bluuebunny/crossref_metadata_2025 huggingface dataset:
Harmonic waves in a solid with periodically distributed inhomogeneities
Authors: Achenbach J. D.
Published: October 2005

A dispersion relation has been obtained for the propagation of harmonic waves in an elastic solid containing a three-dimensional array of regularly spaced inhomogeneities of identical shape. The analysis uses the reflection and transmission coefficients for a single layer of inhomogeneities. In this paper, a solid completely filled with periodically spaced inhomogeneities is considered as a stack of reflecting and transmitting planes. The dispersion equation can then be obtained on the basis of Floquet theory and by using the single-layer reflection and transmission coefficients. The results are valid in a specified frequency range, and provided that the layer spacing is sufficiently large so that exponentially decaying standing wave modes do not interfere with the neighboring layer. The general pattern of the frequency spectrum is one of passing and stopping bands. For spherical cavities and Griffith cracks, results are presented for the lowest acoustic mode (real-valued wavenumber), the transition to the first optical mode (imaginary wavenumber) and for a segment of the first optical mode (real-valued wavenumber) up to the first cutoff frequency.
The effect of tone location on temporal order discrimination
Authors: Barsz Kathy
Published: October 2005

In order to examine the effect of tone location on temporal order discriminations, tones (200-ms onset-onset) in six-tone sequences were either presented all in one spatial location or were alternated between two spatial locations. On each trial a comparison sequence differed from the standard sequence, either such that the tones in each spatial location contained an order change or such that, when the tones were alternated between locations, only one spatial location contained an order change. In a 3IFC task, subjects chose the sequence in which the component tones were in a different order. Discrimination performance remained above chance in all conditions; however, performance was significantly worse when the tones alternated between locations and only one location contained an order change. These results support the hypothesis that temporal relationships between tones presented in the same spatial location are more salient than relationships between tones presented in different locations; they also support the assertion of Warren and Byrnes [Percept. Psychophys. 18, 273–280 (1975)] that subjects can discriminate the order of perceptually unrelated tones better than chance, while extending the result of Bregman and Campbell [J. Exp. Psychol. 89, 244–249 (1971)] that subjects perform worse when discriminating the order of perceptually unrelated tones than when discriminating the order of perceptually related tones.
Detection of a temporal fluctuation in the frequency ratio of two simultaneous tones
Authors: Demany Laurent , Semal Catherine
Published: October 2005

Listeners were presented with two simultaneous frequency-modulated pure tones, each at 45 dB SPL. The two tones were heard dichotically and their carrier frequencies were separated by either 1 oct (1200 cents) or a slightly different interval (1200 ± 25, 50, or 100 cents). Each carrier frequency was sinusoidally modulated by ± 5% at a rate of 2 Hz. Using a 2IFC procedure, we measured just-noticeable phase differences (jnpd's) between the two modulations. When the modulations were in phase, the two tones maintained a steady frequency ratio (the ratio of their carrier frequencies). Dephasing the modulations produced a quasisinusoidal frequency ratio fluctuation, which increased in amplitude with the phase difference. The results show that, for two tones with carrier frequencies below 2 kHz, jnpd's tend to be smaller when the interval formed by the carrier frequencies is equal or close to 1 oct than when it is ± 100 cents from 1 oct. This indicates that deviations from an octave interval may be easier to detect than deviations from an inharmonic interval even when monaural periodicity cues of the octave relationship are absent. However, the observed octave effects only occurred within a limited and listener-dependent frequency domain.
The temporal analysis of nonrepetitlve auditory patterns
Authors: Robin Donald A. , Thomas Cecil W. , Royer Fred L.
Published: October 2005

Subjects were asked to listen to six-element auditory patterns comprised of 440-Hz pure-tone bursts separated by silent intervals. In a given pattern, two of the elements were closer in time (short ISI) than the others (long ISIs). Subjects were asked to report which of the two elements were closest. Tone durations for a given trial were 80, 60, 40, 20, or 10 ms. Long ISIs were 64, 32, 16, or 8 ms. Short ISIs were varying fractions of the long ISI Performance decreased as either tone duration, long ISI, or the difference between long and short ISI decreased. Results suggested that there was a categorical response such that high accuracy (> 80% correct) was maintained to some point and then performance markedly deteriorated. This cutoff point was at similar durations and intervals as found for the unitization of six-element repetitive patterns [F. L. Royer and D. A. Robin, Percept. Psychophys. 39, 9–18 (1986)]. Positions 2 and 4 were the most difficult, followed by 3, 1, and 5. Results are discussed with respect to a temporal frequency analyzer that operates like a bandpass filter, with the cutoff frequencies determining pattern smoothing and thereby subjects' ability to analyze a sequence.
Tone color and spectral spaces for steady sounds
Authors: Papachristou Evi , Strong William J. , Brown Bruce L.
Published: October 2005

