bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of vibration duration on ride quality
Authors: Clevenson S. A. , Dempsey T. K. , Leatherwood J. D.
Published: October 2005

An investigation was conducted to systematically examine the effects of vibration duration on passenger discomfort. A realistic laboratory simulator was used to expose subjects to random vertical vibrations. Variables included the time of exposure (15 s–1 h) and the amplitude of vibration (0.025–0.10 grms). The vibration had a white noise spectrum whose bandwidth was 0 to 10 Hz. Data indicate that for acceleration levels greater than threshold of discomfort (0.027 grms), a systematic decrease in discomfort (less annoyance) occurs as a function of increasing duration of vibration. The magnitude of the discomfort decrement is equivalent to 0.01 grms for each 1/2-h of vibration and is independent of acceleration level. The results suggest that the vibration annoyance does not increase with longer exposure as indicated in the International Standard “Guide for the Evaluation of Human Exposure to Whole-Body Vibration.” ISO 2631-1974(E).
The effects of subject age and complexity of stimulus on evoked brainstem responses
Authors: Hall J. W.
Published: October 2005

The Brainstem Evoked Response (BER) and the Frequency Following Response (FFR) for monaural stimulation were examined for subjects of from 21 to 76 years of age. Evoking stimuli, from a range of 600–1000 Hz, were either (a) sinusoids, (b) two-component complex stimuli, or (c) three-component complex stimuli. For the stimuli used, all subjects had approximately equal loudness thresholds. Older subjects exhibited BER's and FFR's of lower amplitude and longer latency, when compared to younger subjects. BER's of shorter latency were found for higher frequency stimulation. The FFR for a particular frequency was diminished in amplitude when that frequency was accompanied by one or two other frequencies (determined by digital filtering of the evoked response). A FFR to a difference tone (f2−f1), and a cubic difference tone (2f1−f2) was recorded for all age groups. [This work was supported in part by NIH Training Grant No. 1 T32 AG00029 from the National Institute of Aging.]
Children's pure-tone detection: A progress report
Authors: Elliott L. L. , Katz D. R.
Published: October 2005

A three-alternative, forced choice detection procedure has been devised for measuring pure tone auditory sensitivity in young children. Observation intervals are marked on the face of an oscilloscope by the numbers “1,” “2,” and “3” which appear sequentially. Correct responses are reinforced by presenting a smiling face under the number of the corresponding observation interval. The simple, up-down adaptive procedure with 2-dB steps is suitable for testing auditory sensitivity in children as young as four years in both quiet and noise. Preliminary data on samples of 6- and 10-year olds Ss suggests that 10-year-old children have lower “thresholds” than six-year olds for some listening conditions, and that children with learning problems perform more poorly than their age-mates for those same conditions. [Supported in part by BEH, OE.]
“Listening”: Auditory perception for college freshmen
Authors: VanDerveer Nancy J.
Published: October 2005

In Freshman Seminars at Cornell, instruction in writing (“composition”) is combined with content of courses ranging from Art History to Psychology. Last semester a new course in this program, called “Listening,” taught freshmen about the psychology of hearing, using weekly topic units based on readings, lecture/demonstration/discussion periods, and weekly writing assignments. The course was an experimental attempt to reach a broader audience than auditory perception typically receives. Topics such as selective listening, echolocation, deafness, speech perception, and DAF were presented via selected readings, class discussion and lectures, and demonstration experiments in which students participated. Students evaluated some readings as still too technical for an introductory course; on the other hand, most of the demonstration experiments were judged informative and helpful. Of special interest: the units on deafness, noise, environmental sounds, and echolocation were well-received, but the two-week psychophysics unit on pitch, loudness, localization, and theories of hearing (traditional subject matter for an auditory perception course) impressed the students as difficult to understand and lacking in interest and relevance. Some implications for teaching auditory perception will be considered.
Procedures for Characterizing Certain Effects of Prolonged Noise Exposure
Authors: Bennett T. , Bienvenue G. , Anthony A. , Michael P.
Published: October 2005

An interdisciplinary research team at the Pennsylvania State University examined the effects of long duration (16 hours), continuous exposure to an 85 dBA broad band noise in human subjects. Both noise exposure and control (without noise) experiments were completed. The test battery included measurements of blood hormone (cortisol) levels, temporary hearing threshold shift (TTS), loudness discrimination index (LDI) and level of initial masking (LIM). Blood samples were collected in heparinized tubes, centrifuged and the plasma samples were analyzed for circulating levels of cortisol using a solid phase radioimmunoassay procedure. In the audiometric tests, the performance changes for the tasks of threshold sensitivity (TTS) identification of small increments in a tonal stimulus (LDI) and recognition of a tonal stimulus in a frequency-varying tonal masker (LIM) were examined by comparing test results before and after the experimental condition (either 85 dBA noise or low level ambient sound, for 16 h). The results of the investigation are discussed with particular attention to the effectiveness of the test battery in characterizing the effects of the noise and to the elucidation physiological correlates that may underlie certain audiometric phenomena that follow noise exposure. [This project was funded, in part, by a Rockefeller Foundation Grant-in-aid.]
Potential compensation cost and percent of the population exceeding different low fence-high fence combinations and frequency ranges for black and white, male and female populations
Authors: Royster L. H. , Thomas W. G. , Royster Julie D.
Published: October 2005

