bluuebunny/crossref_metadata_2025 huggingface dataset:
What is a bell tone?
Authors: Slaymaker F. H.
Published: October 2005

The partials in a bell tone are, in general, not harmonically related. But the spectrum of a bell tone is made up of discrete partials and is not the continuous spectrum we associate with white noise. Only a few specially shaped structures have normal modes with haromonically related resonant frequencies. When any of the infinite variety of other structures are excited into vibration by an impulse, the tones will sound belt-like if the decay rates of the various partials are relatively slow. Only the bells designed for playing music in harmony, such as cast carillon bells and the hand bells used by bell choirs, have standarized relationships between the partials. Tapes will be played demonstrating the tone of cast bell carillons and also synthetic tones in which the partials are stretched from the harmonic relationship by a factor ns, where n is the harmonic number, or shifted arithmetically by adding or subtracting a constant number from the frequency of each partial. As the frequencies of the partials are changed from the simple harmonic relationship the tones become more bell-like.
Variable timbre in mallet percussion instruments
Authors: Kvistad Garry , Rossing Thomas D.
Published: October 2005

Marimbas, xylophones, and vibes make use of tuned resonators to amplify their fundamental tone. However, throughout much of their range, the first overtone of each bar is tuned to one of the harmonics (3rd in the case of xylophones, 4th in the case of maribas and vibes) in order to generate the customary timbre [C. Rose and T. D. Rossing, J. Acoust. Soc. Am. 58, S131 (A) (1975)]. Tuning a second set of resonators to the first overtone makes it possible to vary the timbre (this can be extended to higher overtones as well). A marimba with variable timbre will be described and demonstrated.
The Louisiana Superdome: acoustics and sound system
Authors: Figwer J. Jacek
Published: October 2005

The Louisiana Superdome, an enclosed stadium with a seating capacity of 95 000 people, was designed for a variety of uses ranging from sports events through entertainment to large conventions. The presentation describes the acoustical treatments included in the stadium to control reverberation and intrusive noise. Also, the loudspeaker systems employed are described as well as the functional and electrical arrangement of components, and some observations on the performance of the system.
The Singapore National Stadium sound system
Authors: Figwer J. Jacek , Philbrick R. Lawrence
Published: October 2005

The National Stadium in Singapore is open air, olympic sized, and seats 60 000 people for national rallies, sports, and entertainment events. The sound system provides high-quality reinforcement with reliable and simple operation. The presentation describes the functional and electrical arrangements of the system with emphasis on the use of line arrays of horn-loaded loudspeakers with highly efficient compression drivers.
A state-of-the-art Special Events Center
Authors: Boner Charles R. , Boner Richard E.
Published: October 2005

The authors have, over the past fifteen years, been involved in the design of over 30 arena-type buildings, seating from 3500 to 22 000 people. A new arena, called a Special Events Center, under construction in Austin, TX, will approximate what the authors consider to be the state of the art in acoustics and audio, based on experience gained in previous spaces. Among the items to be covered will be the sound reinforcing system, which will accomodate all events from opera to rock concerts, and which will be operated by a professional operating company to avoid pitfalls of union soundmen. Salient features of other arenas will be discussed.
Acoustics of the enclosed stadium for the University of Idaho, Moscow ID
Authors: Paoletti D. A. , Lewitz J. A.
Published: October 2005

The enclosed stadium for the University of Idaho, known as the Kibbie-ASUI Activity Center was the recipient of a 1976 American Society of Civil Engineers award for engineering excellence. This unique structure, with a maximum seating capacity of 21 000 is one of the few recently completed enclosed multipurpose stadium structures. The acoustical characteristics of this building will be illustrated and discussed with particular emphasis on the special engineering and operational problems of enclosing such large spaces. [Architects/Engineers: Cline Smull Hamill Associates, Boise, Idaho. The authors were principal consultants for this project while employed at Bolt Beranek and Newman, Inc.]
Combing central and peripheral loudspeaker clusters in a multipurpose arena
Authors: Kaye David H.
Published: October 2005

Oral Roberts University's Mabee Center serves as sports arena (10 600 seats), performance and convocation hall (9000–14 000 seats), and theatre/auditorium (2800 seats). Because “full-house” live events may take place either at the end of the elliptical arena or at the center, one 360°-coverage loudspeaker cluster hangs at each location. A third cluster, serving the theatre seating quadrant, is mounted in a pivoting panel which lowers to provide a fore-stage sound reflector. The roof over most of the arena floor is much lower than over the rear seats, obstructing coverage by the central loudspeaker clusters of the upper half of the seating area. Coverage of the rear seats is provided by sixteen peripheral loudspeaker clusters. These “outer ring” loudspeakers reproduce delayed signals; the amount of delay required varies, depending upon which central loudspeaker is in use. The delays are selected through a matrix programming board; the operator presses only a single button to choose a central loudspeaker and the delay configuration appropriate to it. [This project completed while the author was with Bolt Beranek and Newman, Inc.]
New sound reinforcement system for the Kentucky Fair and Exposition Center
Authors: Fricke John V. , Coffeen Robert C.
Published: October 2005

