bluuebunny/crossref_metadata_2025 huggingface dataset:
Absolute calibration of acoustic sensors utilizing electromagnetic scattering from in situ particulate matter
Authors: Pierce Allan D. , Berthelot Yves H.
Published: October 2005

The present paper initiates a study to understand the errors inherent to a laboratory technique similar to that used by K. J. Taylor [J. Acoust. Soc. Am. 70, 939–945 (1981)] for absolute calibration of microphones. Considered here is the idealized situation when a plane-polarized monochromatic plane electromagnetic wave is incident on a finite scattering volume containing dispersed small dielectric spheres that oscillate under the joint influence of a plane transient acoustic wave and Brownian motion. Any component of the scattered and Doppler-shifted electromagnetic signal at a distant farfield point in an obliquely backward direction is a sum of N terms, each of the generic form An cos(ω0t) + Bn sin(ω0t), where An and Bn depend on the instantaneous position of the nth scatterer. Since these positions change with time, the coefficients also vary, although slowly over intervals comparable to 1/ω0. Statistical properties of the time varying sum functions A(t) and B (t) are studied analytically and with numerical simulations for various models of the sound wave and the Brownian motion. A principal problem adressed is that of determining the statistics of the time interval Δt over which a fixed number K of zero crossings occur for the sum A(t) cos(ω0t) + B(t) sin(ω0t), given that this interval is centered at a particular time, the pertinent quantity of interest being the relative error in the accumulative phase difference 2 π K / Δt − ω0 per unit time. The results support the general conclusions that smaller errors are expected for higher amplitude sound waves and for sound waves of lower frequency. [Work supported by ONR.]
Consonant and vowel intelligibility with the Symbion cochlear implant
Authors: Dorman Michael F.
Published: October 2005

Studies of consonant intelligibility (16 items in aCa format) and vowel intelligibility (12 items in bVt format) were conducted with six patients fitted with the Symbion four-channel cochlear implant. Consonant intelligibility ranged from 52% to 81% correct. Voicing and manner errors were uncommon. Vowel intelligibility ranged from 22% to 79% correct. Errors were usually vowels with similar F1 and/or F2. For the best patient, an analysis of errors as a function of channel stimulated indicated that 81% consonant intelligibility could be achieved with the use of two functional channels, one centered at 500 Hz and the other centered at 4000 Hz.
Speech perception: The effects of recurrent conductive hearing loss in young children
Authors: Clarkson Richard L. , Eimas Peter D. , Marean G. Cameron
Published: October 2005

The ability of five-year-old children with histories of recurrent otitis media (OM) and associated conductive hearing loss to perceive syllable initial stop consonants was investigated. Naturally produced, computer-edited stimuli were created to form continua that ranged in voice onset time (VOT) from 7 to 60 ms. The ability of children to assign these stimuli to adult phonetic categories was assessed by identification and discrimination tasks. Three subject groups were identified: One group (group C) had no history of OM and was linguistically age appropriate; another group (group OM) had considerable involvement with OM and was also linguistically normal; the third group (group OMDL) had an equal involvement as group OM with otitis media, but was linguistically delayed. All groups were matched for age, IQ, socioeconomic class, and educational experience. Results indicate that OM was associated with poorer discrimination scores, regardless of the linguistic status of the individual.
Infant speech-sound discrimination in noise
Authors: Nozza Robert J. , Bond Linda C. , Miller Sandy L. , Rossman Reva N. F.
Published: October 2005

Infant ability to discriminate a speech-sound pair in noise was assessed using the visual reinforcement infant speech discrimination procedure. Sixteen infants between 7 and 12 months were tested on the /ba-ga/ contrast at four S/N's (− 8, 0, 8, and 16 dB). A group of young-adult control subjects was tested also at four S/N's (− 12, − 8, − 4, and 0 dB). The noise was continuously present at 48 dB SPL. Group psychometric functions revealed that infants required a more favorable S/N than adults to achieve given levels of performance. The adult subjects and 14 of the 16 infants were also tested using a discrimination-threshold procedure in which the stimulus intensity was varied adaptively (1-up/1-down). The adaptive discrimination procedure provided, for both groups, estimates of performance that are in good agreement with those from the performance versus S/N functions that were developed using the more time-consuming method of trial blocks at fixed S/N's. [Work supported by DRF and NIH POI NS16337.]
Relation of children's identification of consonant-vowel syllables to their fine-grained auditory discrimination: A progress report
Authors: Elliott Lois L. , Hammer Michael A. , Scholl Margo E. , Anthony Bonnie S.
Published: October 2005