A large industrial population, N > 10 000, has been investigated using different low fences (from 15 dB HTL̄ to 35 dB HTL̄) and high fences (82 dB HTL̄ to 102 dB HTL̄) in combination with various frequency groupings including 0.5, 1, 2 kHz; 0.5, 1, 2, 3 kHz; 1, 2, 3 kHz; 2, 3, 4 kHz; and 3, 4, 6 kHz. The data set was divided into various subgroups including males, females, white males, white females, black males and black females. The analysis yielded significant differences between the subgroups with respect to the percentage of the population exceeding the low fence and total cost. As an example, the criterion of HTL̄0.5, 1, 2, 3 = 30 dB resulted in significantly lower coverage for white females, black males and black females than HTL̄0.5.1.2 = 26 dB. [Work partially supported by the Rockefeller Foundation.]
The effects of a variety of noise exposures on a battery of hearing tests
Authors: Bienvenue G. R. , Carito A. , Michael P. L.
Published: October 2005

The practice of monitoring noise-induced hearing change using only threshold measurements fails to reflect some early signs of the hearing changes following noise exposure. In the present study, researchers examined the temporary effect of a variety of noise exposures on a battery of hearing tests that included temporary threshold shift (TTS), loudness discrimination index (LDI) and level of initial masking (LIM) tests. In addition to systematically varying the parameters of noise exposure, the sequence of test administration was varied. All three tests showed a sensitivity to the temporary hearing changes occurring after noise exposure. Furthermore, the phenomenon of temporary, noise-induced, hearing change is manifested earliest in different aspects of hearing by different individuals. Thus, it was concluded that a battery of hearing tests should be used to characterize the temporary hearing changes that follow exposure to high level sound. The implications of the test results with regard to the growth of noise-induced, hearing changes and to the sequencing of the hearing test battery components were also considered. [Work supported by the Environmental Protection Agency.]
Exposure to loud rock music: Personal factors and reported effects
Authors: Lienau J. A. , Hays D. G.
Published: October 2005

323 students responded to questionnaires on rock music. 54% secondary and 45% college attended 3 or more concerts the previous year. Reports of muffled hearing or tinnitus following a concert was associated with attendance frequency: 65% of high school students attending 1–2 concerts versus 82% attending 3 or more; for college 71% for 1–2 concerts, and 90% for 3+. College students volunteered information on marijuana and alcohol use. Those who used marijuana and alcohol preferred louder levels, liked “hard rock” groups, went to more concerts, and usually attended with a group of friends: all characteristics of the secondary sample. The alcohol only and no-chemical groups preferred softer levels, attended fewer concerts, liked less “hard” music. The alcohol only group had fewer responses to a number of items indicating emotional or intellectual responsiveness to the music. 84% college and 54% secondary students believed concerts potentially dangerous to hearing; however, students who attended frequently and preferred the music loud tended to discount this. Major numbers had attended concerts louder than they preferred: 68% of college and 39% of secondary.
Detection of frequency modulation at large modulation frequencies
Authors: Hartmann W. M.
Published: October 2005

Several studies have been made of the minimum frequency excursions Δf required for detection of frequency modulation, with modulation frequency fm. [E. Zwicker, Acustica, 2, 125–133 (1952) R. H. Kay and D. R. Matthews, J. Physiol. 225, 657–677 (1972)]. The graph of minimum Δf vs fm has a pronounced peak at large values of fm. Further, the minimum Δf increases with decreasing signal intensity. The present paper shows that these results may be understood if fm detection at larger fm is regarded as the detection of the first lower sideband masked by the carrier. From available masking and modulation data it appears that fm sidebands beyond the first do not contribute to detection. To test this idea joint experiments on sine tone masking and fm detection were performed. In each case the masker frequency equaled the carrier frequency, fc of the modulated signal. The signal to be detected had frequency equal to the side band frequency, fc−fm. The results of the experiment support the masked-first-sideband model for fm detection at high modulation frequencies. [Work supported by NSF grant BNS 20225.]
Declination of fundamental frequency (F) in speech production
Authors: Cooper William E. , Sorensen John M.
Published: October 2005

Declarative utterances in English are typically accompanied by a gradual long-term fall in F0. It has been suggested in previous literature that this fall may be represented as a linear function of time, on which various inflections are superimposed. This study was designed to determine the form of F0 declination in phonetically matched sentence materials. Ten practiced speakers read the sentences, which were subsequently analyzed for F0 and amplitude using computerized techniques. The results indicated that, for a variety of declarative sentences, the declination could be approximated by a piecewise linear function in which two-thirds of the F0 fall occurred during the first one-half of the utterance's duration. This piecewise linear function provided a close fit to the data for each of the ten speakers, including both males and females. In additional experiments, F0 declination was examined as a function of systematic variation in syntactic structure, constituent length, and speaking rate. The results of these experiments permit inferences about the organization of the speaker's coding operations, including look-ahead schemes. Implications for speech synthesis-by-rule will also be discussed. [Supported by NIH Grant NS-13028 and an NIH postdoctoral fellowship.]
Errors in short duration ambient noise measurements
Authors: Webster W. J. , Driscoll D. A.
Published: October 2005