Freedom Hall, an 18 000 seat coliseum, which houses the University of Louisville Cardinals basketball team, the National Quarterhouse Championship Show, and many concerts received a new sound reinforcement system consisting of fourteen distributed loudspeaker clusters and three stage location clusters. The stage location clusters provide a time delay base for the remaining distributed clusters. The presentation examines the “distributed cluster” concept of providing a better sound reinforcement system for large audience spaces.
Recent field testing experience of privacy between dwellings using ASTM Recommended Practise 597
Authors: Barron Kenneth E. , Hall Gordon D.
Published: October 2005

Some recent experience with field testing of privacy between dwelling units using the method of the new ASTM Recommended Practise 597 is reported and the effects of airborne flanking paths on the ratings obtained is discussed. The results of the testing experience indicate that the single number rating provided by this new test method is approximately two points less than the Noise Insulation Class Rating (NIC) obtained by grading 1/3-octave-band noise reduction measurements according to ASTM 413. It is suggested that this new single number rating obtained from A-weighted sound pressure level differences utilizing the specially shaped source and absorption test spectra be called the Privacy Index.
Prediction of the sound diffracted around barriers in large rooms using an extension of Maekawa's approach
Authors: Johnson R. A. , Hurst C. J. , Mitchell L. D.
Published: October 2005

A computer program has been developed for the prediction of sound pressure levels in large, irregular rooms utilizing a geometric acoustics approach. Experiments indicated that the program gave good predictive accuracy when receiver positions were in the line of sight of the sound source. However, the accuracy was poor when the receiver was out of the line of sight. The present discussion reports on the further development of the program to include diffraction effects using an extension of Maekawa's approach for thin screens and right-angle wedges. The program is capable of finding all valid diffracted rays which undergo three or fewer reflections before diffraction and three or fewer reflections after diffraction. Limited experimental work indicates good predictive accuracy.
Acoustical solutions for SSA Headquarters
Authors: Moulder Ron , Harris D. A.
Published: October 2005

Speech privacy between closed-plan and open-plan work situations is the goal of the new Social Security Administration (SSA) Headquarters complex in Baltimore. Approximately 1.1 million square feet of office building is being procured by the U. S. General Services Administration (GSA) using the “Systems Approach.” A key element is the “Performance Specification for Office Buildings” which establishes detailed criteria for the “in systems” portion of the building including structure, HVAC, Electrical Distribution, Finished Floor, Luminaries, Finished Ceiling and Space Dividers. The successful system offeror demonstrated system compliance in a technical proposal before submitting an installed and lifecycle cost bid. American Bridge, Wolf and Munier, and Owens-Corning Fiberglas, in joint venture, submitted the low bid, Prototype tests recently completed demonstrate full compliance. Since acoustical attributes affect each subsystem, the criteria includes reference to the PBS C.1 and C.2 test procedures among others. A summary of the procurement process, testing criteria, development parameters and solutions will be available.
Computer-aided, interactive design routine for the prediction of sound levels in irregularly shaped factory spaces
Authors: Blanding J. M. , Mitchell L. D. , Hurst C. J.
Published: October 2005

An interactive computer algorithm is presented which utilizes modified room acoustics theory to predict dBA sound pressure levels in regularly- and irregularly-shaped factory spaces. Irregularly positioned and nonuniform room absorptions are treated. The user-oriented algorithm, suited to remote interactive terminal operation, employs a conversational format to facilitate input of room dimensions, of absorption data, and of locations and noise levels of machinery. A redesign feature is included which employs three options. These allow the user to change sound source data and acoustic treatments in the process of finding the most economical accomodation of OSHA regulations during any phase of the factory design or redesign. [Work supported by NSF.]
Performing arts building for a small liberal arts college
Authors: Cavanaugh W. J.
Published: October 2005

The Michael and Margaret McCarthy Arts Center on the campus of St. Michael's College, Winooski, VT, was occupied and in use for the fall semester of 1975. Its 400-seat theater, 300-seat recital hall, faculty offices, studios, classrooms, individual and group rehearsal rooms serve the performing arts needs of this 1400 student campus. The building was long in the planning stages and several original proposals for the building were discarded primarily for budget reasons. The design and construction of the building in just under 12 calendar Pizzagalli Construction Company undertook the complete design and construction of the building in just under 12 calendar months. This paper reviews the acoustical design considerations and the solutions to the myriad room acoustics, sound isolation, and building noise control problems inherent in a building of this type. Measurements of background ambient noise levels, room-to-room noise reduction, and reverberation times in the completed spaces are given and compared with the design objectives and generally accepted criteria.
Modeling of pressure spectra in a turbulent shear flow
Authors: Beuther Paul , George William K. , Arndt Roger E. A.
Published: October 2005

