bluuebunny/crossref_metadata_2025 huggingface dataset:
Bottom backscattering modeling and model/data comparison for 100–5000 Hz
Authors: Mourad Pierre D. , Dahl Peter H. , Jackson Darrell R.
Published: October 2005

A low-frequency bottom backscatter model that includes both surface and (shallow) volume contributions is described. It is assumed that these different scattering mechanisms are uncorrelated. The surface model [Jackson et al., J. Acoust. Soc. Am. 79, 1410–1422 (1986)] consists of Kirchhoff theory for large grazing angle contributions, spliced into composite roughness theory for backscatter from mid and low grazing angles. This part of the model is applied to isotropic, Gaussian rough surfaces whose surface height spectra are described by a two-parameter power law. These parameters are fixed by previous, high-frequency applications of this surface roughness theory. The volume scattering contribution is based upon an analytic theory for backscatter from uncorrelated, uniformly distributed point scatterers embedded within an upward refracting, constant density, “fluid” sediment layer. For this part of the model, the water/sediment interface is smooth, with discontinuities in compressional sound speed and density. The model predictions are compared with backscatter observations that have supporting geoacoustical data. By using these geoacoustical measurements along with standard bounds in the literature, the model contains only one free parameter: a quantity proportional to the effective volume scattering cross section per unit volume of sediment. [Work supported by NAVOCEANO and APL.]
Poly(vinylidene fluoride) transducers for the detection of laser-induced transients
Authors: Coufal Hans
Published: October 2005

Poly(vinylidene fluoride) (PVDF), a ferroelectric polymer, lends itself to the design and implementation of ultrafast pyro- and piezoelectric transducers for the detection of laser-induced thermal and acoustic transients. Crucial for the performance of these transducers is the depth profile of the polarization in the PVDF films. Polarization profiles in various PVDF foils and the influence of the profile on the observed signals are discussed. Applications of PVDF foils in transducers for thermometry and calorimetry of laser-induced thermal transients and in transducers for bulk and surface acoustic waves are then reviewed. Finally the potential and recent applications of other ferroelectric polymers for NDE are discussed.
Noncontacting surface wave measurements on spherical surfaces
Authors: Telschow Kenneth L. , Lott Layman A. , Characklis Gregory W.
Published: October 2005

Laser techniques have simplified the task of performing ultrasonic measurements on materials in nonplanar shapes, such as spheres and cylinders, since no physical contact is required. The propagation of surface waves on curved surfaces has been measured by using a pulsed laser source and a phase insensitive Fabry-Perot interferometer for detection. This detection method allows nonspecular surfaces and optically penetrating materials, such as ceramics, to be probed. Resonant and nonresonant conditions on nonmetallic spheres of varying size have been recorded. These surface waves exhibited dispersive behavior similar to that observed on metallic spheres [Royer et al., Appl. Phys. Lett. 52, 706–708 (1988)]. [Work supported by the Department of Interior's Bureau of Mines and the Department of Energy.]
Measurement and interpretation of laser-generated scan images in anisotropic materials
Authors: Sachse Wolfgang , Every A. G.
Published: October 2005

This paper describes the results of laser-based point-source/point-receiver measurements in single crystal specimens. By combining all the waveforms detected by a pointlike sensor when the source is scanned across the sample, one is able to generate a scan image. These images contain the spatial as well as temporal dependence of the ultrasonic signals in the specimen. It is shown that in some cases pronounced anisotropy is observed in the amplitudes which is related to the anisotropy of the material. Further, the signal arrivals can be processed to recover the matrix of elastic constants of the material. Monte Carlo simulations based on ray constructs are used to interpret the scan images. The use of these images as a materials characterization tool is demonstrated. [Work supported by Cornell's Materials Science Center (NSF) and the Office of Naval Research (Physical Acoustics and Solid Mechanics Programs).]
Simultaneous versus successive intensity comparisons
Authors: Dai Huanping , Green David M.
Published: October 2005

In profile-analysis experiments, the observer determines whether the amplitude of one or several target components is greater than that of the other nontarget components in a complex. Because the overall level of the stimuli is randomly chosen, detection is based on simultaneous amplitude comparisons of the target and nontarget components. The present experiment examines the ability of observers to make simultaneous versus successive amplitude comparisons of the target and nontarget components. The target and nontarget components were presented either (a) simultaneously or (b) successively in each interval of a 2IFC procedure. In one interval, the amplitude of each component of the target is greater than that of the nontarget; in the other, the amplitude is the same. Three stimulus configurations were used: (1) one target and 20 nontarget components; (2) 10 target and 11 nontarget components; (3) one target and one nontarget component. The threshold was measured as 20 log (ΔA/A) using an adaptive, maximum-likelihood method tracking 94% correct responses. Results show that the simultaneous comparisons are always 10–20 dB superior to the successive comparisons. [Work supported by NIH.]
Dichotic profile analysis
Authors: Whitelaw Gail M. , Hsu Chien-Yeh , Feth Lawrence L.
Published: October 2005

