bluuebunny/crossref_metadata_2025 huggingface dataset:
Phonetic string alignment
Authors: Goudie-Marshall Kathleen M. , Picone Joseph , Fisher William M.
Published: October 2005

This paper will describe a newly developed expert system which uses linguistic knowledge to align the phonetic content of two different words or phrases and score their similarity. The development of the system arose out of a need to have an automatic scoring algorithm for intelligibility testing for text-to-speech systems and other synthetic-speech coding and recognition systems. The system uses an automatic text-to-phone algorithm to translate the input and reference ASCII text strings to phonemic units, aligns them using linguistic knowledge-based decision criteria and a dynamic programming optimization, and outputs the aligned strings as well as tabulating the phoneme confusions.
Pulse propagation at long ranges in an underwater surface duct
Authors: Topuz E. , Felsen L. B.
Published: October 2005

In a previous communication, we have presented a hybrid-ray-mode theory for coping with convergence difficulties occurring near the source depth in the ray acoustic model of long range propagation in a surface duct. The hybrid formulation replaces the problematic acoustic ray fields with a uniquely defined group of surface ducted modes, while retaining the legitimate ray fields intact. Detailed numerical calculations for a high frequency Gaussian pulse propagating in a model environment with exponential velocity profile in depth have now revealed the inherent features of the hybrid scheme. With a solution obtained by modal summation as a reference, the hybrid form is found to be accurate and numerically efficient. It is also capable of explaining in cogent physical terms the features of the received signal by blending automatically and self-consistently the ray arrivals dominant at early times with mode arrivals dominant at later times. The interpretations follow from separate examination of ray fields and mode fields, with clear indications of ray field failure in the transition region noted above. [Work supported by ONR Underwater Acoustics.]
Air-suspended shallow-water acoustic waveguide
Authors: Chamuel Jacques R. , Brooke Gary H.
Published: October 2005

No experimental data have been published to date on the air/water/air acoustic waveguide with flat, sloped, or rough boundaries. In the conventional air/water/solid acoustic waveguide, the presence of the solid introduces the Scholte mode. The solid surface roughness causes not only energy leakage from the water waveguide to the solid, but it causes spreading of the energy over a wide time window. In order to study the normal modes interference and coupling phenomena in a rough waveguide, the problem would be greatly simplified if we could eliminate the Scholte mode and the energy leakage to the solid. A novel experimental technique is described which uses a thin stretched rubber membrane covered with a water layer from above. Controlled pressurized air below the membrane is used to counteract the weight of the water layer and obtain a flat surface at the bottom of the water waveguide. The water layer has a free top surface and a free bottom surface. Ultrasonic broadband pulses are propagated in the air-suspended water waveguide. Theoretical and experimental results are compared for the free flat parallel boundaries waveguide ease. Scattering objects are placed on the surface of the membrane to form a rough or periodic boundary. Experimental findings are presented providing physical insights into the shallow-water acoustic waveguide with rough boundaries.
A new eigenfunction expansion with applications to waveguide acoustics
Authors: Pannatoni Ronald F.
Published: October 2005

A new type of eigenfunction expansion has been developed for analysis of sound propagation in a lossless waveguide having an uneven boundary that is acoustically hard. The method of expansion is novel in that two essentially independent functions are expanded simultaneously. Expansions of this kind provide complete representations of the exact pressure and velocity fields at the boundaries of the waveguide as well as in the interior of the waveguide. The eigenvalue problem that generates the expansion functions has a boundary condition that contains the eigenvalue, and this fact accounts for the ability of the expansions to be valid at the uneven boundary of the waveguide. It also causes the eigenvalues to be complex even though the waveguide is lossless. As functions of range, the coefficients in the expansions of the acoustic fields satisfy a linear system of first order ordinary differential equations that resemble coupled mode equations that arise in the study of plane-parallel waveguides. These equations have been integrated numerically and validated in a few test problems that can be solved by alternative approach involving conformal mapping. [Work supported by ONR.]
Normal mode cycle distance and beam displacement, time delay, etc., for low (non-WKB) frequencies
Authors: Koch Robert A. , Lindberg Jo B.
Published: October 2005

The work of Tindle et al., on the relationship between mode and ray quantities, is extended to the low frequency regime where WKB is invalid. Given the WKB dispersion relation, the eigenvalue of the horizontal wavenumber can be “differentiated” with respect to the mode number. Furthermore, mode cycle distance is equivalent to mode normalization, which in ray terms is the sum of the water column horizontal path length and a lateral displacement along the bottom. In this paper the analogous relationships for low frequency are developed from the impedance boundary condition mode identification of Koch, Vidmar, and Lindberg. The result shows the mode number derivative and mode normalization should not be uniquely related (the WKB result is fortuitous). Instead, some auxilliary condition, such as Tindle's identification of bottom loss per bounce and mode attenuation per cycle distance, must be invoked to uniquely define cycle distance (as opposed to the periodicity of interference between two modes) as a single mode quantity. As a bonus, a straightforward eigenvalue estimator is suggested for numerical eigenmode calculations. [Work supported by ONR.]
Sound channel formation in the Strait of Juan de Fuca
Authors: Browning David G. , Powell J. W.
Published: October 2005