Perceptions of steady sounds are often described in terms of the attribute's pitch, loudness, and tone color (timbre). Tone color may be defined as that attribute by which a listener can judge two steady sounds having the same pitch and loudness to be dissimilar. Various researchers have sought underlying spectral spaces (physical) that would correlate well with tone color spaces (perceptual). For example, Klein et al. [J. Acoust. Soc. Am. 48, 999 (1970)] studied vowel sounds and Plomp [Aspects of Tone Sensation 93 (1976)] studied musical sounds. For purposes of this study, twenty steady sounds (ten vowel and ten instrumental) equated for pitch and loudness were synthesized. Three spectral representations for each of the twenty sounds were used: (1) one-third octave-band spectra normalized to the overall sound level; (2) specific loudness per one-third octave band; and (3) F-weighted loudness per one-third octave band [S.S. Stevens, J. Acoust. Soc. Am. 51, 575 (1972)]. Each of the spectral representations was subjected to a principal components analysis to reduce its dimensionality. The one-third octave spectra and loudnesses produced very similar results for the first four principal components, but the first four components of the F-weighted loudnesses accounted for less of the total variance than those of the other two representations. In separate analysis of the vowels and the instrumental sounds, the two were found to produce markedly different correlation matrices and spectral spaces. Listener tests using paired comparisons are currently in progress.
Frequency microstructure of pitch-level functions
Authors: Burns E. M. , Hoberg K. E. , Schlauch R. S. , Bargones J. Y. , Beaman W. B.
Published: October 2005

In a previous paper [E. M. Burns, J. Acoust. Soc. Am. Suppl. 1 77, S95 (1985)], the finding of no correlation between the frequency microstructure of the absolute threshold, associated with the presence of otoacoustic emissions, and the form of pitch-level functions measured at various points on the threshold microstructure was reported. In the experiments reported in this paper, pitch-level functions are measured at finer (20-Hz) frequency intervals. Cyclical changes in the magnitude and direction of the low-level portions (20–40 dB SPL) of the pitch-level functions that correlate strongly with the approximately cyclical changes in threshold microstructure are found. [Work supported by NINCDS.]
An auditory paradox
Authors: Deutsch Diana
Published: October 2005

This paper describes and demonstrates a pattern of tones with some remarkable properties. When played in one key, it is heard as ascending; yet, when played in a different key, it is heard as descending instead. When a tape recording is made of the pattern and it is played back at different speeds, the pattern is heard either as ascending or as descending, depending on the speed of playback. To add to the paradox, when the pattern is played in any one key it is heard as ascending by some listeners but as descending by others. This effect is shown to be robust in the face of a number of parametric manipulations. Implications for processes underlying pitch perception are discussed.
Vibration damping performance—What we should know about it
Authors: Saha Pranab
Published: October 2005

The vibration damping performance of materials that are used in the automotive industry are usually tested by either (1) the Geiger plate test method or (2) the complex modulus test method. The first test method has some advantages for testing materials that are unique to the automotive industry. Both of these methods have certain limitations, though the second method is a superior one in the sense that it can measure the damping performance with temperature and frequency. The limitations of some of the ways the data are typically presented using this method as well as how design charts can be used to overcome these limitations and compute the damping performance of the composite material (composite loss factor) for a given application are discussed.
A solution for the response of a nonlinear oscillator subject to nonstationary stochastic excitation
Authors: Dimitriadis Emillos K. , Spanos P. T. D.
Published: October 2005

Envelope statistics are being frequently used to describe stochastic processes when a more detailed description is either unobtainable or impractical. The response of a nonlinear oscillator subject to nonstationary stochastic excitations is described. This is accomplished by analytically computing the transition probability density of a one-dimensional Markov process, which approximates the amplitude envelope of the response. For this purpose, an appropriate variation of the solution to the corresponding linear problem is employed. The probability density at various times as well as the mean-square and standard deviation of the amplitude envelope are computed for specific nonlinearly damped oscillators subject to separable and nonseparable nonstationary excitations. The analytical results are compared with those obtained by a Monte Carlo simulation study. The agreement between the two supports the applicability of the method to a broad class of oscillators.
Broadband generalized nearfield acoustical holography
Authors: Williams Earl G. , Washburn Karl B.
Published: October 2005

Generalized nearfield acoustical holography (GENAH) has been applied to the study of the radiation from the vibration of cylinders radiating underwater. This experimental technique provides a complete description of the acoustic field from the surface of the vibrator to the farfield. Pressure, vector velocity, and vector intensity fields in three dimensions are reconstructed from a (two-dimensional) cylindrical hologram of the acoustic pressure measured in the nearfield of the source. One of the limitations of GENAH has been the use of a discrete excitation frequency, usually a resonance frequency of the cylinder structure. A new hologram had to be measured for each frequency of interest. We have eliminated this restriction by developing a broadband excitation technique, so that a single broadband hologram contains several octaves of information. The broad frequency band is derived from a one-cycle, modified sine wave, which powers a mechanical shaker driving the shell. Narrow-band holograms are then created from this broadband hologram by data reduction. Applying GENAH to these holograms provides a complete, three-dimensional description of the radiation from the cylinder over several octaves. Also, the modes of radial vibration are obtained along with a three-dimensional mapping of the vector velocity and intensity fields. Experimental results will be shown.
The “trough” phenomenon in Turkish and in English
Authors: Boyce Suzanne E.
Published: October 2005