Just-noticeable differences (JNDs) and identification (i.e., labeling) functions were obtained for children aged 6 through 11 years. Two consonant-vowel (CV) continua representing the place-of-articulation and voice-onset-time features served as stimuli; the adaptive discrimination task that has been previously described [e.g., L. L. Elliott et al., J. Acoust. Soc. Am. 70, 669 (1981)] was used. Some children produced consistent identification functions for both continua; some were inconsistent in labeling CVs of one continuum only; and some were inconsistent for both continua. In many cases, the children with the poorest identification performance also exhibited the poorest JNDs for the same stimulus continuum. The irregular identification functions observed for some of these normal-hearing children resembled functions that have been reported for some adults [B. E. Walden et al., J. Acoust. Soc. Am. 79, 1101 (1986)]. [Work supported, in part, by NINCDS (NIH).]
Patterns of phoneme confusions with sense and nonsense CVC words for subjects with normal hearing and with presbycusis
Authors: Bosman Arjan , Smoorenburg Guido F.
Published: October 2005

Differences in listening strategy between normal-hearing and hearing-impaired listeners will become apparent in different patterns of phoneme confusions. The confusions were studied with meaningful and meaningless word material of the consonant-vowel-consonant type (CVC words) presented in quiet at fixed presentation levels to a group of young normal-hearing subjects, a group of elderly subjects with normal hearing regarding their age, and subjects with presbycusis. The confusions of the vowels and initial and final consonants were subjected to INDSCAL analysis [J. D. Carroll and J. J. Chang, Psychometrika 35, 283–319 (1970)]. Parameters in the analysis were; word type (meaningful versus meaningless), group of subjects, and phoneme identification score. This latter parameter is perceptually more relevant than presentation level when comparing subjects with different hearing losses. For the normal-hearing subjects, vowel perception was dominated by the first and second formant, whereas for presbycusis subjects the contribution of the second formant was reduced and some influence of vowel duration was present. For the perception of both initial and final consonants voicing was all important. However, the feature of voicing was better perceived by presbycusis subjects than by the normal-hearing subjects.
Source characteristics of diplophonia
Authors: Gerratt Bruce R. , Precoda Kristin , Hanson David G. , Berke Gerald S.
Published: October 2005

Diplophonia describes the perception of more than one fundamental frequency component in a voice. Simultaneous photoglottographic (PGG), electroglottographic (EGG), and acoustic signals were collected from five diplophonic subjects. Results indicate that diplophonia is similar to the beat frequency phenomenon caused by independent vibration of the two vocal folds at slightly different frequencies. In the time domain, modeling vocal fold displacement from midline by summing two sine waves produced area waveforms closely resembling the PGG waveforms obtained from the diplophonic subjects. In the frequency domain, the diplophonic voice spectrum bears little resemblance to that of normal phonation. Instead of the normal set of harmonic peaks at integer multiples of the fundamental, the diplophonic spectrum shows a wealth of very closely spaced energy peaks of which the two fundamentals are often the most prominent but rarely the lowest frequency. The spectral envelope of the glottal area waveform may appear to have poles where no formants are possible and the spectral energy falls off quite rapidly. The locations of prominent energy peaks were predicted by modeling the displacement of the vocal folds from midline using the sum of two sine waves clipped by pulse trains to simulate collision effects of the two vocal folds. [Work supported by NINCDS.]
Elicitation of spontaneous speech production from preschool-aged tactile aid users
Authors: Proctor Adele , Bickley Corine
Published: October 2005

Engineering of sensory supplements that are sufficiently small in size, light in weight, and adequate protocols for measuring device efficacy have long been problems for those involved in designing vibrotactile aids for preschool-aged deaf children. Contributing to the engineering variables influencing tactile aid development are the problems of how to elicit representative samples of spontaneous speech production before, during, and after tactile aid usage and how to quantify effects of tactile aid usage on speech production of children who exhibit nonnormal articulatory patterns. Since visual displays presented on microprocessors are reported to be effective elicitors of vocal output, available databases on articulatory and acoustic characteristics of hearing and hearing-impaired preschoolers, primary acoustic parameters known to influence intelligibility, and available data suggesting effects of tactile aids on speech production were incorporated to design graphic stimuli to elicit speech from 3- to 5-year-old deaf tactile aid users. The purpose of this poster session is to discuss the theoretical basis for selection of stimuli, to demonstrate the protocol for eliciting spontaneous productions, and to present the planned articulatory and acoustic measurements. [Work supported by DOE, Grant No. 133 GH70189.]
Acoustic characteristics of dysarthria associated with cerebral palsy
Authors: Weismer Gary , Forrest Karen
Published: October 2005

This paper will report on qualitative and quantitative observations on the speech production characteristics of adults with cerebral palsy. The subjects were ten adults with cerebral palsy, primarily of the spastic type. Multiple repetitions of selected sentences were analyzed acoustically to determine the spectral and temporal characteristics of segments. In addition, certain qualitative analyses, involving the form of spectrographic displays across utterance repetitions, were performed to address the issue of random versus consistent control of articulatory gestures in neurogenic speech disorders. It is argued that in some cases a patient may produce very aberrant temporal and spectral features which, nevertheless, are quite consistent across repetitions.
Analysis of formant transitions for English fricatives spoken by five male and five female talkers
Authors: Key Kelsey , Klatt Dennis H.
Published: October 2005