Models of turbulent-turbulent and turbulent-shear contributions to pressure spectra in a turbulent shear flow are developed. The spectral model for the turbulent-shear contribution is obtained by directly Fourier transforming the integral solution to Poisson's equation for an isotropic, homogeneous, constant mean shear flow. The turbulent-turbulent model is found in a similar manner with the addition of a quasinormal fourth-order-moment closure approximation. It is found that the turbulent-turbulent contribution is dominant in the high-wavenumber region and possesses a k−7/3 inertial subrange. The shear contribution is dominant in the low-wavenumber region where it increases as k2 for the large scales and rolls off as k−11/3 for scales smaller than the energy containing eddies. Both spectra are related to the type of model chosen for the velocity field; by choosing various spectral forms, it is possible to compute the mean-square pressure of the flow. These results are compared to models for the mean-square pressure developed by Kraichnan, as well as with our own experimental data taken in a 12-in.-round jet and that of several other investigators.
Azimuthal decomposition of the power spectral density of subsonic jet noise
Authors: Yamamoto K. , Arndt R. E. A.
Published: October 2005

The coherence function was measured from two sampled jet noise signals, one from a stationary microphone and the other from a circumferentially moving microphone. The coherence function was then expanded in a Fourier series with respect to the azimuthal angle. For an axisymmetric circular jet the Fourier coefficients thus obtained are equivalent to the power spectral density of the individual azimuthal constituents of the fluctuating pressure in the radiated field. It was found that for Strouhal numbers less than 1.0, the radiated sound is composed of only a small number of azimuthal components. For higher frequencies, nonaxisymmetric components are predominant. The prediction method for single-azimuth-frequency components proposed by Chan [Y. Y. Chan, AIAA J. 12 (2) (1974)] based on the spectral theory of Michalke has been further developed for the present study. [Work supported by NASA.]
Error analysis of CASH method: computer-averaging of noisy periodic signals
Authors: Elder S. A.
Published: October 2005

Computer-assisted synchronous hot wire, or “CASH,” method was developed to permit computer averaging of hot wire data when sampling oscillating velocity profiles. Using emitted sound pressure as phase reference, computer separates periodic component of hot wire signal from turbulent background by averaging over large number of acoustic cycles. So far technique has been utilized in two investigations: (1) interface oscillations of flow-excited cavities, and (2) growth of instability waves in laminar jets. Accuracy depends on the ability to match closely the reference source frequency. Any mismatch produces systematic error. For given amount of mismatch, however, error is minimized by dividing sample into subsets and performing the averaging at two levels. In the cavity resonator problem, random deviations from periodicity in the reference itself make frequency-matching difficult. Measured standard deviations show a predicted periodicity, with greatest amplitude discrepancy occurring 90° after signal maximum. To assure amplitude error of no more than 3% requires that frequency mismatch be kept to less than 0.1%. [Work sponsored by Naval Ship System Command, GHR program, administered by Naval Ship Research and Development Center.]
On radiated noise generated by high-speed trains
Authors: King W. F.
Published: October 2005

Projected speeds for the next generation of railway trains in advanced countries lie between 230 and 300 km/h. Consequently, unless abatement techniques are developed concurrently, the radiated noise generated at these speeds could result in severe deterioration of the noise environment for people living near railway lines. Radiated train noise is generated primarily by wheel/rail interactions and aerodynamic fluctuations. For conventional trains, the former source is dominant up to speeds of at least 400 km/h. With current technology, however, it has been shown that wheel/rail noise levels can be reduced by 10–15 dB, as compared to conventional trains under similar conditions. Such reductions lower the critical speed at which aerodynamic noise levels exceed those produced by wheel/rail interactions. Theoretical, calculations discussed in this paper indicate that on new disk brake equipped trains, aerodynamically generated noise levels can exceed those produced by wheel/rail interactions at speeds of approximately 250 km/h. Other calculations based on air-frame noise studies and measurements made on high-speed railway vehicles also support these results.
Combustion noise from a turbulent premixed methane flame
Authors: Schmidt B. , Gootzait E. , Arndt R. E. A. , Essenhigh R. H.
Published: October 2005

The comparative influence of air/fuel ratio and angle of injection on combustion noise from a cylindrical, double vortex combustor was investigated, extending previous measurements by M. Kuwata and R. H. Essenhigh (AIAA Paper No. 75–1267). Measurements were carried out in a 221.5 m3 calibrated reverberant room. Acoustic power and efficiency were measured for different injection angles and equivalence (air/fuel) ratios. Acoustic power variation with equivalence ratio (φ) was an inverted U, mimicking the burning velocity curve, but with peaks at φ between 1.1 and 1.2. The curve was sharply peaked when mixture injection was nearly radial, but was very flat when injection had a major tangential component. The acoustic efficiency was in the region of 10−6. The results are compared with relationships drawn from the literature. [Work supported by the Cooperative Fund of the Combustion Laboratory, and the Noise Control Laboratory of the Pennsylvania State University.]
Valve noise prediction
Authors: Walter Jeremy L. , Reethof Gerhard
Published: October 2005