Previous studies on several Indo-European languages have shown that for strings of two rounded vowels separated by phonologically rounding-neutral consonants, both EMG and lip protrusion movement traces show double peaks coincident with the two rounded vowels plus an intervening “trough” [Bell-Berti and Harris, J. Acoust. Soc. Am. 71, 449–454 (1982); Perkell, Speech Commun. 5, 47–68]. This has been interpreted as due to independent rounding gestures associated with each vowel and as counterevidence to the claim that rounding coarticulation is anticipatory. In this paper, English speakers' production of nonsense words /kuktluk/, /kuktuk/, /kukuk/, /kutuk/, and /kuluk/ will be compared with that of speakers of Turkish, a language with strong constraints against the cooccurence of rounded and unfounded vowels in the same word. Both movement and EMG evidence will be used to argue that the trough phenomenon is more extensive in English than in Turkish. Implications for cross-language differences in coarticulatory patterns will be discussed. [Work supported by NIH.]
Vowel context, rate, and loudness effects on linguapalatal contact patterns in Hindi retroflex /t/
Authors: Dixit R. Prakash , Flege James E.
Published: October 2005

Tongue position for retroflex /t/ has been shown to differ across languages in the contexts of /a/ and certain other vowels. Degree of retroflexion has also been shown to be affected by vowel context [Ladefoged and Bhaskararao, J. Phonet. 11, 291–302 (1983) and references therein]. Since previous studies have not determined whether the place or length of constriction differs as a function of vowel context, this study examined changes in the articulation of Hindi retroflex /t/ as a function of vowel context, and also as a function of speaking rate and loudness. A 96-channel electropalatograph was used to monitor production of retroflex /t/ in the nonsense words /bitíb/, /batáb/, and /butúb/ spoken in carrier phrase by a native speaker of Hindi. The length of constriction (i.e., the number of contacted rows × 2 mm) changed very little (< 1 mm) as a function of the three factors. However, the anterior-posterior location of the /t/ constriction shifted dramatically as a function of vowel context. The center of constriction was 3.8 mm more posterior in /u/ than in /i/, and 5.8 mm more posterior in /a/ than in /i/. The pattern and area of tongue contact observed for retroflex /t/ and dental /t/ were virtually identical in the /i/ but not in the /a/ or /u/ context. A similar vowel context effect on retroflex /t/ was observed in speech produced at a fast rate, and in loud speech. [Work supported by NIH grant.]
Rate-dependent variability in English and Japanese complex vowel F2 transitions
Authors: Dolan William B. , Mimori Yoko
Published: October 2005

Are the effects of changes in speech rate on F2 transition slopes in languages with and without unitary diphthongs explicable in terms of general phonetic and physiological principles? Five American English diphthongs and four Japanese vowel sequences were recorded, spoken at three different tempos by eight and seven speakers, respectively. LPC spectra were computed at 10-ms intervals, and the resulting F2 contours were analyzed by a computer program designed to objectively define and measure steady-state and transitional portions of the vowel. Contrary to the claims of Gay [J. Acoust. Soc. Am. 44, 1570–1573 (1968)], speech rate was found to significantly affect two measures of transition slope in English, with slope decreasing as speech rate increased. Individual diphthong populations in both languages displayed high correlations between a transition, slope and its F2 range, indicating that rate adjustment is not simply a matter of target undershoot at faster speeds. Japanese showed less rate-dependent variability, suggesting that temporal reorganization for different speech rates is affected by language-specific structures. [Work supported by NIH.]
GEST: A computational model for speech production using dynamically defined articulatory gestures
Authors: Browman Catherine P. , Goldstein Louise , Saltzman Elliot , Smith Caroline
Published: October 2005

A preliminary model of speech production based on the concept of a gestural score, that is, an organization of dynamically defined articulatory gestures, has been developed. These gestures, which also serve as linguistic primitives, are coordinated movements of the lips and jaw or tongue and jaw. The movements are generated using a set of underlying dynamic parameters that are specified for each gesture in the score, namely, stiffness, rest position, and damping. (We assume a critically damped linear second-order system with unit mass.) [Work supported by NSF.]
Oscillation threshold conditions in phonation
Authors: Titze Ingo R.
Published: October 2005

A small-oscillation theory is developed for determining threshold conditions for onset and release of vocal fold vibration as a function of lung pressure, tissue viscosity, glottal aperture, and surface wave velocity in the mucosa (vocal fold cover). It is found that oscillation threshold lung pressure increases in proportion to mucosal wave velocity. In other words, phonation initiates at lower pressures (less effort) if the vocal fold cover is lax and propagates slow surface waves. Experimental evidence on excised dog larynges confirms that a stiffer cover (at greater vocal fold lengths) requires greater lung pressure. The theoretical prediction that increased glottal aperture (spreading of the vocal folds, as in breathy voice) also increases the oscillation threshold lung pressure has been more difficult to verify experimentally, but increased tissue viscosity produces an observable increase. Applications to phonetics and voice care are cited. [Work supported by NINCDS.]
A truncation model for the F2 trajectory in syllables with complex vocalic components
Authors: Ren Hongmo
Published: October 2005