Nonsense words of the form C′VC′VC′VC were recorded for the four voiceless fricatives of English [f,th,s,sh] in ten vowel environments by each of five male and five female talkers. The database was digitized at 16 000 samples/s and digital spectrograms were produced. Formant frequency values, F2 and F3, were measured by hand from the spectrograms at voicing onset and vowel midpoint for each CV transition. These data were examined in order to seek regularities of several possible forms: (1) invariant onset frequencies independent of speaker and vowel environment, (2) existence of locus frequencies that differ as a function of place of fricative articulation, but are similar across speakers, and (3) similar transition behavior (e.g., rising or falling F2 and/or F3) across speakers for a given vowel with no attempt to seek regularities across vowels. In all cases, distributions of transition-related measures across speakers for each place of articulation show disturbing amounts of overlap, even when male and female data are plotted separately. While it has often been said that [f] and [th] are distinguished perceptually by F2 and F3 transition behavior (because frication spectra are often quite similar), the data suggest that it will be difficult for a speech recognition device to make this distinction reliably from observed formant transition behavior in the general population. Some reassessment of the appropriate perceptual cues seems to be required. [Work supported in part by an NIH grant.]
Fundamental frequency contours of preword vocalizations through the emergence of word combinations
Authors: Robb Michael P. , Saxman John H.
Published: October 2005

An increasing number of acoustic characteristics of infant preword vocalizations have been found to be similar in many respects to the vocalization characteristics of children's early meaningful speech. Such findings are suggestive of continuity in the underlying processes involved in acquiring language. To date, few studies exist that have examined in detail the acoustic characteristics of babbling, early words, and word combinations in a single group of children. The present study provides monthly data on fundamental frequency (F0) contours in seven infants who were audio tape recorded over a 12-month period. Within a year's time, each child's communication development progressed from babbling vocalizations to word combinations. The frequency and type of F0 contours in each child's mono-, bi-, and polysyllabic vocalizations are reported. Regardless of syllable type, the children used a large number of rising-falling F0 contours across preword and multiword periods of vocalization development. The least frequently occurring F0 contours in both group and individual data were falling-rising contours. It is proposed that uniformity exists in early vocalizations across preword and meaningful speech periods due to physiologically motivated factors.
Classification of vowels using spectrum moments
Authors: Milenkovic Paul , Forrest Karen
Published: October 2005

Formant frequencies form a set of acoustic features that can be used to classify vowels phonetically [A. K. Syrdal and H. S. Gopal, J. Acoust. Soc. Am. 79, 1086–1100 (1986)]. The advantage of formant frequencies is that they are unaffected by changes in the speech spectrum slope attributable to the voice source. The disadvantage of formant frequencies is in the large errors in frequency that can result from a misclassification of the formant peaks of the speech spectrum. A set of features based on statistical moments computed from the speech spectrum has been successful in classifying a broad class of obstruent sounds [K. Forrest et al., J. Acoust. Soc. Am. Suppl. 1 82, S84 (1987)]. In the case of vowel sounds, moment analysis eliminates the problem of identifying formant peaks but introduces the problem of variability in the moment features resulting from changes in the voice source. In order to correct for between subject variation in the voice source, the long-term average spectrum of all of the speech samples recorded from each subject is computed and used to normalize vowel spectra prior to computing moments. Between subject classification results for adult subjects are presented. [Work supported by NIH grants NS 21516 and NS 13274.]
Factor analysis for vowel and fricative duration in American English
Authors: Pitrelli John F. , Zue Victor W.
Published: October 2005

In an attempt to develop a comprehensive model of segment duration for American English, the duration of vowels and fricatives as a function of segmental and suprasegmental factors was studied. Two databases were used, one consisting of one reading of the 720 Harvard List sentences by one male speaker, and another consisting of the first 500 Harvard List sentences, with each list of ten read by one male and one female speaker. Segment durations were obtained from time-aligned phonemic transcriptions. Factors influencing duration and their interaction effects were studied using analysis-of-variance techniques. Results indicate that vowel durations are largely affected by factors such as vowel class (diphthongs, tense, lax, and reduced vowels), sentence-final lengthening, the syntactic function of the word in which they appear, and lexical stress. Other factors previously thought to be important, such as the voicing characteristic of the following consonant, did not account for much of the variance in the data. Using five of the most significant factors, an account was obtained for 67% of the variance on training data as well as on test data for the single-speaker database, and 63% and 59% for the multispeaker database. The difference in results for the two databases may be attributable to interspeaker differences that include speaking-rate variations. In an oral presentation, the results on the modeling of fricative duration will be discussed. [Work supported by DARPA under contract N00014-82-K-0727, monitored through the Office of Naval Research.]
Spectrographic comparison of whispered voiced and voiceless stop consonants in various vowel environments
Authors: Nábělek Igor V. , Chen Hsiao-Chuan , Maroonroge Sumalai
Published: October 2005