Two distinct oceanographic layers exist in the Strait of Juan de Fuca: a reduced salinity surface layer, approximately 100 m thick, which contains seaward flowing freshwater runoff; and a deeper layer which has access to the North Pacific but is blocked to landward by a sill at the head of the Strait. The annual temperature cycle in each layer is distinctly different, for example, the surface layer attains its highest temperature in July when the deeper layer reaches its lowest. This contributes to a complex evolution of the sound channel during the year, which we describe. In general, we find the sound channel axis to be located in the shallow layer during the winter and in the deeper layer during the summer. [Work supported by NUSC and DREP.]
Measurement of sound propagation, down-slope to a bottom-limited sound channel
Authors: Carey William M. , Gereben Estvan , Brunson Burlie A. , Bradley Marshall R.
Published: October 2005

Signal transmission loss and spatial coherence data for source-receiver separations between 100 and 250 km were acquired in the Gulf of Mexico with a calibrated seismic measurement system (400 m deep), a towed projector (100 m deep) which emitted 67 and 173-Hz tones, and a moored Webb sound source at 988-m depth driven at 175 Hz. Environmental data such as the range dependent bathymetry and sound velocity profiles were measured. The 67-Hz data showed a persistent sound transmission loss of approximately 90 dB whereas the 173 Hz showed several pronounced loss minima between 100–90 dB. Slope enhancements were found to be on the order 2–4 dB at 67 Hz and 6 dB at 173 Hz when compared to flat bottom calculations. Pairwise coherence data show the combined effects of multipath interference and signal-to-noise ratio. Estimates of signal coherence length from the coherent summation of streamer hydrophones yield coherence lengths between 70–300 m at a frequency of 173 Hz. Fast asymptotic coherent and normal mode transmission loss calculations produced results consistent with measured data for the deep flat portion of the measurement tracks when measured geoacoustic profiles or related bottom loss curves were used. The implicit finite difference parabolic equation calculations were consistent with range-averaged data for the flat portion of the track as well as on the slope. These results show that if proper qualitative description of the sub-bottom velocity profiles axe used, then computations with either a parobolic equation or normal mode technique are consistent with experimental results.
Model experiments on mode propagation in a shallow water wedge
Authors: Hobaek H. , Lindberg J. , Muir T. G.
Published: October 2005

Guided mode propagation in a wedge bounded by the ocean surface and a sloped bottom is modeled in a 80-kHz experiment conducted in an indoor tank, under controlled conditions. The bottom is simulated by a sand filled tray, 10 m long, 1 m wide, and 20 cm deep. The tray is suspended beneath the water surface, with one end pivoted so as to vary the angle of the wedge from 0°–10°. A vertical line array of seven elements is used as a source to preferentially excite low ordered modes in the waveguide. The field of propagating modes is studied with a probe hydrophone as a function of range and depth in both the water column and the sand sediment. Measurements on mode conversion in propagation out of the wedge are discussed and compared to theory. [Work supported by the Office of Naval Research.]
Ray finding and time series simulation in a layered-bottom ocean
Authors: Westwood Evan K. , Vidmar Paul J.
Published: October 2005

This paper outlines the capabilities and methods of a computer program which finds ray paths between a source and recover in an ocean/layered-bottom environment and simulates the time series at the receiver due to an arbitrary pressure waveform at the source. The user specifies a range-independent environmental model that may include piecewise-linear profiles of the sound velocity and the frequency-dependent attenuation in an arbitrary number of bottom layers. The ray paths may have multiple surface and bottom interactions, as well as arbitrary numbers of bounces in each of the bottom layers. The program finds rays efficiently by computing the range dependence of the Snell invariant in each layer. For each of the rays found, the arrival time, accumulated reflection/transmission coefficient, geometric spreading loss, and frequency-dependent attenuation factor are calculated and used to form the frequency transfer function. The summation of the products of the source spectrum and the ray path transfer functions yields the receiver spectrum and thus the received time series. [Work supported by Naval Ocean Research and Development Activity.]
Transmission loss displays using color contours for model evaluations
Authors: Keenan Ruth Eta
Published: October 2005

Transmission loss as a function of depth and range are presented in color contour displays. Black and white contour plots are not as effective compared to the color plots which make the information easier to assimilate. However, the color selection is an important consideration in that it can bias interpretation. The color transmission loss displays can be effectively used to judge quality and significance of the predictions. This is demonstrated in this paper by model comparisons using PE, RAYMODE, and FACT. Predictions from all these models at 500 Hz and 15 kHz in a surface duct environment are presented. The PE model is used to illustrate the effects of sound velocity and bathymetry range dependence. [Work supported by WHOI PO 29518 under NORDA Code 270 Contract N00014-80-C-0381.]
Use of acoustic filtering to control the beamwidth of steered microphone arrays
Authors: Flanagan J. L.
Published: October 2005

