bluuebunny/crossref_metadata_2025 huggingface dataset:
Shock-wave propagation in anisotropic solids
Authors: Johnson J. N.
Published: October 2005

The systematic study of small-amplitude (peak acoustic stress <1 atm) acoustic-wave propagation in anisotropic solids has been going on for some time. The corresponding investigations of these materials with finite-amplitude impact- (or explosively) generated shock waves is still in its infancy, but is clearly becoming an interesting and useful area of scientific research. Shock-wave studies consist of single compressive stress pulses with amplitudes between ∼104 and ∼105 atm. The dynamic stress state is itself nonisotropic and can result in plastic flow as well as significant nonlinear elastic effects; in soft, ductile materials the former effect dominates the material response, while in very strong brittle materials the latter effect can be observed. This review presentation begins with the subject of shock-wave propagation in anisotropic elastic solids—common ground with classical acoustical studies—and goes on to the problem of shock-induced plastic deformation in anisotropic elastic-plastic solids. It is shown that plastic wave velocities in anisotropic materials can possess a multiplicity of values (as they do under purely elastic conditions), and that these velocities depend on the slip systems activated under dynamic conditions.
Pressure-shear waves as a means for determining dynamic material properties
Authors: Clifton R. J.
Published: October 2005

Pressure-shear waves involving changes in both normal and shear tractions on planes perpendicular to the direction of propagation are being used to study the shear strength of materials shock loaded to high pressures. The predominantly shear waves generated in these experiments are particularly sensitive to the plastic flow characteristics of the material. This talk presents an overview of theory and experiment related to pressure-shear waves. Solutions are described for boundary conditions corresponding to those of impact of two parallel plates with the direction of approach inclined to the direction of the normal of the impact plane. Experiments for generating pressure-shear waves by such impacts of skewed plates are described. Various techniques for monitoring pressure-shear waves are reviewed. Experimental results are presented for pressure-shear impact of 6061-T6 aluminum, using a transverse displacement interferometer and a normal velocity interferometer to monitor, respectively, the transverse and normal components of the motion of the rear surface of the target.
Shock-compressed liquids
Authors: Nellis W. J.
Published: October 2005

A number of liquids including N2, Ar, and H2O were shock compressed in the pressure range 0.1–1.0 Mbar using a two-stage, light-gas gun. Metal plates were accelerated to 7 km/s and strong shockwaves were generated on impact with targets. Equation-of-state data were obtained by measuring shock and impact velocities and applying the Rankine-Hugoniot conservation relations. Compression factors up to threefold over liquid density and temperatures up to 20 000 K were achieved. The experimental techniques will be described including the shock-impedance-matching method, the two-stage gun, the fast electronics with subnanosecond time resolution, and the cryogenic target holders. By means of the statistical mechanics calculations of Ross, the repulsive pair potential between molecules will be demonstrated to obey the principle of corresponding states for some of the liquids. Electronic excitation will be shown to have a strong influence on the shock velocity in Ar at the high temperatures achieved. [Work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore Laboratory under contract W-7405-Eng-48.]
The use of LPC coefficient interpolation to improve the naturalness of sentence formation by word concatenation
Authors: Levine Arvin
Published: October 2005

A recent experiment [Sanders et al., J. Acoust. Soc. Am. Suppl. 1 64, S1(A) (1978)] showed that an important contributor to the unnaturalness of sentence formation by word concatenation was the use of individually recorded words (isolation forms). Experience at Stanford has shown interpolation and quantization of LPC formant frequencies and bandwidths to be effective as methods of data rate reduction. Another use for interpolation is to improve the perceived naturalness of synthesized speech by smoothing the transitions between independently recorded sounds. Several considerations for successful word-boundary interpolation are: (1) syntactic, semantic and phonetic conditions, (2) the interpolation curve—linear or more complex, (3) the durations and locations of the interpolation region in individual words, and (4) the use of a specially prepared “demisyllabic bridge” to connect words. The relative importance of smoothing transitions involving high-frequency function words (articles, auxiliary verbs, etc.) is compared to interpolating all the junctions in a sentence. [Work supported by NSF grant SED-77-09698.]
Data compression of Linear Prediction (LP) analyzed speech by interpolation and quantization of pseudo-formant parameters
Authors: Sanders William , Gramlich Carolyn , Levine Arvin , Laddaga Robert , Suppes Patrick
Published: October 2005

