bluuebunny/crossref_metadata_2025 huggingface dataset:
Formant tracking algorithm for a speech analysis-synthesis system
Authors: Seeviour P. M. , Holmes J. N. , Judd M. W.
Published: October 2005

A formant tracking algorithm has been developed to provide control signals automatically for a parallel formant speech synthesizer. In voiced sounds, the algorithm first estimates positions of high-energy excitation in the sampled speech waveform to be analyzed. These positions generally correspond to the points of glottal closure, and the interval following each position should correspond to a closed glottis region. For each such position the speech samples in the following few milliseconds are used to calculate a log power spectrum. An analysis-by-synthesis procedure iteratively updates estimates of formant frequencies and amplitudes using spectral matching criteria. A similar spectral-matching procedure is used during unvoiced sounds, but time averaging is introduced as appropriate when deriving the spectra to be matched. To cope with situations when the formant structure is not clearly defined in the power spectrum the iteration is performed separately for several different allocations of formants to spectral peaks. A final choice of formant frequencies and amplitudes is made every 10 msec and depends on both goodness of spectral match and continuity of formant tracks. Demonstrations will be made of the speech quality achieved for a number of male talkers.
Determination of loss coefficients by a direct frequency measurement method
Authors: Cuomo F. W.
Published: October 2005

The resonance method has been widely used in the determination of the damping properties of viscoelastic solids in the 100–10 000-Hz range and loss coefficients have been obtained either by the experimental observation of the decay modulus or the half-power bandwidth of each resonant peak. Both these methods frequently make use of a level recorder in the experimental arrangement whose writing speed becomes a factor in the accuracy of the measurements. This paper discusses another method whereby the direct frequency measurement of the velocity and displacement amplitudes at resonance is utilized, the difference between these frequencies being a measure of the loss coefficient in the sample. Experimental data is presented to illustrate this technique, which is useful for loss factors as low as 0.01 and frequencies approaching the dynamic range of the resonant mechanical system.
Use of a microstructure theory for modeling steady-state wave propagation in layered elastic materials
Authors: Bedford A. , Sorensen A. L.
Published: October 2005

Continuum theories with microstructure have been shown to be capable of modeling the dispersion behavior and displacement and stress mode shapes of the lowest propagation modes in a layered elastic material [D.S. Drumbeller and A. Bedford, Int. J. Solids Struct. 10, 61–76 (1974)]. A second-order microstructure theory has been used to solve the problem of a layered half space subjected to steady state displacement and stress boundary conditions by modal superposition using the minimum-square-error and variational solution procedures described by Wu and Plunkett [C.-H. Wu and R. Plunkett, SIAM J. Appl. Math. 15, 107–119 (1967)]. When the solutions were compared to solutions obtained by superpositions of the exact Postma-Rytov modes for the layered material, it was found that, for frequencies below the cutoff frequency of the first optical mode, the microstructure theory predicted the displacement and stress distributions in the material to within a few percent. An important finding is that, due to resonance effects, stresses in the material can substantially exceed the imposed boundary stresses. [Work supported by NSF.]
Structural damping from random data
Authors: Abrahamson A. L.
Published: October 2005

The usual method of fitting circles to transfer function peaks in the complex plane while yielding reliable estimates of modal damping, is laborious to implement manually and difficult to automate unambiguously. This paper outlines an approach to increasing the efficiency of this operation by combining the topological abilities of a human operator with the numerical power of a computer through an interactive visual display. Transfer functions obtained from structural tests using random acoustic excitation are readily analysed to yield modal damping using this system. [Work performed at the British Aircraft Corporation, Weybridge, Surrey, England.]
Quantifying the impact of a community noise environment
Authors: Galloway William J.
Published: October 2005

In analyzing the relative merits of alternate noise control strategies, such as alternate highway designs, airport locations, or noise control regulations, it is desirable to have a single number quantifier of the effect on public health and welfare expected from the noise environment. This paper describes such a measure, based on the summation of populations exposed to different noise exposures, and the relationships between expected response to these exposures. Each increment of population is assigned a fractional impact depending on the magnitude of the exposure. The sum of fractional impacts is then defined as the equivalent noise impact, the fraction of the total population “100% impacted.” Residential populations are assessed in terms of relationships between annoyance and day-night average level, while nonresidential populations are assessed in terms of relationships between speech interference and hourly equivalent sound level (EPA “Levels” document 550/9-74-004). Applications of the method to a highway case and to a proposed aircraft noise regulation are described.
Noise abatement through band-use planning
Authors: Winzer George E.
Published: October 2005