Computer-steered microphone arrays provide an attractive sound-transducing means for interactive communication by sizable groups of talkers. But the spatial acuity of arrays typically varies with frequency, exhibiting diminishing beamwidth as frequency increases. Frequency-weighting the array is one means to mitigate the variation and to achieve more uniform beamwidth over the useful frequency range. Acoustic low-pass filtering, accomplished in the array design, provides effective and economical modification of beamwidth.
Transient response of an electret microphone
Authors: Cho Whang , Busch-Vishniac Ilene
Published: October 2005

The transient response of an electret microphone without a back cavity is analyzed by examining the motion of the electret foil in response to a transient acoustic signal applied uniformly on the foil face. The analysis uses a normal mode expansion of the motion of the circular diaphragm. The air trapped between the foil and the back electrode is assumed to behave as a pure adiabatic compliance. Damping forces and electrostatic forces are included in the analysis and cause the system to be dispersive. Experimental measurements are presented for the damping of the system as a function of frequency. The experimental damping coefficients are used in the analysis to predict foil motions and the resulting output voltage as a function of time. The results compare favorably with laboratory measurements.
An electret touch sensor
Authors: Voron Dan , Busch-Vishniac Ilene
Published: October 2005

In the research presented here we have examined the response of an electret transducer to forces applied over a localized area of the transducer face. The electret is modeled as a membrane under tension suspended above a flat back electrode. The air between the back electrode and the electret foil communicates with the environment through holes in the back electrode. The electret foil is described by a mesh of nodes, and standard finite difference techniques are used to find the deflection of the membrane in response to pressures applied at selected nodes. Static and dynamic analyses of this model have correlated well with the analytical solution for a uniform pressure on the transducer face. The device has been built and its response to impulses at various locations measured. Experimental results and theoretical predictions are in good agreement. Applications for this force-sensing device are expected to be primarily in the area of robotics.
A cylindrical bender acoustic transducer
Authors: Shirley Donald J. , Owen Thomas E.
Published: October 2005

An acoustic transducer having hollow cylinder geometry has been developed for generation of compressional waves in fluid or solid media or of shear waves in solid media using the bender concept of a two-layered piezoelectric ceramic transducer element. The device can be constructed with either two active piezoelectric layers or with one active piezoelectric layer and one passive layer. The latter configuration allows construction of a cylindrical transducer with a relatively thick metal exterior shell for electrical shielding. The active ceramic can be either monolithic or a mosaic of small elements. Mechanical details of several transducers that have been constructed will be presented with their operational parameters. Low resonance frequency, small size, rugged construction, excellent electrical shielding, and electrically switchable modes of operation are a few of the positive attributes of the transducer design. [Work supported by U.S. Department of the Interior, Bureau of Mines.]
Evaluation of PbTiO3-based piezoelectric ceramics for hydrophone applications
Authors: Nepgen André J. , Kingon Angus I.
Published: October 2005

PbTiO 3 -based ceramics recently developed by Toshiba scientists have interesting implications for conventional hydrophone design. They exhibit virtually no coupling in the 31-mode while the 33-mode is strongly coupled, yielding a high hydrostatic voltage coefficient (gh). The possible application of this material in hydrophones was investigated by comparing the theoretical performance of a PZT-5H cylinder with capped ends to a PbTiO3 disk. Particular attention is paid to calculating the signal-to-noise performance because of the low permittivity of this material. It was found that this parameter is only slightly affected in the presence of a low-noise preamplifier, but it will probably not be acceptable for measuring water noise levels. Sensitivity measurements obtained from a PbTiO3 disk suspended in a rubber boot filled with castor oil gave predictable results. The responses were flat to within ±2 dB up to the thickness resonance. It is indicated that the PbTiO3-based hydrophone generally compares favorably with the conventional PZT designs. The PbTiO3-based hydrophone offers the advantages of a superior wideband performance and a very simple construction. It should also be ideally suited to deep submergence applications.
Commission interpretation of “feasibility” in applying the noise standard
Authors: Cottine Bertram Robert
Published: October 2005

The Occupational Safety and Health Act of 1970 authorized the Secretary of Labor to establish occupational health standards responsive to the hazards created by employees. This legislative authorization permitted the immediate adoption and subsequent development of standards governing workplace hazards. The noise standard represents both early promulgation and later amendment. Through the use of occupational health standards, Congress established economic minima for participation in the national marketplace. The touchstone analysis for compliance was “feasibility”—a term with legislative as well as administrative significance. “Feasibility” was expanded in Continental Can to include a cost-benefit analysis of an employer's noncompliance with regulatory requirements. Commission determinations under the cost-benefit test were inconsistent. In the absence of controlling precedent, the Commission declined to overrule the Continental Can test for institutional reasons in Samson Paper Bag. In Sun Ship, Inc., the Commission interpreted the term “feasibility” consistent with the United States Supreme Court decision in American Textile Manufacturers Ass'n, Inc. vs Donovan. Pending Commission cases were remanded for further proceedings as necessary. The uniform statutory interpretation of “feasibility” was abandoned by the Commission in Sherwin-Williams. This decision creates regulatory, enforcement, and compliance problems.
Equilibrium shapes of acoustically levitated liquid drops
Authors: Trinh E. , Hsu C. J.
Published: October 2005