Pseudoformants and bandwidths, derived from LP coefficients, prove highly susceptible to data compression techniques such as interpolation and quantization because of their low entropy and smooth sequential nature. We have developed a heuristic to label initially unordered pseudoformants in a way that reveals their sequential smoothness, so that linear interpolation can be successfully applied to each pseudoformant separately. A linear least-squares fit is made over several points; the number of points is limited by a bound on the allowed mean-squared fractional difference between the data and the interpolating line, and another bound on the maximum-squared fractional difference. Quantization of the resulting parameters is constrained not to introduce more error than was allowed in the interpolation procedure. All parameters need not be interpolated using the same bound; if the relative importance of the parameters is chosen in an acoustically reasonable way, interpolation can produce very high quality sound at considerably reduced bit rates. [Work supported by NSF.]
Perceived speech quality of Linear Prediction (LP) analyzed speech compressed by means of interpolation and quantization of pseudoformant parameters
Authors: Gramlich Carolyn , Sanders William , Levine Arvin , Laddaga Robert , Suppes Patrick
Published: October 2005

It is possible to produce high quality LP speech with a low bit rate by interpolating pseudoformants and bandwidths derived from the LP coefficients. To the extent that pseudoformants are like the true formants of speech, the importance of each can be inferred from classical acoustical studies. A listening experiment was performed which compared the perceived quality of speech interpolated using several assignments of importance to the pseudoformant parameters: an acoustically reasonable assignment, a uniform assignment, and a number of assignments intermediate between the two. Several levels of total distortion were used. The test shows that if an acoustically reasonable assignment of importance to each pseudoformant is given, the quality of the speech is significantly higher than if equal importance is given to each parameter. By using the acoustically reasonable allocation, very good speech quality can be maintained at a bit rate of 3200 bits/s while if the uniform allocation is used, more than 4200 bits are needed to attain the same quality. [Work supported by NSF.]
High quality system for speech transformations
Authors: Seneff Stephanie
Published: October 2005

A speech analysis synthesis system has been developed which is capable of independently modifying the excitation and the spectrum, and then reconstructing speech from the modified components. Since pitch extraction is not required, the reconstructed speech is more natural sounding than vocoded speech. At the core of the system is a phase vocoder. The excitation spectrum is obtained by dividing the magnitude spectrum by the vocal tract spectral model, and is then either duplicated or foreshortened to alter the number of harmonics present. Correct frequencies are restored by multiplying the unwrapped phase characteristics by the appropriate constant. The desired vocal tract shaping is then reintroduced, using interpolation between samples if necessary. The system can produce several potentially useful modifications to the voice. A male voice can be converted into a female-like voice, and vice versa. Alternatively, the spectrum can be compressed by a factor of three or more, while the pitch remains unchanged; a modification potentially useful for persons with high frequency hearing loss. A third possibility is the restoration of helium speech. In addition, the parameters of the system could be encoded to realize a voice-excited vocoder. A tape will be played illustrating the system's capabilities.
The underwater radiated noise characteristics of a fishing trawler
Authors: Davis E. E. , DiPiazza N. J.
Published: October 2005

The U.S. Coast Guard is responsible for the protection of fisheries resources within the 200 nautical mile offshore zone. In support of this requirement a study was undertaken to examine the feasibility of applying underwater acoustic monitoring techniques, for detection and classification of fishing trawler activities. The approach was to conduct a set of controlled experiments with a cooperating trawler and to employ aircraft/sonobuoy measurement techniques. The specific objectives of the experiments were to (1) determine if significantly distinctive noise characteristics are generated by the different modes of trawler operation, (2) identify the sources of any distinctive noise characteristics and (3) obtain quantitative source levels generated by the trawler for each mode of operation. The experimental objectives were accomplished and the results show a correlation of fishing operations with the radiated noise of a fishing trawler. Noise signature characteristics indicated dynamic acoustic changes during fishing operations, particularly during net deployment and retrieval. In addition, absolute trawler radiated noise levels (source levels) were determined for various fishing operations. [This work sponsored by the Commandant, United States Coast Guard, Washington, DC.]
Hydrographic reconaissance of large undersea topography using scattered acoustic energy
Authors: Schifter D. , Franchi E. , Griffin J. , Adams B.
Published: October 2005

The TOPO test series was designed to measure reverberation from a variety of large-scale topographic features. From this research, an acoustic experimental and processing technique is developing which is applicable to wide-area hydrographic reconnaissance. Results from TOPO ONE are presented to illustrate the potential technique. A towed array receiver and explosive sources were used to obtain data covering a 1 000 000-square nautical mile area of a Pacific basin northeast of New Zealand. After filtering and beamforming, the processing provides spatial stabilization of beams and averaging over multiple shots to correct for left/right ambiguities and to create basin-wide mappings of the major scatterers. The resulting latitude-longitude display of the location and strength of major scatterers reveals both known and uncharted features. From TOPO ONE, isolated, uncharted seamounts appear within the basin and a section of the Louisville Ridge, previously contoured as an elongated plateau, is revealed to be a series of separate peaks. Subsequently, the New Zealand Navy has verified, by depth sounding, the existence of these features first identified in the acoustic data.
Acoustic propagation over ground; a computer study
Authors: Miller G. K. , Babian F. E.
Published: October 2005

