bluuebunny/crossref_metadata_2025 huggingface dataset:
Model of damage due to continuous-wave high-power ultra-sound
Authors: Hsu W. L. , Lele P. P.
Published: October 2005

Thermal mechanisms have been shown to play a dominant role in the destruction of tissue by continuous-wave ultrasound. This damage to tissue can be predicted with a knowledge of the temperature field during irradiation and the lesion boundary temperature (LBT) of the tissue. The LBT is the damage threshold temperature which has been found to be invariant with variations in ultrasonic frequency between 0.9 and 5.4 MHz, with change in base temperature of the animal, with single and multiple burst irradiation dosages, and in different tissues. The LBT was, however, found to vary with the duration of irradiation. These experimental results have been explained by a model incorporating the theory of reaction kinetics. The model has been tested on the results obtained from experiments to produce lesions in cat using a nonultrasonic source of heat. Results are compared with temperature threshold data obtained by other investigators on mammalian tissues and on cell suspensions. [This work was supported in part by USPHS Grant Nos. NIH-5-P01-HL14322 and NIH-5-T01-GM02136.]
Threshold for ultrasonic lesion production in rabbit tissues
Authors: Frizzell L. A. , Linke C. , Carstensen E. L.
Published: October 2005

Thresholds for lesion production were determined for rabbit liver and kidney at 2 and 6 MHz and rabbit testicle at 2 MHz for single pulse exposures from 5 to 60 sec. The presence of lesions as determined from gross observation was virtually in complete agreement with histological evidence. Intensity thresholds for a given pulse length were found to be nearly independent of frequency, but clearly dependent upon the type of tissue. Of the three tissues investigated, liver has the lowest threshold, followed by kidney and testicle in turn. The lesions are believed to result primarily from thermal effects.
Ultrasonic enhancement of cytotoxic effects of nitrogen mustard in mouse leukemia
Authors: Kremkau F. W. , Walker M. M. , Kaufmann J. S. , Spurr C. L.
Published: October 2005

Mouse leukemia L1210 is extensively used as a model for cancer chemotherapy drug screening. Animal median survival time (MST) is proportional to the log of the number of viable (capable of dividing) leukemic cells (LC) inoculated. Chemotherapeutic agents increase MST apparently by rendering a fraction of the LC incapable of dividing. LC obtained from DBA/2 mouse ascites fluid were placed in saline suspension in a Teflon/Saran chamber for 10 min at 22°–30°C. Healthy 18- to 22-g BDF1 mice were then inoculated intraperitoneally with 105 LC from the chamber resulting in MST of 10.0 days (range 8.0–15.5/n = 36 animals). Exposing LC to continuous 1.9 MHz 10 W/cm2 (17 W/cm2 spacial peak) ultrasound (US) for 10 min did not alter MST. Addition of 0.5 μg/ml nitrogen mustard to the suspension without US increased MST to 10.5 (9.0–12.5/n = 21) and with US increased MST to 13 (10.5–14/n = 20). A 2.5 day MST increase is equivalent to 98% cell kill. Doubling nitrogen mustard concentration (1 μg/ml) without US increased MST to 13 (11–15/n = 20) and with US resulted in 13 cures (MST > 30 days) (n = 21). Statistical analysis (median test) demonstrated that ultrasound produced significant (p < 0.001) increases in the nitrogen mustard prolonged median survival times. [Supported in part by a grant from R.J. Reynolds Industries, Inc.]
Pitch shift in masking by narrow-band noise
Authors: Taylor M. M. , Smith S. M. , Goodfellow G. L.
Published: October 2005

When a low-level narrow-band noise is placed near the frequency of a sinusoid, the pitch of the tone is displaced away from that of the noise. The shift may be 30 Hz at 800 Hz for a 10-Hz separation between tone and noise. One theory suggests that the shift occurs because the signal/noise ratio is highest in a filter whose center frequency is displayed away from that of the noise. The optimum displacement depends on the filter shape. Is the displacement dependent on frequency or pitch? If on frequency, the filter may depend on physical mechanisms; if on pitch, the mechanism is more probably neural. Diplacusis permits the separation of pitch and frequency. Over some ranges, the pitch changes more for a given change in frequency in one ear than in the other. Filter displacements over such frequency ranges would be the same for either ear if frequency were primary, but would differ according to the change in diplacusis if pitch were primary. Preliminary results are inconclusive, but suggest that pitch may be more important than frequency.
Residue pitch for a monaural and dichotic two-tone complex
Authors: Cudahy E.
Published: October 2005