Valve noise prediction has become a problem of great interest among noise control engineers and valve manufacturers because no adequate universal prediction scheme has ever been devised. A hopeful technique is proposed that will be based on sound power measurements taken while venting a valve into a reverberant space. The questions to be answered are: (1) What are the effects of downstream pipe configurations? (2) Can the various types of valves be grouped into a few general classes? (3) What are the scaling parameters for predicting noise from different size valves? Preliminary tests conducted in a calibrated reverberant room indicate that downstream pipe configurations may have a small effect on the sound power spectrum of a given valve. However, an extensive experimental program must be conducted before, these questions can be answered conclusively.
Noise reduction of chain conveyors for underground coal mines
Authors: Huggins Geoffrey G. , Burks J. Alton
Published: October 2005

Results of a three-phase program are presented, during which methods of reducing the operator sound level of coal chain conveyors were examined. The three phases were (1) the identification and quantification of important noise mechanisms, (2) an exploration of several alternative methods to reduce the sound level, and (3) selection and implementation of a set of noise control techniques based on a specific set of objectives and constraints. The basic approach was to reduce operator noise levels (in the underground environment) from values as high as 102 to 90 dBA. The mechanism underlying the generation of conveyor noise is periodic impacts as the chain links encounter different portions of the conveyor body. In a comprehensive testing program, the various impact sources were separated and characterized. Having quantized each individual source, a set of noise control techniques was rationally developed and implemented to obtain a reduction of 11 dBA on a working conveyor. [Work supported by U. S. Bureau of Mines.]
Are American National Standards Institute sound level meter tolerance limits adequate for sound dosimeters?
Authors: Carito A. P. , Michael P. L. , Prout J. H.
Published: October 2005

Sound dosimeters afford many advantages over sound level meters for measuring sound exposure levels, and will likely assume a prominent place in hearing conservation programs in the future. This paper discusses the appropriateness of the ANSI Types 1 and 2 sound level meter specifications proposed for dosimeters. For any given set of ANSI sound level meter tolerance limits in decibels at a specified frequency, the dosimeter must have its readout tolerances expressed in percentage units for each level and time of exposure. Therefore, calculations have been made for exposure levels ranging from 85 to 115 dB(A) in 5 dB steps for exposure times of 0.25, 0.5, 1.0, 2.0, 4.0, and 8.0 h at 34 preferred frequencies from 10 to 20 000 Hz. Corresponding dosimeter readout tolerance limits have been calculated for both ANSI Types 1 and 2 specifications based upon the present OSHA formula. Wide tolerance limits result from these calculations at high frequencies, high levels, and long exposure times. For example, the +6.5 and −5.5 dB Type 2 sound level meter tolerances at 6300 Hz, correspond to a dosimeter reading tolerance of +144 to −53 for a 100% exposure. Alternate tolerance limits are discussed.
Effects of hyperoxia on the cochlear potential
Authors: Hou S. M. , Lipscomb D. M.
Published: October 2005

Anesthestized chinchilla with round window electrodes were placed in a Plexiglas chamber. When they inhaled 100% oxygen at 1 atm, two types of neural effects were observed: (1) fast and reversible AP depression in response to brief exposure to 100% O2; and (2) a slowly developed chronic depression of AP and latency shift due to multiple hyperoxic exposures. The severity of the latter is a function of the dosage of the O2 inhaled, i.e., the concentration pressure, and the length of time of hyperoxic breathing. For the type-1 effect, carbon dioxide deprivation is felt to be the immediate cause while the type-2 effect is mainly due to O2 toxicity developed at the intracellular level by high O2 concentration. The possible role of superoxide radical in the auditory O2 toxicity will be discussed.
Classification of auditory-nerve units according to spontaneous discharge rate
Authors: Liberman M. C.
Published: October 2005

To clarify the relationship between rate of spontaneous discharge (spont) and threshold, data were gathered from hundred of units in each of several cats, including four born and raised in a soundproofed chamber. To insure that units with high thresholds and low spont were detected, electric shocks were used as search stimuli. The unit sample from each ear can be divided into three groups according to spont rate in such a way that each group has a distinct distribution of relative thresholds. In a given ear units with spont greater than 18 spikes/second (“high-spont” units) are invariably the most sensitive at any one region of characteristic frequency (CF). “Low-spont” units (rates less than 0.5 spikes/second) can be as much as 70 dB less sensitive than average high-spont units of similar CF. “Medium-spont” units (rates between 0.5 and 18 spikes/second) are typically 10 dB less sensitive than average high-spont units. Other differences in the response of units from the three spont groups will be described. [Work supported in part by NIH.]
Frequency discrimination in several background noise conditions
Authors: Abbas Paul J. , Dalzell Larry E.
Published: October 2005

