bluuebunny/crossref_metadata_2025 huggingface dataset:
Speech-sound perception in normal and learning-disabled children: Effect of lengthened CV transition duration
Authors: Bradlow Ann R. , Kraus Nina , Nicol Trent , McGee Therese , Cunningham Jenna , Carrell Thomas D.
Published: July 2002

Previous research has established that many children with learning problems exhibit perceptual deficits in response to certain auditory stimuli, such as stop consonants in CV context. In order to investigate the precise acoustic features of stop consonants that pose perceptual difficulties for these children, discrimination thresholds were compared for normal and learning-disabled children along two separate synthetic /da/–/ga/ continua that differed only in the duration of the formant transitions. Results showed that simply lengthening the formant transition duration from 40 to 80 ms did not result in improved discrimination thresholds for the learning-disabled children. Similarly, an electrophysiologic response that is known to reflect the brain’s preconscious ability to detect a change from one auditory stimulus to another indicated diminished responses in these children to /da/ versus /ga/, regardless of transition duration. This finding suggests that the brevity of the CV formant transitions is not the sole acoustic basis for the observed perceptual deficits. Furthermore, signal processing techniques aimed at enhancing perception of stop consonants likely need to consider other acoustic features, such as relative amplitude and frequency characteristics, instead of (or in addition to) CV transition duration. [Work supported by NIH R01 DC 01510.]
Listener variability and multiple perception processes
Authors: Lindemann Stephanie
Published: July 2002

The relationship between the perception of individual phonemes and the perception of words is investigated to determine if these are similar tasks for listeners. Since listeners may be able to use top-down processes in full words, it is argued that, at least for some, the task of identifying isolated phonemes may be very different from the task of identifying a full word. Because greater variability in performance is expected from non-native speakers, 15 native speakers of Sudanese Arabic (as well as a control group of 12 native speakers of American English) were tested on identification of American English phonemes in word context and the same instance of these phonemes extracted from the words. The overall agreement between corresponding items on the two tests was significantly better than chance, but scores of individual subjects varied substantially, with phoneme-word test agreement falling below chance for many subjects. Additionally, not all non-native subjects performed better on the full word task, suggesting that they do not all use higher-level information. It is therefore argued that studies of phoneme-level perception are more relevant to some listeners’ word perception than to others’.
Construction of a HATS and its HRTF measurement for 3-D sound
Authors: Kang Kyeong Ok , Kang Dong-Gyu , Hahn Min-Soo , Jho Mun-Jae , Jeong Dae-Kwon
Published: July 2002

Based on the anthropometric data on the head and torso dimensions in Korean male adults, a head and torso simulator (HATS) was constructed. Data, which have no counterparts in the Korean standards, were used with ANSI S3.36-1985. Measuring microphones can be positioned at the eardrum or at the ear canal entrance according to measuring purposes. Head related transfer functions (HRTFs) for the HATS, i.e., binaural impulse responses, were measured at 710 points on a spherical surface of radius 1.55 m using a burst maximum length sequence (MLS) signal of 65 535 samples in an anechoic chamber. The measurement system consists of one part to generate the MLS signal and to drive a Boss 101A loudspeaker and another part to record the output signal of a microphone in the HATS and consequently to measure the impulse response. Also measured were the impulse responses of the driving loudspeaker and some headphones for 3-D sound reproduction in order to get the exact HRTF of the HATS-alone. The impulse-version HRTFs at the sampling frequency of 44.1 kHz, which have filter lengths of 512 points with minimum phase characteristics and can be used for 3-D sound, were finally obtained through a postprocessing procedure.
Three-dimensional solutions to range-dependent problems in shallow water by a pseudo-spectral method
Authors: Turgut Altan , Wolf Stephen N.
Published: July 2002

A pseudo-spectral method is used to solve the acoustic and elastic wave equations in the time domain. The application of such a computation and memory-intensive method to shallow-water propagation and scattering problems is discussed. Three-dimensional solutions are given for two different shallow-water related problems: pulse propagation through solitary internal waves and pulse scattering from bottom inhomogeneities. The size of a typical computational domain for both problems is about (30 wavelength)3. However, for the propagation problem, distances up to several hundred wavelengths have been achieved by moving the computational domain with the wavefront. The accuracy of the pseudo-spectral method has been checked with analytical solutions to simpler problems. Two-dimensional results of moving-domain approach are compared to those of single-domain and good agreement is observed. The existing method is expected to confirm the accuracy of the approximate solutions such as PE in a complicated range-dependent environment. [Work supported by ONR.]
Room acoustic designs for the Tokyo International Forum
Authors: Jaffe Christopher , Holden Mark , Cooper Russell , Kobayashi T. , Kawakami F.
Published: July 2002

