bluuebunny/crossref_metadata_2025 huggingface dataset:
Local consonance and adaptive tunings: Sound demonstrations
Authors: Sethares William A.
Published: October 2005

A relationship between tuning (or scale) and timbre (or spectrum) based on the perceptual results of Plomp and Levelt [J. Acoust. Soc. Am. 38, 548–560 (1965)] was presented by Sethares [J. Acoust. Soc. Am. 94, 1218–1228 (1993)]. This relationship can be used to determine an appropriate scale in which a given timbre sounds most consonant, or to design timbres for play in specified scales. This presentation gives sound demonstrations using stretched and compressed timbres, scales related to FM (and other) timbres, and timbres designed specifically for play in 10-tone equal temperament. The notion of an adaptivetuning is an extension in which the tuning of notes are allowed to vary in real time so as to iteratively maximize a measure of consonance. Sound examples that demonstrate the evolution of notes in an adaptive tuning are presented. Examples include complex tonal clusters that slowly evolve towards consonance, adaptation of nonharmonic notes to related scales, and automatic ‘‘correction’’ of out-of-tune harmonic notes. The sound demonstrations provide concrete auditory evidence of the validity of the theoretical results.
Rhythmogram analysis of percussion performance
Authors: Todd Neil P. McAngus
Published: October 2005

In this paper a new method of performance analysis is described based on a multi-timescale decomposition of the acoustic signal. This analysis is sensitive to a variety of expressive devices employed by musical performers including tempo, dynamics, and articulation. The output of the analysis is a hierarchical tree structure that resembles the time-spanreduction of the theory of Lerdahl and Jackendoff. Analyses of percussive performance are demonstrated for a variety of percussive signals. The model that forms the basis of the analytic method also provides an account of the phenomena of rhythmicstreaming whereby a sequence of events differentiated only by loudness can form coherent streams.
The tritone paradox revisited: Effects of musical training, envelope peak, and response mode
Authors: Cohen Annabel J. , MacKinnon Karen , Swindale Nicholas
Published: October 2005

Eighteen musicians and nine nonmusicians judged the direction of tritone intervals between pairs of octave-complex (Shepard) tones. The tones in each pair had the same spectral envelope centered on either C or F♯ in one of three octaves. Nine of the musicians sang the intervals on one-half of the trial blocks instead of making the usual up/down judgments. Monte Carlo analysis revealed that 83% of the musicians and 33% of the nonmusicians showed a significant direction bias for regions of the chroma circle. This corroborates the notion of a chroma-circle template of definite orientation [Deutsch etal., Mus. Perc. 5 (1987)], but suggests that musical training may play a greater role in either its establishment or access. Biases in upward judgments were toward the C-chroma region, consistent with Deutsch’s [J. Acoust. Soc. Am. Suppl. 1 88, S139 (1990)] findings for native Californians as opposed to British. With the exception of one musician, envelope peak position had little effect on the results. In general, the two response modes, singing and up/down judgments, produced converging evidence.
Shallow water single mode excitation using feedback control
Authors: Buck John R. , Peregrym Denis , Preisig James C. , Catipovic Josko
Published: October 2005

This work presents an adaptive algorithm for exciting a single mode in the shallow water acoustic waveguide. Previous efforts have focused on laboratory waveguides using pre-computed weights for the source array based on precise prior knowledge of the channel [Clay and Huang, J. Acoust. Soc. Am. 67, 792–794 (1980), Gazanhes and Garnier, J. Acoust. Soc. Am. 69, 963–969 (1981)]. In contrast to these open-loop systems, the algorithm presented here uses a reference receiver array to implement a closed-loop feedback control system. The channel is characterized through an effective coupling matrix relating the source weights to the coefficients of the excited modes. The algorithm iterates between estimating the coupling matrix from the reference observations, and determining the source array weights from the estimated coupling matrix. Results from detailed simulations using actual sound-speed and bottom parameters indicate this approach allows the algorithm to adapt and compensate for environmental mismatch and some time-dependent fluctuations.
Acoustic wave propagation in a random, shallow water waveguide
Authors: Creamer D. B. , Orchard B. J.
Published: October 2005

An analysis of acoustic wave propagation in a random shallow water waveguide is presented, in which deviations of the index of refraction are a stochastic process. The specific model studied is motivated by the oceanic waveguide in shallow waters, in which the subbottom sediment leads to energy loss from the acoustic field, and the stochastic process results from internal (i.e., density) waves. In terms of the normal modes of the waveguide, the randomness leads to mode coupling while the energy loss results from different attenuation rates for the various modes (i.e., mode stripping). Monte Carlo simulations of stochastic coupled-mode equations are presented [similar to L. B. Dozier and F. D. Tappert, J. Acoust. Soc. Am. 63, 353–364 (1978)], from which the average modal intensity (second moments of the field) and the scintillation index for this model are derived. It is shown that the usual concept of equilibrium or saturated statistics must be modified. In the context of an unrealistically simplified model with only two modes, an interpretion is provided whereby this result is due to the competition between the mode coupling terms, which redistribute the modal energies, and mode stripping, which results in an irreversible loss of energy.
Modeling of sound propagation over a shear-supporting sediment layer and substrate
Authors: Arvelo Juan I. , Yuan Jianren , Überall Herbert , Chouffani Khalid
Published: October 2005

