bluuebunny/crossref_metadata_2025 huggingface dataset:
Acoustical analysis of 30 words judged to be different in pitch and corresponding to a pitch modal
Authors: Bessel Celia S. , Asp Carl W.
Published: October 2005

In a previous study by Asp, Berry. and Bessel [J. Acoust. Soc. Am. Suppl. 1 64, S20(A) (1978)], listeners used a paired-comparison procedure to judge the pitch of 30 monosyllabic words. These judgments were used to rank order the words from low to high pitch. The rank order agreed with the proposed pitch model used for selecting the words, which included low, middle, and high pitch categories. In the present study, these 30 words were analyzed with a spectrograph and a frequency analyzer for fundamental and formant frequencies, duration, and amplitude spectra. There was a significant correlation between the amplitude spectra and the rank order; visual inspection of the spectra revealed specific patterns associated with the three pitch categories. There was a significant correlation between formant two and the rank order; however, the fundamental frequency was not significantly correlated with the rank order. [Work supported by NIH Biomedical Science Support Grant.]
A low frequency technique for inverting of backscattering data for shape and sizing of acoustic and elastic scatterers
Authors: Cook Bill D. , McKinny Ronald L. , Wilson Shelford
Published: October 2005

A new inversion scheme for backscattered data in acoustic and elastic scaltering is being investigated. There are indications that the ramp response in the time domain yields considerable information about the size and gross shape of the scatterer, albeit fine details may be lost. The theoretical computations show that the Raleigh and lower resonance regions of the scattering dictate the ramp response and that the scattering at higher frequencies is secondary. Computational and experimental results will be presented to support the ramp response concept.
Acoustic test facilities
Authors: Taylor N. D.
Published: October 2005

Two unique acoustic test facilities at the Evendale Plant of the Aircraft Engine Group are used for developing and testing aircraft engines and their derivatives. The large (80 000 cu ft) anechoic chamber at the AEG plant in Evendale, Ohio was built for the purpose of studying and reducing jet noise. One-sixth scale models of two-flow engine nozzles can be tested under simulated in-flight conditions provided by a wind tunnel around the nozzle simulating approach or takeoff. Frequencies to 80 000 Hz are scaled to full engine size. This chamber has the unique capability of making noise measurements in the forward quadrant as well as aft over an extensive range of temperatures and pressures in all three flows. The laser velocimeter has also proved to be a valuable tool in the study of noise source generation. Nozzles tested over the past four years include baseline conic configurations, mixers, suppressors, ejectors, and coannular nozzles with plugs. For supersonic engines, nozzles with inverted flow (fan/core) were examined. The large reverberant test chamber at the AEG plant in Evendale, Ohio was built for the purpose of measuring sound power levels around the LM2500 Gas Turbine Engine Module (derivative of the TF39/CF6-6 aircraft engines). Levels must be measured to insure compliance of 30 000 shaft hp modules which are eventually mounted in power plants or on shipboard where noise environment is critical. Sound levels are measured at the same time that performance measurements are made.
Noise level measurements around F-16 noise suppresser system
Authors: Hentz Richard P. , Boe Rollin O.
Published: October 2005

Several interesting results were noted while taking a complete series of acoustical measurements around an F-16 noise suppressor system. We designed this system for the USAF and were required to demonstrate its conformance with acoustical specifications. Measurements were taken using the same aircraft during a two-day period of stable weather. Although consistant measurements would be the most agreeable, large fluctuations were observed that could not be explained by wind, atmospheric absorption, or background noise. These results lend credence to similar published results [R. N. Foss, J. Acoust. Sec. Am. 66, 1088–1092 (1979)]. These results emphasize the need for a better method of acoustically certifying test cells and hush houses.
A general description of ultrasonic nonspecular reflection and transmission effects for layered media
Authors: Ngoc T. D. K. , Mayer W. G.
Published: October 2005

A numerical integration method is used to determine the profile of an ultrasonic bounded beam reflected from or transmitted through a general layered structure. Calculations are presented for liquid/solid and liquid/solid/liquid systems. Nonspeculareflection phenomena at critical angles for some liquid/solid interfaces are discussed. For a liquid/solid/liquid system, water/brass/water in particular, nonspecular characteristics are investigated for both reflected and transmitted beams. Emphasis is placed on changes in the beam profiles as a function of angle of incidence and beamwidth. [Work supported by Office of Naval Research, U.S. Navy.]
Analytical models for wave propagation in coal
Authors: Hadden W. James , Heng Chew Chye
Published: October 2005

Several wave propagation models have been investigated to determine their suitability as a basis for understanding the loss of amplitude in ultrasonic signals propagating in slabs of coal. The present paper discusses the relative magnitudes and frequency dependencies of attenuation rates implied by models in which coal is viewed as: (i) a porous elastic medium; (ii) an elastic medium with randomly distributed fluid-filled voids; and (iii) a viscoelastic medium. Results of these analyses will be compared with the experimental results presented at the 97th meeting of the Society.
An overview
Authors: Allen Jont B.
Published: October 2005

