienne M. , Kristensen Åge , Bergem Oddbjorn , Lovik Arne
Published: October 2005

Acoustic penetration of a sandy ocean sediment by a narrow beam signal was investigated. A parametric source, the Simrad TOPAS, projected acoustic pulses at a shallow grazing angle into a sandy silt sediment in which a sparse 3-D array of acoustic sensors was buried, in a site off La Spezia, Italy. Although the experiment was conducted in shallow waters, the received signals were free of surface-bounce multipaths, due to the narrowness of sound beam, and excellent penetration was obtained. The collected signals were processed for direction and speed of the sediment acoustic waves. From a theoretical point of view, the medium is treated as a poroelastic solid governed by Biot’s theory of acoustic propagation. Comparisons are made between theory and experiment. [Work supported by Office of Naval Research, Ocean Acoustics Program, Code 321.]
Shallow-water torpedo reverberation data modeling with the comprehensive acoustic system simulation
Authors: Keenan Ruth E. , Weinberg Henry
Published: October 2005

The comprehensive acoustic system simulation (CASS) was used to track a 30-dB variability in the reverberation time series from 38 torpedo pings within a 4-km2 area of the shallow-water U.S. Navy SOCAL range. This data set was extremely well modeled with a fairly simple bottom description. A thorough survey of the bottom characteristics in this area showed that the region transitioned from a current-swept rough-rock bottom to a mud-filled depression. The Gaussian ray bundles (GRAB) model, a component of CASS, simulated the acoustic propagation in this range-dependent environment. With the exception of the forward bottom loss for rock, the component scattering models proposed by the Applied Physics Laboratory, University of Washington [APL-UW TR 9407, AEAS 9501, October 1994] were used in the simulation. Twenty-nine interleaving torpedo pings traversed the rough-rock conditions. The model predictions were internally consistent with the data and the environment when a 6-dB value was assumed for the rough-rock forward bottom loss. [Work supported by the Naval Sea Systems Command (PMS-402 and PMS-406) and the Office of Naval Research (ONR-321).]
A seismic interface wave transducer
Authors: Smith Eric , Wilson Preston S. , Behrens John A. , Muir Thomas G.
Published: October 2005

Use of seismic interface waves in applications such as buried object detection and echo ranging introduce special transduction needs. Because the spectrum of interface wave excitations can be very complicated, involving modes of different polarizations and speeds, a transducer is required that can select isolated modes as well as isolated frequencies. For applications in unconsolidated sediments, problems of consistency and stability must also be overcome. Experiments with such a transducer have been carried out on a natural hard-sand beach of the Gulf of Mexico. The device is an independently amplitude- and phase-controlled bidirectional oscillator coupled to the sediment. Preliminary results indicate that mode isolation is indeed possible, and also that high degrees of mechanical efficiency and consistency can be achieved in coupling to sediments. [Work supported by the Office of Naval Research.]
Automatic classification of low-frequency Arctic ambient noise
Authors: Greening Michael V. , Ozard John M. , Dosso Stanley E.
Published: October 2005

A technique is described which can be used to automatically classify Arctic ambient noise data collected using an array of hydrophones suspended below the ice. The technique is currently designed for analyzing low-frequency (5–60 Hz) noise collected from the central Arctic pack ice. It is capable of distinguishing between nearby or distant active pressure-ridging events, thermal ice-cracking events, biological noise, cable strum, flow noise, and microseisms. Different noise types are distinguished by the power spectra, cross spectral matrices, noise directivity, and modal decomposition of the received sound. The technique is designed to be used in a real-time system which can automatically classify the dominant noise contained in the data over a specified time interval. This technique is applied to data obtained in the Lincoln Sea over 5 days in April 1988 to show how the ambient noise characteristics change with time during this period. Application of the algorithms produced a quantitative classification of the noise type that was clearly recognized in displays of the distinguishing measures.
Early Flemish harpsichord string scalings and their acoustical implications
Authors: Koster John
Published: October 2005