A series of model tank measurements carried out by Glegg etal. at Florida Atlantic University (FAU) has furnished data for range-independent and for downslope sound propagation over consolidated bottom sediments simulating the ocean floor. The modeled ocean floor consisted of an epoxy layer over a semi-infinite concrete basement. The measured range-independent transmission loss is compared here against predicted results from a fast-field propagation model, a normal-mode propagation model, and a parabolic-equation propagation model at frequencies of 15, 20, 25, and 30 kHz. The measured downslope transmission loss is compared against predicted results from the normal-mode and the parabolic-equation models at frequencies of 15, 20, and 30 kHz. The three models were selected for their treatment of bottom elasticity which cannot be neglected in such a hard-bottom case. Mode coupling did not seem to be a significant contributor to sound propagation in the 5-deg downslope case. These comparisons show some unexpected agreement between models and against the measured data in a controlled environment.
Transmission of acoustic pulses from an underwater spark source into water-saturated sandy sediment in the 2- to 10-kHz band
Authors: Changwatchai W. Top , Chotiros Nicholas P.
Published: October 2005

The transmission of acoustic pulses from water into a water-saturated sandbed was observed in the 2- to 10-kHz band. An underwater spark source was used to transmit the pulses to a buried array of hydrophones, which varied in depth from 0 to 60 cm. The spark source was suspended 0.75 m above the sand and pulsed at 0.5-m horizontal intervals up to a distance of 3.5 m. Pulse compression processing was used to sharpen up the wave pulses and separate the direct pulse from reflected pulses, as well as to eliminate electrical interference from the spark generator. Speeds and attenuations of observed waves were computed from measurements. [Work supported by ONR.]
Time-frequency energy distribution analysis of a shallow water acoustics experiment at the AGS site
Authors: Jaya Indra , Badiey Mohsen , Cheng Alexander , Pulaski Mark
Published: October 2005

The short time Fourier transform (STFT), wavelet transform (WT), and Wigner distribution (WD) are used to characterize the time-frequency distribution of air gun signatures in azimuth and range. The signatures were obtained in a shallow water experiment conducted at the AGS site. The distributions are explained in relation to the acoustic interaction with the seafloor. Accurate descriptions of these distributions are important for better understanding of the acoustic field in shallow water. By means of a combination of the time-frequency distribution and empirical orthogonal functions (EOF), the effects of higher-order modes are studied and localized on the features of the received time series. Numerical simulations using the SNAP model are conducted to interpret some of the observed features. Comparisons between the simulated and measured time series indicate that the higher-order modes are more sensitive to the fine layer structure of the seafloor physical properties. a)Present address: Office of Naval Research, Ocean Acoustics program Code 324OA, 800 North Quincy St., Arlington, VA 22217-5000.
Shallow water sediment layer structure and composition effects on range-dependent transmission loss at the AGS site
Authors: Bongiovanni K. P. , Badiey Mohsen , Siegmann W. L.
Published: October 2005

Effects of geological features in shallow water sediment layers on acoustic propagation are examined using numerical simulations and measured experimental data. Accurate geoacoustic data from the New Jersey Shelf AGS site provide profiles of compressional and shear sound speed, attenuation, and density, and along with detailed bathymetry are used for input to transmission loss and wave-number calculations. In order to examine range-dependent effects of geoacoustic properties and geological structures in this region, frequency domain parabolic equation (PE) models (one of which includes sediment shear) are efficient and accurate for the required simulations. Sensitivities to variations in geometrical sediment structure, including numbers of sediment layers and interfacial depth and range dependences, are considered to investigate influences of sediment characteristics on the acoustic field. Uncertainties in material geoacoustic parameters and sensitivities to required horizontal and vertical resolution of modeled geoacoustic data are also examined. Additional comparisons of PE simulations illustrate the influence of shear effects in this shallow water environment. Preliminary discussion of simulation results and of sediment layering effects on acoustic propagation will be given in connection with experiments. a)Present address: Office of Naval Research, Ocean Acoustics program Code 324OA, 800 North Quincy St., Arlington, VA 22217-5000.
Measurement of transmitted and diffracted sound through open screens by impulse methods
Authors: Lyons Richard , Gibbs Barry M.
Published: October 2005