The theory of speech production has been present, and has served us well, for a great many years. Equally important, from a human communications point of view, is the theory of human hearing. Why hasn't hearing theory developed the same following as that of speech theory. Will it (or should it)? As a result of fairly recent experimental and theoretical developments, the substantial gaps in our previous understanding appear to be closing. In this review talk we will discuss the basic principles of hearing theory, pointing out the relevant experimental data which leads to the resulting theory. The basic issues are cochlear frequency response and cochlear nonlinearities.
A physical model of cochlear transduction
Authors: Allen Jont B.
Published: October 2005

One of the basic questions which has persisted in the field of hearing theory is the still unresolved mechanical action of hair cell transduction. The fundamental problem that has historically plagued researchers is the discrepancy between mechanically measured tuning of basilar membrane motion and neurally measured tuning. In this paper we show that the difference between these two measures appears to be accounted for by a specific, physically motivated, micromechanical model. This model gives rise to a spectral zero which we identify as the “second filter” of cochlear transduction. For high-frequency fibers this zero resides at a fixed frequency ratio below CF while for fibers having low frequency CF's the zero appears to go to zero frequency faster than CF (the ratio goes to zero at low frequencies). In this paper we first present and analyze the assumed mechanical model. We then briefly discuss a possible specific physical realization for the nonlinearity of cochlear mechanics. The nonlinear model is based on dynamical variations in outer hair cell stereocilia stiffness.
Analysis and design of laminated, composite-material panels to withstand dynamic loading
Authors: Wallace Martin M. , Bert Charles W.
Published: October 2005

In structural design, one must be well aware of the vibrational environment and ways to damp out detrimental vibrations. This is especially true in the design of aircraft, missiles, and spacecraft. When these vehicles were made from isotropic materials, material orientation did not play a role in the damping. However, with the advent of filamentary composite materials, material orientation now plays a role in damping as well as in strength and stiffness. The purpose of the current research is to develop and experimentally verify the necessary analytical tools to determine the vibrational resonant frequencies, modal shapes, and damping ratios for composite structural elements with discretely varing thickness and material properties. Today, the common technique for analytically determining resonant frequencies and modal shapes is by the use of finite elements. However, for sufficient accuracy this method requires a large number of nodes, which in turn requires very large mass and stiffness matrices. Therefore, the memory storage capabilities of most modern computers becomes the restricting factor. However, when one combines the accuracy of the finite element method with the transfer matrix technique introduced by Pestel and Lecke, the core storage requirement is drastically reduced.
Prediction and measurement of the damping properties of graphite-epoxy composites
Authors: Adams R. D.
Published: October 2005

It is possible to predict the moduli of advanced composites from the properties of the fiber and matrix by using micromechanics. It is not yet possible to do this with precision for damping values. Thus, laminate damping values are best predicted from values measured on unidirectional material. It is therefore crucially important that these measured values are reliable and that a suitable technique then be used for predicting the laminate damping. Methods will be described for measuring unidirectional properties in torsion and flexure together with the precautions necessary to ensure accuracy: results will be given. The theoretical technique for predicting laminate damping values will be described and these predictions will be compared with experimental results for the same laminae. Very good agreement has been achieved between theory and practice. [Work supported by Science Research Council, England.]
An improved prediction method for the noise generated in flight by circular jets
Authors: Stone James R. , Montegani Francis J.
Published: October 2005

A semi-empirical model for predicting the noise generated by jets exhausting from circular nozzles is presented and compared with small-scale static and simulated-flight data. The present method is an updated version of that part of the original NASA Aircraft Noise Prediction Program (1974) relating to circular jet noise. The earlier method has been shown to agree reasonably well with experimental static and flight data for jet velocities up to ∼ 520 m/s. The poorer agreement at higher jet velocities appeared to be due primarily to the manner in which supersonic convection effects were formulated. The purely empirical supersonic convection formulation is replaced in the present method by one based on theoretical considerations. Other improvements of an empirical nature have been included based on model-jet/free-jet simulated-flight tests. The effects of nozzle size, jet velocity, jet temperature, and flight are included.
Perceptual information for voicing of postvocalic fricatives
Authors: Soli Sigfrid D. , Lassalle Ann D. , Summers Walter
Published: October 2005

As voicing in a word-final fricative varies, the duration and the internal temporal and spectral structure of a preceding vowel also vary. We examined the importance of vowel structure variations as a fricative voicing cue. Stimuli were prepared by computer editing of vowel nuclei from utterances [jus] and [juz] which lacked final first formant transitions and differed in both vowel duration and structure. Durations were systematically varied from 350–550 ms to produce pairs of vowel nuclei with equal durations and different structures. Duration of unvoiced friction was also varied from 100–250 ms making a total of 40 stimuli. Identification responses to these stimuli by 15 listeners revealed that friction duration was a weak voicing cue, while vowel duration functioned as a much more effective voicing cue, replicating previous findings [P. Denes, J. Acoust. Soc. Am. 27, 761–764 (1955)]. However, vowel structure was also a strong voicing cue, having a greater perceptual effect than 50 ms changes in duration. Acoustic analyses of the experimental stimuli suggested that proportional durations of the formant transitions and total vowel duration together specify voicing information.
Voicing contrast in four-category stop languages
Authors: Lahiri A.
Published: October 2005