The effects of acoustic radiation stresses on the equilibrium shape of liquid drops have been studied through photographic data obtained with acoustically levitated liquids. The kR parameter was varied between 0.15 and 0.6 by changing the drop radius R while keeping the acoustic wavelength fixed (λ = 2π/k). The variations of the geometrical aspect ratios of the spheroidal drops with the acoustic pressure level were recorded using an ultrasonic levitator operating in air at 20 kHz and room temperature. Results obtained for water, glycerin, silicone oil, and molten metals have been analyzed and compared with the available theoretical treatment [P. L. Marston, S. E. LaPorto-Arione, and G. L. Pullen, J. Acoust. Soc. Am. 69, 1499–1501 (1981)]. A good agreement was obtained in the range of small kR values where the theory was applicable [Work supported by NASA.]
Possibilities of ultra-low noise acoustic parametric amplification in liquid helium
Authors: Rugar Daniel
Published: October 2005

Liquid helium at temperatures less than 0.1 K is a nearly ideal medium for acoustic parametric amplification at microwave frequencies. The desirable qualities of liquid helium include low attenuation, large upward dispersion, and strong nonlinear acoustic interaction. Calculations indicate that an acoustic parametric amplifier operating at gigahertz frequencies can be constructed with signal gain in excess of 50 dB per millimeter of propagation path and would require less than 1 mW/cm2 of pump intensity. When T⩽hf/k, where T is the helium temperature, h is Planck's constant,f is the signal frequency, and k is Boltzmann's constant, then the noise performance of the amplifier is quantum limited and the noise temperature is given by TN = hf/k ln 2. At 2 GHz this corresponds to TN = 0.14 K. Even when transduction losses are included, such an amplifier would have electrical noise performance superior to today's lowest noise maser amplifiers. Another interesting possibility is to use a degenerate parametric amplifier to produce phonon squeezed states. Squeezed states, which have attracted considerable interest in quantum optics, exhibit reduced quantum noise in one quadrature of phase.
Measurements of sound propagation in HeII with partially locked normal component
Authors: Baker Steven R. , Rudnick Isadore
Published: October 2005

We have measured the speed and attenuation of sound in HeII between 1.20 and 2.15 K in six porous solids with nominal grain diameters from 1–500μ. If δvisc is the viscous penetration depth and a is a characteristic pore radius, the range of the experiment spans (δvisc/a) = 10−2 to 102. We have compared these measurements to the predictions of the two-fluid theory of HeII, modified to account for the tortuosity and (normal fluid) flow resistance of the porous solid [S. Baker, D. Rudnick, and I. Rudnick, J. Acoust. Soc. Am. Suppl. 1 74 S59 (1983)]. We find excellent agreement between measured and predicted speed and attenuation provided the attenuation is dominated by the flow resistance. The three adjustable parameters determined in this experiment are the Biot parameters of the porous solid (tortuosity a, permeability k, and high-frequency correction factor δ) [M. Biot, J. Acoust. Soc. Am. 28, 168–191 (1956)], and are the same for any fluid in the pores. [Work supported by ONR.]
Experiment to measure vibration-induced mass transfer
Authors: Shaw Brian , Roy Ronald , Apfel Robert E.
Published: October 2005

A system consisting of a self-resonating aluminum rod on which a “pill-box” of napthalene is affixed provides a method for monitoring the sublimation of the napthalene and thus the mass transfer rate. The rate depends on the vibration amplitude of the rod which can be determined by a microphone that picks up the radiated acoustic signal (at a frequency of about 15 kHz). We shall present a description of our apparatus, which has two self-locking loops, one for maintaining the resonance frequency and one for keeping the vibration amplitude constant, and we shall discuss some of our preliminary results which suggest that the napthalene plug changes the resonance frequency because of mass loading rather than by changing the effective standing wavelength of the rod. [Work supported by ONR.]
Multiple scattering of sound by turbulence in water
Authors: Korman Murray S.
Published: October 2005