Land-use planning is often used as a technique for achieving a suitable auditory living environment. Land use alone, however, cannot be the sole noise abatement measure; noise control at the source combined with compatible land-use planning can be most effective. Noise abatement strategies for planning in the environs of airports include operational changes, schedule restrictions, aircraft type restrictions, technological change, airport system change, traffic demand change, encouraging compatible land use, public use, relocation of incompatible use, sensitivity changes, airport environs planning, compensation legal action, regulation and administrative mechanisms, economic incentives, and information. Relative effectiveness and time effectiveness horizons of each are discussed. Alternate means of reducing conflicts between noise sources and surrounding activities are outlined. Implementation of noise abatement strategies and obstacles to implementation are addressed. Ten U.S. airports were studied, including several involved in the Metropolitan Aircraft Noise Abatement Policy Studies (MANAPS) jointly funded by the Department of Transportation and Department of Housing and Urban Development, in order to determine which noise abatement policies and strategies could be most productive.
Low-frequency negative bottom loss: An effect of the ocean-bottom acting as a focusing mechanism
Authors: Santaniello S. R.
Published: October 2005

Ocean bottom reflectivity is generally described by a single function, the reflection coefficient (R), defined as a ratio of reflected-to-incident intensities; −10 log(R) is bottom-reflection loss. Measuring bottom-reflection loss within the constraints of the definition is virtually impossible. In practice it is estimated by (1) measuring propagation loss of acoustic pulses transmitted via the path which interacted once with only the bottom, (2) calculating the water-region propagation loss only for an idealized bottom-reflection path by assuming a flat, single-interface bottom having a reflection coefficient of one, and then (3) comparing (measured minus calculated) values. This estimate is called bottom loss. The above assumption inherently ignores subbottom refraction and reflection of sound; important effects at low frequencies (<500 Hz). Sound returning from the subbottom can constructively interact with sound reflected from the water-sediment interface, yielding “negative bottom loss” results. This paper presents such results (obtained using a self-calibrating bottom-loss measurement technique) and suggests that the ocean bottom, by refracting 2nd reflecting sound, can partially focus energy over a considerable volume within the ocean. Three following companion papers discuss aspects of this premise. [This work was sponsored by Naval Sea Systems Command, SEA 06H1-4, A.P. Franceschetti.]
Bottom slope determinations: Differences in methods
Authors: Jaques A. T.
Published: October 2005

In an area on the continental rise off the west coast of Florida, conventional 12-kHz precision depth recorder (PDR) data show regional bottom slopes, taken over distances of about 1 mile, to be less than ± 0.05°. However, sound in the frequency range from 2 to 4 kHz reflected from the bottom at oblique angles indicates a regional slope of about 1°. Slope determinations in the latter case were derived from acoustic travel times, travel time differences, and arrival angles of the sound at the receiver, all independent determinations. These results suggest that for the 2–4-kHz sound, reflections do not take place from the interface outlined by the PDR but from a sublayer inclined slightly to the horizontal.
Normal modes of a compound string
Authors: Windham Betty , Rossing Thomas D.
Published: October 2005

A partially unwrapped string on a guitar provides a simple demonstration of overtones which are not harmonics of a fundamental. The modes of vibration can be predicted from solving the wave equation, but a simpler solution may be obtained by the application of transmission-line theory. The measured frequencies are found to agree closely with the predicted ones. This constitutes a novel and instructive experiment for an intermediate laboratory in acoustics.
Acoustic transmission in shallow waters off the East and Gulf Coasts of the United States
Authors: Tulko T. J.
Published: October 2005

Acoustic transmission tests were conducted at a number of widely spaced locations off our East and Gulf Coasts during the month of September. This is the time of year when the greatest temperature difference between top and bottom of the water column would be expected. The results are presented as transmission loss versus range in various octave bands for paths parallel and perpendicular to the depth contours. In these series of tests, the sources were explosive charges at 60 and 300 ft and the receiver (sonobuoy hydrophone) depth was 60 and 300 ft. Comparisons of these results with similar shallow water transmission-loss results are made. [Work supported by Naval Air Systems Command, Code AIR-370.]
Project ANZUS Eddy: Acoustic measurement of a warm core ocean eddy
Authors: Nysen Paul A. , Scully-Power Paul , Browning David G. , Bannister Richard W.
Published: October 2005

Project ANZUS Eddy is a joing program by scientists in Australia, New Zealand, and the United States to study ocean eddies. In March 1975, direct measurements were made of the acoustic properties of a warm core eddy off the east coast of Australia. This typical summer type eddy, 150 km in diameter, was characterized by two acoustic ducts; a 40-m surface duct and a deeper, much lower sound speed, eddy duct which extended over the depth interval 130–310 m. Explosive sound sources were detonated in each duct, at uniform intervals, whilst opening range from a vertical line array of hydrophones suspended at the center of the eddy. Strong acoustic coupling was exhibited between the two ducts, with near-surface sound energy being trapped in the eddy duct, usually after one surface reflection. This coupling was highly frequency dependent, being strongest in the band 100–160 Hz. Both ducts demonstrated low frequency cut-offs in conformity with classical acoustic waveguides. [This work was in part supported by the Office of Naval Research, Code 480, under contract N00014-75-WR50209.]
Travel time in the guinea pig cochlea: Another look
Authors: Schmiedt R. A. , Zwislocki J. J.
Published: October 2005