Since Lisker and Abramson's cross-language study [Lisker and Abramson, “A cross-language study of voicing in initial stops . . .,” Word 20, 384–422 0964)] VOT has been used to describe voicing contrasts across languages. However, VOT is insufficient to distinguish all stop categories in four-category languages like Hindi and Marathi. Acoustic analysis of word initial stops of 3 four-category languages, Hindi, Punjabi, and Bengali, shows that the feature interrupted voicing differentiates the so-called “voiced aspirates” from the other three categories. These stops are characterized by a pattern of prevoicing followed by approximately 100 ms of silence and then resumed phonation. The other stop categories of these languages are characterized by lead, coincident, and lag VOT.
Anticipatory coarticulation in synthetic speech
Authors: Martin James G. , Bunnell H. Timothy
Published: October 2005

In experiments reported at the last meeting of the Society, we cross-spliced 60 sentence pairs (e.g., I say taezi, I say taeza) at the beginning of the last syllable, then compared recognition time (RT) to the final target vowel /i or a/ in cross versus intact (as spoken) sentences. The resulting slower RT to crossed targets suggested effects of vowel-to-vowel anticipatory coarticulation; that is, misleading information in prior context predicts the other (wrong) vowel in crossed sentences. Acoustical analysis supports this interpretation: F2 in the prior context vowel tends to be higher preceding /i/ than preceding /a/. In the present experiments, /kaezi/ and /kaeza/ were synthesized in three conditions: F2 of /ae/ was (a) “normal,” (b) raised, or (c) lowered. We predicted (compared to normal) slower RT to /i/ when F2 lowered (interference), faster RT to /i/ when F2 rose (facilitation), but vice versa for /a/. In Experiment I, using parameters derived from cepstrum and LPC analysis of real speech, the predicted interference, but not facilitation, was found. In Experiment II, using parameters from synthesis-by-rule, both predicted interference and facilitation were found. [Work supported by NINCDS.]
The time course of vowel context effects
Authors: Nusbaum Howard C. , Sawusch James
Published: October 2005

At previous meetings of the Society we presented evidence for the existence of two different perceptual mechanisms mediating anchor-induced contrast effects found with vowels. Extra presentations of an [i] endpoint to subjects identifying an [i]-[I] series caused changes in sensitivity. Anchoring with [I] produced criterion shifts which were dependent on the availability of auditory memory. Since [i] and [I] differ in tenseness, intrinsic duration in natural speech, and acoustic status (point versus nonpoint), the differences in perceptual effects of these vowels cannot be ascribed to any one factor. To explore the role of these variables in vowel context effects, a number of different vowel series from different parts of the vowel space have been examined using a successive contrast paradigm. In this procedure, a context vowel is presented first, followed at varying temporal intervals by a test vowel. Results obtained using this procedure provide new evidence concerning the perceptual mechanisms underlying vowel anchor effects. Further, the pattern of these results obtained with different vowel series have important implications for theories of vowel perception. [Work supported by NSF and NIMH.]
Vehicle passby sound level time histories
Authors: Bradley J. S.
Published: October 2005

An earlier study of particular vehicles of various types [J. S. Bradley, J. Acoust. Soc. Am. Suppl. 1 65, S66 (1979)], indicated that vehicles are directional radiators of sound in the horizontal plane and that the assumption of a point source was incorrect. The present investigation extended the work to include an analysis of a large number of vehicle passby time histories for various vehicle types to determine how representative the particular results were. Average passby time histories were computed for five different vehicle classifications and compared to predicted values. Results showed deviations from a point source model and varied with vehicle speed. Truck passbys were more symmetrical than those for cars. Average passby Leq values indicated that relatively small traffic noise prediction errors would result from the measured directional effects.
Preference differences among vehicular sounds with equal peak A-weighted sound level
Authors: Cermak G. W.
Published: October 2005

Subjects compared recorded sounds of normal automobiles, “hot rods,” motorcycles, and trucks in order to test the conjecture that the sounds of some vehicles can be more aversive than predicted by standard noise measures. The sounds used were 9 s long and nominally equal in peak dBA level. The sounds of normal automobiles were consistently preferred to most of the other sounds. Subjects also compared sounds of normal automobiles with attenuated sounds of other vehicles; the degree of attenuation required at the point of equal preferability was obtained. This attenuation penalty varied from about 10 dBA for two “hot rods” and a motorcycle to no penalty at all for another putative “hot rod.” Descriptors of average sound level and sound level variability correlated poorly with subjective responses, although D-weighted Leq was the best predictor.
Annoyance ratings and acceptability judgments of traffic noises
Authors: Bauer J. W. , Danner Wm. F. , Yaniv S. L.
Published: October 2005