The residue pitch for a two-tone stimulus was investigated. The stimuli were either monaural, with both tones presented to a single ear, or dichotic, with one tone presented to each ear. A two-interval matching procedure was employed. On each trial, a two-tone stimulus, called the standard, was presented in either the first or second temporal interval. In the other interval, an harmonic two-tone complex, which served as a matching stimulus, was presented. The subject was asked to select the interval containing the lower of the two pitches. In each block of trials, the fundamental frequency of the matching stimulus was adjusted until there was no pitch change between intervals. For the monaural stimulus, the pitch shift of the residue obtained from a single subject was very similar to that reported by Smoorenburg [J. Acoust. Soc. Am. 48, 924–942 (1970)]. The pitch shift for the dichotic stimulus closely resembled that of the monaural stimulus when the frequency of the lower component was less than 1500 Hz. With frequencies above 1500 Hz, the dichotic residue pitch was inaudible. The observation that both the dichotic residue and lateralization based on phase differences disappear for stimulus frequencies above 1500 Hz suggests that similar temporal mechanisms underlie both binaural interactions.
Effects of dichotically presented simultaneous synchronous and delayed auditory feedback on key tapping performance
Authors: Cooper W. A. , O'Malley H.
Published: October 2005

A previous investigation [T. Tsunoda, Ind. J. Otol. 18, 78–88 (1966)] reported the use of a delayed auditory feedback key tapping task to isolate ear advantage for speech and nonspeech stimuli. Tsunoda proposed that subjects would demonstrate more performance disruption when delayed stimuli were directed to the ear contralateral to the prepotent hemisphere for those stimuli. This study represents a modified replication of Tsunoda's work. Each of 24 subjects with confirmed right-ear advantages for speech tapped a pattern (• • • • • •) on a key which triggered binaural synchronous stimulus bursts of 50-msec duration to the earphones (SAF). As the subject continued to tap, stimuli of a different intensity and delayed from each tap by 220 msec replaced the SAF to one ear. The other ear continued to receive SAF at the original low intensity level. The presentation of a 1000-Hz pure tone and the vowel /a/ were counterbalanced across stimuli and across ears. In statistical comparison across ears, neither the vowel nor the pure tone differed in their effects. Statistical comparison across stimuli indicated that right-ear performance differed from that of the left ear. It may be possible to interpret this as a reflection of differential cerebral auditory processing.
Phonetic and auditory features in dichotic listening
Authors: Benson Peter
Published: October 2005

Studdert-Kennedy and Shankweiler [J. Acoust. Soc. Am. 48, 579–594 (1970)] report that initial consonants of dichotic pairs of CVC syllables which share a feature are more likely to be perceived both correct than pairs of consonants which do not. Studdert-Kennedy, Shankweiler, and Pisoni [Cog. Psychol. 3, 455–466 (1972)] report the advantage is due to shared phonetic features rather than auditory features, because there was no difference in the advantage for pairs sharing phonetic features only from those sharing both auditory and phonetic features. They did not present pairs showing only auditory features. The present experiment employed a later phoneme boundary for voice onset time for velars than for labials to create stimuli which shared only auditory features, as well as other stimuli sharing phonetic and auditory features, only phonetic, or no features at all. Results for eight subjects show that pairs sharing both auditory and phonetic features are better perceived than pairs sharing only phonetic features which are, in turn, better perceived than pairs sharing no phonetic features. These results suggest that auditory features do influence perceptual ability in dichotic listening tasks.
Interference with processing dichotic pairs of CV syllables after temporal-lobe lesion
Authors: Speaks Charles , Gray Thomas , Miller Joanne , Rubens Alan , Waller Marcie
Published: October 2005

When temporal-lobe patients are presented with dichotic pairs of CV syllables, few correct responses occur for the syllable in the contralateral ear (CE). Analysis of detection scores and the ratio of blend to nonblend errors, however, suggests that the pathways from CE are not suppressed or extinguished and that the syllable in CE frequently interferes with processing the syllable in the ipsilateral ear (IE). The nature of this interference was explored on four patients by analyzing double-contrast, single-response trials. Double-contrast pairings are those in which a contrasting value of place and voicing is presented to each ear. Interference was explored by analyzing 200 pairings on which the response was a blend error, a blending of the features from the two ears to produce a unitary response. Voiced stops in IE, paired with voiceless stops in CE, accounted for 68% of the 200 blend errors. Most (78%) blend errors represented a blending of place from CE with voicing from IE. The results will be discussed in terms of the “lag effect” and the relative strength or quality of the auditory pathways from CE and IE.
Acoustical design of the Boston University Concert Hall
Authors: Crabtree John B.
Published: October 2005

In 1957, Boston University acquired a large, five-story automobile dealership building and hastily converted it into the School of Fine and Applied Arts; the repair shop became a 450-seat concert hall, and its acoustical design was found to be unsatisfactory for all of its many uses. In 1971, the interior of the building was gutted by fire, and a crash program was initiated to rebuild it for occupancy by the opening of the Fall semester of 1972. Owing to severe budgetary limitations, only minor alterations could be made in the existing architectural parameters (cubic volume, basic geometry, etc.), while the demands for adequate sound isolation had greatly increased since 1957 because of the high levels of traffic noise caused by the Massachusetts Turnpike Extension that abuts the concert hall's north wall. The unusual variety of uses of the hall, not only for performance but also for rehearsal (including the accommodation of an 150-piece symphony orchestra), caused by the concert hall's being the only performing space currently on campus, created some striking room acoustics problems; these are discussed, and the solutions finally incorporated are described in full. The steps taken to eliminate the high levels of traffic noise are shown, including before and after measurements. Subjective reactions to the new acoustical design of the concert hall have been highly favorable.
Qualification procedures for free-field conditions for sound power determination of sound sources
Authors: Hubner G.
Published: October 2005