Magnitude and phase of CM recorded with differential micropipettes in scalae media and tympani in the basal turn and corrected for cochlear travel time agree with available mechanical measurements of the middle-ear transfer function up to 4 kHz. Above 4 kHz, the CM magnitude decreases relative to the mechanical measurements. According to M.W. Cannon Jr., an RC-filter effect in the cochlea accounts for the CM rolloff. When the effect is corrected for, the CM phase and magnitude agree with those measured mechanically from 0.1 to 10.0 kHz. Cochlear travel times inferred from CM phase corrected for middle-ear and RC-filter effects agree with those derived from available capacitive-probe measurements, when the latter are corrected for the effect of draining scala tympani. According to Zwislocki, draining one scala increases the wave velocity by √ when both scalae have equal cross-sectional areas. The travel times are 2.8 times shorter than those predicted from Békésy's measurements of basilar-membrane compliance in dead guinea pigs, indicating a maximum phase velocity of 118 m/sec in the base.
Estimation of the cochlear microphonic response to a tone by Fourier transformation of the response to a click
Authors: Altmann D. W. , Weiss T. F.
Published: October 2005

The cochlear potential (CP) in response to a tone or a click is a mixture of components that includes the cochlear microphonic (CM) and neural response. Since CM is approximately linearly related to sound pressure at the tympanic membrane (Pd), the spectrum of CM in response to a click is expected to resemble the frequency dependence of CM response to a tone. The frequency dependence of CP response to a tone was measured at the round window in cats. Averaged CP responses to acoustic clicks were also measured and Fourier transforms computed. For a range of stimulus levels, the frequency-dependent transfer ratios (CP/Pd) computed from tone and click responses were roughly equal in the range 3–20 kHz. The transfer ratios were roughly equal in the range 0.8–20 kHz when the neural component of the averaged click response was reduced by using high repetition rate clicks and masking noise as the stimulus. [Supported by NIH grants.]
Outer hair cells do produce the preponderance of receptor potentials
Authors: Dallos Peter , Cheatham Mary Ann
Published: October 2005

Numerous experiments [e.g., Davis et al., Laryngoscope (1958); Dallos and Wang, Audiology (1974)] in which outer hair cell damage is accompanied by good preservation of inner hair cells, have indicated that, in such cochleas, the CM is suppressed by 30–40 dB. The conclusion drawn from such results was that outer hair cells generate a very large fraction of the recorded CM, and that in fact in a normal cochlea the CM is determined by the output of the outer hair cells. While these experiments are very suggestive, a direct confirmation of the dominant role of outer hair cells in CM production has been lacking. What is required for such confirmation is recording from cochlear regions that are denuded of inner hair cells. We are now reporting on such experiments. With very massive doses of kanamycin one can achieve a pattern of hair cell degeneration in the guinea pig's cochlea, whereby only outer hair cells remain in the fourth (apical) turn, and whatever inner hair cells are preserved are confined to more basal regions. Recordings of CM and SP from the scalar media of the fourth turn of such cochleas is compared to data from normal preparations. While many animals are seen to have severely depressed responses, several possess essentially normal receptor potentials. This finding tends to confirm the suggestion that outer hair cells are the primary source of the cochlear receptor potentials; both CM and SP. [Supported by grants from the NINCDS.]
Inferred response polarities of inner and outer hair cells
Authors: Sokolich W. G. , Hamernik H. P. , Kwislocki J. J. , Schmiedt R. A.
Published: October 2005

Responses of single fibers, produced by trapezoidal deflections of the basilar membrane, were recorded from the auditory nerves of kanamycin-treated gerbils. Fibers typically having elevated thresholds were excited during motion and/or sustained displacement of the basilar membrane in the same direction, and were classified as either scalar-vestibuli (SV) or scala-tympani (ST) excitatory. Fibers having normal or nearly normal thresholds showed the same complex response patterns as fibers of untreated gerbils, and were classified as normal. With the help of a frequency-distance map of the gerbil cochlea, the response of each fiber was associated with the region of its inferred innervation. Our correlations show that all fibers innervating cochlear regions containing only inner hair cells were SV-excitatory, whereas fibers innervating cochlear regions containing full or nearly full complements of both inner and outer hair cells were either SI-excitatory or normal. The findings support the polarity-opposition model of interaction between inner and outer hair cells.
Phenomenological characterization of two-tone suppression
Authors: Sachs Murray B. , Abbas Paul J.
Published: October 2005