Experimental results are presented for the scattering of an ultrasonic pulsed beam (f = 1.90 MHz, τ = 200 μs) interacting in the presence of a submerged water jet (diam = 4.8 cm, Re≃5×105). The transmitting 2.54-cm-diam PZT transducer unit is located 20 nozzle diameters down-stream from the jet orifice and is positioned 1 m from the symmetry axis of the jet. The unit is supported by a radius arm so that the incident beam is free to rotate 360° about the symmetry axis of the jet. A 2.54-cm-diam stationary receiving unit located 2 m from the jet axis detects the scattered energy pulses. Experimental results are reported for both the scattered energy and the spectral broadening of the incident pulse versus scattering angle. Due to the very short wavelength of sound and relatively large interaction volume of the turbulence the classical scattering theories of Lighthill, Kraichnan, Batchelor, and others, which are valid in the Born approximation, cannot be applied here. Theoretical scattering models including the effects of multiple scattering are discussed using some of the recent theoretical results of R. L. Fante [Radio Sci. 17 (3), 1521–1530 (1982)]. [Work supported by NRL (Physical Acoustics Branch) and USNA.]
Summary: An emerging metatheory of auditory sensory coding
Authors: Uttal William
Published: October 2005

As the final presentation of the tutorial, it will be my function to provide an overview of the material developed and presented by the previous participants. Based on the general themes emerging from this session and drawing from the current literature on central auditory and other sensory systems, a statement will be developed of what seems to be the best bet as to the coding schemes and languages used by the central auditory system. At this time, this abstract is necessarily vague but will gain substance as our continued interactions progress.
A technique for measurement of structure-borne intensity in plates
Authors: Williams Earl G. , Dardy Henry D. , Fink Richard G.
Published: October 2005

We demonstrate a measurement technique to determine the structure-borne intensity (power flow) in a point-driven, fluid-loaded, homogeneous thin plate. This intensity is uniquely determined from a knowledge of the normal velocity of the surface of a sinusoidally driven plate. A noncontact method is presented which uses a scanning hydrophone to measure the pressure in a plane very close to the source. It is shown how this pressure measurement is sufficient to compute the two-dimensional structural intensity vector inside the plate. Furthermore, these vectors are used to compute the power injected into the plate from a point driver. Independent measurement of injected mechanical power is shown to be in close agreement. A comparison of the structure-borne intensity with the acoustic intensity radiated into the medium indicates that structual intensity is much more accurate in locating the real source than the acoustic intensity, the latter often failing completely. The examples given in this paper are for a source underwater, but the technique applies without modification to plate sources in air.
A new model of the dynamic response of a bilaminar composite plate
Authors: Hayek Sabih I. , Joung Il-Bok
Published: October 2005

A new approximate theory of the dynamic response of a bilaminar composite plate has been developed by using energy methods. The displacement field, based upon the lowest symmetric and antisymmetric displacement functions in both the thickness stretch and the thickness shear mode, was found by adjusting the cutoff frequency to that obtained from the exact elasticity theory. From this model, the Timoshenko-Mindlin thick plate theory and Bernoulli-Euler classical plate theory can be recovered as special limiting cases. The six-branch frequency-wavenumber spectrum for the bilaminar composite plate and the corresponding coincidence angle-wavenumber and coincidence angle-frequency spectra are computed.
The role of modal coupling in the radiation of sound from vibrating structures
Authors: Keltie R. F. , Peng H.
Published: October 2005

The acoustic power radiated by a finite beam excited by a harmonic point force was formulated analytically and shown to be composed of two sets of terms: the first describing the power radiated by the individual modes, the so-called squared terms; and the second, or cross terms, describing the power radiated by the interaction of different modes. The relative contributions of each were examined as a function of the critical frequency and the drive point location. Results indicated that the cross terms were important primarily below acoustic coincidence and could account for either an increase or a decrease in the radiation efficiency, depending upon the location of the excitation point. In addition, modes with similar wavenumbers were found to interact more strongly than those with significantly different wavenumbers. [Work supported by NSF.]
Application of the boundary integral element method to the acoustic filter plate
Authors: Mobbs Stephen D.
Published: October 2005

In its simplest form the filter plate is a circular metal plate which is thin at the center and has a thickness which increases towards the outer edge. Incident sound is transmitted through the thin central region while the outer region appears opaque. The effective diameter of the transparent region varies with wavelength in such a way as to produce a wavelength independent beamwidth for the transmitted sound. At high frequencies however, when the wavelength becomes comparable with or less than twice the outer thickness of the plate, this mode of operation is observed to break down and the beamwidth is no longer frequency independent. In order to gain a better understanding of the high frequency breakup of the transmitted beam, numerical solution of the problem has been carried out using the boundary integral element method. The method will be described and some results presented. [Work supported by ONR Code 425.]
Contralateral noise effects on the perception of manner for initial voiceless stops
Authors: Pastore Richard , Morris Crystle , Logan Robert , Layer Jody Kaplan
Published: October 2005