A computer model was developed for the acoustic propagation between a sinusoidal source and a receiver when both are located on or above the planar surface of a homogeneous medium of known specific flow resistance. The “locally reacting” assumption is made and the “exact” formulation of Thomasson is numerically integrated. The normal specific acoustic impedance of the ground is obtained using the empirical model of Delany and Bazley. Atmospheric absorption is included as a function of local temperature, relative humidity and barometric pressure, and the effects of the source-receiver geometry, (source and receiver heights and their horizontal separation) are variable inputs. Provisions for approximating non-point sources and for accounting for the presence of wind and temperature fluctuations are being made. Current results clearly show many examples of the importance of the ground effect, and the source-receiver geometry, on the excess attenuation as a function of frequency.
Radiation fields of a violin in the region of the Helmholtz and main body resonances
Authors: Weinreich Gabriel , Arnold Eric B.
Published: October 2005

The measuring system previously described [G. Weinreich and E. B. Arnold, J. Acoust. Soc. Am. Suppl. 1 65, S72(A) (1979)] has been used to analyze the acoustic fields radiated by a violin in the frequency range of the Helmholtz and main body resonances. The violin is driven electrodynamically by an ac current through the string and a permanent magnet mounted over it. The frequency of the driving oscillator is locked to the string resonance by a feedback loop actuated by an acceleration sensor at the bass foot of the bridge, and is adjusted by moving a small Delrin mass which slides on the string, so that the tension maintains its normal value. Observations at the Helmholtz resonance include the nearfield motion of air through the f holes, which is otherwise difficult to see, and the resulting farfield pattern. Because of the 90° relative phase shift between the s wave and p wave as one moves from the nearfield to the farfield, the nearfield pattern, with its strong motion in the forward direction, becomes completely bidirectional in the farfield. [Work supported by NSF.]
Frequency-wavenumber spectral analysis of borehole acoustic waves
Authors: Marzetta T. L. , Leslie D. , Schoenberg M. , Aron J.
Published: October 2005

In a laboratory experiment an acoustic pulse excited waves in a fluid-filled borehole that had been drilled in a solid block of epoxy. Typical wavelengths were the same order of magnitude as the hole radius. Waveforms were received at many different ranges and conventional and high resolution, maximum likelihood methods (MLM) of frequency-wavenumber (ω, k) spectral analysis are applied to this data. The spectra obtained are compared to theoretical dispersion calculations. Good agreement is obtained. Encouraging improvements in wavenumber resolution over conventional spectral estimation are obtained by the use of the MLM techniques.
Compatibility in federal community noise policies
Authors: Hawley Mones E. , Peppin Richard J.
Published: October 2005

Several federal agencies have community noise policies. These agencies include the Environmental Protection Agency, the Federal Aviation Administration, the Federal Highway Administration, the Department of Defense. the Department of Housing and Urban Development, and the General Services Administration. In most cases, the policies are consistent, compatible. and complete. In some cases, they are inconsistent and, in other cases, the coverage is incomplete. This paper describes and compares these policies, their implications for enforcing agencies, and their effects upon citizens.
Community noise ordinance drafting by a city ad-hoc noise committee
Authors: Campanella Angelo J. , Brown P. Gary
Published: October 2005

Through motivation by a city councilman, Charles Petree, an ad-hoc committee was formed to review existing city noise-related codes. Representation included city council staff, the health, zoning, and police departments, an acoustical consultant, the industrial commission and building association, the society of professional engineers, the electric company, and a private citizen. This body met many times over one year to review codes and ordinances. Recommendations included consolidating all noise related codes and ordinances into one addendum to the City Code. Additions against squealing tires, limits on motorboat noise, and the replacement of octave-band limits for manufacturing districts with Leq limits along common residential/institutional/commercial/manufacturing property lines were made. The police department concluded that the existing muffler ordinance requiring “a muffler in good working condition with baffle plates …” was satisfactory for enforcement. These recommendations—to be detailed in the presentation—are being submitted to the City Council for action. Airport noise, as it affects land use and zoning actions, will be treated during calender year 1980.
Cumulative annoyance due to multiple aircraft flyovers with differing peak noise levels
Authors: Shepherd K. P.
Published: October 2005

A laboratory experiment was conducted in which 160 subjects made annoyance judgments of half-hour sessions of aircraft flyover sounds. Each often test sessions contained nine flyovers with various peak noise levels such that the session Leq values had a range of 20 dB. After each session, the subjects assessed their annoyance in the laboratory and also estimated their annoyance to such a noise environment occurring in their homes during the day, evening, and night. The laboratory annoyance judgments were examined in terms of their relationship with various proposed noise rating scales, from which it was concluded the energy summation scales such as Leq and Noise Exposure Forecast were superior to the peak dB(A) concept [R. Rylander, J. Sound Vib. 36(3), 399–406 (1974)] and to Noise Pollution Level [D. W. Robinson, Nat. Phys. Lab. Aero Rep. Ac. 38 (1969)]. The subjects' responses to the projected annoyance questions (time of day weighting) were compared with aircraft noise social survey results. [Work supported by NASA Langley Research Center.]
Effect of unit load and fan speed on induced-draft fan noise at electric generation stations
Authors: Thompson A. R. , Buechler J. P.
Published: October 2005