In order to evaluate the adequacy of several noise descriptors purported to account for the effects of time-varying noise on people, the annoyance of 24 three-minute samples of time-varying traffic noise as heard outdoors, indoors with open windows, and indoors with closed windows were rated by 28 subjects under laboratory conditions simulating a home environment. Included among the noise descriptors were statistical descriptors L10, average sound level Leq, and descriptors that take into account either the variability in the range of levels (NPL) or the rate of change of level with time Leq′, LB. Although correlation coefficients indicated that all descriptors predicted annoyance ratings satisfactorily, more sophisticated statistical analyses revealed that both L10 and Leq predicted annoyance best. An additional finding of this study was that all stimuli below an Leq, of 50 dB were generally acceptable; whereas, those exceeding this level were generally unacceptable to at least 50% of the subjects. All stimuli found acceptable were presented in the closed window condition. [Work supported by DOT/FHWA.]
Acoustic streaming in superfluid helium
Authors: Carey R. F. , Rooney J. A. , Smith C. W.
Published: October 2005

Evidence for the existence of acoustic streaming in superfluid helium has been obtained using a quartz wind transducer configuration operating at 3 MHz. The detection of the streaming and determination of its velocity were made by measuring the deflection of a collimated ion current in liquid helium. The PZT-4 transducer was mounted parallel to the axis of the ion beam and displaced from it. Measurement of the distribution of current along a linear array of small collectors as a function of sound amplitude permitted determination of the streaming velocity. At low amplitudes the streaming velocity increased with the square of the amplitude as predicted by the classical theory for the quartz wind. Above the threshold amplitude for turbulence the streaming velocity increased more slowly but still depended on the square of the amplitude. Evaluation of the rates of increase of the streaming velocity showed that the effective viscosity of the helium was larger by a factor of five above the threshold for turbulence. [This work was supported in part by the Air Force Office of Scientific Research.]
Ultrasonic off-normal imaging techniques for under sodium viewing
Authors: Michaels T. F. , Horn J. E.
Published: October 2005

Methods have been developed for constructing images of objects from ultrasonic data. Feasibility of imaging surfaces which are off-normal to the sound beam has been established. Laboratory results are presented which show a complete image of a typical nuclear reactor core component. Using these techniques, surfaces up to 75° off-normal have been imaged. Details of equipment and procedures used for this image construction are described. The eventual application is imaging of objects under molten sodium in a liquid metal fast breeder reactor.
A contribution towards a model for an artificial voice
Authors: Kuhn George F. , Saner Chris
Published: October 2005

The acoustic pressure amplitudes radiated from the mouth of a storeroom manikin were measured in a 6 cm × 6 cm vertical plane immediately forward of the lips. The sound was produced by an acoustic driver in the manikin's head. The lips were immoveable, forming an approximately trapezoidal aperture with an area of 6.5 cm2. Pressure measurements were made at the 13-Octave band center frequencies from 1.0 to 6.3 kHz. The measured results at 1.25 kHz agree well with the speech measurements at 1.3 kHz reported by Leman [4th Int. Conf. Acoust., abstr. G36 (1962)]. As pointed out by Leman, the spreading of the acoustic wave, on axis, can be described by an ideal point source displaced 1 cm horizontally from the tip of the lips. Below the lips, near the chin surface, the acoustic pressure does not spread spherically. Also, the farfield azimuthal directivity of speech measured by Moreno and Pfretzschner [Acoust. Lett. 1, 78–84 (1979)] is shown to be predicted reasonably well by a point source on a sphere, except in an approximate ±20° sector centered at the shadowed pole. However, the median plane vertical directivity differs from that of a point source on a sphere due to body diffraction. [This work was done while the authors were with the Electrical Engineering Department, University of Wyoming, Laramie, WY 82071.]
A hybrid adaptive procedure for estimation of psychometric functions
Authors: Hall J. L.
Published: October 2005

Adaptive psychophysical procedures that have been described in the literature generally fall into one of two categories. (1) Simple procedures, such as UDTR and PEST, can be implemented without an on-line computer. The decision to change testing level is based on the outcome of the few most recent trials, and the final estimate of threshold is given by the final testing level or the average of a few testing levels. (2) “Maximum likelihood” methods require an on-line computer. A parametric form of the psychometric function is assumed, and after each trial a maximum-likelihood estimate of the parameters of the psychometric function is made on the basis of all preceding trials. This estimate is used to set the next testing level and to estimate threshold. We describe here a hybrid procedure, in which testing levels are determined by a simple procedure, but the final estimate of threshold is made by fitting an assumed psychometric function to all preceding trials. This procedure yields accurate estimates of the parameters of the psychometric function, and it is reasonably insensitive to errors in initial estimates of these parameters. Results of computer simulations and of psychophysical experiments will be presented.
Hearing loss in chinchillas exposed to octave bands of noise centered at 31.5 and 250 Hz
Authors: Burdick Charles K.
Published: October 2005