Some uncertainty is an inescapable consequence of the sampling techniques used to obtain statistical descriptions of environmental noise. One popular manual sampling technique for the L10 owes its success to the fact that it provides confidence limits as a guide in determining the adequacy of the sample. [Fundamentals and Abatement of Highway Traffic Noise, prepared by Bolt Beranek & Newman Inc., Report No. FHWA-HHI-HEV-73-7976-1. U.S. Department of Transportation (June 1973), Chap. 31 Unfortunately, these confidence limits apply only to the conditions at the time of the measurement and may lead to a false impression when used to describe ambient conditions which are generally time-varying. The advent of digital noise monitors has made possible the collection of ambient noise data over extended periods of time, days or even weeks. Such surveys can provide excellent results but economic factors and the need for timely decisions often mandate shorter noise measurements, typically 15 min to 1 h. Estimates of the errors resulting from 15-min or 1-h sound level measurements are based on long-term monitor data collected at three residential sites representative of quiet urban, suburban and rural conditions. Four statistics Leq, L10, L50, and L90 are considered and sampling strategies are discussed in the results.
Why drivers of automobiles do not always hear the sirens of emergency vehicles
Authors: Potter Richard C.
Published: October 2005

Experimental measurements of the interior sound levels of road vehicles, the acoustic transmission loss of road vehicle structures, the sound levels of emergency vehicle sirens, and the aural detection requirements for drivers of road vehicles are used to study the detection distances for three common road/vehicle situations. It is demonstrated that the aural detection distances in some circumstances are such that the driver may not have time to respond before the arrival of the emergency vehicle. It is concluded that drivers of emergency vehicles should not rely on the use of their sirens alone to ensure that their presence has been recognized by other drivers. [Work supported by the Society of Automotive Engineers, Inc. and the U.S. Department of Transportation.]
Noise opinion survey of the State of Florida
Authors: Yost William A.
Published: October 2005

Sixteen hundred noise opinion questionnaires were mailed to a randomly sampled group of Floridians. The results are based on 885 returned questionnaires (57% of the delivered forms, including one follow-up mailing). All the questions involved opinions toward noise or demographic information. Over 50% of the respondents rated their neighborhoods as noisy. Over 40% of the population stated that motorcycles were the most objectionable noise source. Aircraft was regarded as the second most objectionable source (9% of the returned questionnaires). Over 70% of the population appeared willing to have one dollar or more of its tax dollars spent for reducing noise. There were no strong dependencies of these or other opinions on sex or age. These and other statistics will be described. [Work supported by the Florida Department of Environmental Regulation.]
Visual field displacements in human beings evoked by acoustical transients
Authors: Parker D. E. , Littlefield V. M. , Tubbs R. L.
Published: October 2005

Sixty-two of one hundred thirty-three subjects reported visual field displacements when they were exposed to intense (125-dB SPL) repetitive audiofrequency transients. This phenomenon was investigated in three experiments. Frequency (100–5000 Hz) was varied in experiment I; repetition rate (0.2/s to 5.8/s) was varied in experiment II; acoustical transient onset/offset time (0.2–25 ms) was examined in experiment III. The results of these three experiments indicated that the largest proportion of displacement reports followed stimulation in the 500- to 1000-Hz frequency range at repetition rates of about 1/sec. Response differences as a function of onset/offset time were erratic. The pattern of results obtained in this study, in conjunction with the results of previous investigations of acoustical vestibular stimulation, suggests that the visual field displacements resulted from stimulation of the receptors of the vestibular system. These experiments may account for discrepancies in reports of infrasound-evoked eye movements. Finally, it is suggested that intense sound exposure may damage the vestibular receptors with or without concomitant damage to the auditory portion of the membranous labyrinth. [Work supported by USAF.]
The effects of a hypothetical frontal/eddy system on the coherent propagation loss
Authors: Reichl J. L.
Published: October 2005

The effects of multiple profile environments such as fronts and eddies on the predicted acoustic transmission loss are under review for possible application in future antisubmarine warfare training devices. The effects of the horizontal and vertical thermal-salinity gradients, the depth and width of a hypothetical frontal-eddy system on the coherent propagation loss as predicted by typical Navy multiple profile models are discussed. The effects on the transmission loss of varying the frequency, the source-receiver depths, and the relative source-receiver location are given. The accuracy in the predicted propagation loss as a function of the number of temperature-salinity profiles used to describe the frontal-eddy system is also considered.
Modelling of an oceanographic swirl: comparison with experimental data
Authors: Taranto L. C. D. R. R. , Gallagher J. J. , Browning D. G.
Published: October 2005