For determination of sound power of sources by the “method of enveloping measurement surfaces,” the test environment should provide a measurement surface which lies (1) outside the nearfield of the sound source under test, and (2) inside a sound field free of undesired sound reflections from room boundaries or reflecting objects near the source. Methods to check the free-field conditions and to qualify a given measurement surface for an actual source under test are (1) the absolute comparison test using a (small) calibrated reference sound source, (2) the relative comparison test using a small test sound source which radiates broad-band noise that remains essentially constant during the measurement, and (3) the reverberant test which requires measurement of reverberation time. Method 3 is only applicable in closed spaces (rooms). Methods 1 and 2 may be used in rooms and outdoors. Methods 1 and 2 require replacing the source under test by the reference sound source or test sound source in the test site. If the source under test cannot be removed, methods 1 and 2 still allow qualification for free-field conditions with less accuracy. This paper deals mainly with the relative comparison test (method 2) and gives information about the accuracy of the determination of the environmental correction factor K under different field conditions.
Cross-correlation methods for studying near- and farfield noise characteristics of several flow-surface interaction problems
Authors: Pan Y. S.
Published: October 2005

Experimental methods based on well-known cross-correlation techniques are proposed for studying the near- and farfield noise characteristics of several flow-surface interaction problems. By using three kinds of microphone measurements—one flush-mounted on the surface, one located in the nearfield, and one placed in the farfield-farfield noise intensities and nearfield acoustic energy fluxes can be obtained. In both near- and farfields, the noise characteristics due to the flow and the surface contributions can be determined separately. Specific applications to the noise generated by impinging jets, by surface blowing jets, and by turbulent flow over trailing edges are discussed. These methods may prove useful for understanding detailed noise characteristics of STOL aircraft employing the externally blown flap, the augmented wing, or the upper surface blowing, which configurations are now under exploratory development.
Acoustic and propulsion performance facility
Authors: Swift G. , Smith L. G.
Published: October 2005

A unique facility has been developed at the Lockheed-Georgia Company to evaluate, simultaneously, acoustic and propulsion performance characteristics of lift augmentation systems of the type considered for V/STOL aircraft. The facility is ideally suited for concept parametric and systematic noise-reduction investigations where the relationship between farfield acoustics and powered lift propulsion performance is required. The facility comprises an outdoor test rig and a control room. The important features of the test rig include (i) provision of a fully instrumented quiet air supply of up to 20 lb/sec with primary and secondary nozzles, (ii) wing/flap support structures instrumented for measuring aerodynamic loads, and (iii) an arch, carrying a microphone, which can rotate through a hemisphere around the noise source to acoustically map nonaxially symmetric noise fields. The essential features of the control room include (i) remote control of the two airflow pressure ratios, (ii) remote control of the microphone arch location, (iii) data acquisition and reduction capabilities, (iv) on-line display of acoustic and propulsion performance measurements, and (v) central computer access to provide “quick-look” full-scale acoustics. Capabilities are present to make velocity surveys and to measure surface fluctuating pressure levels. Concepts already evaluated include externally blown flap with both lower and upper surface blowing. Applications of this versatile facility include acoustic and propulsion performance studies of (i) a fundamental nature, (ii) powered lift concepts, (iii) single or multiple flow jet noise from various nozzle shapes, and (iv) shielding effect of aircraft structures upon radiated sound.
Release of serotonin from human platelets by hydrodynamic shear
Authors: Williams A. R.
Published: October 2005

Fresh human platelet-rich plasma was prepared from adult blood anticoagulated with EDTA. The platelets were allowed to incorporate tritiated serotonin, washed twice, and resuspended in autologous plasma. Samples of 0.2 ml were sheared for 5 min at 23°C by the acoustic microstreaming field generated around submerged portions of a transversely oscillating steel wire (115-μm radius driven at 20 kHz). Immediately following irradiation, each sample was centrifuged for 5 rain to sediment intact cells and debris, and the quantity of serotonin released into the supernatant was measured using a liquid scintillation counter. It was found that there was no measurable threshold below which serotonin was not liberated, after allowances had been made for the spontaneous release of serotonin induced by the centrifugation procedure. In addition, it was found that the amount of serotonin released by irradiation alone varied with the square of the wire displacement amplitude. Hydrodynamic shear stress and velocity gradient are both proportional to the square of the wire displacement amplitude and are probably the agents responsible for the release of serotonin (together with the simultaneous release of clot promoting and/or accelerating factors).
Perception of complex auditory signals: discrimination of multicomponent square waves
Authors: Pollack Irwin
Published: October 2005