Frequency discriminability of pure tones was measured in a variety of background noise conditions. Difference limens were estimated at 4 kHz using a method of constant stimulus differences, Maskers included wide-band white noise, low-pass noise at 1 kHz, high-pass noise at 6 kHz, and a 500-kHz tone. In all cases the test signal was held at 15 dB SL re quite or masked threshold. Initially measures were obtained with 20 dB of masking for each condition, Frequency DL's in wide-band and in high-pass noise were comparable to those in quite. In low-pass noise and in the low-frequency tonal masker, DL's were significantly greater than in quiet. When the amount of masking was changed (SL of signal held constant). DL wide-band noise was approximately constant while DL in low-pass noise increased with noise level. These results are discussed in relation to single nerve-fiber tuning curves in noise and also in relation to data on two-tone suppression effects.
Central masking effects in air conduction audiometry
Authors: Frank T. , Shanahan J. H.
Published: October 2005

Pure-tone air conduction thresholds were obtained on 20 normal hearing listeners from 250 to 4000 Hz while white or narrow band noise (centered at the test frequencies) masking was presented to the contralateral ear. Each masker was presented at several effective masking levels (EML) of 10, 20, 30. 40, 50, and 60 dB. Thresholds were obtained in 5 dB steps and the amount of masking (threshold shift) was determined for each condition. The shifts increased approximately 0.7 dB for each 10-dB increase in EML between 10 and 40 dB and 3.2 dB between 40 and 60 dB for each 10-dB increase in EML. The narrow band noise produced a greater shift compared with white noise at 250 Hz for the 40, 50, and 60 dB EML conditions. The data suggest that central masking is operating the EMLs below 40 dB: for high EMLs, the increased threshold shifts probably result from a combination of central masking, transcranial conduction, and acoustic reflex action. The clinical implications of central masking will be discussed.
Effects of interaural cue and signal correlation on reductions in backward masking
Authors: Puleo J. S. , Pastore R. E.
Published: October 2005

Recently, we described a series of single-interval (yes-no) detection experiments which investigated the effects of contralateral cueing on monotic backward masking in the presence of a second, continuous masking noise [J. S. Puleo and R. E. Pastore, J. Acoust. Soc. Amer. 60, S49 (A) (1976)]. The cue and signal were presented during the same observation interval and were identical in frequency spectrum, except for phase. While significant reductions in backward masking occurred in all cue conditions, these effects were not affected differentially by the particular interaural correlations of cue and signal employed (0°, 180°, and random phase). This paper described a set of experiments which demonstrate that, through parametric manipulations of cue and signal correlation (i. e., cue both leading and lagging the signal in phase), differential reductions in backward masking were possible. However, such effects could be attributed largely to the pattern of detection improvements which occurred during simultaneous masking. Mechanisms which may have accounted for these results are discussed. [This research was supported by a grant from NINDS.]
The effect of F on the duration of [s]
Authors: Zee Eric
Published: October 2005

The purpose of the study was to determine whether the duration of the prevocalic fricative is influence by the tone of the following vowel. Three Taiwanese tones, low-falling, low-rising, and high-falling, were used in this study. All three tones occur on the syllable [si] in this dialect. The duration of the fricative of [s] in each [si] syllable was measured. Results revealed that there is a direct correlation between the duration of the frication and F0 of the following vowel: the duration is longer for fricatives associated with low-rising and low-falling tones than for the ones associated with high-falling tone. The results may shed light upon the temporal organization of speech production in a tone language, such as Taiwanese. The vocalic portion of the CV, [si], is longer for a rising tone than for either a low-falling or high-falling tone in Taiwanese (Zee and Hombert, 1976). Consequently, the duration of syllables containing a low-rising tone is substantially longer than syllables containing a high-falling tone, and correlatively, the duration of syllables containing a low-falling tone is longer than a high-falling tone. Thus, the duration of the syllable, [si], varies according to the tonal difference of the vowel. [Research supported by NSF.]
Acoustic characteristics of intervocalic dentals
Authors: Zue Victor W. , Laferriere Martha
Published: October 2005

The dental stops /t,d/ in English can be realized in a variety of manners when they appear intervocalically. The exact nature or the acoustic realizations depends on the stress pattern surrounding the stops, the nature of the neighboring sonorants and vowels, and the underlying features of the following syllabic consonants. For example, /t,d/ could be realized in their respective canonic forms with a closure and a release (attorney, adore), as a glottal stop (cotton), a flap (writer, rider), or a nasal-released stop (garden). This study attempts to quantify the acoustic characteristics of the intervocalic dentals as a function of the phonetic environments. The data consist of some 3000 word tokens, each embedded in a carrier phrase, recorded in two separate sessions by six subjects, three male and three female. Each word, either bi- or polysyllabic, contains /t/ or /d/ in all phonetic environments mentioned earlier. With spectrographic and computer-aided analysis, the temporal and spectral characteristics of the dental stops are examined in detail. These results will be presented and possible formulation of phonological rules will be suggested.
Peak magnitudes of supraglottal air pressure associated with affricated and nonaffricated stop consonant productions in Hindi
Authors: Dixit R. Prakash , Brown W. S. , McGlone R. E.
Published: October 2005