In a previous paper (D. G. Browning et al J. Acoust. Soc. Am. 61, S10(A) (1977)) a large oceanographic feature, designated as a swirl, was identified in the Western Mediterranean Sea. Acoustic propagation loss was predicted based on archival environmental data using both single and multi-profile models. These results are now compared with improved predictions using detailed environmental data and with corresponding experimentally measured propagation loss. It is found that the change in sound speed structure across the swirl significantly effects the propagation of sound. (Work supported by NUSC)
The application of fatigue testing at ultrasonic frequencies to materials science and technology
Authors: Weiss Brigitte , Stickler Roland
Published: October 2005

Efforts to develop the ultrasonic fatigue test method for routine application to fundamental fatigue studies as well as to the evaluation of fatigue properties of engineering materials have led to progress in the following areas:

(1) Development of suitable test equipment including advanced control and read-out electronic; efficient system to stabilize specimen temperature; systems to measure vibratory energy and strains; environmental test chambers; set-up for elevated temperature testing;

(2) Improvements in the basic understanding of the resonance system, including the vibratory behaviour of specimens with non-uniform cross-section, non-uniform distribution of mechanical properties, and of specimens containing defects; considerations of the effects of exposure of the specimen to cyclic deformation in the elastic and plastic range.

(3) Accumulation of ultrasonic fatigue test data for a number of bcc and fcc metals and engineering alloys (e.g., C-steels, stainless steels, Al-alloys, Cu-alloys, Mo-base alloys) up to loading cycles exceeding 109, careful statistical analysis of the test results leading to well characterized S-N curves.

(4) Investigation of the frequency effect by comparison with data of conventional fatigue tests and by studies of the mechanism operative during cyclic exposure at various frequencies.

(5) Development of test system to measure crack propagation rates at low stress amplitudes and to determine threshold-stress values for crack growth under cyclic loading; this system appears as a time saving method for the determination of essential fracture mechanics properties.

Experimental results will be presented. Advantages and limitations of the ultrasonic fatigue test method will be discussed in detail.
Direct measurements of acoustic boundary waves
Authors: Claus R. O. , Palmer C. H.
Published: October 2005

Direct optical measurements of Stoneley waves, acoustic boundary waves that propagate along the plane interface separating two solids having suitably related elastic constants, are reported [R. Stoneley, Proc. R. Soc. London A106, 416–428 (1924)]. To obtain these measurements, new solutions to Stoneley's equation suggesting wave propagation between several optically transparent media pairs were determined. Stoneley waves were generated using two acoustic wave conversion techniques on four of these pairs and detected using a modification of a differential interferometric optical technique initially developed for measurements of surface, shear, and dilitational waves [C. H. Palmer, J. Acoust. Soc. Am. 53, 948–949 (1973)]. Theoretical and experimental wavelengths agree to within two percent. Possible applications in seismological modeling and in the nondestructive evaluation of laminated structures and adhesive bonds are suggested.
Measurements of the acoustic emission in a steam sodium interaction
Authors: Carey W. M. , Claytor T. N.
Published: October 2005

The acoustic emissions from the interaction of steam and sodium have been measured in the Argonne Core Components test loop for liquid sodium temperatures of 204 °C and 482 °C, liquid sodium flow rates of 0.23 m/s and 0.69 m/s and steam injection rates between 1.67 and 16.7 mg/s. These measurements were performed with a calibrated high temperature lithium niobate microphone which has a flatresponse to 25 kHz with a sensitivity 0.011 PC/Pa and rises at 12 dB per octave between 30 and 90 kHz to a peak of 0.062 PC/Pa. These data were observed to have low frequency (less than 10 kHz) and higher frequency (greater than 20 kHz) components. The lower frequency data was found to be consistent with hydrogen bubble formation and oscillation. The higher-frequency component was observed to consist of transient events with center frequencies between 20 and 40 kHz. The amplitude of the individual events appeared independent of injection rate; however, the repetition of the transient events was found to be proportional to the steam injection rate to the 0.5 power. These high frequency transients were observed to be between 150 and 500 uμs in duration with peak pressure levels of 140 dB re 1 uμPa. Data at the lower frequencies was found to have some differences in the nature of the transients indicating a temperature dependence on the type of chemical reaction occurring.
Vibrotactile masking: Evidence for a peripheral threshold
Authors: Hamer Russell D. , Zwislocki J. J. , Captaro Anthony J.
Published: October 2005

Vibrotactile thresholds were measured using a criterion-free psychophysical method. 200-Hz signals were presented unmasked and in the presence of three masker types: a 200-Hz vibration in phase with the signal (experiment 1); a 200-Hz vibration shifted in phase by 90° (experiment 2); a narrow-band random noise centered at 200 Hz (experiment 3). The threshold shift was measured as a function of masker SL. The form and position of the masking curves resulting from experiment 1 could be accounted for by an energy-detection model when a peripheral threshold was assumed. The threshold model described the masking curve over its entire length. Without changing subject-dependent parameters, the same equation, adjusted only to account for quadrature summation of signal and masker in the stimulus domain, accurately predicted the effects of the sinusoidal masker in quadrature with the test stimulus (experiment 2) as well as the effects of random noise (experiment 3). Although an energy-detection model without a threshold was consistent with the results of experiments 2 and 3, it did not agree with the results of experiment 1. [Work supported by NIH grant NS-09940.]
Cues for speaker-sex identification
Authors: Robertson Karen L.
Published: October 2005