The majority of profile analysis studies have used monotic and diotic stimulus presentation. Use of dichotic stimulus presentation has been limited in profile analysis experiments, with the presentation configuration primarily consisting of the signal component presented to one ear and the nonsignal components presented to the opposite ear [e.g., Bernstein and Green, J. Acoust. Soc. Am. 81, 1888–1895 (1987)]. In general, results obtained in profile analysis experiments using dichotic stimulus presentation have revealed listener performance inferior to that obtained by either monotic or diotic presentation. Profile analysis is investigated by comparing a monotic condition to a dichotic condition. The monotic signal was generated by producing 21 components using equal logarithmic spacing. Level per component was equal in the standard signal. To create the profile, the odd-numbered components were incremented and the even-numbered components were decremented. The dichotic signal was created by presenting the even-numbered components to the opposite ear. A 2Q-2AFC roving level paradigm was used. Preliminary results suggest that listeners arc unable to perform the profile analysis task when information is presented dichotically. Discussion will center on the implications of failing to obtain a dichotic profile.
Detection of intensity decrements followed by increments
Authors: Sheft Stanley , Yost William A.
Published: October 2005

Data were collected from a modified decrement detection procedure in order to compare subject performance to the predictions of two decision statistics derived from the output of an envelope detector. At roughly the midpoint of each stimulus presentation, there was an intensity increment of the gated wideband noise carrier. The task was to detect an intensity decrement just preceding the increment in the signal interval of the 2IFC task. Decrement duration ranged from 2.5 to 40 ms. Increments of 3, 6, and 9 dB were used with the onset of the increment randomly occurring 150–300 ms from the stimulus onset. Decrement detection was also measured for conditions in which there was no increment. Best performance was obtained with the 3-dB increment. With the 6- or 9-dB increment, thresholds were significantly higher and showed less change as a function of decrement duration. Simulations based on the output of an envelope detector used either the variance or the ratio of the largest-to-smallest value as the decision statistic. For both statistics, simulations approximated subject performance in the conditions with no increment. Simulations, however, did not show the drop in performance with the 6- or 9-dB increment, suggesting involvement of multiplicative internal noise in envelope detection. [Work supported by NIDCD and AFOSR.]
Discrimination of arrhythmic tonal sequences: Effect of delay in onset of second sequence
Authors: Sorkin R. D. , Montgomery D. A.
Published: October 2005

These experiments continued tests of the pattern correlation model [R. D. Sorkin, J. Acoust. Soc. Am. 87, 1695–1701 (1990)] of temporal pattern discrimination. Subjects were presented with two sequences (0.6 s) of eight brief marker tones, and had to report whether the sequences had the same or different patterns of marker inter-onset times. The first sequence was presented to the subject's left ear (all marker tones at 1000 Hz) and the second to the right ear (all tones at 2300 Hz). The experimental variable was the delay in the onsets of the two sequences. The delay in sequence onsets varied from 0 to 2.5 s, and was fixed within a block of trials. In some conditions, the marker and gap durations in the second sequence were randomly expanded by a small uniform factor (0.8 < k < 1.2). When the sequences were presented nearly simultaneously, temporal manipulation of the second sequence produced large decreases in listener performance. This result is consistent with an envelope correlation mechanism, and differed from the effects observed when the sequences did not overlap in time. In the latter conditions, performance was not sensitive to the expansion manipulation, consistent with the prediction of the pattern correlation model. [Work supported by AFOSR.]
Forward masking functions of 3-month-old human infants
Authors: Marean Cameron , Werner Lynne A.
Published: October 2005

Forward masked thresholds for a 1000-Hz tone were measured for 3-month-old infants and for adults. The masker was a broadband noise burst, 100 ms in duration. Masker level was either 65 or 75 dB SPL. The tone had 16-ms rise, 16-ms fall, and no steady state duration. Masked thresholds were measured at Δt of 5, 10, 25, and 200 ms. The Observer-based Psychoacoustic Procedure [Olsho et al., Devel. Psychol. 23, 627–640 (1987)], was used to estimate infant thresholds. Compared to published data from adult listeners, 3-month-olds appear to show relatively more masking at short Δt. In addition, infants may exhibit masking at very long values of Δt, suggesting an additional nonsensory source of masking under certain conditions. Finally, the effects of increasing masker level on the amount of masking seen in infants will be examined. [Work supported by DC00396 to L. A. Werner.]
“Smart” noise control foams: A feasibility study
Authors: Bolton J. S. , Shiau N.-M. , Green E. R.
Published: October 2005