A previous presentation reported on spectra of whispered and phonated speech and on comparison of identification of whispered voiced and voiceless consonants when those consonants were presented in C/a/ syllables. The cues for voicing in whispered plosives were studied using spectrograms. In a follow-up study, spectrographic analysis of whispered monosyllables with plosives in various vowel environments was performed. The results of the analysis—with respect to the voicing differences—will be presented and discussed.
Voice “features” in long-term memory
Authors: Kreiman Jody , Papcun George
Published: October 2005

This study examines the perceptual parameters used to recognize an unfamiliar voice (heard only once before) after a one-week delay, as compared to the parameters used to discriminate among the same voices in a short-term memory (paired comparison) task. Ten groups of ten listeners each heard a short sample of a single voice; after seven days, all listeners heard the full ten voice set and had to determine if their target voice was present or not. Confusion data and similarity ratings were gathered and combined to form full matrices that were analyzed using multidimensional scaling. Differences in the perceptual parameters that underlie confusions and perceived similarities in the short- versus the long-term memory tasks will be discussed, as will changes in the relative importance of different parameters with time. The implications of these findings for models of voice perception and speaker recognition will also be addressed.
Time-gated word identification performance
Authors: Craig Chie Higuchi
Published: October 2005

Listeners who are able to identify words from their earliest onset demonstrate an effective integration of acoustic-phonetic and predictive-contextual cues for real-time speech recognition. In this investigation, a gating paradigm was used to study how presentation time (duration from word onset) influences word identification performance. A digital sonagraph was programmed to store and time gate 50 isolated monosyllabic words drawn from a recording (Auditec) of the NU-6 (list 1A). Twenty normal-hearing young adults were tested monaurally via earphones. Each word was presented repeatedly with presentation times increasing in 60-ms increments with each successive pass. Words were presented in 3–7 passes until each word was completely presented (180–420 ms). Subjects were asked to guess the word, write it down, and indicate how confident they were about each guess. Results reveal the effect of a 60-ms gating paradigm on word identification performance and relations between word duration, listener confidence, and percent of words identified.
Perception of /s/-consonant clusters
Authors: Nábělek Anna K. , Letowski Tomasz , Tucker Frances
Published: October 2005

Nonsense syllables /s/C/at/, where C was /p,t,k,f,m,n,l,w/, were recorded then degraded either by noise or by reverberation. The goal was to compare the effects of reverberant overlap of high-frequency energy of /s/ with masking by speech spectrum noise on the identification of the consonants. The results for 10 normal-hearing subjects indicated that the identification of consonants could be degraded by both noise and reverberation. In noise there was a predominance of manner errors whereas in reverberation there was a predominance of place errors. It is possible that the place errors in reverberation were not related to masking by overlapping energy from /s/ but to temporal smearing within the consonants, which obscured the offset of the consonants. To assess if any masking by energy from /s/ could degrade identification of following consonants, the same syllables were tested with a white noise shaped with spectrum of /s/. In this condition, the consonants were highly identifiable. While energy in the consonant /s/ was relatively high, there was little overlapping of the high-frequency spectrum of /s/ with the low-frequency spectra of tested consonants. It is speculated that degrading effects of reverberation were related to the internal smearing within the consonants. [Work supported by NIH.]
The effect of mean flow gradients, including shear, on the propagation of sound
Authors: Vaidya P. O.
Published: October 2005

In the case of the perturbation analysis of nonlinear acoustics, it is customary to assume that the underlying undisturbed mean flow is uniform or nonexistent. When this assumption is removed, several interesting phenomena occur, which are of considerable practical significance. In this paper, three kinds of mean flow nonuniformities are analyzed. These are shear flows, axial gradients, and mean flows with nonzero divergence. It has been shown that these cases lead to sound attenuation, amplification, and instabilities, as well as the generation of fluctuating vorticity and the acousto-vortical waves.
Modeling structural acoustics for active control
Authors: von Flotow A. H. , Miller D. W. , Pines D. J.
Published: October 2005

Active techniques are beginning to be considered for the control of structure-borne sound. Expertise from many fields is being brought to bear upon this problem, including experience in active control of the acoustic response of ducts and air volumes, and the active control of flexible spacecraft. High-fidelity modeling is a necessary prerequisite to high-performance active control. This paper briefly reviews the past approaches to the modeling of structure-borne sound and approaches taken for their verification. The main body of the paper explains a recently developed approach to such modeling, applicable to a restricted class of structures. The paper closes with the description of two techniques developed for the design of active control systems for structure-borne sound, and describes preliminary laboratory experimental efforts.
The role of formant relationships in the pattern processing of stop consonants
Authors: Garrison Laurie F.
Published: October 2005