Induced-draft fan noise has been recognized as a major source of community noise in the electric power industry. Typically, the dominant path of ID fan noise is from the top of the stack with the noise being both tonal and broadband when centrifugal fans are used. Depending upon site-specific factors, the noise can be a problem at full-load operating conditions. At low-load conditions, the problem can become more severe as airflow is reduced by closing the inlet dampers. This results in higher levels of the tones and the broadband noise. A series of measurements, taken at three units at various load conditions, indicate that the levels of the tones, particularly the second harmonic, increase as the load is decreased. At low loads, when the dampers are relatively closed, significant reductions in the tone levels can be achieved by switching to a lower fan speed. A lower fan speed results in reduction of the tip speed and opening of the dampers for a given load condition.
Construction noise control for a major urban rapid transit line extension
Authors: Cavanaugh W. J. , Tocci G. C. , Muldoon T. A.
Published: October 2005

The northwest extension of the Massachusetts Bay Transportation Authority Red Line Rapid Transit System involves the demolition and reconstruction of the current terminus station—Harvard Square Station, Cambridge—and the construction of three new stations, and associated subway tunnel and track work. This major construction program, scheduled to extend over a five year period, recognizes the potential noise impacts on the densely populated and highly developed communities in which the new construction is to take place. Cambridge, the most significantly affected community, currently has a noise ordinance limiting property line L10 and maximum A-weighted sound levels due to construction operations. The MBTA has incorporated the Cambridge limits into construction contract documents and has also included limits on noise produced by individual pieces of construction equipment. The construction noise specifications and implementation procedures are described along with the experience to date in actual contract applications. [This work is partially supported by the US Urban Mass Transit Administration and the Massachusetts Bay Transportation Authority.]
The effect of stoplights on traffic noise
Authors: Halliwell R. E.
Published: October 2005

A study was undertaken to determine how the noise level due to free-flowing traffic is affected by the insertion of a traffic light. Field measurements were taken at eight different traffic light locations, representing two configurations; that of two intersecting straight roads and tee junctions. A reference level, measured at a point where traffic noise was unaffected by the intersection, was used in conjunction with the NRC traffic noise prediction model to assess the change in noise level in the region about the traffic light.
Electrical stimulation in the descending auditory system
Authors: Glenn J. F. , Oatman L. C.
Published: October 2005

An investigation of the effects of electrical stimulation in the descending auditory pathways on the latency and amplitude characteristics of auditory evoked potentials was carried out in cats. Bipolar stimulating electrodes were stereotaxically placed in the crossed component of the olivocochlear bundle (COCB) and the ventral nucleus of the lateral lemniscus (VNLL). Evoked potential measurements were taken from the round window in paralyzed (Flaxedil) cats both with and without cutting the middle-ear muscles. Auditory stimuli included both clicks and tone bursts presented over a wide range of intensity levels. Biphasic stimulation of either COCB or VNLL produced effects on auditory evoked potentials typical of efferent activation, including decrements in amplitude, shifts in latency, and increased cochlear microphonic output. These effects were greatest at lower intensities. Middle-ear muscle activation did not contribute to these effects. The results will be discussed in relation to central control of peripheral sensory processing.
Performance trade-offs in dynamic time warping algorithms for isolated word recognition
Authors: Myers C. S. , Rabiner L. R. , Rosenberg A. E.
Published: October 2005

The technique of dynamic programming for time registration of a reference and a test utterance has found widespread use in the area of discrete word recognition. Recently a number of variations on the basic time warping algorithms have been proposed by Sakoe and Chiba, and Rabiner, Rosenberg, and Levinson. These algorithms all assume the test input is an isolated word whose endpoints are known (at least approximately). The major difference in the methods are the global path constraints (i.e., the region of possible paths), the local continuity constraints on the path, and the distance weighting and normalization used to give the overall minimum distance. The purpose of this investigation is to study the effects of such variations on the performance of different algorithms for a realistic speech data base. The performance index is based on speed of operation, memory requirements, and recognition accuracy of the algorithm. Preliminary results indicate, in most cases, only small differences in performance among the various methods.
A statistical approach to metrics for word and syllable recognition
Authors: Hunt Melvyn J.
Published: October 2005