A porous layer can absorb a significant amount of acoustical energy only if its thickness is comparable to the wavelength of the incident sound. Thus, a porous layer inevitably becomes a less effective sound absorber as the frequency is decreased. In this paper it will be shown through theoretical calculations that the low-frequency performance of a finite-depth layer of elastic porous material may be enhanced by applying an appropriate force to the solid phase at the front surface of the layer. In particular, it will be shown that at any angle of incidence the solid phase may be forced in such a way to create a perfect impedance match with an incident plane wave, thus causing the sound to be completely absorbed. Complete absorption is not possible when the incident sound field is diffuse; nevertheless, sample calculations will show that considerable enhancement of the passive absorption is still possible. Note that the success of the approach suggested here requires a significant degree of coupling between the motion of the solid and fluid phases of the porous material. Thus it may be expected that partially reticulated, polyurethane foams will be susceptible to this approach owing to the degree of viscous and inertial coupling between their fluid and solid phases. Several methods for actuating the front surface of an elastic porous material and for sensing its surface normal impedance will be discussed.
Acoustic parameters for place of articulation in nasals and stops
Authors: Kurowski Kathleen Mary
Published: October 2005

A metric that identified labial and coronal place of articulation in English nasal consonants with over 80% accuracy had been developed by correlating distinctive patterns of rapid energy change at the nasal release with each place of articulation [K. M. Kurowski and S. E. Blumstein, J. Acoust. Soc. Am. 81, 1917–1927 (1987); K. M. Kurowski, unpublished dissertation, Brown Univ. (1990)]. This study attempted to address two questions. (1) Could the same metric be successfully applied across manner to classify place of articulation in homorganic voiced stops? (2) In the event that the metric failed here, to what extent did the burst onset alter the patterns of rapid energy change predicted by the metric? The same three speakers used in the nasal study (1990) produced CV syllables, consisting of [b,d] followed by [i,e,a,o,u]. The results showed that the classification scores across speakers for the voiced stops (labial = 64%; coronal = 83%) were lower than those for nasals (labial = 79%; coronal = 87%). Still, the general patterning of the results was the same across manner: Labial scores remained lower than those of the coronals due to the intractable problem of classifying labials in the environment of [i]. Two reanalyses using different window sizes demonstrated that the aperiodicity of the initial portion of the burst inflated some targeted areas of energy change, adversely affecting the performance of the metric. Various approaches to the question of how to reconcile formal aspects of the present metric with the added complexity introduced by the voiced stops are discussed in the light of their ramifications for the theory of acoustic invariance. [Work supported by NIH]
An acoustic phonetic description of the American English /ð/ in two modes
Authors: Horna Josephine
Published: October 2005

Phoneticians traditionally describe American English /ð/ as a voiced, nonsibilant, interdental fricative. However, in flowing speech, /ð/ often sounds stoplike. This study investigates the acoustic attributes of stoplike, as well as continuant, variants of /ð/ in “the” occurring in various phonological conditions in text-reading and conversation modes. The results of spectrographic analysis allow for the definition of five degrees of constriction and two types of constriction release, burst and smooth formant transition into the following segment. The degree of constriction is a coarticulatory effect of the preceding phoneme. Smooth formant transitions tend to occur with less constricted degrees of constriction; a burst may occur with any degree of constriction and is prevalent across phonological conditions. Articulatory interpretations that explain these and other variations of /ð/ are forwarded. The results also show intermodal differences in /ð/ in that there is a higher occurrence of some coarticulatory effects of the preceding phoneme in the conversation mode than in the text-reading mode.
Factors influencing the spectral representation of front-back vowels in American English
Authors: Gopal H. S. , Mansella Joyce , Carey Carol
Published: October 2005

It has been proposed that front vowels in American English have an auditory distance of less than 3 critical bands between the second and third formants, whereas, in back vowels, this distance is greater than 3 Barks [A. K. Syrdal and H. S. Gopal, J. Acoust. Soc. Am. 79, 1086–1100 (1986)]. The current study investigates the success of classifying front and back American English vowels into two separate classes using this auditory model given the variations in the acoustic signal due to speaking rate, post-vocalic consonantal voicing, and different speakers. Several researchers have shown that these factors influence vowel formant frequencies. Measurements were made of vowel F1, F2 and durations in /pVC/ target syllables containing one of four pairs of frontback vowels and voiced or voiceless stops or fricatives. Target syllables were produced in sentence context at three different speaking rates by two male and two female native American English speakers. Results will be reported and discussed for an invariant auditory representation of front and back vowels in AE under these influences.
Formant frequencies of lexieaily unstressed English vowels in two speech modes
Authors: Wallace Karen L.
Published: October 2005

Most English unstressed vowels are perceived as varying between schwa and /ɪ/. To investigate this variation, which can be only partially explained by coarticulation with consonantal contexts, words containing such vowels in a wide variety of C_C environments were randomly selected from the conversation of a male speaker of American English. These were compared to the same words in the speaker's reading of sentences from his conversation. Frequency levels of the first two formants were measured at three points within each vowel. A statistically significant percentage of word pairs demonstrated larger F2/F1 ratios in the sentence-reading mode, particularly for formant values obtained at vowel midpoints. Because this result occurred with all consonantal contexts, it can be concluded that unstressed vowels are, in general, more /ɪ/-like in formal speech. Examination of the word pairs that did not conform to this predominant pattern revealed unexpected correlations between formant frequencies of an unstressed vowel and two higher level linguistic factors: position in the word and proximity to a primary stress.
Vowel effects of pharyngeal and uvular consonants in Interior Salish
Authors: Bessell Nicola J.
Published: October 2005