We have previously reported on the relationship between auditory-nerve fiber discharge rate and parameters of two-tone stimuli in cases where two-tone suppression was produced. We have pointed out that there are significant differences between the cases where the suppressing-tone frequency (f2) is less than fiber CF and the case where it is greater. For example, if the ratio of the CF- and suppressing-tone levels is held constant, two-tone rate is a monotonic function of overall stimulus level for f2 > CF, but it is typically nonmonotonic for f2 > CF. In this paper we consider a model for relating stimulus parameters and discharge rate. The last stage in the model is a saturating nonlinearity. For single tone stimuli the input to this nonlinearity is a function of tone level and frequency. For two-tone stimuli, the input to the nonlinearity is attenuated by a factor which depends only on the suppressing-tone level and its frequency. The parameters of the model can all be extracted from our data. The model fits our previous results well. In the model, the differences between high- and low-frequency suppression result from differences in the rate of change of the attenuating factor with suppressing-tone level, which we have reported previously. [Supported in part by the National Institutes of Health and the Air Force Office of Scientific Research.]
Spatial differentiation as an auditory “second filter”: Assessment on a nonlinear model of the basilar membrane
Authors: Hall J. L.
Published: October 2005

The mechanical tuning of the basilar membrane does not appear to be sharp enough to account for frequency selectivity of primary auditory nerve fibers. Various “second filters” have been proposed to provide the required sharpening. We have studied the properties of one such mechanism, spatial differentiation of membrane displacement, on a nonlinear computational model of the basilar membrane. Because the wavelength in response to a tone decreases as the wave travels from base to characteristic place, differentiation produces sharpening resembling the difference between mechanical and neural tuning. Phase (as a function of frequency) of the spatial derivative is similar to phase of the displacement, but frequency selectivity (amplitude as a function of frequency) for frequencies below the characteristic frequency is sharpened. In addition, spatial differentiation provides the distinction between mechanical nonlinearity (related in the model to membrane velocity), and neural excitatory signal required to account for suppression of response to a tone at the characteristic frequency fc by a second tone at a lower frequency fs. Without this distinction, a tone at fs intense enough to suppress the component of response at fc would itself introduce a large component of response at fs.
Two simulus N1 depression
Authors: Norris Charles H. , Guth Paul S. , Daigneault Ernest A.
Published: October 2005

Two-stimulus N1 depression is the descriptive name for the reduction in the N1 component of click-evoked VIII nerve action potential (AP) amplitude produced by a preceding tone-burst or click. The cochlear microphonic potential (CM) is unaffected. This phenomenon has no latency and can be demonstrated out to about 200-msec interstimulus intervals. An attempt was made to delineate the locus at which the inhibition occurs. Two-stimulus N1 depression is unchanged by VIII nerve section and by nerve section plus strychnine. These experiments indicate that the inhibition occurs within the temporal bone and that the olivocochlear bundle is probably not involved. An initial antidromic electrical stimulation of the cut VIII nerve does not produce inhibition of the AP generated by a succeeding click. This may be taken as evidence that an axon reflex mechanism, an ephaptic interaction or an interneuronally-mediated inhibition is not responsible for the inhibition. These experiments then, by elimination, leave the site of inhibition at the point between the generation of CM and the generation of AP. [Work supported by NIH 1RO1 NS 10312 01A2 and Veterans Administration New Orleans, LA.]
Masking of tone glides
Authors: Nábělek Igor V.
Published: October 2005

Masked thresholds of tones (1) changing linearly in frequency from 1000 Hz to 900, 500, and 250 Hz, respectively, and (2) constant in frequency at 1000, 500, and 250 Hz, respectively, were measured as a function of burst duration. The burst duration changed from 5 to 500 msec, the sound pressure level of the masking white noise was 70 dB. Listeners had normal hearing. The faster was the glide the higher was its threshold value. The masked threshold values at 20 and 100 msec burst duration increased in the following order: 500, 250, 1000, 1000–900, 1000–500, and 1000–250 Hz with approximately 5-dB total span. These results will be discussed in terms of auditory temporal integration. [Work supported by NIH Biomedical Sc. Sup. Grant from the GRSB, DRR, BHPEMT.]
Psychophysical tuning curves in forward masking
Authors: Wightman F. L. , Kramer M. B. , McGee T.
Published: October 2005

Using a two-interval forced-choice detection paradigm with fixed signals and variable maskers, we have obtained psychophysical analogs of neural tuning curves. The signal was a 20-msec burst of a 1000-Hz sinusoid, presented at several fixed levels and temporal positions relative to a 200-msec pure-tone masker. Masker intensity was varied according to the PEST procedure to determine the masker intensity required for 75% correct detections of the signal. This required masker intensity was measured as a function of masker frequency to produce the so-called “tuning curves.” With a low-level signal (10 dB SL) presented 10–30 msec after termination of the masker, the tuning curves we obtained were quite similar to those from other psychophysical and physiological experiments, showing the usual asymmetry and values of Q10 dB from 5 to 7 depending on the subject. As signal level was increased (to 30 dB SL) or as the masker-signal interval was increased, the tuning curves become very broad (Q10 dB ≈ 2). When the signal was presented simultaneously with the masker (30 msec before masker termination), the high-frequency skirt of the tuning curve became considerably shallower, but the low-frequency skirt was unaffected. This latter result, we believe, reflects lateral suppression of the signal by the masker. [This research was supported by Grant NS 12045 from NIH.]
Perceptual masking of spondees by combinations of talkers
Authors: Carhart R. , Johnson C. , Goodman J.
Published: October 2005