Interaural transfer in selective adaptation was used to explore pattern processing in stop consonants. Specifically, the role of vowel category as proposed by Klatt [in Perception and Production of Fluent Speech, edited by R. A. Cole (Erlbaum, Hillsdale, NJ, 1980)] was investigated. Here, the onset characteristics of different consonants are “attached” to different vowel categories consisting of front, back, rounded, and unrounded vowels. This experiment tests for pattern processing based on these assumptions. The relationships between formants as well as vowel category for CV syllables were systematically manipulated. Five adaptors were constructed by changing the relationships between F1 and F2. Two adaptors shared the same front vowel percept [bae]. Two other front vowel syllables, [bE] and [bI], and a back vowel syllabic, [ba], were also used. These adaptors were then used in an interaural transfer adaptation experiment on a [bae-dae] series. The results will be discussed in relation to how changes in formant relationships and different vowel categories affect pattern processing of speech syllables. [Work supported by NINCDS.]
Sensory-perceptual transformations in speech analysis
Authors: Miller James D. , Sadoff Steven J. , Veksler Mark R.
Published: October 2005

In Miller's auditory-perceptual theory of phonetic recognition, the sensory effects of sequences of glottal-source spectra, burst-friction spectra, and silences are integrated into a unitary perceptual response by the sensory-perceptual transformations. The mathematical and computational implementations of the hypothesized transformations will be described. One transformation is applied to spectral pattern or shape and is implemented formant by formant. For example, the center frequency of a perceptual formant is calculated by second-order difference equations from the center frequencies, loudness, and bandwidths of the corresponding sensory formants of glottal-source and burst-friction spectra, when either or both are present, and from similar values for a neutral vocal tract during silence. The loudness of the perceptual response, which is calculated as the integrated loudness of the burst-friction and glottal-source inputs, decays slowly after the cessation of sensory input and, in this way, an audible perceptual response can be maintained during brief periods of silence. Examples of application of these concepts to a variety of speech sounds, such as stops and fricatives, will be illustrated. [Work supported by NINCDS and AFOSR.]
Coding of articulatory-acoustic events in a model of the peripheral auditory system
Authors: Wu Z. L. , Escudier P. , Schwartz J. L. , Sock R.
Published: October 2005

In the last years, several investigators have been concerned with speech processing in auditory models. These lines of research were carefully followed and research was restricted to auditory detection of a set of articulatory and acoustic events. The strategy consists of exploring various processing abilities lying in the model of the peripheral auditory system developed (see Dolmazon and Boulogne, Speech Commun. 1, 55–73), and attempting to demonstrate a possible adequacy between some of the physiological abilities and the acoustical structure of speech induced by articulatory constraints. Here, first results about characterization of voicing onsets and offsets and frication onsets and offsets for CVCV utterances in French will be presented and results obtained by various combinations of physiological mechanisms will be compared: with and without neural adaptation, with enhancement or diminution of low-frequency characteristics by temporally or geographically based filtering processes.
Enhanced amplitude of the first harmonic as a correlate of voicelessness in aspirated consonants
Authors: Ringo Carol Chapin
Published: October 2005

Acoustic analysis was undertaken to test the hypothesis that information signaling voicelessness era preceding aspirated consonant may reside in spectral characteristics associated with “breathy voice” at the onset of the following vowel. The study focused upon the enhancement of the first harmonic (H1) resulting from an increase in the open quotient of the voicing source waveform. The relative amplitudes of H1 and H2 were measured in vowels in CVd syllables pairing the consonants /p,t,k,h,b,d,g/ with the vowels /i,ɑ,u,ε,Λ/. The syllables were spoken by three male native speakers of English. Harmonic amplitudes were measured from DFT spectra (computed without preemphasis) of the first few pitch periods of the vowel. In general, the amplitude of H1 was greater than that of H2 for vowels following voiceless consonants; the converse was true for voiced consonants. A perceptual study using synthetic continua (varying in VOT) is being conducted; the continua differ in relative amplitude of H1 and H2. Preliminary results indicate that for some subjects an enhanced H1 may contribute to a voiceless percept: The boundary between voiced and voiceless stops was shifted to smaller VOT values for stimuli in which the amplitude of H1 was greater than that of H2 at vowel onset. [Work supported by NIH.]
Physical aspects of lithotripsy
Authors: Blackstock David T.
Published: October 2005

Lithotripsy is a medical procedure by which focused shock waves are used to break up kidney stones. In the most widely used device, the Dornier lithotripter, the shock wave is produced by an electric spark at the near focus of an ellipsoidal reflector, which is located in a water bath. The patient is positioned so that the kidney stone lies at the far focus of the ellipsoid. The pressure signal there is a positive spike (headed by a shock) of amplitude as high as 1300 atm and duration about 1 μs, followed by a negative pressure of longer duration and magnitude of order 100 atm. Particular emphasis in this talk is on the focused sound field, which is made up of the converging wave reflected from the ellipsoidal surface and a diffracted wave generated at the edge of the reflector. The changing relation between the two waves along the axis of the ellipsoid gives the lithotripter pulse its characteristic waveform. Also discussed briefly are the spark source, pressure signal measurement, cavitation, and stone breakup. [Work supported in part by NIH.]
Fundamentals of piano scale design
Authors: Kent Earle L.
Published: October 2005