Several years ago, we discovered that the perception of an initial voiceless consonant “p” in a monaural CV syllable could be altered by a burst of noise roughly coincident (+/−50 ms) with the onset of the stop. These noise-induced misperceptions were found only when the noise was contralateral to the consonant and approximately equal in intensity (+/−20 dB). We later found that the effect was highly dependent upon the subsequent vowel. Our current research investigates effects of the (a) following vowel, (b) linguistic property of the stimulus (actual word versus nonsense word), (c) the task of the subject (identification of word versus initial consonant), and (d) presentation of no-noise control trials (randomly mixed with noise trials versus blocked separately). The natural token stimuli were spoken by a male linguist, and digitized for later computer synthesis at equal average intensities. We found systematic errors in the perception of “p” as “t” under certain conditions, the perception of “t” as “p” for other conditions and, under some conditions, no errors. Differences also were found for the two types of no-noise control. The possible basis for these noise-induced misperceptions will be discussed. [Research supported by NSF grant BNS-83-02873.]
Supra glottal cues to post /s/ stops
Authors: McCasland George P.
Published: October 2005

As part of an extensive study by this investigator [J. Acoust. Soc. Am. Suppl. 1 75, S65 (1984)] two utterances were chosen for further analysis: it's dill containing the voiced stop and it still containing a stop having equivocal voicing status. As indicated in Pétursson's data [Phonetica 35, 65–85 (1978)], a closed glottis at release provides short VOT for the stop after /s/ in utterances like these. A set of test tokens was edited from a single naturally spoken utterance such that the /s/ noise and following silent interval durations varied in 10-ms steps throughout their trading range. In a perceptual identification test, each test token was evaluated by subjects as to which of the two utterances had been heard. Response profiles for each individual subject as well as for the entire subject group pooled showed that these utterances were distinguished in perception by the parameter tradeoff at the acoustic level. It is only the rule system of English phonology that required the transcription of the word boundary location in addition to the voicing feature of the stop after /s/. There were no separate cues for the juncture.
Consonant identification with various formant eliminations
Authors: Maroonroge Sumalai , Nábělek Igor V.
Published: October 2005

The purpose of this study was to investigate the effect of individual formant elimination on the identification scores of natural voiceless consonants in noise. The consonants were tested with the vowels /i/, /ɑ/, or /u/ in both initial and final positions. Each syllable had the energy eliminated at the frequencies of the first, second, or third formant of the vowels. The syllables were mixed with cafeteria noise and presented to young and elderly normally hearing listeners and to noise-induced hearing loss listeners. The difference between the speech and noise levels was 15 dB. In general, the effects of formant elimination were dependent on individual sounds and groups of listeners. When the first formant was eliminated, the identification scores were similar to those obtained under the wideband setting. The identification of /h/, /ō/, /p/, /t/, and /k/ was affected most by the elimination of the second formant for all groups of listeners. The maximal reduction of identification scores of /t∫/ and /∫/ occurred when the third formant was absent.
Perceptual learning of acoustic correlates of nonspeech categories
Authors: Parker Ellen
Published: October 2005

Although recent evidence suggests that certain phonetic trading relations have an auditory basis, others appear to be the result of listeners' knowledge of articulatory constraints on production, or of their acoustic consequences. The latter group includes the effect of first-formant (F1) frequency on the voicing boundary in initial stop consonants; as F1 is lowered, longer voice-onset times (VOT) are required to perceive stops voiceless. Summerfield [J. Acoust. Soc. Am. 72, 51–61 (1982)] and Hillen-brand [J. Acoust. Soc. Am. 75, 231–240 (1984)] showed for nonspeech stimuli varying in tone-onset time (TOT), simultaneity-successivity judgments did not vary systematically with frequency of the lower tone. This study demonstrates that when listeners learn to associate different frequency components with two nonspeech categories (simultaneous and nonsimultaneous onsets), they will use frequency information in making simultaneity judgments. Two TOT series were generated, consisting of two-component, steady-state, sine-wave stimuli; in each series, the onset of the lower tone (f1) lagged that of the higher tone (f2) by 0–120 ms. For all stimuli, f2 was 1240 Hz; f1 was 750 HZ for one series and 250 Hz for the other. When subjects were trained on the simultaneous endpoint from the high f1 series and the nonsimultaneous endpoint from the low f1 series, subsequent identification performance revealed significantly more stimuli were labeled “simultaneous” for the high-f1 series than for the low-f1 series. These results suggest that general principles of perceptual learning can account for the interaction between VOT and f1 onset in specifying voicing categories in initial stops. [Work supported by NICHHD.]
Perception of duration of medial silent intervals in speech and nonspeech signals
Authors: Kluender Keith R. , Diehl Randy L. , Wright Beverly A.
Published: October 2005