The availability of inexpensive but powerful instrumentation and the rising costs of specialist acoustic facilities have increased interest in impulse response methods for measuring sound insulation, particularly insitu. The method is relatively simple and requires the separation of a direct short duration transmitted signal from subsequent scattered, diffracted, and reflected components, to allow fast Fourier transformation. Where the sound insulation performance of an open acoustic screen is required, internal diffracted components are included in the time window of interest. A description is given of the method of measurement of open screens that applies to both laboratory and field conditions. Measurements are compared with theory and discrepancies are the result of phase changes at high frequencies. These phase changes are not included for in the thin screen theory, however, agreement in general is good. The method works well for open screens, provided that the time signal is properly isolated, and promises a quick accurate method of measurement for complicated open screen geometry’s where theoretical prediction is difficult.
(3,1) drive PVDF vibration sensor for underwater measurements of compliant surface motion
Authors: Caspall Jayme J. , Jarzynski Jacek , Doane John W.
Published: October 2005

A new (3,1) drive piezofilm vibration sensor has been developed. The sensor operates between the lumped element resonance and the first transmission line resonance to provide an output proportional to displacement within a specified frequency range. The demonstration model of this sensor is flat over the range, 2 to 8 kHz. The open circuit voltage sensitivity is 1.5 mV/nm, which is roughly equivalent to a 30-mV/g accelerometer in this frequency range. The mounted mechanical impedance is low, which makes this sensor ideal where mass loading is a concern. Some measurements of compliant materials (neoprene and corprene) are discussed. [Work supported by ONR.]
Acoustical response function of an ultrasonic transducer in contact with a solid medium
Authors: Nguyen van-chi , Noël Estelle
Published: October 2005

Different solutions for the acoustic coupling function from an ultrasonic transducer radiating in a solid with or without flaw are provided. They are obtained by using empirical models [Weight, J. Acoust. Soc. Am. 81, 815–826 (1987); Lhemery, J. Acoust. Soc. Am. 90, 2799–2807 (1991)] or Green’s-formulation [Djelouah, J. Acoust. Soc. Am. 92, 2932–2941 (1993)] for transient ultrasonic fields and reciprocity principle. The coupling function is given as the convolution integrals of partial impulse responses and their time derivatives. Comparisons between solutions will be presented, using numerical and experimental results performed with straight and angle ultrasonic transducers.
Finite element modeling of single periodic curved gratings
Authors: Hladky-Hennion A. C. , Bossut R.
Published: October 2005

The analysis of the scattering of a plane acoustic wave by an in-plane periodic, active, or passive structure has been previously performed with the help of the finite element method [A. C. Hladky-Hennion etal., J. Acoust. Soc. Am. 94, 621–635 (1993)]. In that case, the compliant tubes grating is a single periodic structure that is periodic in one direction and infinite in the other one. The method previously described has been extended to take into account the effect of the curvature of the grating, periodic along the symmetry axis. Within this approach, only a bidimensional mesh is needed because the structure is axisymmetrical. Moreover, only one unit cell of the periodic structure, including a small part of the surrounding fluid domain, has to be meshed, due to the use of a classical Block-type relation between the displacement components of points that are separated by the grating spacing. Finally, the effect of the external fluid domain is accounted for by matching the pressure field in the finite element domain to plane waves expressed in terms of a series of Bessel or Hankel functions. This paper describes the general mathematical model and then provides the results obtained for the scattering of a plane wave form simple axisymmetrical structures, this validating the method. Next, the method is applied to the case of curved compliant tubes gratings, thus showing the influence of the curvature.
Velopharyngeal insufficiency analysis based on the lossless tube model
Authors: Yu Jong-Daw , Barba Joseph , Omori Koichi , Blaugrund Stanley M.
Published: October 2005

The purpose of this study is to design a method to reconstruct the shapes of articulators including the vocal tract and nasal tract during phonation and to quantitatively identify velopharyngeal dysfunction when it occurs. Voice in patients with velopharyngeal insufficiency have the psychoacoustic impression of hypernasality that results from an over abundance of sounds resonating in the nasal tract. Patients with unrepaired soft palate clefts typically demonstrate this abnormal speech. The articulation model of velopharyngeal dysfunction is predicated upon the lossless tube model. During recording of the sustained /a/ sound, subjects were asked to block their nostrils with two fingers. The resulting closed nasal tract introduces zeros and the opened vocal tract contributes poles. Therefore, an ARMA model is formed. PARCOR analysis and the inverse filter technique are used to reconstruct both the shapes of the vocal tract and the nasal tract. The sufficiency of the velopharynx can be determined by measuring the cross-sectional area of velopharynx.
A three-channel model for nasals and nasalization
Authors: Lin Qiguang
Published: October 2005

This paper studies a three-channel model of the vocal tract for nasals and nasalization. Traditionally, a two-channel model has been utilized: One channel for pharyngeal-oral tract and one for the nasal tract. This representation assumes that the left and right branches of the anterior part of the nasal tract are symmetrical and that the corresponding paranasal cavities connected to either branch are also symmetrical. Recently available data of the nasal geometry show, however, an apparent asymmetry between the left and right branches and between the companion sinus cavities [Dang etal., J. Acoust. Soc. Am. 94, 1765(A) (1993)]. To take into account the differences, the nasal tract must be simulated by a two-channel model, resulting in a three-channel model for the whole vocal system. Based on the proposed three-channel model, calculations are made of spectral patterns of nasals and nasalization. The results show a bound pole-zero structure around 2000 Hz. This pole-zero combination stems from the asymmetry between the left and right branches, and conforms with sweep-tone measurements. Other differences from conventional modeling of the vocal tract are also noted. [The simulation program is available upon request.]
Locus equations during compensatory articulation: A test of the ‘‘orderly output constraint.’’
Authors: Sussman Harvey M.
Published: October 2005