Formant values of the vowels /i/, /u/, /a/, and schwa in the environment of the pharyngeal and uvular consonants of several Interior Salish languages are plotted and the results are compared with the formant values of the same vowel phoneroes in nonuvular/pharyngeal environments. The data represent several speakers of each language. Results show a consistent lowering of vowels in uvular/pharyngeal environments, with F1 rising considerably. The rise in F1 is greatest for vowels in pharyngeal environments. Backing (or F2 lowering) is not consistent across vowels or place of articulation. In fact, the voiceless pharyngeal shows some tendency to front the low central vowel /a/. The data are compared to similar material from several Arabic dialects.
Study of vowel coarticulation in British English
Authors: Hieronymus James L.
Published: October 2005

Coarticulation in continuous speech causes the vowel formant tracks to be altered by nearby phonemes. The present study concentrates on 660 phonetically hand-labeled read sentences from one male talker of the RP accent of British English. The 14 monothongal vowels of RP English, /ii, i, a, e, aa, uh, oo, o, u, u″, uu, @@, @, |/ were studied using formants, duration, and syllable stress as parameters. The formant frequency values near at the right and left edges and the center of the hand-labeled vowel region were studied using scatter plots and statististical analysis. No simple relationship between adjacent phoneme place of articulation and the vowel target change has been found because of the presence of “robust vowels” within each vowel category which always reach their target even in the presence of adjacent semivowels. These vowels are not merely stressed, or in content words; instead, they depend on other factors that are being studied. The long duration (prepausal lengthened) vowels were always robust, but some quite short vowels were also. [Work supported by the Alvey Project.]
The influence of consonant duration on vowel-to-vowel coarticulation in Korean
Authors: Choi John-Dongwook
Published: October 2005

This study examines the influence of durational differences associated with the three manner types (unaspirated, aspirated, fortis) on the coarticulatory effects of one vowel on another across an intervening consonant in Korean. F2 and consonant durations were measured in V1CV2 tokens read by five speakers, where Vn = {/i/,/a/} and C = [(bilabial, dentoalveolar, palatoalveolar, velar) × (aspirated, unaspirated, fortis)]. Repeated measures ANOVA tests show that Korean exhibits both anticipatory and carryover vowel-to-vowel coarticulation. There is also anticipatory coarticulation associated with the consonant's manner type, confined predominantly to /a/. The data show greater magnitude differences on V1 = /a/ when the consonant is unaspirated (224 Hz) than aspirated (143 Hz) or fortis (127 Hz). There is no statistically significant coarticulation between manner type and V2. Durationally, unaspirated C's are approximately half as long as the aspirated and fortis C's. The aspirated and fortis C's are durationally distinguished by differences in VOT. These observations will be discussed in the context of dual channel and single channel models of consonant and vowel production.
Estimating interior sound-pressure level arising from ground-borne noise
Authors: Bell Douglas H.
Published: October 2005

Ground-borne noise produced by railroads, subways, and roadways can be radiated as airborne noise in enclosed reverberant spaces. A simple model utilizing site vibration measurements to estimate resultant sound-pressure levels is presented. The model is then extended to devise a broad class vibration criteria that can be used to assess the severity of existing ground-borne noise. To demonstrate this model, sound and vibration measurements were simultaneously measured in a basement space located near a subway line. Predicted sound levels derived from the measured vibration are compared with measured sound levels.
The effect of coincidence transmission on field measurement of facade sound isolation
Authors: Campanella Angelo J.
Published: October 2005

Windows, walls, and doors suffer coincidence transmission (CT). Sound penetration increases with incidence angle, to a maximum near grazing incidence. Construction material “standard” sound isolation is cataloged from laboratory (ASTM E 90 or ISO 140/III) diffuse incident sound transmission loss (TL) tests. Field facade measurements per ASTM E 966 [J. Acoust. Soc. Am. Suppl. 1 88, S135 (1990)] apply 10 log(cos θ) angle correction (proper for open apertures, e.g., ventilators) to compute inside-outside transmission loss (OITL), which is comparable with diffuse TL values. For panels with CT, comparable values using unidirectional (loudspeaker) sound require 45- to 60-deg incidence or “field transmission loss” adjustment CT panel transmissivity derived by Cremer, Beranek, Ver, and Holmer indicates inverse cosine-squared behavior and a transparency (“coincidence”) frequency for each angle. This can be integrated over all diffuse angles for comparison to TL values [e.g., R. E. Jones, J. Acoust. Soc. Am. 66, 148–164 (1979); TL = 26–28 dB at 500 Hz for 16-mm (5/8-in.) drywall]. Comparison indicates integration to 78 or 80 deg. Theory/OITL/TL agreement (“match”) occurs for unidirectional sound incident at around 60 deg. Theory/TL or OITL/TL data by others for a drywall stud wall, block wall, and a window showed “match” angles from 45 to 60 deg. More CT test data on thin panels and three-way comparisons (theory/OITL/TL) are needed to improve OITL precision and reduce bias while expanding the range of test angles and source types (e.g., traffic).
Sound emission from residential ventilation fans
Authors: Quirt J. D.
Published: October 2005