Phonetic orthodoxy treats the acoustic realization of a CVn, syllable (N.B. V = vowel or glide) as the concatenation of consecutive transitions from one element to the following one in the syllable. This study proposes an alternative view of the acoustic structure of this type of syllable, based on LPC trackings of F2 in sets of selected Chinese and English CVn syllables. The basic hypothesis is that the underlying F2 transitions between any two phonologically adjacent elements in the same syllable (e.g., the C → V1, V1 → V2,…) all originate at the same temporal position—the syllable initiation. Each transition has a specified rate. The acoustic realization will be a programmed “truncation” process; that is, the phonologically preceding transition truncates the phonologically following transition (e.g., the C → V1 transition truncates the V1 → V2 transition; the truncated V1 → V2 in turn truncates the V2 → V3 transition). This model provides elegant accounts and quantitative predictions of the undershooting and overshooting phenomena in acoustic target realization. [Work supported by NSF.]
Testing parameters of Vocal tract shape
Authors: Ladefoged Peter
Published: October 2005

In a mini-version of a system for modeling the speech production process on a Macintosh computer, new algorithms have been devised for interpreting values of eleven control parameters: front-back tongue movement; high-low tongue movement; jaw opening; tip of tongue raising; tip of tongue advancing; lip height; lip rounding and protrusion; velic opening; advancing of the tongue root; rhotacization; and larynx raising. New algorithms have also been devised for converting the vocal tract shapes into sets of tubes, whose lengths and areas can be used as a basis for calculating the sounds that would be produced. The phonological features nasal and advanced tongue root can be given direct values in this set of commands. The features high-low and front-back can be interpreted as auditory specifications from which corresponding tongue shapes can be calculated. It is not known if it is possible to devise algorithms for interpreting other features in terms of these commands.
Angular dependence of acoustic backscattering over a Mn nodules field
Authors: Alexandrou D. , de Moustier C.
Published: October 2005

The in-phase (I) and quadrature (Q) components of the seafloor backscattered acoustic returns received by a Sea Beam multibeam echo-sounder over a manganese nodules field in the tropical northeastern Pacific have been digitized and recorded on magnetic tape. Because both the I and Q components of the signals were present, the sidelobe interference inherent in multibeam systems [C. de Moustier, J. Acoust. Soc. Am. 79, 316–331 (1986)] was able to be removed, and a complete angular dependence function of acoustic backscattering between ± 20° of vertical incidence was obtained. These results and the sidelobe interference removal method are discussed. [Research funded by ONR.]
Sound producing instability of a choked jet impinging on a normal flat plate
Authors: Powell Alan
Published: October 2005

An axially symmetric choked air jet expands to a supersonic condition and then contracts to approximate to the sonic exit condition. This “cell” structure is repetitive in the downstream direction until destroyed by dissipation. If a rigid flat plate is introduced normal to the jet axis, a strong transverse shock wave (“normal” or “stand-off”) separates the supersonic jet flow from the locally subsonic divergent flow caused by the presence of the plate. If the plate is small, the flow is unstable and emits intense sound when the plate is positioned near where a cell junction would be. For larger plates, these positions for instability merge together. The frequency then drops steadily with increasing orifice-to-plate distance, but is interrupted by upward jumps, characteristic of acoustic feedback to the orifice. Phased Schlieren photographs make clear some of the main features of the highly nonlinear oscillations of the complex supersonic/subsonic flow: In particular, the stand-off shock wave undergoes large amplitude nonlinear oscillations with consequent violent periodicity of the (mainly) subsonic flow.
De-Dopplerization of aircraft flyover noise data using the WKS sampling theorem
Authors: Hatlestad John D.
Published: October 2005

The classical Whittaker-Kotel'nikov-Shannon (WKS) sampling theorem is applied to the de-Dopplerization of aircraft flyover noise data to remove frequency shift and smearing so that the flyover noise spectra can be more meaningfully analyzed and compared with static noise test data. The sampling theorem is used to reconstruct the uniformly sampled signal at points in time that do not correspond to sample points (i.e., to interpolate between samples). This method of interpolation is compared with one based on oversampling the signal, with linear interpolation between samples [G. P. Howell, A. J. Bradley, M. A. McCormick, and J. O. Brown, J. Sound Vib. 105, 151–167 (1968)]. Advantages of this method include the fact that the signal can be reconstructed to any desired degree of accuracy (albeit with increasing computational load) with no special sampling considerations.
Anisotropy of compressional velocity in sea ice cores
Authors: Vidmar Paul J. , Lindberg Jo B.
Published: October 2005

Laboratory measurements of the propagation velocity of ultrasonic compressional wave pulses were made at four orientations (vertical and at three horizontal directions) on five cores from first year sea ice. Accurately measured relative velocities (± 0.9%) showed that velocities were slightly anisotropic (generally < 5%). As in freshwater ice, it was found that the velocities parallel to the c axis (which was in the horizontal plane) are faster than horizontal velocities perpendicular to the c axis. However, the measured vertical velocity is faster than velocity parallel to the c axis in our sea ice cores. This is surprising since the velocity along the c axis in freshwater ice is faster than the perpendicular velocity. Velocities at 45° to the c axis were found to be either faster or slower than velocities parallel to the c axis, depending primarily on temperature. [This work was supported by the ONR.]
Focused backscattering from hollow spherical shells in water: Lamb waves and the acoustical glory
Authors: Kargl Steven G. , Marston Philip L.
Published: October 2005