The room acoustic design of the Tokyo International Forum centered around the four performance halls: the convention center, the atrium, and the large multi-use meeting/dining halls. This paper will describe the program use of each space and the acoustic criteria developed to meet these requirements. Major emphasis will be placed on Hall A, a 5000-seat congress hall that was to be used to unamplified symphonic concerts and operas as well as highly amplified Broadway musicals and rock concerts, and Hall B, a 1500-seat classical music hall and piccolo opera house that also would be used for conferences and popular entertainment. A unique architectural feature of Hall B is the first design and installation of a Concert Hall Shaper, a device that enables a proscenium theatre with a stagehouse to be converted to a single acoustic volume for events such as symphony concerts requiring a longer reverberation time. Hall C, an extremely flexible space for fashion shows, summit meetings, and large receptions, and Hall D, another versatile space for theater, recitals, and live television productions, will also be described.
Sound and vibration control for the Tokyo International Forum
Authors: Kawakami Fukushi , Kobayashi Tetsu , Jaffe Christopher , Holden Mark , Cooper Russell
Published: July 2002

The acousticians for the Tokyo International Forum were faced with a number of very severe noise and vibration problems related to the siting of the complex in the center of downtown Tokyo, the placement of the performance halls next to one another, and the location of a portion of the mechanical equipment on the roof. In addition, subway lines ran parallel to three of the boundaries of the structure, another line ran under the building, and the main tracks of Japan Rail ran above ground alongside the major atrium. This paper will discuss the noise criteria set for the performance rooms and other noise sensitive spaces, the noise and vibration measurements taken to determine the severity of the train-related conditions, predictions of other noise and vibration sources, and the solutions developed by the design team to meet the criteria required by the program. Among the solutions are a secant wall surrounding the foundation, box in box construction for the four performance halls, blocking mass installations at key locations throughout the steel skeleton of the complex, and isolation joints and sound locks between the performance rooms.
Design of sound reinforcement and acoustic field control systems for the Tokyo International Forum
Authors: Jaffe Christopher , Holden Mark , Scarbrough Paul , Robb David , Shimizu Yasushi , Yamashita Shinjirou , Kawakami Fukushi
Published: July 2002

The extremely varied program use of the four performance halls at the Tokyo International Forum provided the electroacoustic designers with a number of extremely challenging problems. This paper describes the events that were to take place in all of the rooms, the designs selected to accommodate these programs, and the coordination of the design of the electroacoustic systems with the room acousticians, the architects, and the theater consultants. Of special interest is the design of the sound systems for Hall A, the 5000 seat symphony/congress hall which was to be used for opera and symphony performances without employing close-in microphone amplification techniques, and Hall D, which was to be used for live theater and recitals as well as television productions. The final portion of the paper will discuss the sound contractor’s role in completing such an immense project and in particular the relationship that contractors have with designers and owners in Japan.
Acoustical behavior of churches: Gothic-Mudejar churches
Authors: Sendra Juan J. , Zamarreño Teófilo , Navarro J.
Published: July 2002

Traditionally, a particularly good acoustic behavior has been assigned to Christian churches. But this statement, which is not true at all, has led to important errors in church rehabilitation works, more so in those that implicate changes of use, such as auditoriums or theatrical halls, which is the case of many churches in Spain. This research group has worked in acoustical analysis for more than ten years, and has participated in many cases of church rehabilitation, among which is acoustical behavior. We are talking about a type of church very common in the south of Spain, Gothic-Mudejar churches. They are churches with these common characteristics: relatively little volume, plants with three naves, and wooden ceilings. With this work, significant conclusions drawn from the acoustical analysis of ten churches of Seville that respond to this type are presented. Their characteristics are quite homogeneous, so it is possible to get conclusions about the acoustical conditions of this ecclesiastical type.
Acoustical design of Harmony Hall Fukui
Authors: Ono Akira , Yokose Suzuyo , Naniwa Katsuji
Published: July 2002

Construction of Harmony Hall Fukui, which was sponsored by the Fukui prefecture government, was completed on September 3, 1997. The facility contained a large hall, a small hall, and administrative offices. In the central area of the facility is an administrative room, rehearsal rooms, and machinery space. The two halls are situated at the east and west ends of the facility. This architectural zoning brings advantages and savings for effective sound insulation and noise control of the ventilation system. The large hall seats 1456 people and is a concert hall in the shoebox style. The room shape was studied by computer simulation techniques during the design stage, and the details of the wall and ceiling were studied by use of 1/10th scale model experiments before the construction work started. The small hall seats 610 people in an extremely intimate setting. The seating surrounds the stage, and even the height of the balcony seating is staggered to create what may be termed a ‘‘mini-arena’’ style. The unique layout heightens the audience’s feeling of proximity to the stage. Acoustical design and acoustical characteristics will be presented at the meeting.
Timbre effects caused by drumstick tip shapes/sizes
Authors: Irwin James H.
Published: July 2002