Masked threshold for spondees were obtained in (1) steady-state speech spectrum noise, (2) speech spectrum noise modulated by seven talker combinations, and (3) the seven talker combinations. These combinations were 1, 2, 3, 16, 32, 64, and 128 voices speaking continuous discourse. The longterm spectra of all maskers were equalized to a common level by averaging their intensity disparities across the 20 AI bands that contribute to intelligibility. Subsequent excesses in masking by a talker combination over masking by the companion condition of modulated noise are attributable to centrally mediated interference arising because the speech masker and the target signal are more perceptually similar than the target and the modulated noise are. This interference, which we have termed perceptual masking, appeared in the presence of all seven combinations of voices. It averaged 6.2 dB with the one talker and 7.2 dB with the two-voice background. The maximum (9.8 dB) was reached with three talkers. Thereafter it decreased, stabilizing at about 3 dB with 64 talkers. [Supported by NINCDS, NS-09442.]
Parasitic noise from probes and struts in flow
Authors: Hoglund L. , Siddon T. E.
Published: October 2005

When a pressure probe or other obstructing sensor is inserted into a flow for diagnostic purposes, several mechanisms are possible for the generation of contaminant acoustic radiation. Often the parasitic noise will contribute a significant correlatable fraction to the overall sound generated by the parent flow. The problem is of special concern where the probe signal is to be cross correlated with the farfield sound. The magnitude of the unwanted noise depends on the shape and size of the obstructing element as well as on the degree of turbulence in the approaching flow. The effect is calculated from a knowledge of the buffering forces imposed on the probe by the interacting flow. Several processes of interaction are discussed. The composite probe noise will generally consist of a side force dipole field (originating near the “nose” of the probe) and drag force dipole field (originating from drag fluctuations on the transverse “stem” of the probe). Empirical methods are given for estimating the extraneous noise fractions; these lead to ideas for minimizing the contamination effect. A theoretical model is given for predicting the distortion of “causality” correlation signatures (obtained when in-flow probe signals are cross correlated with farfield sound). For a standard probe shape, the theoretical correlations agree well with their experimental counterparts. [Work supported by the National Research Council of Canada.]
Mechanisms of generation of fluctuating pressures on airplane wings
Authors: Ely R. A.
Published: October 2005

Fluctuating pressures were measured at the surface of the wing of an airplane in flight and at the surface of the wing of model airplanes in a wind tunnel. There was strong evidence that specific flow mechanisms in beth configurations were associated with specific narrow ranges of the ratio of the magnitude of the fluctuating pressure to the kinetic energy of the flowing air. A few spectra of the measured pressures provided examples of the details of flow that may be encoded in spectra. The model tests were augmented by oil flow photographs, sublimation photographs, and by measurements of static pressure distributions. That augmentation provided a basis for determinations of flow realms that were independent of the measurements of fluctuating pressure.
Acoustics of attached and unattached flow for simplified OTW configurations with 5:1 slot nozzle
Authors: von Glahn U. , Groesbeck D.
Published: October 2005

The acoustics of simplified engine over-the-wing configurations, with and without jet flow attachment to the shielding surface were studied at model scale. The nozzle used consisted of a 5:1 slot nozzle (equivalent diameter, 5.1 cm) operated at a jet Mach number of 0.6, with the flow directed at angles of 0° to 10° to the shielding surface (flat board). The shielding length of the surface was varied from 16.4 to 54.3 cm, and the nozzle height above the surface was varied from 0 to 7.6 cm. Also, the velocity field at the trailing edge of each nozzle/surface configuration was mapped. With attached flow, the jet flow field is stretched in the flow direction, resulting in locally higher velocities than those for unattached flow or nozzle only. This increased the noise levels for the attached flow cases compared to those with partially or completely unattached flow. With attached flow, the shielding benefits were substantially reduced (up to half) compared with fully detached flow. Increasing the impingement angle of the jet flow from 0° to 10° generally caused the noise levels to increase. In some cases, the noise increase was sufficiently broad-band that the jet noise shielding benefits were noticeably reduced.
On the effects of flight on jet engine exhaust noise
Authors: Stone J. R.
Published: October 2005

Recent flight data on jet engine exhaust noise do not agree with projections based on classical jet noise theories. This paper demonstrates that these flight effects can be explained on the basis of the combination of jet mixing noise and internally generated engine exhaust noise. The source strength of the internally generated noise is assumed to be unaffected by flight, as has been shown in small-scale free-jet experiments. The directivity of the internall generated noise is assumed to be the same statically as that given in the NASA interim prediction method for core engine noise. However, it is assumed that in flight the internally generated noise is subject to the convective amplification effect of a simple source. The absolute levels of the internally generated noise are obtained from an empirical fit of some typical engine data. The static and flight jet noise are predicted using the NASA interim prediction method for jet noise. It is shown that in many cases, although jet mixing may be the dominant noise source statically, much of the flyover noise signature is dominated by internally generated noise.
Distinctive features as units in a phoneme substitution task
Authors: Simpson Carol A.
Published: October 2005