When a short tone burst is incident on a spherical shell in water, the first backscattered echo is the specular reflection. This is followed by radiation from the Lamb waves on the shell [R. Hickling, J. Acoust. Soc. Am. 36, 1124–1137 (1964)]. The angular dependence of the largest Lamb wave echo has been modeled and measured as the receiver is shifted an angle γ away from the backscattering axis. The sphere was made of stainless steel with an inner-to-outer radius ratio b/a = 0.84. For the frequencies used, 50 < ka < 65 and the largest Lamb echo is predicted to be the lowest flexural mode. Previous SWT results (for solid spheres) were applied to calculate the surface wave's phase velocity csw and angular damping parameter β and were extended to include a subtle effect of β on the Lamb echo amplitude psw. It is found that psw ≈ ps A0|J0(u) − iβγJ1(u)|, where ps is the specular ampliture at γ = 0, u≈kaγc/cw, A0 = |G|exp[− 2β(π − θsw)], sin θsw = c/csw, and G is a coupling coefficient. Measured psw near the central peak at γ = 0 generally agree, but near the γ where psw is minimized, dispersion (not included in the model) becomes significant. [Work supported by ONR.]
Hyperbolic-umbilic focal sections: The wavefield and the merging of rays at caustic lines
Authors: Marston Philip L.
Published: October 2005

A wave whose amplitude in the xy plane is exp[ik(g − ct)] propagates to produce a hyperbolic-umbilic focal section (hufs) if g(x,y) = (αx3 + 3γy2x)/6 + a1(x2 + y2) with sgn(α) = sgn(γ) and ɑ1⩽0. Such a wave may be produced, e.g., by reflecting sound from a curved surface. The hufs lies in a plane a distance z = − (2ɑ1)−1 from the xy plane. Let u and v denote the transverse coordinates in the hufs such that the axes are parallel to the x and y axes, respectively. The uv plane contains caustic lines which meet at (u,v) = (0,0) with an apex angle Ψ given by tan (Ψ/2) = (γ/α)12 = β [P. L. Marston, J. Acoust. Soc. Am. Suppl. 1 80, S73 (1986)]. The present research describes how the rays merge so that the caustics locate a transition from a four-ray region to a uv region containing no rays. The diffraction integral was also approximated for the hufs wavefield in the case α > 0 by changing g in an analysis previously given [P. L. Marston, J. Acoust. Soc. Am. 81, 226–232 (1987)] for the transverse cusp. The amplitude in the hufs is (k13243π/irα23β)exp(ikr)Ai(q1)Ai(q2), where r = (z2 + u2 + v2)12 and the Ai are Airy functions of the indicated arguments: qj = − k23(u ± β−1 v)/(2α)13z,j = 1,2. [Work supported by ONR.]
The influence of extraneous components on vowel F1 estimation
Authors: Roberts Brian , Moore Brian C. J.
Published: October 2005

The contribution of extraneous components to vowel F1 estimation was investigated by constructing a continuum perceived as changing from /ɪ/ to /ε/ as F1 was varied. The phoneme boundary location is a measure of the perceived F1, and hence of the influence of the extraneous component. Adding an extraneous component whose frequency is an integral multiple of F0/2 gives a complex consisting only of components harmonically related to F0/2. This component may thereby be incorporated by acting as a “false harmonic.” Adding a false harmonic on the lower skirt of F1, at a level above the vowel spectral envelope, shifts the phoneme boundary upwards. However, adding a component at any other frequency in this region has a similar effect. The effect of further adding several false harmonics remote in frequency from F1, at levels equal to the spectral envelope of the vowel, is currently being investigated. Preliminary results suggest that adding these components increases the incorporation of the component added in the F1 region, but only if that component frequency is an integral multiple of F0/2. [Work supported by the SERC and the MRC, U.K.]
Vowel identification: Are formants really necessary?
Authors: Jagharghi Amir J. , Zahorian Stephen A.
Published: October 2005

It has generally been assumed at least since the time of the comprehensive study by Peterson and Barney [J. Acoust. Soc. Am. 24, 175–184 (1952)] that the formant locations in vowel spectra are the most significant cues to vowel identity. In this experiment vowel spectra were represented by two methods: (A) by the locations of the first three formants, and (B) by the overall smoothed spectral shape in terms of a discrete cosine transform of the power spectra. Stimuli consisted of four repetitions of the widely separated vowels /u/, /i/, /a/, spoken by each of 12 female and 12 male speakers (4⋅24⋅3 = 288 stimuli total). For each of the two spectral encoding methods, A and B, the vowel data were projected to a three-dimensional space such that the vowel categories would be well separated and the vowels within each category well clustered [S. A. Zahorian and A. J. Jagharghi, J. Acoust. Soc. Am. Suppl. 1 79, S8 (1986)]. Significantly better clustering was obtained with method B, based on overall spectral shape, than for method A, based only on the first three formant frequencies. Since these results are not based on perceptual experiments, no direct conclusion can be drawn regarding the perceptual importance of spectral peaks versus overall spectral shape for human perception of vowels. However, the results do indicate that automatic machine identification of vowels can be improved by parameterizing the overall spectral shape rather than only the spectral peaks.
High-frequency reflection and scattering of sound by ellipsoidally embossed surfaces
Authors: Lucas R. J. , Twersky V.
Published: October 2005