The relationship between the shape/size of a drumstick tip and the resulting initial spectrum produced by hitting a drumhead was investigated. Contrary to tensioned plate theory, and popular opinion, the amplitudes of the various induced partials were not significantly different when the shape/size of the tip was changed dramatically. The work was extended by using various diameter steel balls to strike the drumhead and it was found that the initial spectra did change for extreme differences in ball diameter. Further investigation showed two, or possibly three, timbre groupings. Present results indicate that small diameter balls (less than 15 mm diameter) induce significant energy above the first few partials of the drumhead, medium diameter balls (15 to 25 mm diameter) induce most of their energy in the first few partials, and perhaps large diameter balls (greater than 25 mm diameter) induce little energy above the lowest partial. These effects are linked to the membrane and plate characteristics of the drumhead. Since most drumstick tips have diameters in the medium range little distinction occurs among their spectra. In all cases the spectra were normalized for energy input, and the drum tension and position of impact were fixed.
Phenomenological theory of the translational relaxation times in gases
Authors: Zuckerwar Allan J.
Published: July 2002

The classical equations governing the translational dispersion and absorption of sound in a gas yield a solution of such complexity as to obscure the relaxational character of the associated viscous and thermal transport processes. The approach taken here is to solve the secular equation by the method of Pade’ approximation, which even to the relatively low order R11 yields a remarkably close approximation to the exact solution over a wide range of frequency/pressure ratios. As a result, translational relaxation can be ascribed the attributes of a conventional relaxation process such as relaxation times, relaxation strength, collision numbers, additivity relations, etc. To extend the theory to extremely high values of frequency/pressure ratio, a model is proposed to account for the noncontinuum behavior of the transport coefficients (viscosity and thermal conductivity) as the molecular mean free path approaches the acoustical half-wavelength. The theory shows good agreement with measurements in argon over the classical, Burnett, and transition regions as defined by Meyer and Sessler [E. Meyer and G. Sessler, Z. Phys. 149, 15–39 (1957)].
Ultrasonic flowmeter for the accurate metering of gases for semiconductor processing
Authors: Calabrese Adam M. , Tison Stuart A.
Published: July 2002

Semiconductor production processes such as chemical vapor deposition rely upon accurate control of the flow rate (in the range of 1–1000 standard cm3/min) of several ultrapure, yet highly toxic and/or reactive gases. Currently, thermal mass flow meters (TMFMs) are widely used in industry for these processes. Complications with the use of TMFMs arise because the flow must be divided (due to limited dynamic ranges) and calibration is normally performed with inert gases. In the present research, an ultrasonic Doppler shift flowmeter has been developed to measure gas flows. Measurements of the flow-induced phase shift of an acoustic plane wave propagating in an unobstructed tube, combined with the speed of sound of the gas, are used to determine the mean gas velocity. The combination of the mean gas velocity with measurements of the pressure and temperature allow calculation of the mass flow rate. The experimental system uses stainless steel tubes of diameter 0.05–0.1 cm, and frequencies near 100 kHz. No division of the flow is necessary. Prototype meters indicate that sensitivities on the order of 0.75°/standard cm3/min are possible. Experimental data of two prototype systems using different geometries and receivers will be presented. [Work supported by NIST.]
Anomalous excess noise in inhomogeneous elastic and piezoelectrical solids
Authors: Dykhne Alexander M.
Published: July 2002

The description of the macroscopic behavior of a microinhomogeneous material and the determination of its internal structure may be obtained from its response to external action. The parameters related to the second moments of the field are the simplest to determine. This is the work of deformation. Additional information about the material can be deduced from the higher moments of the respective field. These higher moments are most important in the case of a field with a highly nonuniform spatial dependence. For certain types of the heterogeneity geometry, some points of the elastic field concentration can exist where the field strength increases faster than a certain power function of the distance. The fourth moments of the field can diverge, which will lead to abnormally high excessive noise. The measurement of the excessive noise gives information about the structure of the material. A simple method for determining the high distribution moments of a field is based on measurements of the excessive noise arising from the fluctuations in material constants such as elasticity moduli. This is related to, for example, the deformation of a solid under a fixed external load or the eigenfrequencies of elastic vibrations. In the case of piezoelectrical materials, the excess noise may originate from both elastic and electrical external fields. Their measurement gives more information about the internal structure of the material.
Human auditory system maturation: A neurophysiological comparison between normal-hearing children and children who use a cochlear implant
Authors: Ponton Curtis W. , Don Manuel , Kwong Betty , Waring Michael D. , Eggermont Jos J.
Published: July 2002

Auditory-evoked responses provide detailed, objective measures of maturational change in the central auditory system from the level of the brainstem to the cortex. Auditory-evoked responses can reflect activity originating from three pathways: the lemniscal and nonlemniscal pathways as well as from a modality nonspecific pathway originating in the reticular activating system (RAS) and its associated thalamic nuclei. Maturational time courses for these pathways were derived from evoked response data recorded from 156 normal-hearing subjects ranging from 5–20 years of age. Analyses of these data indicate that each pathway may have a unique developmental sequence. For normal-hearing children, the lemniscal pathway appears to follow a longer developmental time course than either the nonlemniscal or RAS pathways. For children with implants, the developmental sequences for these pathways are differentially affected depending on onset and duration of deafness. Specifically, maturation of the lemniscal pathway is delayed by an amount that approximates the period of deafness, whereas maturation of the RAS pathway may be related to the age at onset of deafness.
Active control of curve squeal caused by trains
Authors: Heckl Maria A.
Published: July 2002