The determination of optimum piano string diameters, speaking lengths, and total lengths is complicated due to the interaction between the strings, their breaking strengths, available space for them, the energy they can accept from hammers, and the utilization of string energy to produce sound. Many economic, philosophical, and psychological factors in addition to the physical considerations are involved. No universally accepted definition of good piano tones has been established. Though it is not practical to lay down a set of specific rules for piano scale design, it is helpful to consider the relationships between involved parameters in order to guide the design, rebuilding, and repair of pianos. A set of string design relationships is given to serve as a bench mark in establishing piano string dimensions and as a basis for making comparisons in existing pianos. It seems reasonable to consider starting with well chosen string dimensions since the strings are the starting sources of piano tones.
From twenty years of violin acoustics research
Authors: Jansson Erik V.
Published: October 2005

A very fruitful year as research associate to Arthur Benade in 1967 started my professional work as a scientist. This year formed much of my way of thinking and future work on strings, some of the “highlights” of which are reviewed. Normal modes of plates of a violin under construction were mapped by means of hologram interferometry (with Molin and Sundin). Experiments with the air cavity, employing Fransson's Ionophone, disclosed a large number of air volume modes. Long-time-average spectra of quality judged violins implied that high level below 1 kHz, low at 1.3 kHz, and high around 2.5 kHz are favorable (with Sundberg and Gabrielson). Normal modes of the complete violin were mapped with “speckle interferometry” and input admittance measurements, and implied that “equally strong” low-frequency modes and a marked “bridge hill” at 2.5 kHz are positive for quality (with Alonso Moral). The influence of material properties and design of free plates were investigated in physical experiments and finite element calculations indicating that the thickness is the main factor (with Jakub Niewczyk, Molin, and Lindgren). The properties of plates in a simplified violin body are presently investigated (with Benedykt Niewczyk). I believe that the learnings from my year with Arthur Benade, thus, have further been spread during the last 20 years to my fellow colleagues in Sweden and guest researchers from Spain, Poland, and Australia.
Reminiscences of Art Benade
Authors: Miller Harry B.
Published: October 2005

In the early 1950's, Art Benade gave a two-semester evening course on atomic physics. I was a member of the class. We soon got into after-class discussions of applied acoustics and these never really stopped until his death. Some of this will be recounted.
Gap discrimination in normal listeners and cochlear implant patients
Authors: Shannon Robert V. , Neff Donna L.
Published: October 2005

Gap discrimination was measured as a function of standard-gap duration and marker level in both normal-hearing listeners and in patients with Nucleus and Symbion cochlear implants. For normal listeners, the standard gap ranged from 0 to 400 ms and the broadband-noise markers were 30 to 90 dB SPL total power. For the implant patients, the range of standard gaps and marker levels was similar, but the markers were either sinusoids or pulse trains. Normal listeners were tested under both monaural and dichotic (one marker to each ear) conditions. When expressed as ΔT/T, the gap discrimination functions for both normals and implant patients are nonmonotonic with a peak at standard durations of 10–20 ms. Performance at the shortest standard durations is markedly poorer with dichotic presentation. The nonmonotonicity appears to reflect a change from a task limited by peripheral processes to one limited by more central processes. Cochlear implant patients exhibit a similar change. [Work supported by NIH.]
Difference limens (DLs) for phase in normally hearing subjects and subjects with unilteral cochlear hearing loss
Authors: Moore Brian C. J. , Glasberg Brian R.
Published: October 2005

Complex tones containing the first 20 harmonics of 50, 100, or 200 Hz, all at equal amplitude, were used as stimuli. All of the harmonics except one were added in cosine phase. The remaining harmonic started in cosine phase, but was shifted in phase halfway through either the first or the second of the two stimuli used in a 2-AFC trial. The task of the subject was to identify the stimulus containing the phase-shifted component. An adaptive procedure was used to meaure DLs for phase for three normally hearing subjects and four subjects with unilateral cochlear impairments. When the normal ears were tested at a level of 70 dB SPL per component, DLs were smallest (2°–4°) for harmonics above the eighth and for the lowest fundamental frequency (F0). Changes in phase could not be detected for harmonic numbers below four at the lowest F0 and below 8–13 at the highest F0. The DLs increased markedly with decreasing level, except for the highest harmonic, where only a small effect of level was observed. The DLs for the impaired ears were generally larger than those for the normal ears when the comparison was made at equal SPL but the discrepancy was reduced when the comparison was made at equal SL. For low harmonic numbers, a few cases were found where DLs were smaller for the impaired than for the normal ear of a given subject, even at equal SPL. This effect may be explicable in terms of the broader auditory filters of the impaired ears. The results will be compared to measures of temporal resolution and pitch discrimination using the same subjects. [Work supported by the Medical Research Council, U.K.]
Frequency resolution at equivalent sound-pressure levels in normal-hearing and hearing-impaired listeners
Authors: Nelson David A.
Published: October 2005