Peak magnitudes of supraglottal air pressure, under a variety of conditions, were obtained during stop productions from three normal adult speakers of Hindi. The stops were produced in CVCVC nonsense utterances which were embedded in the carrier phrase, “ye—hae.” Significant differences in peak magnitudes were found as a function of the place of articulation of a stop and its position in an utterance. Peak magnitudes were always significantly higher for unvoiced stops than for voiced stops. Aspirated stops, in general, showed higher peak magnitudes than unaspirated stops, but a significant level of difference in peak magnitudes was reached only under voiced conditions. Differences in peak magnitudes as a function of stress were significant under voiced conditions; under unvoiced conditions the differences were less pronounced.
Estimation of laryngeal control parameters from glottal waveforms
Authors: Talkin D. T. , Titze I. R.
Published: October 2005

Clinical assessment of phonatory skills and laryngeal abnormalities would be facilitated ff a method of relating laryngeal muscular control and glottal configuration to glottal waveforms could be found. A computer model of the vocal folds, described earlier, which uses control parameters closely related to laryngeal muscular contractions, and which allows for sufficient flexibility in tissue properties and configuration, has been used to generate prototype waveforms of glottal transconductance and glottal volume velocity. The relationship between model control parameters and the resultant waveforms is determined by multiple regression. Success in predicting model control parameters from waveform parameters is demonstrated, and the applicability of this method to clinical situations is discussed.
Vertical larynx position in whispered speech
Authors: Riordan Carol
Published: October 2005

A number of studies have shown that vertical larynx position varies depending on the vowel or consonant uttered. Voiceless stops, for example, are generally produced with a higher larynx than their voiced cognates. It is not clear, however, whether the larynx is perturbed upward for voiceless stops or downward for the voiced stops. The latter possibility is suggested by the increase in pharyngeal cavity size for voiced stop articulation, presumably to maintain the transgottal flow necessary for voicing [Bell-Berti, 1975], and by the similarity in larynx height data for sonorants and voiceless stops [Ewan, 1976]. The present experiment is designed to determine the effect on larynx height of sounds with aerodynamic requirements different from those of stops. Vertical larynx position is monitored photoelectrically while English speakers produce intervocalic /t, d, n, l, r, f, v, s, z/ first under normal speech conditions and then in whisper. Implications of these results are discussed. [Supported by NSF and the Veterans Medical Service.]
Sound level increase close to enclosure' boundaries
Authors: Giminéz de Paz J. C.
Published: October 2005

The increase of the average of the potential sound energy density close to enclosure's boundaries (and the corresponding sound level) is theoretically studied, showing that in the corners this value is greater than the 9 dB commonly accepted one. This is due to the presence of interference terms. The study was made on the basis of the eigenmode model applied to a room with hard walls, which allows for stationary waves, in which we suppose a sound diffuse field, and a range of frequencies as large as to excite the normal frequencies of the room and consider them as independent. Finally, the work shows explicitly the expressions for the oblique, the tangential, and the axial modes.
Acoustical designing for performers
Authors: Shankland Robert S.
Published: October 2005

The normal procedure in acoustical designs usually emphasizes audience acceptance. This approach often results in unfavorable acoustical conditions for performing artists, both instrumental and vocal. The imbalance occurs from neglect of the musician's need for mutual communication, and too great an emphasis on achieving “optimum” reverberation conditions. There have been notable examples of halls meeting accepted reverberation criteria which have nevertheless proved to be unsatisfactory, and many of these gave trouble because of performance difficulties as transmitted to the audience. Conversely, reverberation conditions can differ considerably from the norm, and still provide a satisfactory hall if the stage properly designed. Study of a variety of halls strongly suggests that an essential requirement for music is that conditions should be suitable for performers. Architectural designs that provide ample sound reflecting and diffusing structures on stage to enable artists to hear each other well, blend the sound, and achieve favorable “local reverberation” are usually judged to be excellent by both performers and audience. This essential result can be achieved even in rooms which depart appreciably from standard reverberation time criteria. Several specific examples will be discussed.
Critical distance measurement of rooms from the sound energy spectral response
Authors: Jetzt J. J.
Published: October 2005

At any point in an ideal room, the standard deviation of the acoustic energy spectral response from its mean is shown to be a function of the direct-to-reverberant acoustic energy ratio at that point. This function yields a method for measuring critical distance, at which these energies are equal, which is more powerful than the traditional total energy response method. The new method uses measurements made within the critical distance; it does not require that the reverberant energy be uniform in the room. Calculations made for computer-simulated rooms show that the method is valid for rooms having a wide range of average absorption coefficient. In some cases, results can be obtained with the new method where the total energy method fails.
Reactive acoustic attenuator
Authors: Fuller C. R. , Bies D. A.
Published: October 2005