Earlier results for coherent reflection and incoherent scattering by random distributions of relatively arbitrary bosses on rigid or free base planes [V. Twersky, J. Acoust. Soc. Am. 29, 209–225 (1957); 73, 85–94 (1983)] are applied to rigid and free ellipsoidal bosses with axes large compared to wavelength. The asymptotic procedures used originally for circular cylinders and spheres (1957) and subsequently for elliptic cylinders [J. E. Burke and V. Twersky, J. Acoust. Soc. Am. 40, 883–895 (1966)] are generalized to triaxial ellipsoids, and results for the corresponding bosses are obtained by the original image method. Illustrative curves exhibit the effects of boss shape and orientation on the coherent reflection coefficients and incoherent differential scattering cross sections per unit area. To facilitate comparison with available low-frequency curves, the same isotropic and anisotropic surfaces were considered as before [R. J. Lucas and V. Twersky, J. Acoust. Soc. Am. 78, 1838–1850 (1985)] and emphasize anisotropic forward (specular) and backscattered effects for applications to sea-air, sea-bottom, and sea-ice programs.
Modeling the general pdf of intensity in terms of the scattering parameters for WPRM
Authors: Ewart T. E.
Published: October 2005

The intensity correlations for WPRM can be predicted for forward scatter from solutions of the parabolic 4th moment when the space-time autocorrelation function, the scattering stength parameter γ, and the scaled range X are known. Thus, the intensity variance and its time/depth correlations can be predicted. However, the intensity pdf has not been predicted for all ranges of γ and X. T. Ewart and D. Percival [J. Acoust. Soc. Am. 80, 1745–1753 (1986) I have shown that the generalized gamma distribution function (GGDF) models the probability distribution of intensity in forward scattering over wide ranges in γ and X. In this study the two parameters of the GGDF are obtained as functions of γ and X by fitting the distribution to many realizations of simulated intensity data. Realizations of the intensity were generated by Monte-Carlo techniques [C. Macaskill and T. Ewart, IMA J. Appl. Math. 33, 1–15 (1984)]. The mapping of the distribution parameters to γ and X provides a convenient way to examine the behavior of the distributions as they vary smoothly from lognormal to exponential with increasing X for constant values of γ. A heuristic model of the mapping is presented. Implications and future expectations are discussed. [Work supported by ONR.]
Effects of fiber motion on the acoustical behavior of an anisotropic, flexible fibrous material
Authors: Dahl Milo D. , Rice Edward J. , Groesbeck Donald E.
Published: October 2005

The acoustic behavior of a flexible fibrous material was studied experimentally. The material consisted of cylindrically shaped fibers arranged in a batting with the fibers primarily aligned parallel to the face of the batting. This type of material was considered anisotropic with the propagation constant depending on whether the direction of sound propagation was parallel or normal to the fiber arrangement. Normal incidence sound absorption measurements were taken over the frequency range of 140–1500 Hz and with bulk densities ranging from 0.0046–0.067 g/cm3. When the sound propagated in a direction normal to the fiber alignment, the measured sound absorption showed the occurrence of a strong resonance that increased absorption above that attributed to viscous and thermal effects. A model for the material indicated that this resonance was due to fiber motion. When the sound propagated in a direction parallel to the fiber alignment, indications of the additional sound absorption due to fiber motion were not present in the data.
Prediction of point-to-point acoustic transfer function within a three-dimensional enclosure using ray path methods
Authors: Wayman James L. , Esperti Robert V. , Vanyo James P.
Published: October 2005

This report details a study conducted for the General Motors Corporation to construct a model for predicting point-to-point acoustic transfer functions in automobile passenger compartments for the purpose of predicting entertainment system performance. The model is based on ray path methods and includes effects of curved enclosure surfaces and complex boundary impedances. Comparisons between model results and experimentally obtained transfer functions are promising.
Criteria and analysis for fan/floor vibration isolation in elevated mechanical rooms
Authors: Campanella Angelo J.
Published: October 2005

In selecting isolators for fans and other mechanical equipment mounted on elevated mechanical room floors, it is necessary to know the degree with which their vibrations will affect the occupants of the floor on which it is mounted, as well as the floor below. A computational procedure was developed based on a two degree of freedom model representing the resulting floor motion for known masses, resonances, and damping of the floor and fan mount. A computational criterion was developed for vibration input and human vibration tolerance based on values commonly found in the literature. A FORTRAN program featuring interrogatory input prompts and a screen graphics output of the floor vibrational velocity over the frequency band of concern executes in about 30 s. With this tool, one can immediately judge the effectiveness of various fan masses and spring constants. Two case studies are discussed.
Perception of multidimensional complex sounds
Authors: Kidd Gary R. , Watson Charles S.
Published: October 2005