Forward-masked psychophysical tuning curves (PTCs) were obtained for multiple-level 1000-Hz probe tones from 15 normal-hearing and 23 hearing-impaired ears with cochlear hearing loss. Comparisons between normal-hearing and hearing-impaired PTC characteristics were made at equivalent masker levels near the tips of PTCs. The low-frequency slopes of PTCs from hearing-impaired listeners were not different from those of normal-hearing listeners, i.e., hearing-impaired listeners did not demonstrate abnormal upward spread of masking when equivalent masker levels were compared. Only 8 of the 23 hearing-impaired listeners demonstrated abnormally broad PTCs, due exclusively to abnormally gradual high-frequency slopes to their PTCs. This demonstration of abnormal downward spread of masking was only observed in listeners with hearing losses greater than 40 dB HL. From these results, it would appear that some, but not all, cochlear hearing losses greater than 40 dB HL influence the sharp tuning capabilities usually associated with outer hair-cell function. The restriction of abnormal findings in this study to the high-frequency sides of PTCs alone is likely due to the use of equivalent masker-level comparisons, and also to the use of flat-envelope nonsimultaneous maskers rather than fluctuating-envelope simultaneous masker. [Work supported by NINCDS.]
Growth of masking in listeners with cochlear impairments and impairments simulated by masking
Authors: Buus Søren , Florentine Mary
Published: October 2005

The higher-than-normal masked thresholds observed in many impaired listeners may be explained by nonlinear additivity of masking by the external masker and an hypothetical internal masker [Jesteadt et al., J. Acoust. Soc. Am. Suppl. 1 81, S77 (1987); Humes et al., J. Acoust. Soc. Am. Suppl. 1 81, S77 (1987)]. To test this hypothesis, Békésy tracking was used to measure growth-of-masking functions for 250-ms tones with frequencies at and above those of continuous low-pass or octave-band noise maskers. Results for four impaired listeners show that the minimum-effective-masker levels (MEMLs, above which masking occurs) are higher than normal for small masker-signal separations, Δf's, but approach normal values for larger Δf's. Above the MEMLs, masking grows 1 dB/dB or less. Results for simulated impairments are similar to those for real impairments, but MEMLs tend to be higher and masking often is less in simulated than in real impairments. These results indicate that nonlinear additivity of internal and external masking accounts for some, but not all, of the excessive spread of masking observed in many impaired listeners. [Work supported by NIH.]
An analytic model for vibration of turbomachinery rotor blades
Authors: Charpie James P. , Burroughs Courtney B.
Published: October 2005

An analytic model for the vibration response of turbomachinery rotor blades that includes the effects of variations in blade thickness, curvature of the blade edges, and variations in the curvature of the blade middle surface in two dimensions is developed. Mathematical fits to both surfaces of the blade are generated in terms of polynomial equations with constant coefficients. The polynomial equations for the blade surfaces are then used in shell equations, based on Love's thin shell assumptions, to generate differential equations governing the vibration motion of the blade. The coefficients in the blade-fitting polynomials act as parameters in the equations of motion for the blade, so that equations for a new blade can be developed easily by changing the coefficients in the governing equations to those generated for the new blade. An approximate method of solution for the resonant response of a sample blade is presented.
Modification of Lamb wave spectrum in fluid coupled plate
Authors: Rokhlin S. L , Chimenti D. E. , Nayfeh A. H.
Published: October 2005

It has been accepted previously that for most practical eases when a plate is immersed in a liquid the Lamb wave spectrum is only slightly perturbed due to energy loss related to leakage of the wave from the plate to the liquid. In contrast it was recently discovered by D. E. Chimenti and A. H. Nayfeh [Appl. Phys. Lett. 49 (9) (1986)] that for leaky Lamb waves in a graphite epoxy composite plate in water a strong anomaly appears in the topology of the S0 mode as a function of frequency. Although it was caused by the fluid, the reason for this anomaly was still not clear. The nature of the anomalous behavior of leaky Lamb waves is discussed in this paper. It is shown that for an understanding of the spectrum topology, the full complex spectrum of propagating and nonpropagating modes should be considered. It is demonstrated that the topological changes in the S0 mode are related to its nearness to the first complex branch of the spectrum. Increasing liquid density leads to interaction between these modes and mutual interchange between their branches in the complex plane. It is shown that, in general, as the density of the immersion liquid increases from zero to infinity the complex spectrum of plate modes gradually transforms from a spectrum of Lamb waves in a free plate to a spectrum of waves in a plate clamped on its surfaces with slip (boundary conditions σxy = 0, Uy = 0).
Sound radiation from a vibrating body in motion
Authors: Wu Xiao-Feng , Akay Adnan
Published: October 2005