Studies emphasizing laryngeal fundamental as the cue for speaker sex do not account for the fact that in modal register there is a large range of f0 that is produceable by both sexes. Evidence that vocal tract resonance characteristics are a cue to speaker sex is presented. Listeners rated whispering voices on a confidence scale as to speaker-sex identification. A significant nonparametric correlation was found between a measure of vocal tract resonance characteristics and listener ratings. The fact that the male voice with the vocal tract resonance characteristics most like those of the females was the only voice not confidently and accurately identified and the fact that when the distinctly female and distinctly male voices were taken separately there was no significant correlation suggest that there is a cutoff point between what is considered female voice quality and male.
Lateralization of high-frequency signals by interaural time: Evidence from auditory neurophysiology
Authors: Crow Glenn , Langford Ted , Moushegian George
Published: October 2005

In this study the response characteristics of inferior colliculus neurons were investigated. Three types of binaural, high-frequency stimuli were used: (1) two-tone complexes, (2) noise bands, and (3) transients. For two-tone complexes, frequency and depth of modulation were varied. Continuous, binaural, low-pass, uncorrelated noise was used to mask the difference tone. For high-frequency transients the low-pass masker had either a 3 or 5-kHz upper cutoff frequency. Neurons were found which responded differentially to interaural-time differences for one or all three of the stimuli employed. This study therefore provides a possible neural correlate of the psychophysical findings that humans can lateralize continuous, complex, high-frequency stimuli on the basis of interaural time. The data also imply that lateralization of transients may be performed by high-frequency neurons. [Supported by NIH.]
Synthesized compound action potentials (CAP's) of the auditory nerve
Authors: Wang B. , Kiang N. Y. S.
Published: October 2005

Using a computer program based on the model proposed by Goldstein and Kiang [J. Acoust. Soc. Am. 30, 107–114 (1958)], we synthesized CAP's from single-unit data recorded from the cat's auditory nerve. The quantities used in the synthesis were (1) poststimulus-time histograms of units in one animal sampled according to characteristic frequency (CF) and spontaneous rate (SR);(2) the contribution of a single spike to the CAP recorded at the round window, estimated by crosscorrelating round window potentials with spike trains; and (3) an estimate of the cochlear innervation density as a function of unit CF and SR. The synthesized CAP's were compared to round-window gross responses that were recorded simultaneously with the single-unit recordings. The peak latencies of synthesized and recorded CAP's differ by no more than 20 uμs; the amplitudes differ by no more than 35%. The significance of these results for electrocochleography will be discussed. [Work supported in part by NIH, FAPESP, CNPq, and UNICAMP.]
Noise onset effects in masking of tonal responses of single auditory-nerve fibers
Authors: Abbas Paul J.
Published: October 2005

The activity of auditory-nerve fibers in cats was measured in response to a short (10-ms) tone burst in the presence of a burst of wide-band noise. The effective masking for tones presented near noise onset was compared to that for tones presented during the steady state noise response. PST histograms were plotted showing the response pattern to the noise along with the activity phase-locked to each tone burst. In addition, average discharge rate over a 5-ms time window was calculated before and during each tone burst. As expected, in some fibers the tone evoked a net increase in rate while in others the tone suppressed the response to the noise. In either case, activity phase-locked to the tone could be seen as a series of peaks and troughs in the histogram. These peaks were consistently larger in amplitude for the tone near noise onset than for steady state. However, if the peak amplitude was normalized to the average discharge rate during the tone burst, these differences were diminished.
Average-rate, fundamental and harmonic-distortion components of responses of cat cochlear nerve fibers to single-frequency continuous tones: Comparisons with an exponential model
Authors: Kim D. O. , Rigden M. C. , Molnar C. E.
Published: October 2005