Measurements of string lengths and diameters in historical harpsichords such as those made by the Ruckers family, active in Antwerp from 1579 to the 1680s, are commonly used to calculate: (1) the pitch at which they were intended to be tuned, based on the assumption that strings were stressed to the practical limits of their tensile strength; and (2) the resulting tensions. Consideration of early music theory and workshop design practices have led to the proposal of alternative assumptions that some pre-Ruckers’ makers employed shorter string lengths. With other variables remaining constant, higher calculated coefficients of inharmonicity result. The strings, however, were probably thinner, therefore resulting in inharmonicities similar to those of Ruckers’ instruments. Further, coupling with sympathetically vibrating generally undamped strings of the earliest harpsichords might have reduced the theoretically calculated inharmonicities of the upper partials of bass and tenor strings. Other aspects to consider in light of early instrument makers’ use of traditional geometrical methods of design include: (1) the Ruckers’ slight lengthening of virginal (rectangular harpsichord) E, F-sharp, and G-sharp strings intended to be tuned in meantone temperament, in which these pitches are flatter than in equal temperament; and (2) the development of reasonable plucking points.
Influences of cornett lower end
Authors: Hoekje P. L.
Published: October 2005

The lack of a distinct bell at the large end of the renaissance cornett is associated with some unique properties. The typical cornett has a conical shape with a length between 55 and 65 cm, and an open end diameter of 2.5–3.5 cm. Its range is from A3 to D6 (about 220–1175 Hz). With all holes covered, it usually overblows a minor ninth from the first register to the second. Notes with open holes overblow an octave, and adjustment of tone-hole dimensions can bring the ratios of second- to first-mode frequencies close to 2:1 for diatonic scale notes. Besides benefitting tuning, this also improves low register response due to intermode cooperation. The cutoff frequency of the tone-hole lattice is typically between about 600 and 900 Hz. Higher frequencies pass down the bore but are reflected back at the open end, whose cutoff frequency exceeds 3000 Hz. This sustains several higher modes whose frequencies are strongly affected by the total bore length. The length directly affects the tuning of some third-register notes, and a second-register note can benefit when the bore length is adjusted so that a higher mode frequency lines up with a harmonic of the tone.
Mechanisms of vocal vibrato
Authors: Titze Ingo R.
Published: October 2005

A model of vocal vibrato is proposed that incorporates a late reflex (about 70 ms in loop delay) between the stretch and joint receptors of the vocal fold and the cricothyroid and thyroarytenoid muscle activations. The negative feedback loop is modeled with an adjustable gain and additional latencies in muscle contraction and rotation between the cricoid and thyroid cartilages. With these latencies and known mechanical properties of the laryngeal system, vibrato frequencies on the order of 5–7 Hz have been obtained.
Computer simulation of drum sounds
Authors: Irwin James H. , Beauchamp James W.
Published: October 2005

A difference equation derived from a physical model of a stiff membrane is used to simulate the acoustic signal produced by a drum head. The physical model was extended beyond the classical model by the inclusion of terms which represent viscous damping, air loading, and time-varying tension. Fixed phase vocoder and tracking spectral analysis show that the simulated sound contains correct theoretical frequencies when the damping and stiffness are set to zero. As stiffness is increased, the partial frequencies increase as predicted by plate theory. Simulations of zero (vacuum) and typical air loads show no significant changes. As a means of corroboration, measurements were made on an actual drum head mounted in a vacuum chamber. The drum signal was generated by striking the drumhead with a plastic tip mounted on a solenoid core and measured with an accelerometer mounted upon the drumhead. Spectral analysis results for this signal are qualitatively similar to the simulation measurements although they differ in some details.
Automatic recognition of musical notes
Authors: Kapadia Jimmy H. , Hemdal John F.
Published: October 2005

A system for the automatic recognition of musical notes was designed and implemented on a IBM-PC using commonly available hardware. The input to the system was a recorded piece of monophonic music while the output was its musical score. The recognition was carried out in the time as well as the frequency domains. Different characteristics of the note, like its frequency (or its name) and its time value, were found. The approach for this project was primarily from a digital signal processing (DSP) point of view. Various DSP fundamentals, like comb filter analysis and cepstrum analysis, were used for achieving the ends. The emphasis was more on trying out different approaches than on achieving a desirable result. Finally, an attempt was made to recognize a chord.
The effect of duct cross-sectional area variation on acoustic and flow performance: Herschel Venturi tubes versus Universal Venturi tubes
Authors: Selamet A.
Published: October 2005