This paper describes the acoustics part of a study to evaluate a draft Canadian standard for rating the air-handling and sound emission of residential ventilation fans. This included laboratory sound-power testing of 11 ventilation units using the CSA C260 draft procedure, which combines requirements from ANSI S1.32 sound-power test with installation requirements from the Home Ventilating Institute (industry) test method. The laboratory tests were structured to verify that the method is practicable and to estimate reproducibility of the test method. Subsequent field measurements (on the same fans, when installed in homes) were included to demonstrate the relationship between sound-power ratings and the resulting sound pressure in practical application.
Passive fetal heart rate monitor using piezopolymer pressure sensors
Authors: Zuckerwar Allan J. , Stoughton John W. , Pretlow Robert A. , Baker Donald A.
Published: October 2005

Fetal heart rate monitoring is performed routinely by pulsed Doppler ultrasound, but is currently confined to a clinical setting because of the bulkiness and high cost of the equipment. A passive monitor, using piezopolymer pressure sensors located on a belt worn by the mother, has been developed to detect the fetal heart tone and to determine the fetal heart rate through appropriate signal processing. The sensors are constructed to fulfill the following functions: detecting pressure pulses on the abdominal surface, shielding against 60-Hz interference, isolating the patient electrically, insulating against ambient sound, and canceling maternal rigid-body motion. The signal processing employs linear prediction techniques to identify the fetal heart tone from among competing background signals and yields a real-time evaluation of the fetal heart rate. The monitor has been applied to conduct clinical fetal nonstress tests simultaneously with ultrasound, and the results are compared. The monitor is not only inexpensive but lends itself to an ambulatory mode of operation, whereby the mother can conduct the fetal nonstress test in her home.
Signal processing for an acoustically based fetal heart rate monitor
Authors: Pretlow Robert A. , Stoughton John W.
Published: October 2005

A least-mean-square (lms) linear prediction algorithm has been developed to accomplish detection of fetal heart tones and thereby derive heart rate from a raw signal generated by a previously described passive acoustical sensor array. The desired heart tone signal has a characteristic signature but is of extremely low amplitude and contaminated with noise consisting of large-amplitude maternal heart tones, abdominal sounds, body motion, and environmental sounds, and also mild 60 Hz. The predictor coefficients were derived by adaptively “training” on ideal fetal heart tones recorded from several patients. The lms algorithm detects a heart tone event when the predictor mean-square error falls below an adaptively updated threshold level. The algorithm contains logic for correction of spurious and missed heart tones. A real-time working system was fabricated consisting of a sensor belt, front end electronics, a TMS320C25 digital signal processing board, an 80386 PC, and a strip chart recorder. The apparatus allows performance of the fetal nonstress test (NST) in a manner similar to that conventionally accomplished via ultrasound. The acoustical system was implemented in parallel with a commercial ultrasound unit on a series of patients undergoing NSTs. The heart rate records are compared.
Structural acoustic analysis using the fast Fourier transform
Authors: Kasper Peter K.
Published: October 2005

Fourier analysis has long been an important tool in acoustical and structural dynamics technologies. Many of the classical problems in acoustics and dynamics can, for example, be solved in closed form using Fourier transforms. The fast Fourier transform (FFT), itself, is an efficient method for calculating the Fourier transform of discretized or sampled variables. The current paper describes a general approach using the FFT for obtaining numerical solutions of fundamental acoustics and structural dynamics differential equations. Specific examples treated include harmonic response of finite strings and beams. The general approach involves the application of a discrete Fourier transform to a Helmholtz or biharmonic equation with generalized harmonic load. For consideration of finite structures, the finite Fourier transform is used. The use of a finite Fourier transform provides a convenient way of incorporating boundary conditions. The paper presents example calculations showing the numerical solutions as compared with closed-form classical solutions. Numerical accuracy and extension to multidimension structures are discussed.
Demonstrations for education in acoustics from laboratory research and development
Authors: Gabrielson Thomas B.
Published: October 2005

In an effort to help science teachers at local secondary schools and colleges, several classroom demonstrations have been developed as spin-offs from basic research and systems development work at the Naval Air Development Center. While this transition program is informal, the demonstrations have been well received as long as they are made simple enough for the intended class. The acoustics-oriented demonstrations include an outdoor sound-speed experiment suitable for junior or senior high school, several implosive and explosive sources of sound with a little thermodynamics, and a computer animation of the thermoacoustic cycle.
Musical acoustics: A vehicle to enhance science teaching
Authors: Hansen Uwe J.
Published: October 2005