Squeal noise is generated by a feedback mechanism. It occurs if two bodies are in contact and move relative to each other so that dry friction acts in the contact area. This can lead to an unstable oscillation driven by the feedback between the friction force and the relative velocity of the bodies. Sound is radiated from one or both oscillating bodies. Some well-known types of noise are generated by this phenomenon, for example squeal and the sound of a bowed string. Curve squeal (the noise produced by the wheels of a train that travels fast around a tight bend) is considered in this paper. The frequency spectrum of curve squeal is dominated by one or a few sharp peaks which correspond to certain bending resonances of the free wheel. Squeal noise can be controlled and even suppressed by a secondary feedback system, consisting of a sensor (to pick up the wheel oscillation or the squeal noise), filter, phase-shifter, amplifier, and transducer (to apply the control signal). This type of control amounts to the stabilization of an originally unstable wheel oscillation and is a special form of active control. A mathematical model for this secondary feedback method will be presented. Numerical results for its effectiveness will be shown.
Induced damping in Heckl’s beam experiment
Authors: Feit D. , Strasberg M.
Published: July 2002

In 1961, Heckl described an experiment showing that the loss factor of a beam in flexural vibration was increased considerably by the attachment of a large number of small cantilevered strips along the span of the beam, their lengths varying so that their frequencies of antiresonance extended over the first five modal resonance frequencies of the beam [J. Acoust. Soc. Am. 33, 640–651 (1961)]. The increase in loss factor occurred even though the total strip mass was much smaller than the beam mass. More recently, an approximate theoretical estimate of the loss factor of Heckl’s beam with attached strips, using a simple expression for induced dissipation based on ‘‘fuzzy’’ substructure concepts was presented [J. Acoust. Soc. Am. 99, 335–344 (1996)]. This estimate agreed well with Heckl’s measurements at some frequencies, but disagreed at others for unknown reasons. In an attempt to understand the cause of the partial disagreement, new calculations have been performed using a finite-element model of the beam and strips, the loss factor being estimated from resonance bandwidths in steady-state frequency response and transient decay rate.
The estimation and control of rolling noise from trains
Authors: Remington Paul
Published: July 2002

Throughout his career Manfred Heckl contributed significantly to the body of knowledge that helped to clarify the mechanisms governing the generation of rolling noise from trains. During a brief period at the Technical University in Berlin this author had the opportunity to collaborate with Prof. Heckl and to learn from his insights and expertise in this field. Here an important mechanism for the generation of noise from trains, the interaction force in the zone of contact between wheel and rail produced by the small scale roughness on their running surfaces, will be examined. Analytical techniques for predicting the interaction forces that include the effects of load and wheel and rail profile will be described. The implications for controlling the noise at the source will be examined and the noise reduction achieveable will be estimated using measured wheel and rail roughness data. [Work was supported by the European Rail Research Institute, Utrecht, The Netherlands.]
Acoustics teaching and Manfred Heckl
Authors: Rossing Thomas D.
Published: July 2002

If allowed to have only a dozen acoustics books in my library, one of them would certainly be Structure-Borne Sound by Cremer, Heckl, and Ungar. This book, which is the epitome of clarity, could only be written by skilled acousticians who are also great teachers. Although the entire book is the result of a close collaboration between these master teachers, the Foreword tells us that the chapters on Damping, Impedance, and Radiation were written by Manfred Heckl. He also animated several of the figures from the chapter on Radiation for a classroom video he created. His lively lectures, often punctuated with thoughtful demonstrations of acoustical phenomena, serve as examples to teachers of acoustics around the world.
Recollections of Professor Manfred Heckl
Authors: Maidanik Gideon
Published: July 2002

Professor Manfred Heckl was one of the scientific giants in the area of acoustics. He combined theory and experiment so well that both were made simple and transparent. I met Manfred at BBN in 1960. I realized he was one of those individuals that you could approach even when the question was not properly formulated. He helped and taught you how to formulate the question and directed you to the answer. He was an exceptional mentor and generous colleague. When he left BBN to return to Germany to assist in establishing Muller-BBN and to be groomed to succeed Cremer’s professorship in Berlin, I lost a major impetus in my early development in acoustics. We tried to maintain close professional contacts, but his personal touch was missed and the efforts were not successful. Periodically, we did have face-to-face professional contacts and these were immensely enjoyable and beneficial, but the day-to-day influence was gone and I was poorer for it. Early in our relationship at BBN we became friends and we remained so to the end. I had many opportunities to test this friendship and it withstood intact the passage of time. It is this friendship that I will cherish forever.
Measurement of multicomponent point mobilities on thick plates and deep beams
Authors: de Jong Christ A. F.
Published: July 2002