Following an earlier work by Selamet etal. [Proc. Inter-Noise 95, 425–430 (1995)], the present analytical, computational, and experimental study investigates the effect of duct cross-sectional area variation on the wave attenuation and flow performance. Two different Venturi configurations, Herschel Venturi tubes and Universal Venturi tubes, are compared. Four Venturi tubes are fabricated in each category with duct to throat cross-sectional area ratios varying from 2 to 16 and used in the experimental effort. The results from these configurations are then discussed in terms of the acoustic attenuation versus flow efficiency.
Coupled response and noise of roller chain drive systems
Authors: Liu S. P. , Hayek S. I. , Wang K. W. , Trethewey M. W. , Chen F. H. K.
Published: October 2005

A chain drive system consists of a closed loop roller chain wrapped around two or more sprockets. One of the most significant noise sources in an operating roller chain drive emanates from the repeated impacts between the chain links and sprocket teeth during their meshing. Previous studies on the local-global meshing of the chain with the sprockets only considered the dynamic transverse motion of an axially moving chain while uncoupled from the sprockets. In this study, the analysis is extended to axial-transverse motions of the moving roller chain coupled with the dynamic response of the rigid sprockets over which the chain is wrapped around. The analysis thus integrates the local impact meashing to the global response of the chain-sprocket system. Numerical simulations of the analytical model showed that the coupling effects between the two sprockets, the two chain spans, and the chain-sprocket meshing impulse intensity increase with decreasing sprocket inertia and chain longitudinal stiffness. Controlled tests on a roller chain/two-sprocket system verified the results of the numerical simulations; that the meshing noise SPL is directly related to the chain speed and its vibrational characteristics. [Work supported by the GM Currently at GM Research & Development Center.
Acoustical testing and treatment of elementary schools, St. Louis International Airport environs
Authors: Schweiker Jerry W. , Wentz Philip J. , Taylor Robert
Published: October 2005

Since 1986 a school acoustical treatment has been funded by Airport Community Programs Office (ACPO), St. Louis International Airport. The program has included selection of candidate schools, inside–outside noise tests, providing acoustical treatment recommendations, construction, and the postconstruction testing of elementary schools within the environs of St. Louis International Airport (Lambert Field). This paper summarizes the results of the first eight schools. Three schools remain in the program and await funding for the construction phase. Although the instrumentation and the type of noise tests has varied somewhat over the years, the primary goal was to reduce the classroom noise to below the Leq 45 level per FAA guidelines. SEL and 1/3-oct band data from overflights were also evaluated in some schools. The improvement in classroom Leq varied from 8 to 15.7 dBA in the classrooms tested. The acoustical improvements specified included acoustic windows and doors, interior acoustical treatment, new roofing, and air conditioning. The cost of construction varied from $253 000 to $500 000 per school.
The meaningfulness of reductions in aircraft noise exposure in airport neighborhoods
Authors: Fidell Sanford , Silvati Laura , Pearsons Karl
Published: October 2005

As quieter aircraft have begun to replace some of the noiser ones in the civil air transport fleet, aircraft noise exposure levels in certain airport neighborhoods have declined to some degree. Federal agencies with interests in aviation noise have not yet offered policy guidance for gauging the smallest decrease in aircraft noise that may be considered meaningful under these circumstances in airport neighborhoods. An empirical study of this issue was thus underken in residential areas near a large airport at which noise exposure levels had declined by several decibels over the last few years. Very few neighborhood residents either noticed a decrease in aircraft noise in the recent past or decribed themselves as less annoyed by aircraft noise than in prior years.
Sequential classification of moving objects from higher-order information
Authors: Dwyer Roger F.
Published: October 2005

Objects in motion, due to the Doppler shift, modify their spectra and to a greater extent modify their higher-order spectra. Sequential classification methods have been developed to exploit higher-order spectral information in active sonar returns. To demonstrate the ability to sequentially classify moving objects from higher-order spectra, five spheres of different composition and velocity were tested. The sequential classifier correctly identified the sphere and its velocity based on higher-order information. A comparison of the sequential classifier’s performance as a function of signal-to-noise ratio using higher-order information and second-order information will be presented.