Workshops following the Baltimore meeting, supported with ASA “Initiative” funds, sponsored by the Technical Committee on Musical Acoustics and the Education Committee, include one section that is a direct outgrowth of a series of workshops funded with Title II funds at Indiana State University during the past several years. Workshops have been conducted at both the elementary and secondary levels with elementary classroom and music teachers participating as well as junior high school science, high school general science, physical science, and physics teachers. The object of the workshops is to use musical acoustics as a vehicle to generate enthusiasm for science. At the elementary and secondary general science levels, this is accomplished by assisting teachers to build simple instrumentation illustrating various musical resonance phenomena. Additional sophistication is added to the high school physics program by using a keyboard as an introductory Fourier synthesizer. In this presentation, the workshop program will be discussed, a simple device illustrating string and air column resonances will be demonstrated, as will be a keyboard-computer combination to show simple Fourier analysis and synthesis.
Acoustics of the violin as a function of its parts
Authors: Jansson Erik V.
Published: October 2005

During the last 20 years, Carleen Hutchins has successfully developed methods for testing and tuning of free top and back plates with Chladni patterns. Her methods have been successfully used by other makers in Sweden too. For the engineer/physicist, it is, however, difficult to understand how and how much of the quality of a violin is predicted by the free-plate tuning. Therefore, data from KTH experiments have been used to investigate relations between free plates and assembled violins. Eigenmodes of free top and back plates have been calculated and measured. Effects of thinning the top plate free and in an assembled violin have also been investigated. Comparison of the frequency of the main resonance of the violin (T1 at about 500 Hz with mainly the top plate vibrating along the bass bar side) is affected somewhat similarly to thinnings of the ring mode of the free plate (i.e., it is most sensitive to off-center thinnings and it should be a balance in stiffness along and across). Thus the present result is qualitatively in agreement with that of Dr. Hutchins—the ring mode of the free plate is the most important for tuning. Recent playing tests imply, however, that the lengthwise stiffness of the top plate is more important than the one across. [Work together with Luleå Technical University, L. Frydén, Stockholm, L and B. Niewczyk, Poznan.]
The dynamics of musical strings
Authors: Hancock Maurice
Published: October 2005

The resonance contours of a number of musical strings have been traced when operating in isolation from an instrument body, with more precisely defined loading and terminal conditions than are found in normal use, and with very small excitation amplitudes. For plain steel piano strings, results from the fundamental to the 25th overtone are broadly in accordance with the predictions of the standard classical theory for a lossy stiff string, but close agreement with calculated data cannot be obtained for any one set of the relevant parameters, and some disturbing influences are clearly in operation. Some of the resonances show double peaks suggestive of close coupling between slightly dissimilar modes, and for these and the single peaks, associated transverse resonances perpendicular to the line of the driving force are often found. A copper wire string hammered to produce an exaggerated linear distribution of deformation shows a more pronounced pattern of double and transverse resonances, and it is surmised that these occurrences with the steel strings are due to small departures from exact cylindrical uniformity. Overwound strings show similar anomalies with significantly higher losses.
Acoustical significance of the violin octet
Authors: Hutchins Carleen M.
Published: October 2005

The 30-year acoustical and musical development of the violin octet has shown the following. (1) New instruments of the violin family can be created with fine tone and playing qualitites based on acoustical parameters, free-plate tuning, and skilled violin making. (2) The prime controlling factor differentiating overall tone quality of the violin from that of viola, cello, and string bass is frequency placement in relation to string tuning of the body length air cavity mode (A1) originally called the “main wood” resonance. (3) The secondary controlling factor for tone quality, especially on the two lower strings is frequency placement in relation to string tuning of the A0 cavity mode originally labeled “Helmholtz” or “main air” resonance. (4) For instruments smaller than the cello, the A0 cavity mode frequency is controlled more by air volume than by compliance of the top, back, and ribs (sides). (5) For cello and larger instruments the A0 cavity mode frequency is controlled more by compliance of the top, back, and ribs than by air volume. (6) Due to greatly increased compliance of the wooden walls of basses, it has been found structurally unsafe to make ribs shallow enough to place the A0 cavity mode seven semitones above the lowest note as our scaling theory projected originally. These findings will be discussed and illustrated.
Quasiperiodicity and bifurcations in wolf tones
Authors: Caussé René , Puaud Jean , Gibiat Vincent
Published: October 2005

The wolf tone, often obtained on the lower bowed stringed instrument, is studied with an experimental setup that mimics the true instrument with the help of a digital bow [Caussé and Weinreich, Proceed. 13th ICA, Belgrade 1989]. In this experiment, the resonant frequency of the bridge can be adjusted so that it is low enough for a good coupling with the fundamental frequency of the string, while keeping the bridge as rigid as possible. With this experimental setup, verification of the well-known result that the wolf tone depends strongly on the pressure and speed of the bow and on the bowing point of the string has been made. By changing bow speed and pressure, by bifurcations after the normal periodic sound (Helmholtz motion), various quasiperiodic tones built on two or three basic frequencies have easily been obtained. Other possible scenarios related to bifurcation theory are indicated by observations of more complex signals.
Linear and nonlinear propagation of a pulsed sound beam in a dissipative fluid
Authors: Frøysa Kjell-Eivind
Published: October 2005