We have examined interrelationships among the average rate of spike discharge R0 and the amplitude and phase, R1 and Θ1, where R0 = (1/K) ⋅  ∑ k=0K-1 rk; Ri = (Ric2 + Ris2)1/2; Θi = tan−1 (Ris/Ric); Ric (2/K)⋅  ∑ k=0K−1 rk cos (2πik/K), and Ris = (2/K)  ∑ k=0K-1 rk sin (2πik/K), for i = 1, 2, 3,…; rk. is K times the number of spikes registered in the kth bin of the period histogram, divided by the total sampling time; and K is the number of bins. The neural responses have been compared with an exponential model in which the instantaneous average rate is λ(t) = ρ⋅exp[A⋅cos(2πft + φ)], where ρ is equal to the spontaneous rate (SR). As shown by Molnar [J. Acoust. Soc. Am. 56, S21(A) (1974)], this model predicts R0 = (SR)⋅l0(A), R1 = (SR)⋅2li(A), Θ = i⋅Θ1, for i = 1, 2, 3, ⃜ where l1(A) is the modified Bessel function of order i. Thus, according to this exponential model, (R0/(SR) vs (R1/SR) plots should lie along a curve specified by l0(A) vs 2li(A), and (Ri/SR) vs (R1/SR) plots along the curve of 2li(A) vs 2l1(A). Responses from hundreds of single cochlear nerve fibers to 1000-Hz stimulation at 20, 45, and 70 dB re 20 μN/m2 show remarkable overall agreement with the exponential prediction, both in amplitude and phase. Systematic deviations from the exponential prediction of amplitude and phase for various stimulus frequencies suggest that the parameter ρ may change with stimulation, and that a low-pass filter is needed following the exponential nonlinearity.
Average-rate, fundamental and harmonic-distortion components of responses of cochlear nerve fibers to single-frequency tone bursts: Comparison with an exponential model
Authors: Rigden M. C. , Kim D. O. , Molnar C. E.
Published: October 2005

The effects of stimulus envelope on the response characteristics of cochlear nerve fibers can be studied with a class of stimuli of the form p(t) = ex(t) sin (ωt). In this study, the modulating function eg(t) was chosen to produce a train of tone bursts of specified duty cycle and rise/fall times. The technique of Fourier analysis of period histograms described by Kim et al. (preceding abstract) has been extended to handle variations in response components R0,R1, and θ1 as a function of time both within and between each tone burst in a train of bursts. Using tone bursts of 320 ms duration and 20 ms rise/fall times with a duty cycle of 21% we have observed that, during the course of a tone burst: (1) both R0 and R1 rapidly reach a peak value and then decline over the following 50–100 ms to quasi-steady—state values; (2) the time courses of R0 and R1 during a tone burst are almost identical in shape, i.e., the ratio, R1/R0, reaches its maximum value rapidly and remains constant throughout the duration of a tone burst despite noticeable fluctuations in R1 and R0; (3) the fundamental phase θ1, is constant throughout the total duration of a tone burst; (4) R1R0 saturates at lower sound pressure levels (SPL) than either R0 or R1; (5) the shapes of R0 and R1 vs SPL curves change substantially and progressively for successive periods during the onset portion of the response; and (6) in some cases, the R0 and R1 versus SPL curves for individual periods during the first 12–20 ms following tone burst onset show pronounced nonmonotonic behavior with maxima occurring at as low as 50 dB re 20 μN/m2.
Considerations in dynamic time warping algorithms for discrete word recognition
Authors: Rabiner Lawrence R. , Rosenberg Aaron E. , Levinson Stephen E.
Published: October 2005

The technique of dynamic time warping for time registration of a reference and test utterance has found widespread use in the area of discrete word recognition. As originally proposed, the algorithm placed strong constraints on the possible set of dynamic paths—namely, it was assumed that the initial and final frames of both the test and reference utterances were in exact time synchrony. Because of inherent practical difficulties with satisfying the assumptions under which the above constraints are valid, we have considered some modifications to the dynamic time-warping algorithm. In particular an algorithm in which an uncertainty exists in the registration both for initial and final frames was studied. Another modification constrains the dynamic path to follow (within a given range) the path which is locally minimum at each frame. This modification tends to work well when the location of the final frame of the test utterance is significantly in error due to breath noise, etc. To test the different time warping algorithms a set of 10 isolated words spoken by 100 speakers was used. Several different comparisons between the algorithms were made and will be described in the talk.
Exact effect of surface roughness on the reverberation time of a uniformly absorbing spherical enclosure
Authors: Joyce W. B.
Published: October 2005

We assess the validity of the Sabine, Eyring, and Kuttruff reverberation time expressions, and of the mean-path-length formula 〈l〉 = 4V/S, by determining the exact geometrical acoustics reverberation time and asymptotic sound distribution for a uniformly absorbing spherical enclosure with any amount of air absorption and with a surface that can be continuously varied from nonabsorbing to completely absorbing and from specular to randomly reflecting. In disagreement with an extensive literature that presents the Eyring formula as a correction to that of Sabine, we find, on the one hand, that Sabine's formula and the applicability of 4V/S are vindicated in this application under Sabine's stated conditions of weak absorptivity and (any nonzero amount of) irregular reflection, while. on the other hand, we find that Eyring's and Kuttruff's expressions are less accurate than Sabine's unless the surface is quite rough or absorptive. Related concepts are also discussed.
Optical studies of sidewall designs for a concert hall
Authors: Aziz Javaid
Published: October 2005

Reflections analysis of various design alternatives with pencil and paper is very tedious even for one source position; moreover, it is feasible to study in this manner only the first-order (or, at the most second-order) reflections. Reflections involving several bounces are too complicated for this procedure. However, with optical modeling, reflections analysis can be studied very efficiently to modify sidewall designs. The surfaces of interest in the hall under study are modeled with mirrors, and a light source is used to simulate a sound source on the stage. The reflections analysis is photographed to compare various design alternatives during the preliminary design stage and to thoroughly study the final architectural design.
Evaluation of auditorium acoustics: A practical approach
Authors: Pirn Rein
Published: October 2005