The purpose of this study was two fold: first, investigate the suitability of using A-weighted intensity levels in damage-risk criteria (DRC); second, determine the frequencies of hearing maximally affected by exposure to low-frequency bands of noise. Two groups of monaural chinchillas were noise exposed for three days: Group 1 and Group 2 were exposed to octave-band noise centered at 31.5 Hz at 120 dB SPL (81 dBA) and 250 Hz at 103 dB SPL (94 dBA), respectively. The peak compound threshold shifts (CTS) were found at 4000 Hz (36 dB) and 2000 Hz (61 dB), respectively, for Group 1 and Group 2. A peak permanent threshold shift (PTS) at 2800 Hz (13 dB) resulted from the 31.5-Hz exposure and a peak PTS at 250 Hz (11 dB) resulted from the 250-Hz exposure. The results indicate high-frequency hearing losses from exposure to these low-frequency bands of noise and that A weighting, at least for the 250-Hz noise band, may be satisfactory for DRC.
A case-control study of the interaction of the aftereffects of illnesses affecting hearing and industrial noise exposure on the hearing sensitivity of workers
Authors: Hétu R. , Lemoine O.
Published: October 2005

What is the contribution of the functional aftereffects of illnesses affecting hearing to the permanent threshold shifts measured among workers exposed to noise? To answer this question, a first case-control retrospective study was undertaken on a population of 965 foundry workers. Samples were recruited from 15 workers or more who reported having suffered from each of the following: mumps, otitis media, sinusitis, or tonsillitis. The subjects selected were paired with controls having the same length of service in the plant but no history of illnesses as established by means of an interview. Results show, for all illnesses studied, that the variance of the age-corrected hearing threshold levels (HTL's) was significantly smaller among the control subjects at 2 kHz and below. Otitis media and mumps were associated with HTL's that were 2 to 5 dB higher than the controls at 0.5 and 1 kHz. The groups representing the effects of sinusitis and tonsillitis had significantly lower HTL's than their controls at 3 kHz and above. The results are discussed in terms of type II error in statistical decisions.
Auditory performance and central nervous system damage
Authors: Divenyi Pierre L. , Signoret Jean-Louis
Published: October 2005

Patients with diverse parietal and/or temporal cortical lesions were tested in two auditory experiments. Among the patients, 17 had predominantly left- and four predominantly right-hemispheric lesions; all but three of them had exhibited some degree of expressive and/or receptive aphasia. One further subject had bilateral sylvian lesions and had been diagnosed as having bilateral cortical deafness. The first auditory task consisted of detecting, in a 2AFC situation, the presence of a 100-ms sinusold presented in bandlimited pink noise. The frequency of the tone was fixed (500 or 1500 Hz) in some blocks, while, in other blocks, it was uncertain (500 Hz/1500 Hz). For most subjects, the threshold increase in the uncertain-frequency condition over the fixed-frequency condition was nearly normal (3–6 dB). For some aphasic patients, however, this increase was much larger. In the second experiment, the subjects had to discriminate the direction of a 23-octave linear frequency sweep presented at various rates. Here, thresholds of only a small number of aphasic patients approached those obtained for inexperienced normal control subjects (∼20 ms/sweep): the threshold obtained for some patients was as high as 250 ms. These results indicate the important role that the left hemisphere plays in auditory functions involving close monitoring of spectral changes in the stimulus, especially rapid ones. [Supported by the Veterans Administration and by INSERM, France.]
Empirical method for prediction of business executive jet cabin noise levels
Authors: Moses Nissim M. , Roziner Tanya
Published: October 2005

As a result of flight noise measurements made at various locations in the cabin of the standard lined/no interior Westwind model 1124 business executive jet, it was possible to develop an empirical method for predicting the overall sound pressure level and the 13rd octave band spectrum level at any required location in the cabin. The cabin overall sound level in dB (linear) may be found from nomographs related to aircraft altitude, Mach number, or velocity. The noise spectrum at any location may be found from a reference spectrum shape corrected for local parameters. The paper further presents computer programs for the TI-58 calculator for the generation of the nomographs. The accuracy of the prediction method when verified with additional test performed was found to be ± 1 dB.
Impaired listeners' discrimination of speech presented dichotically through high- and low-pass filters
Authors: Haas Gustav F.
Published: October 2005

Fifty-word phonetically balanced word lists were presented to hearing-impaired subjects dichotically, with the signal going to one ear high-pass filtered above 780 Hz (HP), and the same signal simultaneously presented to the other ear through a low-pass filter with the same cutoff frequency (LP). Performance with this split-signal presentation was compared to both unfiltered diotic and HP diotic presentations. The split-signal scheme did not show a significant advantage over both the unfiltered and HP diotic presentations in any of the 22 impaired subjects tested; in one subject it showed a significant disadvantage. Group differences were near zero for 16 subjects tested at the presumed maximum of their performance-intensity function and showed only a weak (insignificant) advantage for the split-signal scheme over the unfiltered presentation when the most comfortable level and the best of three filter cutoff frequencies were chosen individually for six subjects. The conclusion was drawn that the split-signal presentation neither increases nor decreases word discrimination scores at relatively high levels in quiet in a predominantly older population.
Methods for controlling wheel/rail noise in urban rail transit
Authors: Kurzweil Leonard G.
Published: October 2005