Time-warping pattern-comparison algorithms are widely used in speech recognition. Two words or syllables being compared are described by a series of time frames each containing values of a set of acoustic parameters. After time alignment, the squared distance between the patterns is summed over the parameters within a frame and then across frames. The sum obtained is assumed to be proportional to the log probability of the two patterns having the same identity. This assumption is generally invalid, but it may be made substantially true by analyzing the variability between different examples of the same syllable and adjusting the metric accordingly. Variability is estimated both as a function of frame position within the syllable as a function of the acoustic parameters. In the latter case, within- and between-class covariance matrices can be estimated and standard linear discriminant analysis methods applied. This permits the combination of disparate acoustic parameters into a single distance measure. In particular, combining frame and frame-difference parameters allows one to use time development information and to take inter-frame correlations into account.
Reciprocity calibration of transducers in a plane wave resonator
Authors: Garrett Steven
Published: October 2005

The recently published expression for transducer calibration in a plane wave resonator by the reciprocity method [I. Rudnick, J. Acoust. Soc. Am. 63, 1923 (1978)] has been tested against a Rayleigh disk. The resonator tube was terminated at one end by a dual electret transducer and at the other end by an electro-dynamic transducer. All three transducers were reversible allowing three independent reciprocating calibrations which agreed to better than 1% (0.1 dB). The deflection of the disk was measured by monitoring the change in inductance of a coil surrounding the resonator and the disk. The disk angle detection system was self-calibrating and permitted absolute measurement of the flow velocity in the vicinity of the disk when the moment of inertia of the disk and damping coil were known. [Research supported by the F. V. Hunt Postdoctoral Fellowship of the Acoustical Society of America with funds provided by the Office of Naval Research.]
Sound analysis-synthesis and interactive composition
Authors: Beauchamp J. W.
Published: October 2005

Two distinct projects are under way: (1) Derivation of synthesis models from the analysis of acoustic musical instrument sounds and their use with software-based synthesis programs on large computers. (2) Development of an interactive computer-controlled synthesizer system housed in the University of Illinois Music Building. It is hoped that in the not-too-distant future these projects will be joined. Current focus in analysis is to estimate the resonant filter characteristics of a wind instrument and use this in conjunction with time-variant Fourier analysis to derive an excitation signal. This is further processed to reveal a nonlinear distortion function and an index signal. In the simplest case, synthesis over wide dynamic and pitch ranges is possible by merely varying the fundamental frequency and the index signal while keeping the filter and distortion parameters fixed. The interactive system uses a compositionally oriented language called PLACOMP written for the PLATO IV time-sharing system. A PLACOMP score is translated into numbers which are quickly delivered to a hard-wired synthesizer. The turnaround time between delivered completion and audible result varies between a few seconds and a few minutes depending on the complexity and length of the composition.
Combining physical modeling information and statistics in prediction of airport noise in communities
Authors: Bishop Dwight E.
Published: October 2005

The prediction of noise in communities due to transportation noise sources typically utilizes determinalistic information about sound sources and sound propagation combined with statistical approaches for aid in selecting measurement positions and analyzing noise data acquired over limited time periods. In determining community noise levels to a given statistical confidence level, it will generally be most efficient, in terms of time and resources, to make utmost use of physical modeling concepts and noise source information, together with information from previous studies as to the types of temporal and spatial variations that may be involved. Tradeoffs between statistical analyses and modeling calculations will depend, obviously, upon the accuracy of the modeling concepts and the extent of factors that cannot be quantified in the model. Examples of current techniques for describing the noise environment due to aircraft noise, which combine physical modeling augmented by statistical analyses of noise monitoring data, will be described.
Development of temporal sampling strategies for monitoring noise
Authors: Schomer P. D. , Neathammer R. D. , DeVor R. E. , Kline W. A.
Published: October 2005

This paper addresses the problem of the estimation of the long term (yearly) mean of the Community Noise Equivalent Level (CNEL) or day/night average sound level (LDN). Examination of daily average noise levels (either in mean-square pressure or in decibel units) shows that while the data may be stationary with respect to mean level over a several month period, they exhibit a strong pattern of autocorrelation in which positive correlation predominates. As a result, the sample sizes required to achieve a desired level of precision in the sample-mean estimate are much larger than they would otherwise be if the data were uncorrelated serially in time. For the data examined, to obtain an estimate of the mean level within a 5-dB range (±50% of the mean in mean-square-pressure units), sample sizes in the range of 20 to 50 consecutive daily averages would be required. If the daily averages were uncorrelated in time, only 5 to 15 consecutive daily averages would be required. The data used in this study were obtained from continuous monitoring at a number of sites in the vicinity of a busy Naval Air Station. Some data obtained from a large commercial airport were also analyzed and found to have even stronger positive autocorrelation and therefore requiring even larger sample sizes for mean-value estimation.
Environmental noise assessment: Single family residential spatial analysis and methodology error analysis
Authors: Putnicki George J.
Published: October 2005