The acoustical qualities of an auditorium are highly dependent on the listener's own subjective judgments. Correlation between such judgments and measurable acoustical properties has been sought by numerous workers. New and complex measurements have been experimented with, but interpretation remains difficult. Without really breaking new ground, the acoustics of some recently completed auditoria were evaluated by simply measuring (1) the reverberation times, (2) the loudness, and (3) the background noise levels, and by relating the results to “preferred” standards. Ultimate judgment was left to the listener. This paper discusses these measurements and their interpretation, as presented to the layman.
Sound propagation in industrial spaces
Authors: Kurze U. J.
Published: October 2005

Sound fields in industrial halls and open plants have been investigated. Point sources are considered to contribute via direct sound. specularly reflected sound. and diffusely reflected or scattered sound. The diffuse sound field is calculated from solutions of the differential equation describing diffusion processes in homogeneous media filled with absorptive scatterers. Simplified approximations are found from a combination of the farfield solution of diffusion processes and the direct field. From consideration of boundary conditions at reflecting and absorbing planes, complete descriptions are derived for the sound propagation in shallow halls with different acoustical treatment of the ceiling. The theoretical results are consistent with data obtained from model studies and field investigations of industrial halls. Relative to free-field conditions an increase in sound level is observed due to scattering and specular reflection at distances up to a few free path lengths from the source. At larger distances. absorptive properties of scatterers and the ceiling cause an exponential decay. Data from measurements of sound propagation in an open chemical plant were found consistent with theoretical data for a completely absorptive ceiling of a shallow room.
Report on qualification of the Du Pont Company's Reverberant Acoustical Test Facility
Authors: Ingard K. U. , Dear T. A. , Lechner A. , Samborski J. A.
Published: October 2005

This report documents the data records and findings of qualification of the Du Pont Company's Reverberant Acoustical Test Facility for broadband and pure-tone measurements of sound power in accordance with current specifications and test procedures of the American Society for Testing and Materials (ASTM) and the American National Standards Institute (ANSI). The report also describes the use of the test facility for measurement of acoustic absorption coefficient and transmission loss in accordance with the current specifications. A brief history of the development of acoustical testing in the Du Pont Company and the evolving need for the subject facility is presented. Details of construction, special design considerations, and operating parameters are also discussed. Theoretical considerations and formulae used in the development of unique test methods and procedures as applied are presented as a tutorial basis for understanding the testing philosophy used in these qualification procedures. The test procedures and results are discussed in detail with description of instrumentation and applications thereof as appropriate. The report recommends some modifications of present standards as regards pure-tone qualification to avoid ambiguities and increase accuracy. Written comments regarding the contents of this report are invited from those with expertise and/or interest in such qualification procedures.
Impulse technique for structural frequency response testing
Authors: Brown D. L. , Allemang Randall J. , Halvorsen W. G.
Published: October 2005

Structural frequency response testing also known as “modal analysis” is becoming an integral part of the development and testing of a wide range of industrial and consumer products. It is an essential tool for the definition and solution of many types of structural dynamics problems, such as fatigue, vibration, and noise. This paper discusses one of the most useful techniques for experimental structural frequency response testing—one based upon excitation of the structure with an impulsive force. In many situations, this is the simplest and fastest of the various techniques commonly used today. However, the nature of the excitation and response signals in the impulse technique requires special signal processing techniques if accurate frequency response measurements are to be obtained. This paper discusses the application of the impulse technique and reviews the special problems encountered in practice and the techniques that have been developed for dealing with these problems.
An overview and literature survey of mechanical signature analysis
Authors: Volin R. H.
Published: October 2005

Operational characteristics of dynamic systems and how they have been applied to determine condition and predict failure or malfunction will be described. A literature review of applications and some of the techniques that have been used will be presented. Emphasis will be placed on unusual applications of machinery condition monitoring and failure prediction that have been well documented in the literature. Standards and criteria are mentioned and sources of noise and vibration in machinery such as bearings, and gears will be described. A discussion of known payoffs in mechanical signature analysis will be included as well.
Use of scaled plastic models in turbomachinery foundation studies
Authors: Bannister R. L.
Published: October 2005

The static and dynamic behavior of turbomachinery foundations can be investigated by use of scaled plastic models. Experimental data from various model investigations show that resonant frequencies, mode shapes, and average response levels can be obtained in the laboratory. Accuracy is dependent on the degree to which similitude requirements are met. This paper reviews the techniques that are used to design, construct, and test scaled plastic models. Model deflection and vibration spectra are compared with measurements made on full-size structures and calculated from analytical models. The results show that laboratory models can be used to optimize a given structural design or verify the adequacy of a complex analytical model.
What can mini-computers do for machinery reliability?
Authors: Harker Roger G.
Published: October 2005