Listeners' abilities to perceive information independently encoded in different dimensions of complex sounds were examined in experiments that required simultaneous attention to three dimensions. Stimuli consisted of sequences of one, three, five, or seven brief pulses that were generated by adding five 100-ms sinusoidal components. Each pulse had one of two values on each of the following complex dimensions: (1) harmonicity (harmonic versus inharmonic relations among the components); (2) spectral shape (linearly decreasing amplitude versus a two-peaked amplitude profile); and (3) amplitude envelope (slow versus rapid rise and decay times). Stimuli were selected such that the two values on each dimension were highly discriminable. In a classification task involving combinations of dimensional values, listeners showed an impressive ability to integrate information over pulses within sequences, with performance at about 5% to 10% below ideal performance for all sequence lengths. However, performance was not a simple function of the discriminability of the individual dimensions, and there were major differences among listeners' tendencies to differentially attend to each of the dimensions. [Work supported by USN/NMRDC and by AFOSR.]
Frequency response and perceived sound quality
Authors: Gabrielsson Alf , Hagerman Björn , Till Ove
Published: October 2005

The perceived sound quality of sound-reproducing systems can be described in terms of perceptual dimensions as clarity, fullness, brightness, spaciousness, and others [A. Gabrielsson and H. Sjögren, J. Acoust. Soc. Am. 65, 1019–1033 (1979)], and fidelity may be considered as a weighted combination of the perceptual variables. The frequency response probably affects all these variables. An experiment, in which the frequency response was manipulated, showed that, among other things, brightness and sharpness increased with increased frequency response at higher frequencies, fullness and nearness decreased with decreased response at lower frequencies, and clarity increased with a certain rise above 1 kHz in comparison with a flat response. The results were more pronounced for normal hearing than for hearing impaired persons, but both categories preferred a frequency response increasing above 1 kHz to a flat response. Similar results were obtained from an analysis of the frequency response of high-fidelity loudspeakers used in an extensive listening test [A. Gabrielsson and B. Lindström, J. Aud. Eng. Soc. 33, 33–53 (1985)]. This was especially evident when the frequency response was measured directly in the listening room.
Detection of envelope phase disparity
Authors: Wakefield Gregory H.
Published: October 2005

The sensitivity of the auditory system to temporal variations across frequency in the time-varying spectrum of a signal by measuring the detectability of a phase disparity between the envelopes of two sinusoidally amplitude-modulated carriers is discussed. Signals were 500 ms in duration and were gated by a 30-ms linear window. A 2IFC procedure was used to obtain psychometric functions for relative phase between the envelopes of a 0.5- and 2-kHz carrier. The results indicate that the psychometric function is independent of modulation frequency from 8 to 64 Hz. A phase shift of approximately 45 deg is necessary for a d′ of 1. Changes in the upper carrier frequency (e.g., 1 or 4 kHz) do not affect sensitivity. Furthermore, little change in performance is observed when additional SAM carriers are present. [Work supported by the EECS Department, Kresge Hearing Research Institute, and AFOSR.]
Temporal integration of amplitude modulation
Authors: Sheft Stanley
Published: October 2005

The threshold for detection of sinusoidal amplitude modulation of a gated broadband noise carrier was measured for modulating signal durations varying from 12.5 to 400 ms. Stimuli were shaped by a 25.6-ms rise-fall time with modulation onset subsequent to shaping. Carrier level was first adjusted to compenste for change in rms due to modulation, then randomized ±3 dB about a mean spectrum level of 25 dB SPL to ensure detection not based on change in overall level. As in the results of Viemeister [J. Acoust. Soc. Am. 66, 1364–1380 (1979)], modulation transfer functions for gated noise carriers exhibited a bandpass characteristic. Addition of a 500-ms fringe proceeding modulation indicated that the high-pass segment was not due to fast-acting adaptation. For modulation frequencies above the high-pass segment, the amplitude of the modulating signal at threshold decreased roughly 7 to 8.5 dB per decade increase in modulation duration. Results suggest that the output of an auditory modulation detector is summed by a second integrator in a similar manner as seen in a broadband signal detection task.
Perception of bird calls by budgerigars and humans: A multidimensional scaling analysis
Authors: Brown Susan D. , Dooling Robert J.
Published: October 2005

A combination of behavioral testing and multidimensional scaling analysis was used to test budgerigar perception of a natural vocalization: the “contact” call. For comparison, humans were tested on the same set of sounds. Individual differences multidimensional scaling (SINDSCAL) revealed that budgerigars and humans perceive budgerigar contact calls differently. Acoustic properties of the calls that covary along the dimensions determined by multidimensional scaling were identified. For humans, the absolute pitch of the call was most salient, while, for budgerigars, the spectral shape was most salient. These results are discussed in terms of the basic auditory capabilities of budgerigars and humans and in terms of the coding of information in budgerigar vocal signals.
English and prevoiced VOT (voice-onset-time) discrimination by monkeys and humans
Authors: Sinnott Joan M. , Adams Frank S.
Published: October 2005