Previous research [Sussman etal., J. Acoust. Soc. Am. 90, 1309–1325 (1991); 94, 1256–1268 (1993)] showed that frequency of F2 onsets (for syllable-initial voiced stops /bdg/) is a linear function of F2 as measured in the vowel nucleus and the particular linear function relating these parameters is itself a function of stop place of articulation. This linear relationship has been demonstrated cross-linguistically as well as across consonantal manner classes (fricatives, nasals, approximates). The purpose of this study was to determine how altered articulatory kinematics (via bite blocks) affects the linearity and place coding of locus equations. Six speakers produced CV/t/ tokens with initial /bdg/ followed by ten medial vowels. F2 onset (Hz) and F2 midvowel (Hz) were measured via spectrographic, LPC, and FFT spectra. Despite bite blocks locus equations were remarkably linear, and slopes/y intercepts consistently contrasted stop place. A functional role for the acoustic linearity of CV transitions in the output signal, despite gross alterations in articulatory gestures, is offered based on auditory perceptual requirements necessitated by the neural encoding of F2 transitions. These ideas are described within a new theoretical framework—the ‘‘orderly output constraint.’’
Acoustic correlates of glottal characteristics of female speakers
Authors: Hanson Helen M.
Published: October 2005

In the past, voice characteristics such as DC flows and glottal abductions of different kinds have been studied using airflow measures, inverse filtering, and endoscopic observations. In this study, the possibility of using acoustic measurements alone to gain insight into these individual differences has been investigated. Acoustical theory suggests that the bandwidth of the first formant and the strength of tracheal poles should be relevant measures of glottal abduction. Voicing waveform characteristics related to mode of closure may also be expected to show up in the speech waveform or spectrum. Data were collected from 13 female speakers. The waveforms and spectra of several tokens of a few vowels were analyzed for estimates of F1 bandwidth, subglottal coupling, open quotient, and spectral tilt. F1 bandwidth and spectral tilt were found to vary greatly between individuals, and seem to be directly correlated. Most of the speakers show some evidence of subglottal coupling; a few speakers display rather strong tracheal pole/zero pairs. A clear understanding of how these measurements are correlated remains to be understood, possibly with the aid of physiological measures. [Work supported in part by a grant from NIDCD.]
A reconsideration of locus equations as invariants for place of articulation of stop consonants
Authors: Brancazio Lawrence , Mitra Joy
Published: October 2005

It has been claimed that locus equations, representing linear relationships between F2 at vowel midpoint and onset for CV syllables, predict place of articulation for stop consonants [H. M. Sussman etal., J. Acoust. Soc. Am. 90, 1309–1325 (1991)]. However, the slopes of these regression lines are shown to be flexible. Insofar as the slopes reflect the influence of vowels on preceding consonants, they can be changed by manipulating the degree of coarticulation. In this study, speakers produced /b/, /d/, and /g/ followed by various vowels at fast, normal, and slow rates of speech. In the fast productions the consonant was preceded by the same vowel that followed it, and in the slow productions it was preceded by the vowel schwa, which placed competing demands on the articulators to reduce anticipatory coarticulation by the following vowel. The fast productions resulted in higher slopes for each consonant, while the slow productions resulted in lower slopes. Subjects in a perceptual study were presented with tokens of /b/, /d/, and /g/ with identical slopes and asked to identify the consonants. Results indicate that identification of consonants is not predicted by the slopes of their regression lines. [Work supported by NICHD Grant No. HD-01994.]
A model of jaw movement control based on the equilibrium point hypothesis
Authors: Laboissièrre R. , Ostry D. J. , Feldman A. G.
Published: October 2005

A seven muscle model of human jaw and hyoid motion based on the equilibrium point hypothesis of motor control (λ model) is presented. The form of central neural control signals underlying speech and whether jaw muscle geometry needs to be accounted for in speech planning is explored. According to the model, central neural commands specify the equilibrium position of the jaw by controlling the muscle lengths (λ’s) at which motoneuron recruitment begins. Motor functions are specified by various combinations of λ’s. One combination of λ’s is associated with the level of coactivation of muscles. Others are associated with motions in specific degrees of freedom such as jaw rotation and translation. The vertical and horizontal positions of the hyoid may also be controlled. These control signals may act alone or be superimposed to produce combinations of rotation, translation, and muscle cocontraction. It is demonstrated that in each phase of movement, constant velocity shifts in threshold lengths of all muscles can account for patterns of jaw motion in speech. It is also assessed whether the same commands for rotation and translation would produce essentially the same movements from any starting jaw position. [Work supported by ATR Human Information Processing Research Laboratories, Japan; NSERC, Canada; Québec-France.]
Modeling speech production using finite difference techniques
Authors: Cummings Kathleen E. , Clements Mark A.
Published: October 2005