A phoneme substitution task was developed to study the role of distinctive features in speech production. It was hypothesized that speakers substituting one phonetic segment for another would change only those features necessary to obtain the target segment rather than substituting an entire phonemesized segment. Subjects listened to recorded sentences and repeated them back changing each [b] to one of four target segments: [m], [d], [z], or [g]. The target segments differ from the original [b] by varying numbers of distinctive features. Differences in error scores and response times for the different target segments are interpreted as supporting the hypothesis that speakers manipulate feature-sized units during speech production. In addition, an interesting interfering effect for orthographic imagery was found despite the aural/oral mode of stimulus presentation and subjects' responses. Analysis of error data revealed numerous anticipation, perservation, and generalization errors. Considering these results, the phoneme substitution task promises to be a useful paradigm for generation of production data for several areas of research interest.
Conditions for vowel devoicing and frication
Authors: Ohala John J.
Published: October 2005

The incidence of vowel devoicing and/or frication in several languages—both synchronically and diachronically—exhibits some interesting asymmetries: it occurs most with high close vowels such as [i, u, y] and least with low, open vowels such as [æ, Λ]; the order of consonantal environments most favorable to it are (from more to less) as follows: voiceless, especially voiceless aspirated stops; voiced stops; and sonorants. Explanations of these patterns are given by reference to a computer model of speech aerodynamics which calculates air flow and air pressure at various points in the vocal tract, given the relevant cross-dimensional areas. [Work supported by the National Science Foundation and by the Computer Center, University of California, Berkeley, CA.]
Relative durations of movement and muscle activity for /s/ in clusters
Authors: Borden Gloria J. , Gay Thomas
Published: October 2005

It is known that there is a tendency for the /s/ before the bilabial stop /p/ to be shorter in the duration of the acoustic signal than the /s/ before /t/ or /k/ is consonant clusters. [M. Schwartz, J. Acoust. Soc. Am. 47, 1143–1144 (1970) and D.H. Klatt, MIT Res. Lab. of Elec. QPR 103, 111–126 (1971)]. The purpose of this paper is to investigate these durational differences on the movement and EMG levels to see if they correspond to the known acoustic differences. Acoustic measurements were compared with durational data derived from both tongue movement for /s/ seen by tracking pellets on the tongue with cine x-ray and from EMG activity for /s/ obtained from recordings from hooked wire electrodes placed in extrinsic and intrinsic tongue muscles. Problems of segmentation of movement information and muscle activity are discussed. Durational aspects associated with the /s/ as a single consonant in initial and final positions are also considered. Finally, some factors which seem to determine the durational differences in the fricative are proposed. [Work sponsored by NINDS and NIDR.]
Motor equivalence coordination in the labial-mandibular system
Authors: Abbs J. H. , Hughes O. M.
Published: October 2005

Upper lip, lower lip, and jaw displacements were recorded for repetitive productions of [æ, i, and ɛ] in [hV1bV2b] context. These data were analyzed to determine the displacement contribution of each of these articulators to the vertical dimension of oral opening. These analyses revealed that while the vertical oral opening remained relatively constant across repetitions, the individual contributions of the upper lip, lower lip, and jaw to that opening varied considerably. These observations suggested that the specific motor programs for these articulators varied reciprocally across repetitions, i.e., repetitions where the jaw had large displacements, the lower lip had correspondingly small displacements, and conversely. Such variation implies that programming of the labial-mandibular system for speech occurs functionally at two major levels (at least)—one which specifies overall oral opening and a second which generates specific commands for individual articulators. The second, and apparently lower level of programming, appears dependent upon the peripheral status and the motor programs of other coparticipating articulators. Hypotheses concerning neuromuscular mechanisms underlying these observations are presented. [Supported by NINDS grants N8-11780 and NS-10247.]
Undergraduate research projects in acoustics
Authors: Crenwelge Otto
Published: October 2005

There is presently a need for courses and research at the undergraduate level in acoustics and noise control. Several projects which have utilized undergraduate engineering and technology students in the areas of transportation and industrial noise research are presented. It has been found that students profit greatly from the confidence and experience gained by attacking and solving real problems.
X-ray observation of movements of the velum and the tongue
Authors: Fujimura O. , Miller J. E. , Kiritani S.
Published: October 2005