Complex sounds, consisting of up to six square waves, were constructed and presented in detection, discrimination, and identification tests. Excellent discrimination of small differences was achieved when the separate components were spaced at successive octaves or harmonics. By contrast, extremely poor discrimination was obtained with only minor mistunings in the octave. To this extent, the auditory system fails to extract frequency information of individual component frequencies, but shows exquisite sensitivity for deviations from whole-numbered “musical” relationships.
Simultaneous three-channel signal detection
Authors: Pohlmann L. D. , Sorkin R. D.
Published: October 2005

Observers were required to detect the presence of signals presented simultaneously and independently at three separate frequencies (500, 810, and 1320 Hz). The signal at each frequency was present randomly on one-half of the trials and was independent of the signal event at other frequencies. Signal-frequency and two-frequency conditions were run as comparison conditions. The two-channel condition was identical to the one previously reported by Sorkin, Pohlmann, and Gilliom [J. Acoust. Soc. Am. 53, 1045–1050 (1973)] except for the frequencies used and the collection of order-of-report data. Several dedicated conditions were also run in which a detection response was required for only one specified frequency. A decrement in performance was observed for all the multichannel conditions compared to the single-frequency conditions. A conditional analysis indicated that the performance decrement was a function of the signal events at the other frequencies. Some hypotheses about the origin of this cross-frequency interference are considered. The relationship between the observers' response criteria and the order-of-report are discussed.
Acoustic characteristics of vowel nasalization
Authors: Carré R. , Tribolet J.
Published: October 2005

In order to study the nasalization of vowels, a set of CVCV utterances read by several speakers has been analyzed. The consonent C consisted of nasal consonant (/m/,/n/,/ŋ/) and voiced stops (/b/,/d/,/g/). The vowel V was one of seven vowels. The utterances were analyzed using predictive coding and cepstral prediction technics (to detect zero frequencies). Formant frequencies and bandwidth frequencies were studied to find acoustic correlates of vowel nasalization. The associated vowel affected which acoustic correlate of nasalization was most salient. For instance, the nasalization of the vowels /a/ and /æ/ are mainly characterized by a weakness of FI, whereas for the vowel /i/ a nasal formant with large bandwidth can be detected between the first and the second formant. Furthermore, the degree of shifting of the formant frequencies depends on the vowel. Possible application of the results to the detection of nasalization and the identification of nasalized vowels is discussed.
Session L. Physical Acoustics (Biophysics) III: Bull Session, Interaction between Ultrasound and Biological Media
Authors: Dunn Floyd , Nyborg Wesley L.
Published: October 2005

There will be opportunity for informal discussions on various topics, including (i) mechanisms for biological effects of ultrasound, (ii) safety levels for medical ultrasound, and (iii) dosimetry.
Response of geological media to shock waves from explosive sources
Authors: Baron Melvin L.
Published: October 2005

This paper treats the response of layered soil and/or rock media to shock wave excitations from explosive sources. It is divided into two main sections: (1) a treatment of the nonlinear inelastic models that are currently being used for geological media; and (2) a treatment of methods used in studying wave propagation in such media. Considerable progress has been made in recent years on the modeling of geological materials, resulting in the development of several types on nonlinear elastic-plastic models. These models are fit to laboratory and in situ test data and are used in the large finite difference ground shock calculation codes to obtain the response of the media to explosive excitations. This paper briefly discusses some theoretical constraints on the models (uniqueness and continuity), and specifically deals with the current series of elastic-nonideally plastic cap type models which are most generally used today. The second part of the paper deals with problems associated with wave propagation in layered media, including descriptions of the general types of codes in current usage. An introduction to the soil island concept and its use in structure-media interaction problems is also given.
Discrimination of the temporal separation between pairs of sinusoidal bursts
Authors: Divenyi P. L. , Danner W. F. , Bieker J. J.
Published: October 2005

In 1948, Henry [J. Exp. Psychol. 38, 734–743 (1948)] found that duration of pure tones is most discriminable in the 0.5–2-kHz frequency range. The present study represents an attempt to examine whether frequency effects can be observed also in the discrimination of time intervals marked by two bursts of pure tones, identical in frequency. The frequency of the markers covered a range from 0.5 to 4 and their level was 86 dB SPL. Each tone burst marker had a 20-msec total duration and its envelope was smoothened so that the major part of the sound energy be kept within the 50-Hz range surrounding the tonal frequency. Data of three trained listeners, obtained for interburst intervals (t) ranging from 20 to 140 msec, indicate that the logarithm of the interburst interval difference discriminable at threshold (Δtd′=1.0) is a nearly linear function of log t. The slope of this function is close to 0.5 for the 0.5- and the 4-kHz markers, whereas it is approximately 0.8 for the 1- and 2-kHz markers. Pitch difference cues in the pairs of markers may only partly account for the observed frequency effect. [Supported by NINDS Grant No. 03586.]
Acoustical characteristics of police sirens
Authors: Jones F. E. , Quindry T. L.
Published: October 2005