Linear and nonlinear propagation of pulsed sound beams is considered. The combined effects of diffraction, absorption, and nonlineartry are discussed within the linear and the weakly nonlinear (quasilinear) approximation of the Khokhlov-Zabolotskaya-Kuznetsov nonlinear parabolic equation. For the special case of a Gaussian on-source amplitude distribution, short pulses can be followed all the way from the sound source and into the dissipative far field, both within a linear and a weakly nonlinear model. The results obtained are related to the theory of scattering of sound by sound [Berntsen et al., J. Acoust. Soc. Am. 86, 1968–1983 (1989)], and to the self-demodulation of transient carriers [H. O. Berktay, J. Sound Vib. 2, 435–461 (1965)]. [Work supported by the Norwegian Research Council for Science and Humanities.]
My love affair with Ruth Bender
Authors: Franklin Barbara
Published: October 2005

In 1982, The American Auditory Society saluted J. Donald Harris as its Renaissance Man. His unique ability to combine science and the humanities is exemplified in his chapter, “My love affair with Ruth Bender: A history of binaural aids for babies” [Harris, in Binaural Hearing and Amplification, edited by Libby (Zenetron Inc., Chicago, 1980)]. Binaural hearing was a subject very dear to his heart and he praised the pioneering work of Ruth Bender and others in fitting infants and young children with two hearing aids. Dr. Harris served as mentor and major advisor to the writer during the time he was an adjunct professor at CUNY. He supervised her dissertation that compared discrimination scores when a low- and high-pass band of speech was presented to the same ear or opposite ears of normal-hearing subjects. This study was subsequently replicated by the writer with hearing-impaired individuals, both congenital and adventitious. This paper will present an overview of this research and will conclude with a study that investigated the use of split-band amplification—high frequencies in one ear and low frequencies in the other. The writer received ongoing advice, encouragement, and support from J. Donald Harris for her research. The passing of our Renaissance Man has left an unfillable void for many.
Experiments in binaural hearing: Masking, speech intelligibility, and binaural hearing aids
Authors: Levitt Harry
Published: October 2005

The late J. Donald Harris had a great interest in binaural hearing and binaural amplification systems for the hearing impaired. This paper is dedicated to his memory. Research on binaural release from masking has been substantial. A similar but smaller research effort has focused on binaural improvements in intelligibility and related issues involving binaural hearing aids. There have been few attempts, however, to integrate the two areas of research. Methods for predicting binaural improvements in intelligibility from models of binaural release from masking will be reviewed. Data from an experimental evaluation of one such method will be presented and the implications for the design of binaural amplification systems for the hearing impaired will be discussed.
Circadian rhythm-dependent gentamiein-induced hearing loss in rodents
Authors: Roy Mary , Langill Coleen , Yonovitz A.
Published: October 2005

The use of gentamicin as an antimicrobial agent has been shown to produce as an untoward effect, ototoxicity. The purpose of this study was to investigate differential effects of gentamicin ototoxicity as a function of Rx timing with regard to circadian rhythms. Sprague-Dawley rats received a daily subcutaneous dosage of 100 mg/kg of gentamicin. The rats were maintained on a light-dark 12:12 illumination cycle with light commencing at 0000. One group of rats received gentamicin at 0200 with the other group at 1400. Hearing loss was assessed with the auditory brainstem response using pure-tone stimuli of 8, 16, 24, and 32 kHz. These measures were obtained at baseline, 2 and 4 weeks after the initial dosing. Measures of blood-gentamicin level and nephrotoxicity were contrasted for the groups. Ototoxicity was greater for gentamicin when given to the rodents during their diurnal rest span (0200) in comparison to their nocturnal activity span (1400). These circadian dependent effects are thought to be related to rhythmic variations in the disposition and accumulation of gentamicin in cochlear tissues.
Surface variational principle analysis of the response of an eccentrically loaded submerged disk in a baffle
Authors: Ginsberg Jerry H. , Chu P. T.
Published: October 2005

As an initial step in the extension of the surface variational principle (SVP) to an assumed mode analysis of vibratory displacement and surface pressure on submerged axisymmetric structures subjected to arbitrary nonsymmetric loading, the present study considers a harmonic point force applied at an arbitrary location of an elastic plate supported by an infinite, rigid baffle. Fourier series expansions of the azimuthal dependence of pressure and displacement are shown to be uncoupled, with each harmonic being governed by equations that are similar in form to those for the analogous axisymmetric problem [J. H. Ginsberg, P. T. Chen, and A.D. Pierce, J. Acoust. Soc. Am. 88, 548–559 (1990)]. Recursion relations using coefficients developed in the course of solving the axisymmetric problem are shown to substantially expedite the evaluation of the additional azimuthal harmonics. Results for a force located at r=a/2 when ka = 3.35, where a is the radius of the plate, are presented in terms of the radial variation associated with each harmonic, as well as overall surface distributions. It is shown that m = 0 to m = 4 azimuthal harmonics are comparable in magnitude, and that other harmonics are insignificant. In addition, radiated power is evaluated as a function of m. [Work supported by ONR, Code 1132-SA.]
Intelligibility in competing noise by males with partial laryngectomies
Authors: Gerdeman Bernice , Trudeau M. , Pearl D. , Wilhelms R.
Published: October 2005