Velum movements have been studied by tracking a metal pellet placed on the velum with computer-controlled radiography. The tongue gesture was observed simultaneously by tracking two additional pellets on the posterior part of the tongue. A set of utterances consisting of Japanese words in isolation contained syllable initial and syllable final nasal consonants in comparison with non-nasal segments, i.e., vowel elongation and consonant gemination. It is shown that (1) the syllable final (moraic) nasal in Japanese shows a velum lowering to a considerably larger extent than the syllable initial nasal, (2) there are cases where a transitional raising of the velum above the normal non-nasalized level is observed, (3) an apparently inherent lingual gesture is found for the labial nasal consonant, (4) there seem to be characteristic gestures of the tongue for the (syllable final) geminate consonant both in the pertinent time segment and in the (impertinent) initial consonant of the syllable. A quantitative analysis of dynamics of the velum movement is discussed with reference to syllable structures.
Digital processing of physiological data describing articulatory dynamics
Authors: Christopher D. K. , Rabiner L. R. , Bock D. E. , Flanagan J. L.
Published: October 2005

Simultaneous physiological measurements were made for several articulartory functions during connected speech. Electromyographic (EMG) activity in three laryngeal muscles, subglottal air pressure, transillumination of vocal-cord motion, and the speech sound wave were recorded on multitrack FM tape. The data were obtained in a clinical environment by Dr. Thomas Shipp of the San Francisco Veterans Hospital. These data were then digitized using a multiplexed seven-channel A/D converter with a sampling rate of 6250 Hz per channel. Computer analysis was performed to study relationships between the physiological data and articulatory events. The three EMG signals (representing, respectively, the activity of the posterior crico-arytenoid, the thyroarytenoid, and the crico-thyroid muscles) were processed to display their energy as a function of time. The time variation of fundamental frequency (voice pitch) was analyzed from the speech waveform, from the fine-structure variations in the subglottal pressure, and from the transillumination of vocal-cord motion. Further, voiced/unvoiced distinctions were analyzed from the speech waveform and from the transillumination data. The results permit correlations to be calculated between the EMG signals and the dynamic behavior of the vocal-cord system.
Comparative regularity and irregularity in glottal pulsing rate as an indicator of relative fineness of glottal muscle control during the production of a sentence
Authors: Abler William L.
Published: October 2005

Because the vocal cords are not resonating reeds, any regularity or near-regularity shown in the glottal pulsing rate reflects a high degree of fineness in neuromuscular control associated with phonation. In order to compare degrees of fine control over the muscles of phonation at different positions during the production of a sentence, an experimental sentence was selected (“After you go, ask Annie”), in which periods of continuous phonation (vowels) both preceded and followed periods of silence at sentence terminal and sentence medial positions. The greatest degree of irregularity in glottal pulsing rate occurred at sentence final position: The second greatest degree of glottal irregularity occurred at sentence initial position, amounting to approximately 25% of that encountered at sentence final position: Sentence medially, a degree of glottal irregularity, was encounting to a maximum of 12% of that encountered at sentence final position. The results suggest that fine control over the muscles of phonation during speech exhibits a rapid onset, then a period marked by a relatively steady degree of fineness, followed by a longer, more protracted period of decline and decay.
Pressure amplitudes for surface-wave modes radiating from an elastic cylinder in a fluid
Authors: Dickey Joseph W. , Simanowith Raymond C. , Uberall H.
Published: October 2005

A numerical approach is used to calculate the pressure amplitudes for various surface wave modes which radiate from an elastic cylinder into a fluid. The Sommerfeld Watson transformation is used to separate the various surface-wave modes according to physically distinct types; e.g., Rayleigh, Stoneley, Franz, and Whispering Gallery. Each mode is identified with a singularity of the scattering amplitude in the complex wave-number plane and the contribution of each mode to the total radiated (or scattered) field is evaluated. Specific examples are used of plane waves in water and air incident on an aluminum cylinder. The resulting surface waves and their individual contributions to the scattered field are presented. The allowable modes with dispersion and attenuation curves are given for each surface wave, and the grouping of the infinity of surface waves into four physically distinct families is shown naturally by the mathematics. The individual surface wave contributions to the scattered field are summed and the resulting differential-scattering cross section is given for elastic, rigid, and soft cylinders. The wavenumber-radius product ka ranges from 10 to 300. The reduction of the problem to the case of an elastic half space is treated briefly.
Environmental effects on microphones of various constructions
Authors: Hruska Gale R. , Magrab Edward B. , Penzes William B.
Published: October 2005

The change in the sensitivity of condenser, electret, and ceramic microphones was determined for numerous combinations of temperature (−20° to 50°C), percentage relative humidity (25% to 95% RH), and frequency (100–5000 Hz). To measure the sensitivity changes, three condenser microphones and the reciprocity technique in an acoustic coupler were used at each combination of temperature, relative humidity, and frequency to obtain a primary reference source. This reference source was then used to determine the sensitivity of each of the other microphones. Furthermore, insert voltage techniques were used for all the microphones, thus canceling the effects of the environmental conditions on the electronics. For the combinations of temperature and humidity at each frequency considered, the range of the change in sensitivity in decibels relative to sensitivity at 20°C and 44% RH was (1) for the condenser microphones: (−0.8, 1.0) and (−1.0, 1.4); (2) for the electret microphones: (−3.1, 1.1) and (−2.3, 1.9); and (3) for the ceramic microphones: (−2.1, 1.5) and (−5.0, 1.6).
Surface, subsurface, and intercompartmental audio induction communication as influenced by large metallic surfaces, superstructures, and barriers
Authors: Cohen Abraham B. , Sebesta George J. , Hofer Alan
Published: October 2005