Measurements have been made to determine the directivity and the sound power spectra of four electronic sirens and nine electromechanical sirens. Also investigated briefly were destructive interference effects (1) between a pair of electronic sirens, and (2) between the direct signal from a siren and the signal reflected from the pavement. A discussion is given of the data and the implications of the results regarding the efficacy of these sirens as warning devices on emergency vehicles.
Progress in acoustooptics
Authors: Korpel A.
Published: October 2005

In this talk, the working principles of acoustooptics are discussed briefly. A review of present-day applications ranging from light modulation to acoustic imaging is given.
Short-term TTS after exposure to pure tones
Authors: Young I. M.
Published: October 2005

Tones at 30 dB and 90 dB re O.0002 μbar were presented to normal-hearing subjects at frequencies 950 and 2000 Hz for 1 min. Following each exposure, subjects traced thresholds on a Békésy-type audiometer to the stimulating frequency, and to frequencies 1/4, 1/2, 3/4, and 1 octave above, and 1/4 and 1/2 octave below the stimulating frequency. Temporary hearing loss measured at the stimulating frequency was not greater when the stimulating intensity was 90 dB SPL than when 30 dB SPL, as demonstrated by other researchers. Following an exposure at 30 dB SPL, temporary hearing loss was negligible at frequencies 1/4 and 1/2 octave both above and below the stimulating frequency. At 90 dB SPL, however, this loss increased with frequency up to 1/2 octave above the stimulating frequency, and then decreased monotonically with frequency. These findings were similar to physiological fatigue in that the greatest loss occurred at the frequencies approximately 1/2 octave above the stimulating frequency. While the temporary hearing loss was not significantly different at the stimulating frequency for the two exposure levels, the fact that the loss at higher frequencies was so different may indicate that these findings are probably due to different processes.
Assessment of hazard posed by training to military personnel wearing ear protection and its relationship to questionnaire responses
Authors: Loeb Michel , Cameron Paul D. , Luz George , Luz Shelden , Vanderhei Sharon
Published: October 2005

Temporary hearing loss following small arms fire was monitored for a group of trainees at a U.S. Army post. Audiograms were also taken for another group, and questionnaire responses were elicited regarding such matters as perceived quality of hearing, difficulty in hearing and communicating in noisy situations, and use of protective devices. Generally it appeared that trainees' hearing levels were within acceptable limits and that the temporary shifts after firing, while significant, were not excessive. There was a small but statistically significant hearing loss within the first eight weeks of training, and hearing levels and loss in training were related to responses on certain items on the questionnaire.
Distributional characteristics of simultaneous speech in conversation
Authors: Feldstein S. , Debba M. Ben , Alberti L.
Published: October 2005

Seventy-two half-hour conversations—the interactions of 36 female dyads on two successive occasions—were automatically analyzed for instances of simultaneous speech (SS), defined as speech uttered by the participant who does not have the floor while the participant who does is talking. On the basis of outcome, SS segments were divided into two categories: nonencompassed SS(NSS) culminates in a change of which speaker has the floor while encompassed SS(ESS) does not. Duration frequencies of ESS and NSS segments were distributed exponentially over subjects. Comparing ESS and NSS occurrence frequencies in the first and second halves of the conversations yielded consistency estimates of 0.77 and 0.61 for occasion 1 and 0.72 and 0.54 for occasion 2. Comparing the occurrence frequencies of both occasions yielded stability estimates of 0.54 for ESS and 0.50 for NSS. However, comparing ESS and NSS frequencies over subjects and occasions yielded an r of 0.36, indicating the two categories share only about 13% of their variance. The results suggest that the frequencies with which speakers engage in ESS and NSS represent different but equally reliable aspects of their conversational styles, and provide a basis for examining lexical and psychological correlates of SS outcome.
Normal-mode calculations of underwater sound propagation from directional sources
Authors: Haug A. J. , Graves R. D. , Überall H.
Published: October 2005

We have obtained the normal-mode solution for the problem of sound propagation in an under-ocean sound channel with velocity profile c(z), for the case of a sound source with arbitrary directional emission properties. The wave equation is separated in cylindrical coordinates assuming harmonic time dependence. The normal-mode depth functions used are those of a parabolic profile [H. Überall and N.C. Nicholas, J. Acoust. Soc. Am. 44, 1259 (1968)] or of an arbitrary numerical profile [I. M. Blatstein, A.V. Newman, and H. Überall, J. Acoust. Soc. Am. 54, 271 (1973)]. The pressure is obtained in terms of an integral Green's function solution, which becomes a multipole series upon expansion of the source in spherical multipoles. Illustrative examples are given for dipole and quadrupole sources. [Supported by the Office of Naval Research.]
Identification of the separate tones heard in a woodwind multiphonic sound as grouped subsets of its spectral components
Authors: Benade A. H. , Livingston L. J.
Published: October 2005