Discrimination of synthetic English and prevoiced VOT (voice-onset-time) continua was assessed in Old World monkeys and humans using a repeating standard AX procedure and positive-reinforcement operant conditioning techniques. The DLs were measured at VOTs of +70 ms (English /pa/), 0 ms (English /ba/), and −70 ms (prevoiced /mba/). Monkey DLs for /ba/(standard)-/pa/(target) were 17 ms, compared to 8 ms for humans. Monkey DLs for /pa-ba/ were 25 ms, compared to 11 ms for humans. More pronounced differences between monkeys and humans appeared for prevoiced VOT. Monkey DLs for /ba-mba/ (35 ms) were about four times humans' (8 ms). Monkeys did not reliably discriminate /mba-ba/, although humans experienced no difficulty with this contrast and produced DLs of 18 ms. Monkey VOT sensitivity is compared with that of human infants previously tested with the same stimuli by Aslin et al. [Child Dev. 52, 1135–1145 (1981)]. [Work supported by NIH.]
Observations on the release of /t/
Authors: Hamlet Sandra L.
Published: October 2005

Palatographic data were examined for the release of prevocalic /t/ in both aspirated and unaspirated contexts. Thirty-two tongue contact points in the alveolar region were sampled every 2 ms. Although a plosive burst is a sudden acoustical event, the dynamic tongue release gesture is more gradual. The burst is associated with the sudden opening of a narrow central channel between the tongue and palate. The tongue then continues to pull away from contact centrally, with the final contacts remaining laterally even after voicing for the following vowel has commenced. At some point during the release of /t/, the tongue contact pattern passes through a configuration virtually identical to that for the greatest constriction of /s/. This implies that a brief period of frication generated at the point of release may follow the burst. The sequence of acoustical events at the release of aspirated /t/ would be: burst-frication-aspiration. Tongue releases in a unaspirated context (/st__/) were also examined. The palatographic pattern of tongue release was no different for the unaspirated context, although the timing of its initiation was later relative to the beginning of the following vowel. [Work supported by NIDR.]
Evidence against acoustic invariance in initial voiced stop consonants
Authors: Zahorian Stephen A. , Nossair Zaki B. , Coleman Robert F.
Published: October 2005

A perceptual experiment was conducted with naturally spoken intitial stop consonants in order to test recent claims for acoustic invariance in the initial portions of stop consonants [for example, S. E. Blumstein and K. N. Stevens, J. Acoust. Soc. Am. 67, 648–662 (1980)]. The original stimuli consisted of tokens of the stops /b,d,g/ with the vowels /i,a,u/ as spoken by two male and two female speakers. A computer graphics waveform editor was used to locate the initial portions of the waveform up to the first, second, fourth, and sixth voicing pulses. Three experimental conditions were evaluated: (a) the initial segment only; (b) the initial segment plus the original steady-state vowel; and (c) the intitial segment plus an alternate steady-state vowel. Ten listeners participated in a forced-choice recognition experiment to determine the conditions for which perceptual cues to consonant identity are retained. Recognition accuracy was consistently highest for condition (b), lower for condition (a), and lowest for condition (c). These results, therefore, argue against vowel-independent cues to stop consonant recognition and are more consistent with studies which conclude that the perception of stop consonants is strongly influenced by the following vowel [for example, M. F. Dotman et al., Percept. Psychophys. 22, 109–122 (1977)]. Thus attempts to isolate the perceptually important cues to stop consonant identity should take into account the vowel context.
Vocal fold contact area
Authors: Titze Ingo R. , Druker David , Durham Paul
Published: October 2005

Vocal fold contact area is generally inferred from the electroglottographic (EGG) signal. To our knowledge, only one attempt has been reported to measure contact area directly [Scherer, Druker, and Titze, Vocal Fold Physiology Conference, Tokyo, Japan (1987)]. This direct measurement is needed to identify artifacts and ambiguities in the EGG signal that may lead to questionable interpretations of vocal fold movement. In particular, the spatial distributions of contact area (anterior-posterior and vertical) is not always clear by simple inspection of the EGG signal. In this study, excised dog larynges were prepared and mounted such that one vocal fold could vibrate against a sheet of electroconductive glass. The area of contact was then extracted by videostroboscopy and image processing techniques. Comparisons are made between three-parameter and four-parameter simulation models of EGG and the experimentally determined contact area. [Work supported by NINCDS.]
Source-system coupling in voice production in excised larynges
Authors: Cooper Donald S. , Florman Steven H.
Published: October 2005

An apparatus was constructed to study the effects of subglottal and supraglottal resonances on voice production in excised human larynges. The approach was based on an earlier study of W. Trendelenburg and H. Wullstein [summary by D. S. Cooper in Otolaryngology—Head and Neck Surgery, edited by C. W. Cummings et al. (Mosby, 1986), Vol. 3, pp. 1766–1776]. The resonance of the pseudolung was adjustable, while variation of supraglottal resonances was achieved by construction of vowel resonators based on Fant's area functions. Activity of intrinsic laryngeal muscles was simulated by weights attached through pulleys to the larynx. In order to examine the effect of acoustic loading with a full range of variation of the first formant, voice production with supraglottal resonances based on /i/ and /o/ was compared with phonation without the resonator. The resting glottal configuration and average air flow were maintained constant, while the effects of varying supraglottal resonances on voice production were observed in terms of acoustic and glottographic measurements.