Past studies of acoustic radiation problems have been concerned with sound waves generated by either a vibrating body or a moving point source with no dimensions of its own. This paper presents a method for determining the acoustic field radiated from an arbitrary object undergoing, simultaneously, a harmonic oscillation and a spatial motion with respect to the surrounding fluid medium. At this stage of the investigation, the turbulence and flow distortion caused by the motion of the vibrating body are neglected. The method is based on the assumption that the surface of the vibrating body can be described in terms of a distribution of simple monopole and dipole sources. Utilizing a linear coordinate transformation, one is then able to reduce the problem to that of radiation from a stationary source for which the analytical solution has been obtained [Morse and Ingard, Theoretical Acoustics (Princeton U.P., Princeton, NJ, 1986)]. The total acoustic field is the sum of contributions from all the simple sources on the surface of the moving object. The method is illustrated using a vibrating sphere moving with either constant or time-dependent velocity profiles relative to the surrounding medium. Extension of this method to impulsive motions is discussed. [Work supported by NSF and WSU Institute for Manufacturing Research.]
Transient structural vibration created by a laser beam
Authors: Abo-Mossallam Yousef A.
Published: October 2005

Experimental work is conducted to investigate the transient vibration of a structure by an argon laser beam. The conversion of laser light into mechanical energy has been studied through focusing laser beam to vaporize material from a target attached to the structure. The rapid ejection of target material results in an impulsive reaction transmitted to the structure. Different target materials are tested to enhance the efficiency of energy conversion. A clamped beam and a cantilever beam are used in the experiments and the measured natural frequencies are compared favorably with the calculated ones. Beam splitters and multiple targets are used to test the concept of multipoint simultaneous impulsive loading.
Sound radiation control for two plates assembled in an L shape
Authors: Millot Pascal F. , Guyader Jean-Louis
Published: October 2005

Reduction of sound radiated in a cavity by an L-shape structure excited by mechanical forces, can—in some instances—be achieved by taking advantage of the phenomena that are unique to that geometrical shape. Instead of relying only on the control of the velocity of the structure to reduce the sound radiated, it will be shown that it is possible to select modes of the assembled plates that have a low-radiation impedance, by positioning correctly the mechanical excitation forces. At low frequencies, improvements can reach several decades for the mean-squared pressure inside the cavity for identical plates, while above the limit frequency of the cavity no improvement should be expected with this method. Below the limit frequency, improvements will greatly depend on the respective dimensions of the plates, as well as on the values for the first resonant frequency of the plates and of the cavity. Theoretical results, derived from a modal approach for the cavity and the plates, as well as experimental results obtained for plaster plates in laboratory, will be presented.
Computation of the Biot drag and virtasl mass coefficients for a three-dimensional pore space
Authors: Yavari B. , Bedford A.
Published: October 2005

Application of the Biot theory to the study of the acoustic waves in ocean sediments requires evaluation of the drag and virtual mass coefficients. These coefficients depend on the frequency and microstructure of the sediments. Recently, a method was developed to evaluate these coefficients by Bedford et al. [J. Acoust. Soc. Am. 76, 1804–1809 (1984)]. The method requires solving for the motion of the fluid in the pores when the pore walls are subjected to an oscillatory motion. The finite element method has been used to determine the fluid motion. The drag and virtual mass coefficients have been determined for a microstructure composed of spherical grains saturated with water. The qualitative behavior of the coefficients is shown to be similar to the two-dimensional results presented previously [J. Acoust. Soc. Am. Suppl. 1 82, S121 (1987)]. The behavior is also shown to be qualitatively similar to that of an exact solution for the case of straight cylinder pores obtained by Biot and other investigators. Wave velocity and attenuation of compressional waves calculated based on these coefficients are shown to agree reasonably well with experimental data. [Work supported by ONR.]
Preliminary results from a shallow water bottom interaction experiment in the Gulf of Mexico
Authors: Lynch James F. , Frisk George V. , Rajan Subramaniam D.
Published: October 2005

In order to help assess our present capability to predict the details of sound propagation in shallow water environments, a cw acoustics experiment was performed at a site in the Gulf of Mexico near Corpus Christi, TX. This site was chosen because it was both relatively simple acoustically and previously well-studied. Indeed, the site chosen was the same as was studied by Rubano in an earlier experiment [L. A. Rubano, J. Acoust. Soc. Am. 67, 1608–1613 (1980)]; moreover, a compilation of archival records (seismic data, etc.) by a NORDA group gave a second geoacoustic model to complement Rubano's [J. E. Matthews, P. J. Bucca, and W. H. Geddes, NORDA Report 120, June 1985]. The data were taken at 50 and 140 Hz on radial tracks typically 5 km long, and sampled at least at the spatial Nyquist frequency (every half-wavelength in range), so that each data track was effectively a 5-km synthetic aperture array. The data were then Hankel transformed to display the normal mode structure of the waveguide [G. V. Frisk and J. F. Lynch, J. Acoust. Soc. Am. 76, 205–216 (1984)], and the mode structure was in turn inverted to yield a geoacoustic model [S. D. Rajan, J. F. Lynch, and G. V. Frisk, J. Acoust. Soc. Am. 82, 998–1017 (1987)], which we compare to the NORDA and Rubano models. Comparisons of pressure field predictions, modal structure predictions, and geoacoustic models are discussed. [Work supported by ONR.]