Because of limitations in computing resources and analysis methods, speech processing techniques have relied on linear models that make simplifying assumptions about the manner of propagation, losses, and the geometry of the vocal tract. This research has developed a new, more sophisticated model of speech production that is based on numerical simulation of wave propagation in the vocal tract. The model uses a numerical analysis technique, finite differencing, to solve for wave propagation in a complicated geometry that is more representative of the vocal tract than previous models. The objective in developing this model of speech production is to enable the researcher to investigate and compare theories of speech production of varying complexity. The model is designed as a research tool in which it is possible to vary the driving equations and boundary conditions as well as the vocal tract geometry and the excitation to the vocal tract. Simulations that compare the speech produced given several different glottal models in a fixed geometry have been conducted. The model has also been used to study speech produced in several geometric configurations representing several different vowels. [Work supported by NSF Grant No. CDA9211129.]
Physical constraint of tonal production: A study of F0 movement in groups of T3 syllables in Mandarin Chinese
Authors: Liao Rongrong
Published: October 2005

Productional constraints and formation of F0 contours of special tonal sequences in Mandarin Chinese is discussed in this paper. Three female native speakers were asked to produce sentences containing only syllables with the third tone (T3, a low falling tone) in a relatively casual style. Each speaker was also asked to spontaneously tell a story and read the transcription of her own story. F0 movement in all sequences of T3’s, in both tonal controlled and uncontrolled data, were examined. Unexpected F0 contours, according to the phonological rules of T3 sandhis, and unusual phenomena of tonal realization corresponding to stresses, are exhibited. Two basic patterns of F0 contours are found to occur inside intermediate phrases: a basic rising (-level)-falling contour and a rising-falling-rising-falling contour, with or without pre- and/or post-adjustment. To explain this phenomena, physical constraints on the production of tones are hypothesized. It is assumed that T3 sandhi is affected both by the constraints of tonal production and by local stress pattern, and that the effect of the productional constraints overrides the effect of stress pattern.
Complete neutralization of manner of articulation in Korean
Authors: Kim Hyunsoon , Jongman Allard
Published: October 2005

There is a lively debate in the phonetic literature as to whether phonological neutralization is phonetically complete. Almost all phonetic studies of neutralization have focused on word-final devoicing, with findings supporting either complete or incomplete neutralization. The present study investigated a different type of neutralization, namely that of manner of articulation. Korean has a rule of manner neutralization whereby underlying /s/ surfaces as [t] in syllable-final position. Underlying /t,th/ will also surface as [t], resulting in minimal pairs that differ in terms of the manner of the final consonant in the underlying but not in the surface representation. Making use of the fact that vowels preceding fricatives are longer than when preceding oral stops, we examined vowel and closure durations to determine if the speech signal contained any cues to the underlying manner distinction. Data from four speakers suggest that this neutralization of manner is phonetically complete. Implications of these results for the relation between phonological and phonetic representations will be discussed.
Acoustic contrast and the origin of the human vowel space
Authors: Carré René , Lindblom Bjorn , MacNeilage Peter
Published: October 2005

An algorithm is described that takes an arbitrary VT area function (normalized to a length of 18 cm), calculates its formant frequencies and their ‘‘sensitivity functions,’’ and uses those functions to induce VT shape changes that increase or decrease a given formant frequency. The computations are performed recursively, and for each formant separately, until extreme values are established. Irrespective of the starting configuration, the procedure converges on a given set of formant ranges that closely match observed spoken values. Thus in its efforts to enhance ‘‘acoustic contrast’’ (increase formant ranges), the algorithm gradually ‘‘rediscovers’’ the human vowel triangle. Final VT perturbations show isomorphism with the ‘‘distinctive regions’’ of the DRM model [Carré and Mrayati (1992)]. One significant consequence of that finding is that an input configuration lacking a human ‘‘pharynx’’ will eventually be transformed into a shape that does have such a cavity. These results are compatible with the role accorded to ‘‘acoustic contrast’’ in the formation of vowel systems. Also they throw some new light on the old issue whether the evolution of VT tract morphology was (in part) an acoustically driven process. a)This work was performed during a stay at Dept. of Linguist., Univ. of Texas at Austin.
What explains habitual speaking rate?—Neuromuscular constraints and sociolinguistic consideration
Authors: Tsao Ying-Chiao , Weismer Gary
Published: October 2005