A number of sampling techniques have recently been developed to assist municipalities in assessing and evaluating the total environment noise climate within the community and to identify the intrusive noise sources. One methodology was developed by Wyle Research, El Segundo, California for the U.S. Environmental Protection Agency and published in July 1976. The University of Texas at Dallas, Graduate Program in Environmental Sciences, has modified the Wyle methodology for use in conducting an environmental noise assessment for the City of Dallas, Texas. This publication reports on the modifications made to the Wyle method and the results of a spatial survey conducted in a spatially homogenous single family residential land use area. The purpose of the spatial analysis was to determine the number of monitoring sites required. Prior to using the modified methodology, an error analysis was conducted for the purpose of determining the accuracy of the methodology. Nine primary monitoring sites were selected for this analysis. Using commercially available digital monitoring equipment each site was monitored for four or more continuous 24-h periods and the day-night average sound levels, Ldn's, measured were compared to the 24-h Ldn's computed using selected 30-min periods obtained on weekdays, weeknights, weekend days, and weekend nights. From these analyses, the required number of sites was determined and the accuracy of the methodology was validated.
Visualization of acoustical processes in gases consisting of many interacting particles
Authors: Heckl Maria
Published: October 2005

For most acoustical calculations the carrier of the sound waves (air, water) is considered to be a continuous medium. This, however, is oversimplifying as it is known a gas consists of particles which move with randomly distributed speeds and interact by many impacts. The intention of this paper is to visualize—with the help of a film—acoustical processes under these conditions. The particles are considered as totally elastic mass-points which hit together and exchange energy and momentum according to the well-known conservation laws. With this model some simple phenomena such as sound propagation, damping, and reflection will be discussed.
A versatile fast scanner for ultrasound temperature tomography and wide aperture synthetic focus imaging
Authors: Johnson Steven A. , Grahn Allen R. , Baker Charles D. , Randall George , Christensen Douglas A. , Jacobs Steven R. , Berggren Michael J.
Published: October 2005

A versatile laboratory scanner of modular design is described which can support a wide variety of ultrasound transducers and transducer arrays. The basic design consists of a rotating platform on which are mounted various types of interchangeable, temperature regulated water tanks. The platform is rotated in 0.02° steps by a high torque stepping motor. Various transmitter and receiver geometries or configurations are arranged in each water tank. One tank configuration uses spherical or cylindrical acoustic waves and a curvilinear, circular receiver array for high speed (1 to 10 s) data collection for reconstruction of tissue temperature. This method makes use of acoustic refractive index reconstruction tomography and the temperature dependence of the acoustic refractive index. This tank configuration also permits the use of microwave or high-power, focused ultrasound beams for tissue heating while simultaneously reconstructing the temperature of the tissue samples. A second tank configuration uses plane waves and a rectilinearly scanned receiving array for diffraction tomography studies. A third tank configuration permits the use of a new high resolution reflection or scattering imaging technique now known as either “synthetic focus imaging” or “reflection tomography.” [Supported by NIH grants NCI IR01 CA 23430 and H2-00170 and PDP-110 from American Cancer Society.]
Effects of substrate free vascular perfusion of the cochlea
Authors: Kambayashi J. , DeMott J. E. , Comegys T. H. , Thalmann I. , Marcus N. Y. , Thalmann R.
Published: October 2005

During vascular perfusion of the cochlea with substrate free synthetic blood, the endolymphatic potential (EP) is maintained for 85 ± 20 (SD) minutes. The subsequent decline of the EP can be prevented by 0.8 mM glucose or by 11 mM lactate, but not by succinate (although 20 mM succinate effects a partial recovery of the EP when it has declined by 40 mV). Significant breakdown of strial glycogen occurs only when the EP starts to decline. Glycogen stores in the stria are virtually depleted when the EP has dropped to about 30 mV. At about the same time, the further decline of the EP is arrested, presumably due to activation of a new substrate pool. Only following a stabilization of some 30 min does the EP resume its decline. It appears that the prolonged initial maintenance of the EP during substrate free vascular perfusion is due to the utilization of glucose from cochlear fluids, since the EP starts to decline immediately when the perilymphatic glucose pool is removed simultaneously by perilymphatic perfusion. [Supported by NIH and NSF.]
Effects of acute noise traumata on cochlear frequency analysis as observed in whole-nerve and single-cell recordings
Authors: van Heusden E. , Smoorenburg G. F.
Published: October 2005

Tuning curves were obtained in cat by masking the whole-nerve action potential (AP), applying a forward-masking paradigm. The Q10 values of the tuning curves appeared to be about half the values found for threshold tuning curves of single nerve fibers. After inducement of a noise trauma by a 105 dB SPL wide-band noise that lasted for 30 min, Q10 values of the AP tuning curves became noticeably smaller. We carefully checked that this decrease of Q10 should be attributed to a loss in tuning selectivity and not to changes in the masking phenomenon itself. A decrease of Q10 values due to the noise trauma was found also for tuning of single cells in the anteroventral cochlear nucleus. For both the whole-nerve and the single-cell responses, the decrease of Q10 is not simply an effect of stimulus level. The decrease is found for tuning curves just above pre- and post-trauma thresholds as well as for tuning curves at the same SPL before and after inducement of the trauma. [Research supported by the Netherlands Organization for the Advancement of Pure Research, ZWO.]
Current practices in shipboard airborne noise control and future needs
Authors: Nelson Daniel L.
Published: October 2005