The application of the mini-computer for machinery monitoring, diagnostic analysis, and performance evaluation is described. The function of various computer subsystems is described in relation to the entire system. Typical basic examples of operator/computer interaction, monitoring, dynamic data logging, data retrieval, and machinery diagnostics features are discussed. Minicomputer systems including back-up and diagnostic subsystems are an exceptionally flexible and versatile tool that permits machinery personnel to reduce maintenance, improve operating efficiency, and increase the safety of rotating equipment.
Structural modal analysis from the acoustic response
Authors: Shapton William R. , Van Karsen Chuck , Allemang Randall J.
Published: October 2005

This presentation describes the use of the acoustic response of a structure to define the structure's mode shapes. An impact is applied to the structure at each location at which the modes are to be defined and the transient acoustic response analyzed. The technique is particularly useful for investigating very small or lightweight parts where loading might otherwise be a problem.
Scaling of mufflers
Authors: Laville F. , Soedel W.
Published: October 2005

This paper presents some scaling rules for muffler design for single cylinder engines. Some of the rules are developed using Buckingham's Pi principle, but it is shown that approximate scaling rules obtained first by inspection of a computer simulation program and then verified by an approximate analysis extend the usefulness of scaling into regions not possible before. Scaling of engine parameters is included.
Thoughts on the effect of acoustic back pressures on engine performance
Authors: Laville F. , Soedel W.
Published: October 2005

Engine performance can be aided or degraded by the proper or improper design of manifolds and mufflers. In some literature, the tuning of intake and exhaust pipes is discussed and the idea of wave interference aiding performance is advanced. In this paper, this concept is critically examined, extended from smooth pipes to any muffler system. It will be pointed out that instead of a magic increase in performance by tuning, the best achievable case is as if the manifolding is absent. All arguments are based on a simulation program that investigates pressure waves in single cylinder engine manifolds.
Elastic waves generated by valve impact
Authors: Pandeya Prakash N. , Soedel Werner
Published: October 2005

Noise generated by the impacting valve reeds is the major source of noise in compressors. As a first step towards calculating this noise generation, the elastic waves created by the impact between the valve reed and the valve seat have to be understood. This investigation studies the impact waves of a valve reed impacting the seat colinearly. The following cases are treated:

(1) Valve reed impacting a seat made of the same material. (2) Valve reed impacting a seat made of different material. (3) Valve reed impacting a seat which is coated with a protective layer. In this case it will be discussed as to what will happen if the protective layer is softer or harder than the valve reed material.
Effects of excess attenuation on echosonde measurements
Authors: Clifford S. F. , Brown E. H.
Published: October 2005

Quantitative active acoustic remote sensing measurements of atmospheric properties are seriously affected by the excess attenuation due to turbulence. An earlier paper [E. H. Brown and S. F. Clifford, J. Acoust. Soc. Am. 60, 788–794 (1976)] studied excess attenuation on a one-way, line-of-sight path. This paper considers a more complex problem: the effects of attenuation by turbulence in the paths to and from a volume of scatterers on the accuracy of echosonde measurements of the turbulence parameters within that volume. The study shows that, for typical atmospheric turbulence profiles, the excess attenuation contributed by beam broadening on an upward path beginning at the transmitting acoustic antenna is much greater than the excess attenuation suffered by the sound scattered back to the receiving antenna.
Experimental observations of the coupling of airborne sound into the ground
Authors: Bass H. E. , Bolen L. N.
Published: October 2005

The coupling of airborne sound into the ground has been measured as a function of frequency (100–500 Hz), sound source height (1–10 m), and propagation distance with a regularly spaced linear array of microphones and geophones. The results suggest that the largest seismic signal is due to energy coupled into the energy near the geophone locations, however, the ranges available would not allow us to rule out a seismic signal arriving much later than the primary which one might expect if a Rayleigh wave was generated near the source. Other experimental results will also be presented in an attempt to spark discussions which might help us to resolve the behavior of the observed coupling coefficient with frequency and angle of incidence. [Work supported by the Army Research Office and Waterways Experiment Station.]
Radiation of sawtooth waves from the open end of a pipe
Authors: Kuhn Jeffrey R. , Blackstock David T. , Wright Wayne M.
Published: October 2005

The radiation of sawtooth waves from the open end of a circular pipe is considered. Time domain piston radiation theory is used to compute the waveform for all regions of the field. For example, the waveform on the axis in the farfield is predicted to be a series of impulses, one for each of the shocks in the sawtooth at the mouth of the pipe. Experiments done with a 3.04-m long, 0.0467-m i.d. pipe generally confirm the predictions. The sawtooth wave was achieved by generating intense sinusoidal waves (8-kHz tone bursts, SPL 138 dB re 20 μPa) at the other end of the pipe. Nonlinear propagation distortion transformed the sinusoidal wave into a sawtooth as it traveled through the pipe. (Use of linear theory to compute the radiation into the open medium is justified because the wave rapidly diminished in amplitude when it was no longer confined to the pipe.) The work has application to horn radiation, both in air and underwater, and to radiation of core noise from jet engines. [Work supported by NOAA and ONR.]