Communication by induction systems on base audio frequencies may be considerably aided by the presence of ferrous metallic planes and enclosures, unlike equivalent deterioration for radio frequency links. The ferrous structures behave as bridging laminations of an otherwise large open air core audio transformer, with effects dependent upon the configuration of the ferrous surfaces and the degree of coupling of the induction coils to the structure. In practice, a master transmitting loop, either of one surround perimeter, or convoluted over several areas to be covered, is permanently fixed, while the subminiature receiving loop and amplifier is personnel carried over the area to be covered. Audio field patterns in, around, and through such ferrous structures are presented for a simulated typical shipboard installation, for cordless secure communication for moving personnel on board, and for underwater operations close to the ship.
Community noise survey: Its purpose, techniques and results as related to land use planning
Authors: Bixler Otto C.
Published: October 2005

A large community noise survey (200 sites) was performed in and for the County of Orang (completed April 1975) to provide a basis for the generation of the State of California mandated Noise Element of the General Plan. Responsible fulfillment of this mandate requires both analytical and empirical assessment of the noise generating mechanisms present in the community. Noise from both stationary and mobile sources was measured for a variety of land use categories. A digital data sampling technique was used to approximate CNEL values from measurements made during the three time periods: 0700–1900, 1900–2200, and 2200–2400 for each site monitored. Computer processed sampled data CNELs were compared to, where possible, CNELs predicted from analysis based on highway noise modeling. Additional measurement studies investigated noise propagation through typical residential housing tracts adjacent to the San Diego Freeway for above, below, and at grade conditions.
Urban noise impact
Authors: Garrelick J. M.
Published: October 2005

Environmental noise data, including 24-hour noise surveys, taken at various urban locations throughout the United States have been compiled and compared. The data were taken from the open literature and also from the files of the U.S. Department of Housing and Urban Development. It is suggested that the urban noise scene is sufficiently different from the nonurban situation so that, prediction and evaluation schemes commonly used in environmental impact statements are impractical or invalid. For example, relatively sophisticated approaches to traffic noise impact, e.g., the Highway Research Board's design guide (Rep. 117), prove to be intractable for moderately sized projects in urban areas. However, an analysis of the data infers alternate approaches and these are discussed.
Practical problems in building acoustics
Authors: Wetherill Ewart A.
Published: October 2005

Even for the small number of building projects in which they are involved, acoustics consultants may have little or no influence upon the matters that ultimately determine the success or failure of the design. Often important design decisions are made on the basis of any one of a dozen criteria without any consideration—or understanding—of their effect upon acoustics. During construction, the problems are compounded further by unknowing workmen. This paper reviews some of the prevalent situations that lead to acoustics problems. They can be broadly grouped into three categories: difficulties of interpretation, changes in materials and techniques, and getting things built as specified.
Optical model of sound waves in the ocean
Authors: Fain G. , Estes L. , Molinski T.
Published: October 2005

Starting with the wave equation, it is shown that by scaling with wavelength and maintaining ratios of index variations, a coherent light source can be used to simulate the propagation of an acoustic beam. An argon-ion laser is used as a source. Appropriate optics are used to develop directive or nondirective transitters and receivers as desired. To data a frozen turbulent model has been developed. Specifically, micron-size glass particles have been uniformly distributed in a plastic substrate. Assuming a 3-kHz acoustic wave, the model which is 1.5 cm thick represents 23 km of ocean. The scatterers vary in size from 2 to 100 wavelengths. The model was made with readily available materials with a resulting index variation of 5%. Other materials are available to produce closer index matching. Various transmitted configurations were used, the model was moved with uniform velocity, and power spectral densities of the received signal for various receiver configurations were made. Tests performed with polarizing filters showed little sensitivity to polarization.
Full diffraction theory numerical simulation of sound propagation in the ocean in the presence of sound-velocity variations
Authors: Estes L. E. , Fain G.
Published: October 2005

We describe a numerical technique which uses a fast Fourier transform to make a plane-wave decomposition of the transmitter field. Spatial propagation is realized by multiplying the transmitter spectra with a spatial transfer function. An inverse FFT is performed on the resulting spectra to determine the field down range. Sound velocity variations, such as velocity gradients and those associated with turbulence which exist between the transmitter and receiver, are modeled. The distance between transmitter and receiver is broken up into slabs. The slab thickness is chosen to be the Rayleigh length of the smallest significant size in the problem. The velocity variations within a slab are modeled as a phase mask at the front of the slab. The remainder of the slab is assumed to be free of velocity variations. Since diffraction effects are not important over the Rayleigh length, the slab decomposition used represents a good model of the actual problem. We present results of simulations of direct path propagation in the presence of velocity gradients and turbulence.