The spectrum of a woodwind multiphonic sound consists of a large number of unharmonically related heterodyne components. Musicians have a need to notate these sounds. They usually write “chords” whose individual notes each represent a perceived subset of spectral components. Each subset normally includes components that are in quasiharmonic relationship, and its perceived pitch approximates that of a corresponding tone having exact harmonics. The variety of subsets which are perceived at the same pitch is illustrated by the following examples, all of which match the ordinary note C4 a whose components are multiples of 261.6 Hz: (278,467, 620, 786, 1046); (267, 534, 641,764, 1071); (275, 512, 620, 796, 1026); (272,544, 622, 819, 1033). Pitch assignment is not particularly sensitive to component amplitude, making tonal perceptions stable despite the vagaries of sound transmission in a room. Various clarinet and oboe multiphonics are discussed and illustrated.
Calibration of wide-band microphones with N waves
Authors: Anderson M. O. , Cornet E. P. , Wright Wayne M.
Published: October 2005

In the course of testing a numerical method for predicting the waveform of an intense traveling sound wave, we found it necessary to develop an accurate method for calibrating fast-rise-time (∼0.5 μsec) condenser microphones. The calibration procedure developed is based upon the fact that the amplitude P and duration T of an N wave vary with distance r in a way that depends on the absolute amplitude of the wave. We used spherical N waves produced by electric sparks. A calibration can be obtained by measuring P and T at only two range points [B.A. Davy and D.T. Blackstock, J. Acoust. Soc. Am. 49, 732–737 (1971)]. However, since the same N wave cannot be used for more than one measurement, the precision of the method is limited by the reproducibility of the N waves. We achieved much-improved precision by measuring P and T at numerous range points and using a special averaging technique based upon the fact that ∂T2/∂lnr and PrT are both constants. Application of the calibrated microphones is also discussed. [Work supported by AFOSR and Naval Ship Systems Command. ]
Measurements of diffraction and interaural delay of a progressive sound wave caused by the human head. II
Authors: Abbagnaro L. A. , Bauer B. B. , Torick E. L.
Published: October 2005

A decade ago, two of the authors presented a paper reporting on diffraction and interaural delay of a progressive wave caused by the human head [J. Acoust. Soc. Am. 36, 1993(A) (1964)]. Six live subjects were used in those experiments. The publication was delayed pending measurements on artificial heads then being planned. In this paper, two series of data obtained with the aid of the Acoustical Manikin [J. Acoust. Soc. Am. 42, 204–207 (1967)] are compared with the earlier experiments: (a) Data based on phase measurements; (b) Data obtained using a bandwidth-limited delta pulse. All three methods provide useful information about interaural diffraction and delay, albeit the third method appears to be the most reliable.
Lateral superior olivary nucleus: a comparative analysis
Authors: Irving R. E.
Published: October 2005

The lateral superior olivary nucleus in 37 species of mammals was drawn with a Zeiss drawing tube from protargol-silver stained material. The pattern of laminar infolding generally conformed to the S-shaped and U-shaped convolutional patterns described by Hoffman (1908). In species with a relatively large cell number and a relative small cross-sectional area, there tends to be substantial laminar infolding within the convolutional pattern. Two independent estimates of the amount of laminar infolding were made and contrasted with the number of segments in the general convolutional pattern. Neither amount of laminar infolding nor number of convolutional segments was found to correlate with number of cochlear turns. However, in species in which the laminar pattern is well defined, the convolutional pattern and amount of laminar infolding appear to conform well to the sensitivity range and area of greatest sensitivity as seen in behavioral audiograms for the species.
What information enables a listener to map a talker's vowel space?
Authors: Verbrugge Robert , Strange Winifred , Shankweiler Donald
Published: October 2005

It is commonly assumed that a listener identifies an unknown talker's vowels in terms of the relation between their acoustic structure and that of other vowels produced by the same talker: the listener “normalizes” the variant acoustic signals on the basis of information about their source (vocal-tract characteristics). In order to measure the vowel ambiguity attributable to talker differences, we compared identification of nine vowels in /p—vowel—p/ environment produced by a single talker with the same vowels produced by 15 talkers (men, women, children) who differed widely in vocal-tract sizes and characteristic fundamental frequency. Mean error rates were 9% and 17%, respectively. Acoustic differences attributable to talker accounted for fewer than half of the perceptual errors. Lieberman [Am. Anthropologist (1972)] has proposed that the point vowels, /i, a, u/, are the “primary calibrating signals” by which the listener determines the size of the talker's vocal tract and normalizes the acoustic signal. In a second study, one group of listeners received each test word preceded by syllables containing /i, a, u/ and another group heard the test words preceded by nonpoint vowels /I, æ, Λ/. There was no significant overall reduction in errors of vowel identification for words preceded either by point vowels or by nonpoint vowels. Although perception of certain vowels improved when preceding syllables were present, perception of other vowels deteriorated.
Consonantal environment specifies vowel identity
Authors: Strange Winifred , Verbrugge Robert , Shankweiler Donald
Published: October 2005