Numerous methods for controlling the noise resulting from steel wheel/steel rail interaction on urban rail transit systems have been examined. For each technique, the acoustic performance, costs, and compatibility with transit operations have been summarized. Several innovative techniques are discussed and requirements for future work are presented. [Work supported by the Urban Mass Transportation Administration.]
Use of boundary magnitude information based on syntactic condition in the development of pitch control
Authors: Umeda Noriko
Published: October 2005

Under an assumption that boundary forms a continuum in magnitude rather than a dichotomy (presence or absence), a perception experiment in which listeners detected a boundary signal in running speech was conducted. The result indicated that there was a positive correlation between the number of listeners perceiving a boundary signal and the duration of the word prior to the boundary. A detailed data analysis showed that syntactic condition was one of the dominant factors determining the magnitude of a boundary between two words. A variety of syntactic conditions were classified into five groups according to boundary magnitude. Group I (the highest): between clauses, between nouns and their appositions, etc. Group 2: between nouns and modifying clauses headed by “that” or by a preposition plus a relative pronoun, between introductory prepositional phrases and the subject. etc. Group 3: between the subject-noun and the predicate-verb, between nouns and modifying prepositional phrases, etc. Group 4: between adjectives and nouns in noun phrases, between verbs and prepositional phrases, etc. This boundary magnitude information leads to a pitch control with different degrees of phrase termination which produces a desirable variety in intonation for longer sentences and paragraphs in synthetic speech.
Durational cues to phrase boundaries: foot lengthening versus phrase-final lengthening
Authors: Scott Donia R. , Darwin C. J.
Published: October 2005

The prosodic importance of the foot or interstress interval is assessed by experiments in which subjects are asked to judge the phrase structure of sentences such as “Pat or Antonia and Dave will help.” In such sentences a syntactic boundary may occur in the middle rather than at the end of a foot. Lengthening the whole foot produced identical perceptual results to lengthening the phrase-final vowel and subsequent pause by the same total amount. However, simply lengthening that part of the foot that occured after the phrase boundary was not as effective at influencing listeners' judgments as was lengthening only the phrase-final vowel (and pause). Both the interstress interval and the duration of syllables within the foot influence listeners' judgments of phrase boundary position.
Rough surface backscatter with secondary diffraction and without Kirchhoff approximation
Authors: Medwin H. , Novarini J. C.
Published: October 2005

The backscatter from a randomly rough, long-crested surface has been restudied by using the closed-form Biot-Tolstoy solution for wedge diffraction [J. Acoust. Soc. Am. 29, 381–391 (1957)] as a building block in the description of the ocean surface. A delta function point source is assumed and the computer adds the facet impulse reflections to the wedge impulse diffractions for the sequence of wedges that closely approximates the surface. This total impulse solution is then transformed to the frequency domain for calculation of backscattering cross section, coherence, etc. The technique permits the identification of the contributions of facet reflection, diffraction, and secondary scatter as functions of sound frequency and angle of incidence. Results are compared with our previous publication [J. Acoust. Soc. Am. 64, 260–268 (1978)] in which only primary diffraction of facets was considered and the Kirchhoff approximation was accepted. [Research supported by ONR.]
On the frequency dependence of the backscattered field from randomly rough surfaces
Authors: Welton P. J.
Published: October 2005

In this paper, we investigate the relationship between the physical characteristics of randomly rough surfaces and the surface roughness spectrum (i.e., wavenumber spectrum). This spectrum is important because at low grazing angles (i.e., far from normal incidence), the backscattered field is proportional to the surface roughness spectrum. Consequently, both the frequency dependence and the level of the backscattered field are determined by the surface roughness spectrum. [Part of this work was performed at the University of Paris VII, Paris, France.]
Discovery of a sunken vessel by parametric sonar
Authors: Konrad W. L. , Clay W. L.
Published: October 2005

During evaluation of a parametric sonar at the Seneca Lake Facility of the Naval Underwater Systems Center, a very strong and discrete sonar return was observed on the mud bottom at a range of 2000 m. Subsequent use of a conventional side-scan sonar and high-resolution parametric depth sounder suggests the target is a barge which sank during the latter half of the 19th century. The output of the various sonars used are presented as “A” scan photographs and line scan recordings.
Acoustic intensity measurements of transient noise sources
Authors: Fahy F. J. , Elliott S.
Published: October 2005