Attenuation of low-frequency sound in air conditioning ducts has always been a difficult problem. The usual method is to employ a system of resonators or lined cavities. These devices have the disadvantage of excessive size or high pressure drop. In this paper a reactive acoustic attenuator that combines a low-pressure-drop coefficient (0.46) with a 10 dB insertion loss over 3/4 of an octave is discussed. At the design frequency an insertion loss of greater than 40 dB can be expected. The attenuator is fitted into any convenient bend in the duct system and relies on inherent path difference between the outside portions of the bend. A profiled center body splits the incident acoustic plane wave into two halves with different path lengths and the resulting impedance mismatch causes reflection of sound. Equations for sound propagating in straight and curved ducts are used to describe the attenuator. Experimental and theoretical predictions of three parameters, sound power transmission coefficient, insertion loss and variation in pressure amplitude in curved sections are discussed.
Whole-field measurements of sound-structure interactions
Authors: Clark J. A.
Published: October 2005

An optical refraction method for analyzing acoustic fields has been combined with a photoelastic method for analyzing dynamic stress distributions in solids. The combined methods permit simultaneous visualization of sound waves interacting with an immersed structure and stress waves excited within that structure. Results of a study of the interaction of a normally incident waterborne acoustic pressure pulse (produced by an electromagnetic transducer) with a solid (urethane rubber) cylinder are presented. The length of the pressure pulse is of the same order as the diameter of the cylinder. Progression of the sound field through different stages of interaction with the cylinder is followed by means of a time sequence of refraction fringe patterns while the initial excitation, and subsequent vibration of the cylinder is revealed by a simultaneous time sequence of isochromatic fringe patterns. The results indicate the feasibility of employing this combined measurement method to analyze scattering mechanisms associated with sound-structure interactions and to predict the acoustic target strength of immersed structures. [Research supported by ONR.]
Ultrasonic three-phonon interaction in isotropic plates
Authors: Brower N. G. , Mayer W. G.
Published: October 2005

An experimental investigation of the ultrasonic three-phonon interaction in an isotropic nonpiezoelectric plate is considered. Two Lamb waves are excited on a metal plate via the liquid-wedge method. An optical probe is used to detect the Lamb modes. The pump modes are allowed to interact and a third mode is detected. The amplitude of the mode is proportional to the product of the amplitudes of the two pump Lamb modes. The conditions for generation of the third Lamb mode are discussed. [Research supported by NSF.]
Diffraction of sound pulses by a circular cylinder
Authors: Chen Pocheng , Pao Yih-Hsing
Published: October 2005

The diffraction of sound pulses by a circular cylinder in a fluid medium is analyzed by applying the Poisson's summation formula and Laplace transform. The inverse Laplace transform is computed analytically by using a modified Cagniard method. This newly developed method avoids the tedious calculation of residues of complex-ordered Bessel functions. Because asymptotic approximations of the modified Bessel functions have been used, the solutions so obtained are good for the early-time transient waves or for pulses with short duration, for which the normal-mode solution is poorly convergent. Analytical solutions for the incident, reflected and diffracted pulses in the illuminated and shadow zones are obtained by a unified approach. Each pulse is represented by a ray integral with a unique arrival time which conforms to Fermat's principle. The numerical results obtained for an incident square pulse emitted by a line source resemble the actual experimental observations reported by others [G. R. Barnard and C. M. McKinney, J. Acoust. Soc. Am. 33, 226 (1961)] for the backscattering of a hard cylinder in water. [Supported by NSF through a grant to the Materials Science Center at Cornell University.]
Scattering of rays into the deep sound channel by the effective sound speed profile
Authors: Floyd Edward R.
Published: October 2005

A frequency-dependent mechanism for theoretically scattering sound into the deep sound channel is presented. For points sources of sound in the oceanic thermocline, the effective index of refraction has periodic ripples that are a function of source depth and acoustic frequency. These ripples induce scattering. For sufficiently large ripples, it is sufficient to consider only direct paths and refracted paths with a single vertex in order to ensonify the entire deep sound channel. All profiles considered were assumed to ice depth dependent only.
Volume-scattering measurement techniques
Authors: Johnson R. K.
Published: October 2005

A computer-controlled system for the acquisition of volume-scattering data is described. It operates at many frequencies using several transducers and a single heterodyne receiver. The system is also used to analyze the data in terms of the depth distribution of scattering and the scattering spectra at any depth. These results are used to estimate types and abundances of the scatterers. [Work supported by ONR.]
Effects of category specification by subject and by experimenter in tests of categorical perception of vowels
Authors: Smith Mary Regina
Published: October 2005

Previous tests for categorical perception of vowel sounds have used forced-choice procedures in which the number and phonemic identity of the categories were designated by the experimenter. In the present experiment subjects served as their own controls in a test of the effects of specification of categories by subjects and by experimenter. Sixteen subjects chose their own categories for identifying seven vowel sounds on an F1-F2-F3 continuum. In the control condition subjects were limited to responding with the vowels /i/, /I/, and /ε/ to the same continuum. The stimuli were presented at both 50- and 300-msec duration, providing two identification tests for each condition. After completing each identification test, the subject took the appropriate AX discrimination test, which used a within-comparison ISI of 250 msec. The obtained discrimination functions were compared to the predicted curves and multivariate analysis was performed on the resulting vectors. Results suggest that specification of categories by the experimenter may distort vowel categorization and consequently, the apparent degree of categorical perception.
Acoustic properties of the interaural pathway in the chicken
Authors: Rosowski J. J.
Published: October 2005