Vowels are longer before voiced consonants than before voiceless consonants, and a number of studies have demonstrated that perception of voicing, in syllable-final and intervocalic positions, is in accordance with this production regularity. We present a study, using nonspeech stimuli, that suggests that this agreement between production and perception for segmental duration is grounded in auditory processing of complex stimuli in general. Two types of square-wave analogs, modeled after a speech series ranging from “aba” to “apa” were constructed. The two nonspeech stimulus series varied in duration of a silent interval from 20–110 ms bounded by frequency transitions out of and into steady-state segments. One series had an initial segment duration of 155 ms, whereas, the initial segment duration of the other series was 245 ms. Duration of the final segment was 188 ms for both series. Listeners judged significantly more of these nonspeech stimuli to be similar to the short silent interval endpoint when the initial segment was long than when the initial segment was short. This result parallels the finding for speech that listeners perceived more voiced /b/ than voiceless /p/ consonants following longer vowels. These results call into question explanations of this production/perception concordance that suggest either mediation of perception by knowledge of production regularities, or direct perception or articulation. [Work supported by NICHHD.]
Recognition of Spanish intervocalic consonants
Authors: Franco Horacio , Gurlekian Jorge A.
Published: October 2005

The hypothesis of focusing triggered by energy variations, and the role of stationary formant patterns are explored in the recognition of Spanish /β, δ, γ/. The stimuli consisted of VCVCVCV sequences where the overall amplitude contour and/or the F1 contour were flattened. Listeners perceived each sequence as a long continuous vowel, when both amplitude and F1 contour remained flat. For the /a,e,o/ context, only one cue is enough to allow recognition. For the /i,u/ context, amplitude contour alone may play the role of focusing. In a second experiment, F2-F3 formants were made uniform in VCV sequences, during the duration of the sequence (exp. 2a), and only during the temporal portion corresponding to the transitions (exp.2b), smoothing their amplitudes at the boundaries to avoid the effects of frequency discontinuity with the /a/ formants. Subjects reported a clear identification as /β,δ,γ/, although in exp. 2b vowel quality increased. These experiments show both the relative amplitude as an initial detector of consonant group, and stationary formants as a possible cue for group members.
Complex frequency poles and transient acoustic scattering amplitudes of fluid layers
Authors: Nagl Anton , Überall H. , Yoo K. B.
Published: October 2005

The acoustic reflection coefficient of a fluid layer, located between two half-spaces of different fluids, is examined in the time domain using incident sinusoidal pulses (wave trains). Poles of the reflection coefficient are obtained in the complex frequency plane, and their interplay with the frequency spectrum of the incident pulse clearly identifies their contributions to single and multiply reflected echoes. The half-widths of the pole resonances are derived exactly, and are compared with expressions previously obtained by us [A. Nagl, H. Überall, and K. B. Yoo, “Acoustic exploration of ocean floor properties based on the ringing of sediment layer resonances,” Inverse Problems (in press, 1985)]. It is shown that measurements of resonance spacings and widths are sufficient to determine the physical parameters of the layer and the medium on its far side. [Supported by the Office of Naval Research.]
Experimental observations of interface wave and acoustic propagation over a rough granite seabed
Authors: Chapman David M. F. , Staal Philip R.
Published: October 2005

Experimental measurements of explosive sound propagation in a shallow ocean area over a rough granite seabed have revealed several interesting features concerning low-frequency acoustic and seismic transmission phenomena. The data were collected using DREA's shallow water research array Hydra, which was deployed as a 38-m vertical line array consisting of eight hydrophones. The time series data from explosives at distances from 2 to 40 km show a strong 5-Hz interface wave (or Scholte wave) arriving at a group speed of around 1200 m/s after the high-frequency arrivals. The dispersion of this wave is consistent with a simple theoretical model consisting of a uniform water layer over a semi-infinite elastic solid having a shear speed higher than the sound speed in the water. The propagation loss data show a notch of very high loss between 10 and 100 Hz centered at 30 Hz. A commonly used transmission loss model using the same geoacoustic input does not predict these high losses, but agrees at seismic frequencies. We speculate that the discrepancy is due to a physical loss mechanism not present in the model: scattering at the rough surface of the granite seabed.
Low-frequency sound absorption in the Baltic Sea
Authors: Mellen R. H. , Mallo P. , Candau S. J.
Published: October 2005

Interpretation of attenuation measurements in the Baltic Sea [H. G. Schneider, R. Thiele, and P. C. Wille, J. Acoust. Soc. Am. (to be published, 1985)] indicates a need for estimating sound absorption in low salinity waters. While the magnesium sulfate component depends simply on the first power of salinity, the low-frequency boric acid relaxation is more complex. The mechanism involves exchange with carbonate in which the ion-pair calcium carbonate affects only the absorption magnitude αmax. Absorption measurements by the resonator method (at elevated boric acid concentrations) show roughly 0.5 power dependence on calcium concentration in the range of interest. The Baltic salinity is roughly 14 normal while the carbonate and acidity (pH≃8.0) are both normal. Since αmax depends on the concentration product, S1.5 dependence gives a reduction by the factor 8 which makes it negligible. The relaxation frequency fr depends on a sum of concentrations and is estimated to be reduced by the factor 1.6. Laboratory measurements of fr in Baltic water samples by the temperature-jump method show reasonable agreement. We conclude that the boric acid relaxation probably plays no role in Baltic Sea attenuation.
Traffic noise analysis and a model standard for Trans-European Motorways (TEM)
Authors: Kurra Selma , Gedizlioğlu Ergun , Yayla Nadir , Yilmaz Sevtap
Published: October 2005