The accuracy of power-based prediction methods for sound and vibration transmission in built-up structures, such as statistical energy analysis, is crucially dependent on the estimation of the input power as well as the power transmitted at junctions. These transmissions are governed by multi-component mobilities. When the excitation area is small compared with the structural thickness, the mobilities are strongly influenced by the volumetric near fields. Recent theoretical studies of concentrated excitation of plates and beams of arbitrary thicknesses [Petersson and Heckl, JSV 196(3) (1996) and Petersson ICA’98] have lead to some manageable estimation procedures for the mobility components. This paper describes a series of dedicated laboratory experiments undertaken to validate the estimation procedures. The mobility components are extracted from measured frequency response functions via an inverse method. The experimental procedure and the difficulties encountered are described. The results are compared with the estimated mobilities.
Vowel devoicing and the loss of lexical accent in Tokyo Japanese
Authors: Kitahara Mafuyu
Published: July 2002

The fundamental frequency of words with devoiced syllables was measured in order to see how the conflict between devoicing and the pitch accent is resolved in Tokyo Japanese. Previous studies found that the pitch after the devoiced accented syllable is elevated in order to compensate for the loss of the accent. Earlier results [M. Kitahara, J. Acoust. Soc. Am. 101, 3195 (1997)] show that the pitch elevation occurs only when there is no phrasal high tone before the devoiced region. The present study further eliminates the possibility of accent shifting by controlling the moraic structure of target words. They contain one or two devoiceable syllables and a moraic nasal in front of the devoiceable region. Four speakers of Tokyo Japanese pronounced target words embedded in a carrier phrase. If the accent shifts away from the devoiced syllable, pitch elevation should not occur because the accent is realized somewhere else. Preliminary analysis of the data shows that the accent on the devoiced syllable is not shifted but simply lost under these conditions because the moraic nasal cannot bear an accent in Tokyo Japanese. This result is discussed in connection with intra- and interspeaker variations of the accentual pattern.
Syntactic ambiguities and their resolution in prosody: Observations in Japanese, Korean, Mongolian, and Turkish
Authors: Sato Shigeru , Choi Young-Sook , Yoshimoto Kei
Published: July 2002

Acoustic measurement was made of utterances of syntactically ambiguous sentences in Tokyo and Sendai Japanese, Seoul and Kyongsang Korean, Mongolian, and Turkish to observe prosodic strategies for disambiguation. Materials were sentences of the types ADV-VP1-NP-VP2 and ADJ-NP1-NP2-VP, where the former is ambiguous in terms of adverbial modification, ADV modifying either VP1 or VP2, and the latter creates ambiguity for the adjective ADJ modifying either NP1 or NP1+NP2. For these constructions, the four languages show identical constituent structures, and accordingly create same ambiguities. After defining the syntactic depth of a boundary, F0 of the phrase before and after the boundary, and duration of the syllable and pause before the boundary were measured. The results for differentiating the syntactic depth: (1) Tokyo Japanese and Kyongsang Korean make use of F0 rise after the boundary, (2) Seoul Korean lengthens the duration, (3) Turkish uses F0 rise before the boundary followed by a pause, and (4) pause is the indication for Sendai Japanese and Mongolian.
A comparative study of speech motor programming in stutterers and nonstutterers
Authors: Kumar N. Aravind , Savithri S. R.
Published: July 2002

The present study was undertaken to verify the credibility of theories that attribute the locus of stuttering aetiology to be a central speech planning dysfunction. Ten stutterers and ten nonstutterers participated in this study which utilized a choice reaction time paradigm to determine the effects of three independent variables, viz., word length, phonetic complexity, and linguistic complexity on dependent variable-speech reaction time (SRT). By varying the response complexity in this manner it was intended to manipulate the response preparation in a way that if stuttering depends on a premotor programming, then the response complexity would adversely affect response preparation time and this effect of ‘‘complexity’’ would be greater for stutterers (with aberrant speech programming) than for nonstutterers. The results obtained supported the above and significant differences were elicited in both within and across group conditions. However, some peculiar ‘‘effects,’’ viz., ‘‘paradoxical complexity effect’’ and ‘‘motor ceiling effect’’ were also evidenced and are subsequently discussed. The results of the study suggest that the stutterers may be endowed with inefficient motor programming capabilities that are aggravated by increased production demands especially under time stress conditions.
Modeling of articulatory dynamics using cascaded first-order systems
Authors: Sonoda Yorinobu , Ogata Kohichi
Published: July 2002