Neuromuscular and sociolinguistic hypotheses were proposed to explore and account for the nature of individuals’ idiosyncratic speech rates. In the study, four speech tasks including a script reading, a paragraph production, an isolated sentence production, and five sentences with varying lengths were performed at both habitual and maximum rates by 50 male and 50 female adults. A faster and a slower groups of talkers were selected for both genders based on their script reading times in the distribution of overall speaking rates. The average articulation rates for both sexes were then calculated, respectively, from both groups of talkers. Although the slow talkers increased their rates from habitual to maximum to a greater degree than the fast talkers, their maximum rates fell well short of the maximum rates of the fast talkers. Fast talkers may have changed their rates less dramatically across the rate conditions because their habitual rates were already close to maximum rates. These findings were true for both genders and suggested that neuromuscular constraints yield the crucial contribution to the control of individuals’ speech rates. [Work supported by UW—Madison Speech Acoustic Laboratory.]
A report on the vowels of traditional speakers of Western Navajo and the implications for a theory of vowel dispersion
Authors: McDonough Joyce
Published: October 2005

Navajo has a marked vowel space, four long and short vowel pairs with a gap in the high back area. A consistent (monodialectic), conservative (near monolingual) group of Navajo speakers were recorded in the field. Vowel formants were measured and plotted on a bark scale, statistics were performed on vowel pairs and groups. Dispersion and quantal theories predict specific tendencies which do not occur. The results showed a very marked triangular vowel space: two front vowel pairs are compacted into a small area, a high back gap is maintained. Three issues are examined: vowel quality enhancement of the long-short contrasts, distribution of vowels in the tight high front space, and the dispersion of the mid back vowels and their relation to mid front vowels. A quality enhancement is consistently reported in the literature for the high front vowel alone. While statistically reliable differences were found in the vowel pairs along the F1 axis, only the high front vowel showed differences along F1 and F2′ axis. These results imply different, possibly acoustic, targets for the long and short high front vowels while the differences in other pairs is due to undershoot. [Work supported by NIH and American Philosophical Society.]
Ambient noise and reverberation in the Littoral Region west of Mallorca
Authors: Shooter J. A. , Huang H. J. , Hackert C. L. , TenCate J. A. , Muir T. G. , Kristensen Å. , Caiti A. , Michelozzi E. , Max M.
Published: October 2005

Experiments were carried out in the area west of Mallorca, Balearic Islands where the seafloor is a relatively flat, thin (∼1 m), calcareous sand sediment atop a hard limestone bottom some 100 m below the sea surface. A linear, uniformly spaced array of 24 hydrophones with element separations of 2 m was deployed. Reverberation measurements were made with wideband (SUS) and narrow-band sources with the array deployed vertically and horizontally on the seafloor. The measurements show the area to be quite unique, due to the hard, flat, high velocity bottom. It is highly reverberant with unusually low ambient noise. Transmission loss measurements were made at several depths and have been analyzed with computations using OASES (SAFARI). For this area, the transmission loss and scattering strength are strongly frequency dependent. Both show a relatively high-frequency minimum in the 500- to 800-Hz band. Other unique features of this area are presented. [Work supported by Advanced Research Projects Agency, Maritime Systems Technology Office.]
Acoustic prediction in shallow water from sparse data
Authors: Porter Robert P. , Siderius Martin , Fox Warren L. J. , Rouseff Daniel
Published: October 2005

Consider the problem of estimating acoustic propagation over extended ranges in shallow water. Such predictions would be useful in deploying assets, locating sources, or oceanographic monitoring. Given adequate environmental information, standard numerical techniques could be applied. For a highly variable site, however, the medium would rarely be known with sufficient resolution to make accurate calculations. Direct acoustic measurements suffer from a similar lack of resolution; isolated point-to-point measurements cannot fully characterize acoustic propagation over a large region. In this talk, a hybrid numerical/experimental technique is examined. In the proposed approach, sparse environmental measurements are supplemented by making a limited number of acoustic measurements. By appropriately combining the two data sets and extrapolating, acoustic propagation over an extended region can be accurately predicted. The method is tested using archival sound speed and bathymetric data for a strongly range-dependent site. The relative effects on the propagating acoustic wave front of variations in bathymetry, imperfect knowledge of the sediment, and variability in the water column are quantified. [Work supported by ONR and NRL.]
Observer weighting of concurrent binaural information
Authors: Stellmack M. A. , Lutfi Robert A.
Published: October 2005

On each experimental trial, a two-component complex consisting of a 553- and 753-Hz pure tone was presented to listeners over headphones. Each component had an interaural delay that was independently and randomly chosen on each presentation from a single uniform distribution ranging from −100–100 μs. In different conditions, listeners were instructed to make a left–right judgment indicating the lateral position of the 753-Hz component relative to center, the 553-Hz component relative to center, the total signal relative to center, or the 753-Hz component relative to the 553-Hz component. The observer weights for each component and an estimate of internal noise were derived by computing the correlations between the interaural delays of the components and the listeners’ left–right judgments. Three of the four listeners were found to adjust their weights appropriately for each listening task, while the fourth listener consistently gave almost no weight to the 553-Hz component regardless of the listening condition. Estimates of internal noise were largely unchanged across listening conditions for all listeners. [Research supported by NIDCD.]
Changes in the binaural intelligibility level difference (BILD) with age
Authors: Summerfield Quentin , Marshall D. H. , Palmer A. R. , Foster J. R. , Moorjani P.
Published: October 2005