The acoustic transmission properties of the avian interaural pathway were measured in the chicken with a sound probe placed within the middle ear. Ten chickens, 3–9 days old, were anesthetized, both external meati were surgically excised, the animal was placed in a head holder, and sound tubes with associated probe microphones were sealed over the right and left tympanic rings. The left middle ear was opened, and a 1-mm-diam sound probe was placed in the middle ear. The ear was then resealed. Continuous pure tone stimuli of approximately 110 dB SPL and of various frequencies was presented first to one ear and then to the other. With each stimulus presentation SPL was measured at three places: the stimulated external ear, the opposite external ear, and in the middle ear. A reduction in SPL of 25–30 dB was noted in the left middle ear regardless of whether the left or right external ear was stimulated. These observations suggest that the interaural pathway imposes no attenuation on transmitted sound at frequencies within the audible range of the chicken. The importance of the interaural pathway in avian hearing has yet to be determined. [Work supported by NSF.]
Relationship between loudness discomfort level and the acoustic reflex threshold for normal and sensorineural ears
Authors: McLeod H. L. , Greenberg H. J.
Published: October 2005

The relationship between loudness discomfort level (LDL) and the acoustic reflex threshold (ART) was determined by comparing the ART to LDL obtained by the psychophysical method of constant stimuli. Prerecorded, randomly selected stimuli of 1000 Hz, 2000 Hz, and a multitalker speech noise were presented to normal and sensorineural hearing-impaired listeners. Both LDL and ART were found to be significantly higher for the hearing-impaired group. In addition, LDL for the hearing-impaired group consistently fell below the ART. Significant differences were shown to exist between mean LDL and ART thresholds. However, contrary to previous research [A. Olsen and N. Hipskind, J. Aud. Res. 13, 71–76 (1973)] a multiple regression analysis indicated highly significant correlations between LDL and ART. The ability of each dependent variable to predict the presence or absence of a hearing loss is included with a discussion of the dangers involved in using ART data to predict the LDL.
Influence of alcohol on the acoustic reflex and temporary threshold shift
Authors: Robinette M. S. , Brey R. H.
Published: October 2005

Blood alcohol levels between 0.09% and 0.15% were found to reduce the protective action of the acoustic reflex in five normal hearing human subjects. Specifically, acoustic reflex thresholds were raised, reflex magnitude decreased, and TTS increased under alcohol conditions. Stimuli consisted of a narrowband noise (500–1000 Hz) and a 500-Hz pure tone. Measurements were made at blood alcohol concentrations from 0.05% to 0.15%. TTS at 1000 Hz was determined three minutes following a 10-min exposure of narrowband noise at −5, +5, and +20 dB relative to the subject's pre-alcohol acoustic reflex threshold. [Work supported by NIH.]
Growth of right ear advantage following callosal section in an adolescent
Authors: Lenhardt M. L.
Published: October 2005

Material previously reported to the Society (92nd meeting, Abs. No. WW3) described a thirteen year old boy's performance prior to and post surgical section of his corpus callosum on dichotic CVs (provided by Kresge, LSU). Pre-operatively, no ear advantage was observed. After section, a clear right ear superiority emerged. Correct performance almost doubled for the right ear, whereas the left ear performance dropped to chance level. The error pattern did not vary after surgery. Prior to section only a few “double corrects” were reported for dichotic stimulation. This may have been influenced by the anxiety of the upcoming surgery. Initial post surgical testing revealed no “double corrects.” Present data, approximately 10 months later, revealed an increase in “double corrects,” as well as in ear advantage and performance. Data on time-staggered CVs suggested a changing information processing situation. Implications of the data will be discussed.
Results of an extensive acoustical testing program for loaders and dozers
Authors: Peppin Richard J. , Wehr Samuel E.
Published: October 2005

In a study performed for the Environmental Protection Agency, the authors tested several dozen different wheeled and tracked tractors (used a loaders and dozers) in order to determine some parameters that could be used to (1) predict equipment noise levels; (2) predict “A-weighted” sound propagation rates; and (3) help develop a reasonable acoustical test methodology for the machines. Machine sound levels based on SAE J88A acoustical test procedure, machine overhead sound levels and several other parameters of machine noise source measurements were determined. In addition; repeatability of data relative to several variables, methods to determine the average noise levels of various noise control techniques, diagnostics, and work cycle noise levels, were also investigated. This paper presents some of the results of the program. [This work was supported, in part by the U. S. Environmental Protection Agency and U. S. Army MERADCOM.]