This paper proposes modeling of articulatory dynamics using cascaded first-order systems. The model, which consists of simple first-order components, can be a good approximation for the behavior of a complex system. In the paper, the approach to modeling the articulator movements was performed on several articulatory organs: tongue, jaw, etc. Parameters describing the model were obtained from observed articulatory data in such a way that time patterns of impulse response of the model were approximated to velocity ones of movements. Good approximations were obtained on time patterns of articulation for vowels and consonants. Therefore, successive movement patterns for continuous speech including consonants were approximated by combining several models with high accuracy. By modeling articulatory dynamics for vowels and consonants based on articulatory measured data, complex articulatory patterns in a form of [-V C V-] were synthesized and the time instant of input commands for articulation of vowels and consonants were estimated in a connected speech sound including consonants. [Work supported by SCAT.]
Testing a normalization procedure for articulatory recovery
Authors: McGowan Richard S.
Published: July 2002

In order to recover articulatory movement from human speech in the analysis-by-synthesis procedure used in a current project it is necessary to adapt, or normalize, the anatomy of the vocal tract of an articulatory synthesizer. A normalization procedure was tested in which the vocal tract length and the functions determining the conversion of midsagittal distance to cross-sectional area were adjusted until there was an acoustic match between the synthesizer and the human over a selected set of utterances. Testing of the normalization procedure was performed using vowel data on two subjects from the Wisconsin x-ray microbeam data set to find how many utterances with known midsagittal shape and acoustic information were necessary so that the adjusted synthesizer vocal tract was able to predict output of novel utterances. Another part of the normalization procedure is to find a mapping between the settings of the articulators of the synthesizer and the corresponding midsagittal shapes of the human vocal tract. Neural networks were trained to map from the settings of the articulatory synthesizer to the positions of pellets over limited sets of vowels. The ability of these networks to generalize was tested with novel vowels. [Work supported by grant DC-01247 from the NIH.]
Characteristics of phonation offset and onset in normal adults and children
Authors: Koenig Laura L.
Published: July 2002

A major goal of research into the dynamics of vocal fold vibration is to specify the physical requirements for self-sustained oscillation, i.e., phonation. In recent years, theoretical and modeling studies have sought to define the necessary conditions for initiating phonation in laryngeal models of varying complexity, focusing especially on requisite pressure levels (the phonation threshold pressure), structural configurations (glottal width and the glottal convergence angle), and their interrelations. Conditions surrounding phonation offset have received somewhat less attention but are generally understood to involve different scale values of the same set of variables. This paper investigates voicing behavior around abduction for /h/ in normal English-speaking adults and 5-year-olds. Recordings consist of intraoral air pressure and oral airflow collected using a Rothenberg mask. DFT analyses of airflow signals from speakers whose /h/Us had voicing interruptions reveal that spectral changes accompanying phonation offset differ from those seen at phonation onset. Speakers show various individual patterns but the difference is typically most evident in the amplitude and bandwidth of the first harmonic. These results add to the empirical literature indicating that initiation and cessation of voicing do not occur under identical conditions. [Work supported by NIH.]
Signal processing for sound capture
Authors: Rabinkin Daniel V. , Renomeron Richard J. , Sharma Atul , Flanagan James L.
Published: July 2002

High-quality electret microphones and single-chip processors are economical enough to be used in large numbers. This latitude opens opportunities for dynamic source location and sound capture with spatial selectivity in three dimensions. This report discusses algorithms for matched-filter processing of microphone arrays and for coordinate tracking of moving talkers. A prototype conferencing system is demonstrated in which the automatic source locator steers both a video camera and a beam-forming microphone array to capture image and audio from a moving talker. [Components of this research are supported by NSF Contract 397-26740 and DARPA Contract DABT63-93-C0037, the New Jersey Commission on Science and Technology, and the corporate members of the Rutgers Center for Computer Aids for Industrial Productivity (CAIP).]
Localization of acoustic emissions in aerospace structures
Authors: Wells Paul J. , Stephens Arthur , Ibbotson Andy
Published: July 2002

Health Usage and Monitoring Systems (HUMS) offer the potential to revolutionize the civil aircraft industry’s approach to routine scheduled inspections. Developments in acoustic emission measurements allow the direct detection and localization of fatigue damage in complex primary aircraft structures. This information has been used to successfully guide inspections and to locate damage in regions inaccessible to conventional NDT methods. The use of such a system in flight will lead to inspection costs being reduced significantly and will promote confidence in the structural integrity of next generation civil aircraft. This paper will examine the question of the optimum positioning of sensors for a given sample using methods such as genetic algorithms and simulated annealing. The use of dimensional reduction projection techniques is also discussed. In an aerospace structure the propagation of sound will not be isotropic because of the variation in the thickness of the structure. This anisotropy will limit the accuracy of localization unless accounted for. The magnitude of this effect is determined empirically for an aircraft wing panel, and a method for calibrating acoustic emission measurements to minimize the effect of this anisotropy is suggested.
Approximate computational model for sound generation due to unsteady flows in pipes
Authors: Krane Michael , Sinder Daniel , Flanagan James
Published: July 2002