The theoretical background to the measurement of sound energy flow generated by transient sources, such as impact machines, will be presented. Various means of implementing the estimation process will be discussed and reference will be made to the problems of field measurement. Results of measurements made on a drop forge and other impulsive sources will be presented. It will be shown that directly radiated and reverberant sound can be satisfactorily separated.
Effect of rise/decay time on phase detection in lateralization
Authors: Kunov Hans , Abel Sharon M.
Published: October 2005

Experiments in lateralization were performed to evaluate the relative contribution of onset and phase cues in the integration of binaural signals. A 1-kHz signal was presented with interaural stimulus delays ranging from 0–100 μs, i.e., phase shifts of 0–360°. For a given value of delay, the leading signal was presented randomly to the right or left ear over a block of 100 trials, and the laterality of the resultant image was judged. The probability of a correct response was plotted as function of delay with rise time as a parameter. Particular attention was paid to the trade-off between phase and onset in the region of phase shifts from 180° to 360°. It was noted in particular, that the onset cue was eliminated only for rise times in excess of 500 ms, and that there were wide individual differences in the use of the two cues. [Work supported by Natural Sciences and Engineering Research Council, Canada.]
Acoustic intensity measurements of the sound power of a truck
Authors: Pope J. , Hickling R. , Feldmaier D. A.
Published: October 2005

An indoor method of measuring the sound power of a truck is described in which acoustic-intensity measurements are made over a hypotheoretical “shoe-box” surface enclosing the truck in the near field and integrated to obtain the total radiated sound power. Tests were run on a quieted dynamometer roll at three different speeds. The same vehicle was tested on two separate occasions, two months apart. Excellent repeatability was obtained, typically ±2% in the sound power in watts. Tests were run both in a semi-anechoic environment and with boards covering up the acoustically absorbing material on the walls, with negligible effect on the sound power measurement.
Surface intensity measurements on a diesel engine
Authors: McGary Michael C. , Crocker Malcolm J.
Published: October 2005

The use of surface intensity measurements as an alternative to the conventional selective-wrapping technique of noise source identification and ranking on diesel engines was investigated. A six-cylinder, in-line, turbocharged, 350 horsepower diesel engine was used. Sound power was measured under anechoic conditions for eight separate parts of the engine at steady-state operating conditions using the conventional technique. Sound power measurements were repeated on five separate parts of the engine using the surface intensity technique at the same steady-state operating conditions. The results were compared by plotting sound power level against frequency, overall sound power level, and noise source rankings for the two methods. A specialized piston-tube experiment was developed to alleviate the phase shift problems encountered with the surface intensity method by earlier researchers. The results of the experiments demonstrate that the surface intensity method is a viable alternative to the selective-wrapping technique. Further experiments using the two-microphone acoustic intensity technique are being made for comparison with the surface intensity results.
Measurement of sound power of closely spaced sources
Authors: Seybert A. , Imredy J.
Published: October 2005

In this paper we discuss the application of the acoustic intensity method to the identification of sources in semi-reverberant environments. The results of an experiment will be presented in which the acoustic intensity method was used to quantify the sound power of two closely spaced sources. The sources were uncorrelated initially, but subsequent tests were conducted in which correlated sources were used. An attempt was made to estimate the sound power level of each source in a semi-reverberant environment at various distances from the sources. Potential sources of error due to reverberant field contamination are discussed.
Radiation and attenuation of waves in a random medium
Authors: Wenzel Alan R.
Published: October 2005

A theoretical analysis of the wavefield radiated by a point source in a weakly inhomogeneous one-dimensional random medium is presented. The analysis is based on a perturbation technique, and includes all single- and double-scattering terms, as well as some scattering terms of higher order. An expression for the mean intensity (i.e., the mean square of the modulus of the complex wave amplitude) of the wave as a function of source-receiver distance, or propagation distance, has been obtained. This expression shows that, inside a certain region of space containing the source, the mean intensity of the wave is increased by the randomness of the medium, whereas outside of this region it is decreased. The result of this redistribution of mean intensity in space is a more rapid rate of decrease of the mean intensity (or the log of the mean intensity) with propagation distance than would be the case in the absence of randomness, which can be interpreted as an excess attenuation of the wave as a result of the randomness of the medium. The relation of the present theory to previous theories of attenuation of waves by randomness, or turbulence, is briefly discussed. [Work sponsored by NORDA.]
Wavefield behavior at optimum pass-through frequency in an inhomogeneous, lossy, arbitrary, medium
Authors: Akers G. R.
Published: October 2005

A variational method is employed to develop the wavefield form at optimum pass-through frequency for propagation in an inhomogeneous, lossy, arbitrary medium. The variation is taken with respect to wavenumber of an integral for the composite wavefield over all harmonics of frequency. The necessary and sufficient conditions that the integral remain stationary arise in the form of analogous counterparts of the Lagrange equations of motion of mechanics carried over into general wave propagation. Solving the partial differential equation in Lagrange form for wave propagation, and examining the solution in the far field, one arrives at the attenuation order interaction coefficients for the optimum passthrough frequency. From this, the general displacement wavefield is obtained which shows the optimum pass-through frequency waveform to be somewhat more slowly oscillatory than the general formulation, as well as possessing less distortion and attenuation.
The behavior of weak shock waves near focal points and caustics
Authors: Obermeier Frank
Published: October 2005