Although levels of intelligibility among alaryngeal speakers using various speech modes have been investigated [J. G. Clark and J. C. Stemple, J. Speech Hearing Res. 25, 333–338 (1982); M. Kalb and M. Carpenter, J. Speech Hearing Disoral. 46, 77–80 (1981)], little data are available for speakers with partial laryngectomies. The specific research questions of the investigation were “To what degree do the patients with hemilaryngectomy or supraglottic laryngectomy maintain intelligibility when speaking in various levels of competing noise?” and “Are there differences in speech intelligibility as a function of whether the partial laryngectomy was in the vertical or horizontal plane?” Nine hemilaryngectomees, nine supraglottic laryngectomees, and nine normal laryngeal male speakers recorded 20 SPIN test sentences with no competing noise and with 75 dB A white noise. Intelligibility scores (identification of each sentence's final word by 30 normal-hearing listeners) were analyzed using logistic regression and indicated that the two surgical groups did not differ significantly from each other in either noise condition and that in both conditions the two groups differed significantly from the normal laryngeal group.
The influence of segmental sonority on immediate memory for syllables
Authors: Speer Shaft R. , Surprenant Aimee M.
Published: October 2005

Four experiments demonstrate that the sonority of a syllable's component sounds predicts the presence and magnitude of recency effects in immediate memory. Sonority is determined by co-occurrence restrictions on vowel and consonant sounds within syllable-internal structure. Recency effects were most pronounced in memory for CV strings with different vowels (high sonority) and least apparent for CV strings with different stop consonants (low sonority). Strings with different nasal consonants and glides (moderate sonority) produced intermediate recency. In addition, lists of high vowel-contrasting syllables (high-moderate sonority) were tested against lists of low vowel-contrasting syllables (high sonority). Overall, results suggest that recall performance for the final positions of an auditory list is predicted by the sonority of the contrast segment. The results are consistent with findings in the categorical perception and auditory memory literatures, and support the notion of a common dimension underlying these well-known effects and the linguistic notion of sonority. The experiments provide additional evidence to support the view that memory for a sound does not differ according to its identity as a vowel or consonant, but instead is influenced by its acoustic properties. [Work supported by NICHD.]
Use of stress in an isolated word recognizer for French
Authors: Bishop Kathleen M. , Huang Caroline B.
Published: October 2005

An isolated word recognition system for French is now being developed. This effort is part of an ongoing collaborative project between Dragon Systems, Inc. and Lernout and Hauspie Speechproducts n.v. to port and adapt Dragon's large vocabulary speech recogition system for American English to five European languages: French, Spanish, German, Italian, and Dutch. In English, unstressed syllables have been observed to be quite reduced compared to stressed syllables, while unstressed syllables in French have not been observed to be greatly reduced compared to their stressed counterparts. In the American English recognition system, performance is enhanced when the syllable stress is taken into account. Whether taking stress into account will enhance performance of the French recognizer is now being investigated. The preliminary French system recognizes 1000 words and is speaker adaptable. In developing the system, 3000 tokens from one native speaker of French have been collected. The capabilities of the recognizer will continue to expand and the collection of data will continue to take place. Preliminary results from the acoustic analysis of the speech data and from the experiments with the recognizer will be discussed. [This work is supported by a joint program between Dragon Systems, Inc. and Lernout and Hauspie Speechproducts n.v.]
Generalized Fresnel corrections for scattering in underwater sound channels with rough boundaries
Authors: McDaniel Suzanne T.
Published: October 2005

The Fresnel corrected Kirchhoff approximation for forward scattering from rough surfaces is extended to treat the general case of boundary scattering in a refractive underwater sound channel where multiple interactions with the surface may occur. Expressions are obtained for the reflected intensity and the spatial covariance of the scattered acoustic field in the high-frequency limit. Numerical examples are presented to demonstrate the strong predicted dependence of both the reflectivity and spatial covariance on refraction. [Research supported by ONT with technical management provided by NCSC.]
Basic formulation for the simulation of underwater reverberation
Authors: Sudo Yasushi
Published: October 2005

A basic equation to simulate underwater reverberation for monostatic sonar is obtained. The derivation is based on these simple assumptions: The phase shift caused by scatterers has a uniform distribution, the scatterers are independent of each other, the reverberation is approximated as a quasistationary Gaussian process, the bandwidth of the transmit signal is narrow, and the sound propagation speed is constant. Using these assumptions, the stochastic property of a modified DDM (Doppler density matrix) is examined, which is an extension to the original DDM of REVGEN [D. W. Princehouse, tr7511, Appl. Phys. Lab., Univ. of Washington (1975)]. The correlation of the modified DDM has a simple form. Using the modified DDM, the reverberation is expressed as an overlapped summation of the randomly modulated convolution of the transmit signal and white noise of finite duration. The modulation is related to the Doppler shift caused by the motion of the sonar platform and the scatterers. Using the formulation, an extension to the many beams case is also examined.