Listeners make remarkably few errors in identification of randomly presented tokens of vowels produced by a panel of talkers in fixed consonantal environments. The present study was designed to investigate the sources of perceptual confusions among vowels and to determine whether or not the effects of talker differences on vowel identification are independent of consonantal environment. Tokens of nine American English vowels were spoken in three contexts: (1) in isolation, (2) in a variable consonantal environment (/C1—vowel—C2/, where C1,2 = /b, p, d, t, g, k/), and (3) in a fixed consonantal environment (/p—vowel—p/). Test lists were produced by three representative single talkers (man, woman, child) and by a panel of talkers who differed in vocal-tract size and characteristic fundamental frequency. Whether produced by the panel or by a single talker, isolated vowels were significantly more often misidentified than were vowels in consonantal environments. Reliable differences in identification of medial vowels were found among consonantal environments. Of the two variables shown to affect vowel identifiability, consonantal environment was found to be of greater importance than talker variation. The results indicate that vowels are not identified primarily on a segmental basis.
Same-different reaction times to pairs of nonsense syllables
Authors: Reed C. M.
Published: October 2005

Reaction times were measured for the same-different discrimination of selected pairs of VC nonsense syllables in four normally hearing subjects. Five phonemes were selected as standards for experimental study and each of these standards was contrasted with four phonemes. Lists contained equal numbers of same and different presentations. Syllables were stored digitally and then trimmed to a uniform length of 335 msec prior to recording. Intersyllable interval was 750 msec. Results showed that the error rate which resulted from calling same stimuli different was relatively constant at about 0.05. The error rate for calling different stimuli same was found to vary for specific phonemic comparisons and was directly related to the size of the difference between different and same RTs and inversely related to d′, to the criterion measure β, and to the number of features (Wickelgren, 1966) by which the pair contrasted. The results are related to a theory of stimulus codability and difficulty as determinants of the relative size of same and different RTs. [Supported by Public Health Service Award NS-7790.]
Theoretical evaluation of sound fields in circular or annular ducts with rigid or nonrigid radial splitters
Authors: Mungur P. , Kapur A.
Published: October 2005

In aircraft engines, extra attenuation can be obtained by installing lined radial or circumferential splitters or both. A study of the governing wave equation and its solution in the lined radial splitter environment is presented. It is shown that the general solution can be written in the terms of modified Bessel and Neumann functions of complex fractional orders and complex arguments. This is due to the fact that the circumferential wavenumber is in general complex, noninteger, and a function of the radial coordinate. In the analysis, the circumferential wave vector is evaluated first as a function of the radial coordinate and in terms of the angular separation between the splitters and the frequency parameter; this function is then used in the radial integration, yielding the mode shapes and the corresponding complex axial wavenumbers. The model attenuations are higher for two reasons: the increased surface area of absorptive materials and the much higher cutoff frequencies of the modes. This analysis can be extended to the evaluation of sound field between blades.
Electrophysiological correlates of behaviorally determined loudness recruitment in primates
Authors: Pugh J. E. , Moody D. B. , Anderson D. J.
Published: October 2005

Reaction time of a subject's response to an auditory task has been found to be an index of loudness in human experiments, and this technique has been used to generate equal-loudness curves in subhuman primates. In this experiment, macaque monkeys were conditioned to respond to 8-kHz tones and response reaction times were measured. Whole-nerve cochlear action potentials were recorded from chronic inner-ear electrodes. A loudness recruitment phenomenon was experimentally produced by a one-hour exposure to a high-intensity 8-kHz octave band of noise. Excellent agreement was observed between the reaction time function and the action potential input-output function at postexposure testing intervals of 0.5, 12, 24, 48, and 84 hours. These recruitment data are discussed in relation to theories of loudness coding.
Evaluation of cortical auditory evoked response and threshold of the stapedius reflex in cat as indicating auditory function
Authors: Yonovitz A.
Published: October 2005

Evoked potentials to pure-tone pulses were recorded with chronically implanted electrodes on the dura at the vertex of three awake cats. Auditory stimuli (0.125 to 12.0 kHz) were presented in a calibrated free field. A visual detection limit (VDL) was used as the measure of threshold auditory evoked response (AER). The VDL AER threshold was found to parallel roughly the behavioral threshold of cat, the AER thresholds being 30–40 dB higher. The input-output curves obtained from each cat were best fit to a logarithmic function (linear on semilog plot) and from this function AER thresholds were estimated by extrapolation (EXT). The EXT threshold variability was greater than that of VDL threshold. Also, a modified electroacoustic impedance bridge (Madsen, model ZO-70) was used to measure the threshold (frequencies from 0.125–10 kHz) of the stapedius reflex (TSR) in ten lightly anesthetized cats. Results were consistent with human data and indicated that the TSR in cat parallels the behavioral audiogram at a sensation level approximately 80–90 dB. Test-retest reliability using both techniques (AER and TSR) was excellent. These techniques appear to have potential usefulness as a practical and useful method of measuring certain auditory responses of animals.
Simulation of deaf speech as a diagnostic tool
Authors: Osberger M. J.
Published: October 2005