The paper is concerned with the theoretical description of focusing weak, N-shaped shock waves. The shock rise times of the incoming shock fronts are assumed to be very small, but finite. Furthermore, focusing is assumed to be caused by only slightly concave wave fronts. The functional correspondence of refraction effects included already in a linear wave theory and steepening effects described by nonlinear wave theories are discussed in details by singular perturbation methods. Preliminary numerical evaluations of the resulting implicit solution agree well with known experimental data.
Distribution of aspartate and glutamate in cochlear nucleus (CN) following destruction of organ of Corti (OC)
Authors: Thalmann R. , Comegys T. H. , Thalmann I. , Webster D. B.
Published: October 2005

Webster and Webster [ORL 86, 342 (1978)] have shown that degenerative changes in the CN are maximal three weeks after surgical destruction of the OC in the guinea pig. A1 this time aspartate and glutamate are reduced by 28% (p < 0.05 or better) and 19% in the anteroventral CN, and 25% and 23% in the posteroventral CN, respectively, when compared to the opposite, nonoperated side. Both regions receive heavy primary innervation. Only minimal changes occur in the molecular and fusiform layers of the dorsal CN, regions receiving little primary innervation. In the deep dorsal CN, with moderate innervation, aspartate and glutamate are reduced by 13% and 10%, respectively. These results support the concept that these substances may be involved in primary afferent transmission in the CN. By comparison, aspartate and glutamate are only 17% and 11% lower in the whole CN of 90 day old Waltzing guinea pigs (a mutant in which the OC degenerates within several weeks after birth) than in controls [Wenthold and Gulley, Brain Res. 158, 295 (1978)]. Subdivision of the CN should show changes closer to those following surgical destraction of the OC. [Supported by NIH.]
Consonant discrimination as a function of presentation level in hearing-impaired listeners
Authors: Gutnick H. N. , Kent R. D.
Published: October 2005

Computer-synthesized consonants in two vowel contexts, /a/ and /i/, were presented in CV form to normal-hearing listeners and hearing-impaired listeners having a high-frequency sensorineural loss. The CV's were presented at 10 to 65 dB SL. The performance of the consonants comprising each of 11 a priori acoustic-phonetic features improved directly with increases in sensation level for both subject groups, but was better in the /a/ than in the /i/ vowel context. The performance of the hearing-impaired listeners was significantly poorer than the performance of the normal-hearing listeners only for the features characterized by higher-frequency energy. The lower-frequency features of voicing and sonorance were transmitted in the errors of the hearing-impaired listeners at sensation levels of 10 and 20 dB; only at 35 to 65 dB were higher-frequency features transmitted in errors of the hearing-impaired group. The question remains as to whether low-frequency energy suppressed the emergence of high-frequency features at the lesser presentation levels.
Perception of frequency lowered consonants
Authors: Lippmann Richard P.
Published: October 2005

A new real-time frequency lowering system for use by persons with high-frequency hearing loss was evaluated. In this system speech levels in various high-frequency bands control the levels of low-frequency 13 octave bands of noise. These noise bands are added to unprocessed speech at a level that does not significantly mask normal low-frequency speech information. The lowered signal contains spectral and temporal information concerning speech cues at high frequencies. This signal is perceived as speech-like but perceptually distinct from low-pass filtered speech. Consonant discrimination and identification by normal hearing naive subjects was measured. Frequency lowered and unprocessed speech materials were low-pass filtered at 800 Hz and presented to subjects in a wide-band noise background (S/N = 20 dB), to simulate some of the characteristics of a sensorineural hearing loss. Performance of frequency lowering systems with different high- and low-frequency bands was evaluated. In preliminary experiments one configuration of the above system improved consonant discrimination and identification by roughly 10% correct. Most of this improvement was related to improved perception of acoustic cues for the duration and affrication features specified by Miller and Nicely. [Work supported by NIH.]
Spectrographic analysis of hearing aid and nonhearing aid transduced speech
Authors: Owen Jeffrey H.
Published: October 2005

A large proportion of hearing aid recommendations result in dissatisfied hearing aid users. Efforts to reduce the number of dissatisfied users have centered around modifications of hearing aid evaluation procedures. However, a second source of user dissatisfaction may be the hearing aid itself. To determine what effects the hearing aid has upon a signal, spectrographic analysis of hearing aid and nonhearing aid transduced speech was conducted. Speech samples consisted of sentences spoken by female and male speakers who spoke with a General American Dialect. Speech stimuli were presented at 50 dB HTL in quiet and at 0, +10, and +20 dB signal-to-noise ratios. The competing signal was speech noise. Certain characteristics of the resultant spectrograms will be discussed, including fundamental frequency and formant structure/composition of the speech signal. Additionally, the effects of noise and hearing aid frequency response on the recorded speech formants will also be addressed.