The time course of the development of the BILD was measured in a cross-sectional study of 113 subjects with normal hearing who were approximately evenly distributed in age on a logarithmic scale between 3 and 30 years. An adaptive procedure was used to measure the minimal level at which subjects could distinguish the names of 14 familiar toys in the NoSo and NoSπ conditions in pink noise (60 dB A) and in quiet. Between age 3 and adulthood, thresholds fell by 5 dB (NoSo), 11 dB (NoSπ), and 13 dB (quiet), and the BILD (NoSo–NoSπ) increased from 2.5 to 8.5 dB. The changes in thresholds followed the same time course in the three conditions, suggesting a common cause. If it is assumed that the within-subjects standard deviation of thresholds can be taken as an index of the variability of the internal representations of speech and noise, the data can be described adequately by a model in which the internal signal-to-noise ratio required for correct identification declines with age as subjects become more familiar with the acoustic differences between the test words. Thus, it may be possible to account for the development of the BILD without invoking the maturation of binaural analysis.
Cross-frequency interaction for interaural time and intensity discrimination in listeners with normal hearing and impaired hearing
Authors: Smith Laura , Koehnke Janet , Besing Joan
Published: October 2005

The ability to discriminate interaural differences in complex signals was examined in listeners with normal hearing and with bilateral sensorineural hearing impairment. Just noticeable differences (jnds) for interaural time and interaural intensity were obtained using 1/3-octave narrow band noise (NBN) stimuli centered at 500 and 4000 Hz in three conditions. In condition 1 the NBNs were played in isolation; in condition 2 the NBNs were played simultaneously with congruent interaural information across frequency; and in condition 3 the NBNs were played simultaneously with either the 500-Hz band dichotic and the 4000-Hz band diotic (3a) or the 500-Hz band diotic and the 4000-Hz band dichotic (3b). The best interaural time and intensity discrimination for the listeners with impaired hearing is seen when both bands contain congruent interaural information (condition 2). Subjects with impaired hearing and normal hearing show reduced sensitivity to interaural time differences when the 500-Hz band is diotic and discrimination is based on the 4000-Hz band (3b). The listeners with impaired hearing also demonstrate poorest interaural intensity discrimination for this condition (3b). Results suggest that subjects with impaired hearing may benefit from congruent interaural information in more than one frequency region. [Work supported by the Dept. of Veterans Affairs and NIH Grant No. DC00428.]
The discrimination of independent samples of noise under monotic and dichotic conditions
Authors: Heller Laurie M. , Trahiotis Constantine
Published: October 2005

Listeners’ ability to discriminate between independent tokens of 800-Hz-wide (79 dB SPL) bands of noise was measured in a two-cue, two-alternative, temporal forced-choice task where the second or third interval contained a noise that was different from that presented in each of the other three intervals. Discriminability was best in the diotic condition. Next-best performance occurred in a dichotic condition where the three nonsignal intervals contained identical noises that were uncorrelated across ears, while signal intervals contained new interaurally uncorrelated noises. Worst performance occurred in a dichotic condition where one noise was repeated in all four intervals in one ear, while another, independent noise, was presented in the other ear during the nonsignal intervals. The signal interval contained a new (and interaurally uncorrelated) sample of noise presented to the latter ear. Performance was poorer than that obtained in the strictly monaural condition. This indicates that listeners were unable, effectively, to ignore the identical, and hence noninformative, waveforms presented to one ear across the four temporal intervals of each trial. Data obtained from several other dichotic conditions will also be discussed. [Work supported by NIH and AFOSR.]
Binaural spectral interference effects measured with masking and with discrimination paradigms
Authors: Bernstein Leslie R. , Trahiotis Constantine
Published: October 2005

This study concerned binaural spectral interference. First, detection thresholds were measured for a 125-ms, 4-kHz tonal signal masked by a 145-ms, 100-Hz-wide band of noise (centered at 4 kHz) in NoSπ or NoSo configurations. These thresholds were compared to those obtained when a spectrally-remote ‘‘interferer’’ consisting of a 100-Hz-wide band of noise centered at 500 Hz accompanied the masker. Interferers were either diotic or were interaurally uncorrelated and were presented either continuously or were gated on and off simultaneously with the masker. About 7 dB of interference was obtained (i.e., thresholds increased) in the presence of the uncorrelated, gated interferer and about 5.5 dB of interference was obtained with the diotic, gated interferer. Interference was reduced substantially when the interferer was presented continuously. Reversing the roles of the spectral regions containing the signal and interferer (i.e., measuring detectability of a 500-Hz tone) yielded little interference. That is, interference effects were spectrallyasymmetric. Comparable results were obtained when interference was assessed for detection of interaural temporal disparities. In contrast, very little interference was measured for detection of interaural intensitive disparities. [Work supported by NIH and AFOSR.]
More on the precedence effect in three planes
Authors: Rakerd Brad , Hartmann William Morris
Published: October 2005