The speech of congenitally deaf children was simulated in order to determine quantitatively what errors have the greatest effect on speech intelligibility. The simulation was performed by a normal speaker who mimicked the deaf children's utterances using a shadowing technique. Mimicking was continuous over long periods until a high level of fidelity with the original was achieved. Error types in the simulated utterances were based on the errors which were found to occur most frequently in the speech of each child. These errors were systematically eliminated so as to represent various levels of improvement in speech production. The original deaf utterances and the simulated utterances were then played to listeners not familiar with speech of the deaf. Intelligibility was measured by the number of words correctly identified in a single utterance. Results to date for one deaf subject show that errors involving nasal consonants have the greatest effect on speech intelligibility. In this particular case, fricative errors and timing errors were also eliminated in all possible combinations with the nasal consonant errors. Preliminary data on other children indicate that individual differences are large and that predominant error types may differ from child to child. An advantage of this technique is that it provides a diagnosis that is specific for each child. [Supported, In part, by Office of Education Program Support Grant.]
Phonation characteristics: a comparison of normal hearing, deaf trained orally, and deaf trained in the Rochester Method
Authors: Bishop M. E. , Horii Y.
Published: October 2005

This paper is concerned with a quantitative description of the phonation characteristics of deaf talkers and the manner in which those characteristics differ as a function of the student's training background. A total of 40 deaf high school students (20 male and 20 female), ages 15–18, served as subjects. All subjects were prelingually deaf, with hearing losses of 90 dB or more in the better ear. Eighteen of the deaf subjects had received all of their formal speech training at the Clarke School for the Deaf, where only the oral method is used. Twenty-two deaf subjects had received all of their communication training at the Rochester School for the Deaf, where the method of combining fingerspelling and speech is used. An analogous group of normally hearing high school students was used for comparison. Speech samples were recorded as the subjects read a phonetically balanced paragraph. The high-quality speech recordings were digitalized and subsequently processed using a period-by-period computer analysis program. This method provided information about each subject's mean fundamental frequency, variability and skewness of the distribution, and phonation time ratio. The results are discussed both in terms of group performance and individual differences.
Scattering and diffraction from plates
Authors: Hayek S. I.
Published: October 2005

Acoustic diffraction and backscattering experiments were conducted in a water tank on bare steel plates and on steel plates coated by closed-cell Neoprene rubber. The plates were pulsed by pure-tone short pulses at frequencies below the coincidence frequency of the bare plate. The experimental data have shown that the Sommerfeld theory of diffraction is inadequate in predicting the diffracted and backscattered fields. A proposed modified theory that accounts for the roundedness of the plate edge and the impedance of the diffractor surface was shown to give results that agree more closely with the experimental results. [Supported by the Naval Ordnance Systems Command.]
Annoyance judgments of aircraft with and without acoustically treated nacelles
Authors: Borsky Paul N.
Published: October 2005

A series of subjective response laboratory tests was conducted to determine the effectiveness of reducing aircraft noise by treating the aircraft engine nacelles with acoustically absorbent material. A total of 108 subjects participated in the magnitude estimation tests. The subjects were selected from persons who had previously been interviewed and classified according to selected psychological characteristics. The subjects lived in three general areas located at three specified distances from New York's Kennedy Airport. The aircraft signals used in the tests consisted of tape recordings of the landing approach noise of a B-727 aircraft under normal operating conditions. These recordings were electronically altered to simulate an aircraft with acoustically treated nacelles to achieve noise reductions of approximately 6 and 12 EPNdB. The results from these tests indicate that significant reductions in annoyance resulted from the synthesized nacelle treatments.
Human perception of apparent direction and movement of aircraft noise
Authors: Gunn Walter J. , Scholl Harland F. , Dempsey Thomas , Gibson Fred , Whitted Nancy
Published: October 2005

NASA Langley Research Center is developing an Aircraft Noise Reduction Laboratory which will, among other things, have the capability of simulating both indoor and outdoor home-like settings which provide visual and auditory realism. Although visual realism is easily understood, there was some question as to just what constitutes auditory realism. While it is clear that loudness changes, spectrum changes, and Doppler shifts are easily perceived by people in their homes, it is not so clear just what is perceived in regard to apparent motion and direction of real aircraft flying overhead or off to the side. In order to resolve this question, a study was conducted in which subjects, both indoors and outdoors, made judgments of apparent direction and movement of various large and small aircraft which were flown a number of times over the house in which the subjects were located. Results of this study will be discussed.
Psychological effects of exposure to high industrial noise: a field study
Authors: Gulian Edith
Published: October 2005

A comparative investigation was carried out on two samples of industrial workers. One group (60 persons) working in noise (85–106 dB) and a control group (40 persons) working in relative quiet (under 82 dB). Noise annoyance and neuroticism were assessed by means of questionnaires, and performance level by two psychological tests, the Stroop test, and a test of concentration of attention. Comparisons between the two samples were performed as a function of age and of time worked in noise. It was found that neuroticism rises primarily as a function of time worked in noise and secondarily as a function of age. There is a critical age or time interval after which neuroticism develops quickly. It was also found that, as compared to the control group, the noise group (1) manifests greater annoyance, but only after two years on the job; (2) displays a higher ability to focus attention; but (3) makes more errors on the Stroop psychological performance test and fers a higher degree of interference with performance.