The future traffic noise generation from Trans-European Motorways still under construction throughout Europe was analyzed in a study aimed to introduce standard noise control systems into the TEM Recommendations. Different prediction techniques developed by national institutions of nine countries were employed in computations of noise levels at 15 m from curbsides for varying traffic parameters. Comparisons between results relative to the procedures demonstrated that the USA method (FHWA) yielded about 5 dBA higher levels than European models especially in mountainous terrains and at higher percentages of heavy vehicles. Applying a statistical regression analysis, a simplified mathematical model for TEM noise predictions was developed with a satisfactory correlation coefficient. A new combined parameter, T(u,s,n,h,g), corresponding to interrelated TEM traffic variables (volume, speed, number of lanes, heavy vehicle percentage, and road gradient), affecting noise generation, was analytically defined and represented in the model. Reviewing the existing traffic noise criteria in the world and TEM countries, the prediction model was then improved to establish TEM noise standards taking into account environmental factors and was implemented for the required performances of the noise abatement measures applicable in every type of TEM. [Supported by Directorate of Turkish Highways within the TEM project coordinated by United Nations, Transport Division.]
An investigation of modal coupling between a sound field and the walls of a reverberation room
Authors: Jie Pan , Bies David Alan
Published: October 2005

The nature of the coupling between a sound field and the walls of a reverberation room is studied experimentally at low frequencies. The first few modes of the floor and some of the walls are identified and their response to modes of the room of near resonance frequencies investigated. The observed modal response of the floor and walls shows that at low frequencies the usual concept of locally reactive does not apply; strong evidence of modal coupling between the modes of the room and the modes of the walls and floor is demonstrated. The influence of a diffuser on the modal coupling is also observed and correlated with observed variation in reverberation time with diffuser orientation. The experiment also shows that modal coupling can be varied by varying the stiffness of a wall; the resulting variation of modal coupling results in corresponding variation in reverberation time.
Effects of source separation and phasing on acoustic power in a semireverberant space with application to active noise control
Authors: Schein D. B. , Parrot T. L.
Published: October 2005

The acoustic response of a semireverberant enclosure with two interacting, velocity prescribed source distributions was analyzed using standard modal analysis techniques with a view towards a better understanding of active noise control. Different source and enclosure dimensions, source separations, and single wall admittances were studied over representative bandwidths of 10 Hz, and between 40 and 300 Hz, with source relative phase as a parameter. Results indicate that power radiated into the enclosure correlates with the spatial average of the mean-square pressure even though the reverberant field is nondiffuse. Power reductions can therefore be used to estimate global noise reduction in a nondiffuse semireverberant environment. Parametric studies indicate that maximum power reductions of up to 25 dB can be achieved when secondary and primary sources are compact and closely spaced, as might be expected. Although there is less reduction with increasing frequency and source separation or size, significant reductions of up to 8 dB still occur over 1- or 2-Hz bandwidths.
Tutorial on modal analysis
Authors: Morse Ivan E.
Published: October 2005

A brief tutorial presentation of modal analysis methods and experimental techniques with examples and comparisons to finite element results. Samples of animated mode shapes will be shown.
Normal modes of some axisymmetric percussion musical instruments
Authors: Perrin R.
Published: October 2005

Finite element calculations of the normal modes of various axisymmetric percussion instruments have been made including church, carillon, hand, and fire-alarm bells. Agreement with experiment is good in most cases. The results will be presented and comparisons of these for the various systems made, which give some new insights into the mode production mechanisms. These in turn have implications for the ways in which the normal modes for these systems ought to be classified and have serious consequences for design.
Vibration and sound radiation of a piano soundboard
Authors: Suzuki Hideo
Published: October 2005

Vibration and sound radiation of a piano soundboard (6-ft grand) were studied using modal analysis and surface intensity methods in the frequency region below 210 Hz. The first mode (49.5 Hz) looked like a trampoline. The second (76.5 Hz) and third (85.3 Hz) modes were the first breakup modes in the length direction. The fourth mode (116.1 Hz) showed the first breakup mode in the width direction. There were seven major resonances below 210 Hz with an average modal density of 1/25 Hz. The radiation was very inefficient below 90 Hz and the surface intensity method was not adequately accurate below this frequency. The radiation pattern (intensity distribution) showed some similarity to the forced vibration pattern for the lower-order modes (but not for the higher-order modes). On an average basis, the radiation efficiency (the ratio of the power radiated from the upper side of the soundboard to the mechanical input power) was approximately 15% above 100 Hz. A normalized radiation resistance was also used to evaluate the efficiency of radiation. A comparison of the normalized radiation resistance to the volume velocity confirmed that the interaction among the sound radiated from different areas on the soundboard is the major cause of the large fluctuation in the normalized radiation resistance.