Following previous experiments [Rakerd and Hartmann, J Acoust. Soc. Am. 92, 2296 (A) (1992)] the precedence effect was studied in azimuthal, frontal, and sagittal planes. The first two planes involve binaural differences, the third plane does not. Experiment I required the listener to localize a target click, presented in an anechoic room, in competition with a lagging click, presented from a different location in the plane under study. The lagging click followed the target by a delay of 0.5, 1, 2, or 5 ms. For each plane, the experiment tracked the decrease in precedence effect as the level of the lagging click became greater than the level of the target (0–12 dB). The results showed similar dependencies in all three planes, indicating a universality of precedence effect. Experiment II required the listener to report perceived echoes, thus determining echo threshold, as a function of the same delay and level-difference variables. The results showed higher echo thresholds in the sagittal plane compared with the other two. Both experiments indicate significant precedence effect in the absence of binaural differences. [Work supported by the NIDCD, DC00181.]
Absence of ‘‘amblyocusis’’ after atypical binaural experience
Authors: Gray Lincoln , Wilmington Debra , Jahrsdoerfer Robert
Published: October 2005

Binaural hearing in patients after surgical correction of congenital conductive hearing losses suggests that ears do not respond like eyes to atypical early experience [D. Wilmington, L. Gray, and R. Jahrsdoerfer, Hear. Res. 74 (1/2) (1994)]. Data from patients with aural atresia, born with one normal ear and receiving a newly functional ear at various ages, are reviewed. All aspects of binaural processing improved after surgery, but horizontal localization did not improve as much as many discriminations. Unlike the visual system where asymmetric inputs must be corrected before about 8 years of age, the human auditory system is much more forgiving of early atypical experience. Even after years of asymmetric input, a corrected atretic ear has near-normal discriminations—as revealed by normal monaural audiometry, interaural time and intensity differences, and binaural unmasking of signals in noise. The phenomenon of amblyopia, or dull vision, does not occur in hearing. A speculative difference between hearing and vision is discussed: details are heard better than patterns after early auditory deprivation, and patterns are seen better than details after early visual deprivation.
Sound radiation from two semi-infinite dissimilar plates subject to a harmonic line force excitation in mean flow. Part I: Theory
Authors: Wu Sean F. , Zhu Jinshuo
Published: October 2005

Formulations are derived for predicting sound radiation from two semi-infinite dissimilar plates subject to a line force excitation at the joint in the presence of mean flow using the Wiener–Hopf technique and Fourier transformations. The acoustic pressure is solved in the wave-number domain first and expressed in terms of decomposition factors and eight parameters associated with displacements, slopes, bending moments, and shear forces at the joint of two plates. The decomposition factors are evaluated via contour integrations, and eight parameters are determined by a set of simultaneous equations derived from boundary conditions and the finiteness requirement imposed on the joint. It is shown that the set of equations reduces to a 2×2 matrix for a welded joint, a 3×3 matrix for a hinged joint, and a 4×4 matrix for a free–free joint, i.e., two plates being mechanically unconnected. The frequency-domain acoustic pressure is subsequently obtained by taking an inverse Fourier transformation, and expressed as a sum of residues enclosed by a deformed contour plus contributions from integrations along the branch cut. Asymptotic behaviors of the plate flexural displacement and acoustic pressure in the frequency-wave-number domain are obtained. Effects of mean flow on resulting sound radiation are examined. [Work supported by ONR.]
Sound radiation from two semi-infinite dissimilar plates subject to a harmonic line force excitation in mean flow. Part II: Asymptotic formulation and numerical results
Authors: Zhu Jinshuo , Wu Sean F.
Published: October 2005

Asymptotic formulations are presented for describing radiated acoustic pressures from two semi-infinite dissimilar plates subject to a line force excitation at the joint in mean flow. Analysis shows that mean flow affects acoustic radiation in three ways: (1) it enhances the wave number and amplitude of an acoustic wave propagating in the upstream direction, while suppresses those of an acoustic wave propagating in the downstream direction; (2) it reduces the decay rate of the upstream propagating wave in the plate normal direction, while increases that of the downstream propagating wave; and (3) it rotates radiation beam angles toward the downstream direction. The effects of mean flow are obvious when the excitation frequency is above the plate coincidence frequency, but reduced significantly below the coincidence frequency. The joint condition does not change the characteristics of the radiation patterns, but merely their amplitudes. The looser the joint, the higher the amplitude of the resulting acoustic pressure. The asymptotic results agree very well with those obtained by direct numerical integrations in the far field. Numerical results for the evanescent, traveling, and radiated waves in the near field from two dissimilar plates under welded, hinged, and mechanically unconnected joints are also demonstrated. [Work supported by ONR.]