In recent years, shipboard airborne noise criteria have been applied much more stringently than in the past. Further, noise criteria are likely to be lowered for future ship designs. In response to this, more noise sources and transmission paths need to be considered in the acoustical design process. This paper considers noise control treatments which are presently coming into accepted practice in this country and discusses the merits as well as liabilities of these treatments. Needs for future research and development efforts are also presented in light of more restrictive noise criteria.
Allophonic, stress, and prosodic cues for word perceptions
Authors: Nakatani Lloyd H. , O'Connor-Dukes Kathleen D.
Published: October 2005

Speech is apparently rich in phonetic parsing cues which enable listeners to recover the words of an utterance. Listeners easily distinguished between phrases such as “stronger ranger”/“strong arranger” and “maiden forced”/“maid enforced.” No contextual cues were available, so listeners had to use phonetic cues to distinguish the phrases. By acoustic analyses and careful listening, phonetic differences between the phrase pairs were identified; these differences constituted the possible parsing cues. Of these, allophonic and other segmental variations were the most salient parsing cues; stress pattern variations were also salient, but prosedic variations in pitch and rhythm were not very salient.
The role of morphology in a word boundary decision task
Authors: O'Connor-Dukes Kathleen D. , Nakatani Lloyd H.
Published: October 2005

We investigated how listeners use their knowledge of English morphology to divide nonsense phrases into “words.” We looked at two types of syllables which occur as affixes in English. One type occurs as both morphological prefixes and suffixes, such as /di/ in “trema demarneted”/“tremady marneted.” Another type occurs only as prefixes, such as /pro/ in “cler proventched” but not *“clerpro ventched”; or only as suffixes, such as /bl/ in “afeemable talse” but not *“afeema bultalse.” We found that morphological considerations affected listeners' judgments of boundary location when phonetic differences between the phrases were weak or absent. But when there were strong phonetic differences between the phrases, these differences dominated the perception of word boundaries, overriding the influence of morphological effects.
Syllable durations and phonological groups
Authors: Condax I. D.
Published: October 2005

The phonological organization of Fijian can be accounted for without positing the word as a phonological unit. Instead, the units syllable and measure appear adequate to account for much of the phenology [A. J. Schutz, Univ. Hawaii Working Papers in Linguistics 8.2, 75–100 (1976)]. In this system the phonological measure is a group of syllables; the boundaries of the measure need not be coterminous with the boundaries of morphemes. The more syllables in a measure, the shorter each syllable is. This result is comparable to findings for English words [I. Lehiste, in Lass (ed.), 225–229 (1976)]. Examples in support of this analysis are of the type given below: an underlyingly long vowel in a morpheme such as sā remains long when it is in a measure by itself. When sā joins another syllable in making a disyllabic measure, the sā is shortened, whether or not the following syllable is a monosyllabic morpheme or part of a polysyllabic morpheme. The shortened sā is never as short as an underlyingly short sā, which would be a different morpheme.
Children's detection of mispronounced words in fluent speech
Authors: Kulick Maria , Wiedmer Beatrix , Kuhl Patricia
Published: October 2005

Children's ability to recognize mispronounced words in fluent speech was measured using an error-detection task in which the children rang a bell when they heard a mispronounced word in a story. Mispronunciations of the same word occurred in contexts in which they were semantically predictable and semantically unpredictable. The mispronunciations occurred word-initially on stop consonants and consisted of changes in voicing or place of articulation. Data were analyzed for the effects of semantic context, feature change, age, and sex on the percentage of errors detected and on the latency of response. Results indicated that four- to six-year-olds were very accurate (nonsignificant age differences) at detecting mispronunciations (⩾78%). Detection of mispronunciations in semantically predictable contexts were significantly better (and latencies were significantly shorter) than in unpredictable contexts, for all age groups. There were no significant differences in the overall detection of mispronunciations involving a change in voicing versus place; however, significant differences for direction of change within feature occurred for both voicing and place. Females were significantly more accurate than males at detecting mispronunciations.
Sound decays in a reverberation room
Authors: Warnock A. C. C.
Published: October 2005

The decay of the sound field in the reverberation room at the NRC has been examined using a computer-controlled real-time analyzer. This system provides the means of studying in detail the spatial variations of reverberation times and decay linearity. Many decays were recorded for a number of diffuser systems and microphone positions including corner microphones. The results obtained are compared with the requirements on spatial variation and linearity in ASTM method of test C423. The requirements are not easily met.
St. George's Theatre, London
Authors: Charles Jeff
Published: October 2005