A model for the generation of sound due to unsteady vortical flow in pipes of varying cross-sectional area is described. The model is based upon Howe’s acoustic analogy and an approximate model for the vorticity field. This formulation allows the sound generation to be specified in terms of properties of the unsteady behavior of the vortical flow and the potential flow solution for the pipe that would exist in the absence of vortical inhomogeneities. The approximate model for vorticity formation and evolution is presented, and the potential flow solution is obtained from the axial duct shape. Computed estimates of the time evolution of both a jet passing through a pipe constriction and the sound this flow produces are presented and compared to experimental data. [Research supported by NSF/ARPA IRI-9314946 and ARPA DAST 63-93-C-0064.]
Nondestructive SAW technique of acoustic transient spectroscopy to study deep centers in semiconductor heterostructures
Authors: Bury Peter , Jamnický Igor
Published: July 2002

A new technique of acoustic deep level transient spectroscopy (A-DLTS) using a high-frequency transverse acoustoelectric signal produced by a surface acoustic wave (SAW) electric field was used to study deep centers in semiconductor heterostructures. The basic idea of the presented A-DLTS technique is connected with the fact that the time development of the acoustoelectric response signal arising from the interaction between the SAW electric field and free carriers at heterostructure interface after an injection bias voltage pulse has been applied reflects relaxation processes associated with the thermal recombination of excited carriers moving toward their equilibrium state. The technique of computer evaluation of isothermal acoustoelectric transients applying the date compression algorithms [P. Bury and I. Jamnický, Acta Phys. Slovaca 46, 693–700 (1996)] was used to calculate deep center parameters as activation energies and capture cross sections. The technique has been applied for both Si MIS and GaAs/AlGaAs heterostructures. [Work supported by Grant of Slovak Ministry of Education No. 1/4261/97.]
Source type effect on the efficiency of noise barriers
Authors: Jean Philippe
Published: July 2002

The use of numerical techniques such as the Boundary Element Method (BEM) is well suited for the study of noise barriers of complex shapes. Full studies, up to 4000 Hz, can only be done with 2D approximations, where the geometry of the problem is infinite, which is a realistic approximation for noise barriers. It also implies that the sources are infinite coherent line sources, which is a gross approximation for traffic noise. Recent transforms have been presented in the literature to overcome this last restriction. Simple integrals of 2D results now permit the rapid consideration of any combination of point sources or infinite incoherent line sources. Such transformations have been tested with a BEM code based on a variational formulation. The efficiency of different screen modifications is analyzed in the light of these more realistic source representations, and the importance of such developments is assessed by comparing the results with the classical coherent source approximation.
Scattering of acoustic impulse waveforms by turbules
Authors: Don Charles G. , McLeod Ian D.
Published: July 2002

When a short duration acoustic pulse propagates through the atmosphere its waveform can be markedly altered. Some are broadened, others have increased peak heights while occasionally ‘‘inverted’’ regions occur in the tail. In an effort to explain such changes, scattering by a turbuloid characterized by a Gaussian profile was considered. The effective size of the turbuloid, s, can be estimated from the correlation length, L, of the wind speed trace obtained as the pulse was propagating. The strength of the turbuloid, q, can be positive or negative, depending on whether the wind speed decreases or increases, while its magnitude depends on L as well as the number of turbuloids and the standard deviation of the refractive index variation. The received pulse waveform is sensitive to the values of s, q, and the position of the turbuloid relative to the source. By appropriate adjustment of the parameters, many of the observed waveforms can be reproduced; the choice of parameters giving some insight into the conditions which must have existed in the atmosphere during propagation.
The effects of atmospheric turbulence on the cross correlation between wind and travel time fluctuations
Authors: Norris David E. , Kristensen Leif , Mann Jakob , Thomson Dennis W. , Swanson David C.
Published: July 2002

Previous measurements over flat, hard ground showed strong coherence in received acoustic phases across frequencies from 90 to 660 Hz [D. E. Norris and D. W. Thomson, J. Acoust. Soc. Am. 101, 3102(A) (1996)]. A recent test program was conducted at the same site in which concurrent acoustic and wind data were recorded. Similar coherences in the phase and travel time fluctuations were observed, and cross correlations between wind and travel time fluctuations were calculated. A theory was developed to predict the cross correlations by considering the effects of the two-dimensional horizontal wind spectrum on the direct source–receiver path. The theoretical parameters include the horizontal separation between the acoustic and wind sensor positions, and the bearing offset between the wind and propagation directions. Calculated and predicted cross correlations were compared and found to be in good agreement. The bearing offset was found to significantly influence both the magnitude and shape of the cross correlations.
Calculation of sound reduction by a screen in a turbulent atmosphere using the parabolic equation method
Authors: Forssén Jens
Published: July 2002