St. George's Church was consecrated in 1867. The designer was George Truefit, who, it is said, modeled the Church on the 5th century Crusader church of St. George in Salonica. The church survived two world wars, although some damage was caused by flying bombs in 1944. After the war the church became derelict and empty, and the St. George's Elizabethan Theatre Limited Organization produced plans for the conversion of the church to a theatre. After purchasing the church in 1973, the theatre opened to the public on St. George's Day for a 6-month Shakespearean festival. Regrettably the acoustics left very much to be desired and the first season was marred by a considerable volume of complaints from the audience after performances and critics' headline comments such as “The Play's the Thing—but I could not hear it.” The paper discusses the remedial acoustic measures that have been undertaken to make the theatre acceptable.
A case study of acoustical performance of prefabricated music practice rooms
Authors: Boner Charles R.
Published: October 2005

The basis for procurement of 115 rooms for the new music building for the University of Texas at Austin College of Fine Arts/Performing Arts Center, now under construction, consisted of noise control testing and interior noise level testing of rooms in the plants of four manufacturers. The results of the testing were of invaluable aid in preparing specifications for procurement. The rooms were installed in temporary facilities while the new building is under construction and will all be relocated to the new building following it's completion.
Digital recording of audio for commercial release
Authors: Stockham T. G. , Bloomenthal J. I. , Ingebretsen R. B. , Rothoar B. C.
Published: October 2005

Several hundred commercial recordings, released or scheduled for release, have already been made by a handful of companies worldwide. This paper will discuss some technical aspects of those recordings made by the author's group and will present a high quality demonstration of a few selected samples.
Direct digital conversion in acoustic transducers
Authors: Flanagan J. L.
Published: October 2005

We offer some views, some computer analyses, and some preliminary experimental measurements on acoustic transducers designed to operate directly with digital signals. In particular, we describe a condenser receiving element and acoustic filter system that functions directly as a digital-to-analog converter (DAC). The transducer accepts the binary digital signal of PCM-encoded speech and produces the decoded analog acoustic output. We also suggest a design for a transducer that performs the reverse operation, that is, analog-to-digital conversion (ADC). Initial results are very tentative; many problems remain. But the techniques hint at routes to digital communication that can obviate, at least to some extent, the expense and complexity of conventional ADC and DAC circuitry.
An integration of current research on the singing voice
Authors: Allen E.
Published: October 2005

The extremely specialized voice use of singers has been the subject of a small but significant body of research during the last few years. Since this innovative work has such a short history, the integration of investigations of the voice subsystems and the incorporation of physiologic, acoustic, and perceptual data had to await the collection of sufficient material to be effective. Such integrations are the focus of this presentation. The ramifications of Sundberg's conclusions on the shape of the vocal tract during singing, Shipp's larynx height data, Hixon's chest wall positioning data, Baker's model, and Large's register work will be included, among others. In addition, the continuing challenges of the aesthetic/research interface and the need for more refined instrumentation will be addressed.
Studies of the Garcían model for vocal registration
Authors: Large J. W.
Published: October 2005

This paper reports a series of studies in which a model for vocal registration central to the well-documented vocal method of Manual García (1905–1906) was utilized. García was the teacher of Jenny Lind, Mathilde Marchesi, and Julius Stockhausen and the inventor of the laryngoscope. Equalized and nonequalized paired tones (same fundamental frequency, sound level—A-weighting, and vowel—/ɑ/) in the areas of register overlap in both male and female premier singers were recorded (1) on a high-fidelity tape recorder for perceptual evaluation and Sonagraphic analysis, (2) by a pneumotachographic system for measurement of airflow rates, and (3) with photography for analysis of laryngeal movements. The results of these investigations suggest the existence of physical correlates for singers' subjective sensations of different registers. These sensations coupled with the percepts of expert vocal pedagogues are responsible for the continued use of Garcían terms such as “chest” register, “falsetto” register, and “head” register.
Theoretical and experimental study of acoustic scattering in turbulent water
Authors: Eisler T. J. , Clark J. A.
Published: October 2005

The scattering of waterborne sound by turbulent flow from a jet is being examined. Turbulence is produced in this laboratory experiment by flow from a pressure vessel, through a 3-mm-diam tube, into a tank. Flow velocities out of the tube orifice in the tank are from about 1 to 10 m/s. The turbulent flow is insonified by tonebursts of about 500 ms duration from a 2.5-cm-diam, collimated acoustic beam. The region of insonification extends downstream from a point about 10-tube diameters away from the orifice. Acoustic frequencies are in the range from 500 kHz to 1 MHz. Scattered signals are detected by a directional hydrophone and a heterodyne receiver. Predictions of the acoustic scattering cross sections derived from theoretical models of turbulent flow will be presented and compared with experimental measurements. The dependence of scattering cross sections on flow velocity, acoustic frequency, bistatic angle, and the angle between the insonifying beam and the flow direction will be discussed. Doppler effects visible in the detected signals and anomalous scattering from vortex structures large compared to the acoustic wavelength will also be described. Implications of these results for underwater remote acoustic current sensors will be noted.