Results from applying a Crank–Nicholson parabolic equation method (CNPE) are presented in situations with a thin screen on a hard ground in a turbulent atmosphere, and with the acoustic source at ground level. The results are evaluated by comparison with Daigle’s model, which uses the sound scattering cross section by Tatarskii together with diffraction theory. The results show a fairly good agreement for situations where the receiver is above ground, thus indicating that both methods are applicable to the problem. When the receiver is at ground level the two methods lead to significant differences in insertion loss since only the PE method predicts that turbulence causes an increased sound level in the case without a screen. For the situations considered in the paper a turbulent atmosphere shows a significant influence on sound reduction by screens. [This work is financially supported by the Swedish Environmental Protection Agency (SNV) and the Swedish Transport and Communications Research Board (KFB).]
Experimental measurements and theoretical modeling of acoustic scattering by a cube
Authors: Humphrey Victor F. , Zhang Jingdong , Chinnery Paul A.
Published: July 2002

Acoustic backscattering can be used to assess quantitatively the size and concentration of suspended sediments above the seabed. This technique depends on a knowledge of the backscattering form function for the scattering particles, which for simplicity are normally assumed to be spheres. In order to investigate the scattering from other shapes a series of measurements have been made of the acoustic backscattering behavior of both nonmetallic (glass) and metallic (steel) cubes over a wide frequency range. A laboratory system using a parametric array was used to make measurements between 20 and 200 kHz on cubes of side 20 mm, corresponding to ka values up to 10. Results are presented for a range of incidence angles involving incidence on a face, an edge, and a corner. At higher frequencies elastic resonances are observed, while at lower frequencies the average form function shows characteristics similar to those due to creeping waves on a sphere. The results are compared with theoretical predictions obtained with a boundary element model and a combined finite element/boundary element model. The agreement is observed to be very good. [Work partially supported by the MAST program of the EC, contract MAS3-CT95-0017 (TRIDISMA).]
Synthesis of the radiated sound field from a vibrating plate-strip with free edges
Authors: Machens Kai-Ulrich
Published: July 2002

A multipole expansion in elliptical coordinates was employed to calculate the directivity pattern of the radiation from free vibrations of a plate-strip with free edges. The Helmholtz equation can be separated in elliptical coordinates and an exact solution for a cylindrical geometry with elliptical cross section can be constructed by Mathieu functions. The radiation problem was solved by mapping the normal velocity of the rectangular cross section of the plate-strip onto an acoustically equivalent elliptical cross section and applying a multipole expansion. A comparison between this method and a standard wave-number transform showed good agreement in the case of a baffled plate, which proved the validity of this procedure. The directivity patterns of baffled and unbaffled plates are compared in order to estimate the influence of hydrodynamic short-circuit around free edges on the radiation. The compact representation of the sound field by the source-strengths is advantageous for the determination of the interference of superimposed eigenmodes for radiation. For applications in active noise control, a direct optimization criteria for secondary forces with respect to the radiated soundpower was obtained. It permits the study of efficiency and stability of the active measure with regard to number and location of the secondary forces.
Adapted waveform analysis in sound processing
Authors: Coifman Ronald R.
Published: July 2002

Adapted Waveform Analysis [R. Coifman et al., Wavelet Analysis and Signal Processing] is a processing toolkit extending the traditional spectrogram and Fourier methods by adapting to local structures in audiosignals. The various libraries of waveforms such as localized cosines and wavelet packets permit a flexible time/frequency analysis and give rise to a ‘‘mathematical musical transcription’’ of sound. The waveforms considered could be viewed as musical notes with characteristic duration, pitch, amplitude, and time localization. They are tied to fast computational algorithms which enable a fast search for an optimally efficient transcription of a clean simple signal as a mathematical ‘‘score.’’ More complex signals are then orchestrated as superposition of scores. Various applications to sound, compression, automatic speech segmentation for recognition, structural sound denoising and music restoration [with J. Berger and M. Goldberg, ‘‘Removing Noise from Music Using Local Trigonometric Bases and Wavelet Packets,’’ J. Audio Eng. Soc. 42(10) (1994)] will be provided. Moreover the relations between efficient waveform transcription and fast numerical analysis for acoustic design and simulations [B. Bradie et al., ‘‘Fast Numerical Computations of Oscillatory Integrals Related to Acoustic Scattering,’’ Appl. Comput. Harmonic Anal. 1, 94–99 (1993)] will be indicated.
The virtual orchestra; pedagogical and creative issues
Authors: Bianchi Frederick W. , Campbell Richard H.
Published: July 2002

The interactive multichannel computer music system known as the ‘‘Virtual Orchestra’’ has been used several times in professional opera and theater as an alternative to a live pit orchestra. The technical issues associated with this emerging technology, and the logistical problems of implementing it are presented in a companion paper. This paper describes the equally important issues regarding the creative and pedagogical impact this technology will have on the industry. In particular, the paper suggests that many of the fundamental premises of opera production will change as the industry begins to retool. This would include the way opera is rehearsed and performed, how it is created and disseminated, and how it will adjust to the changing demographics of the country. In addition, the paper addresses the notion of the technologist/musician and examines the role of education and professional training in computer music and musical acoustics.