bluuebunny/crossref_metadata_2025 huggingface dataset:
Perplexity—a measure of the difficulty of speech recognition tasks
Authors: Jelinek F. , Mercer R. L. , Bahl L. R. , Baker J. K.
Published: October 2005

Using counterexamples, we show that vocabulary size and static and dynamic branching factors are all inadequate as measures of speech recognition complexity of finite state grammars. Information theoretic arguments show that perplexity (the logarithm of which is the familiar entropy) is a more appropriate measure of equivalent choice. It too has certain weaknesses which we discuss. We show that perplexity can also be applied to languages having no obvious statistical description, since an entropy-maximizing probability assignment can be found for any finite-state grammar. Table I shows perplexity values for some well-known speech recognition tasks.

Perplexity Vocabulary Dynamic

Phone Word size branching factor

IBM-Lasers 2.14 21.11 1000 1000

IBM-Raleigh 1.69 7.74 250 7.32

CMU-AIX05 1.52 6.41 1011 35
On determining partial correlation coefficients by the covariance method of linear prediction
Authors: Atal Bishnu S.
Published: October 2005

Partial correlation coefficients of speech samples (sometimes called reflection coefficients) are an important set of parameters in linear prediction analysis of speech and have proved to be useful for many practical applications, such as speech encoding, speech synthesis-by-rule, etc. So far, it has been thought [Gibson, IEEE Trans. ASSP, p. 93 (Feb. 1977)] that the covariance method does not provide a direct method of computing the partial correlations unless the covariance matrix is a Toeplitz matrix. Indirect computation of partial correlations from the predictor coefficients have obvious disadvantages. It will be shown that the partial correlation coefficients are indeed obtained as a set of intermediate parameters by the covariance method even when the covariance matrix is non-Toeplitz. These intermediate parameters are obtained as a solution of a set of linear equations through Choleski decomposition of the covariance matrix and, after appropriate normalization, are transformed to the partial correlation coefficients. The above method of determining partial correlations has been extensively tested with both real and synthetic speech data and has been found to work satisfactorily with analysis intervals as short as one pitch period.
On reducing radiographic dosages in pellet-tracking experiments
Authors: Perkell Joseph S. , Donahue Robert
Published: October 2005

Radiographic dosage levels continue to present an increasingly difficult barrier to obtaining valuable data on the movements of pellets attached to internal articulatory structures during speech production. Two methods of reducing dosage have been explored. The first method involves the use of a high-speed recording film (Kodak 2475) in conjunction with a “normal extended” commercial cine-developing process, A test run was made in which a head and neck phantom and small lead pellets suspended on a moving wooden pendulum were exposed at normal and reduced cineradiographic dosage levels. It was found that the high-speed film and extended development allowed for perfect pellet visualization at dosage levels one-fourth as great as those normally delivered by the apparatus with conventional cineradiographic filming and developing techniques. The second method used videotape of a fluoroscopic image of a human subject and tracings of “field-by-field” photographic transparencies made from a video monitor. Initial results suggest that even lower dosages may be obtained with this method, but at the cost of decreased resolution and increased effort or expense in obtaining data. [This work was supported by the National Institutes of Health Grant NS04332.]
Subjective quality testing of a perceptual-model-based variable frame rate (VFR) LPC vocoder
Authors: Huggins A. W. F. , Viswanathan R.
Published: October 2005

Subjects judged the degradation of quality caused by processing speech through three LPC vocoder systems, one of which was the VFR system based on our functional perceptual model of speech [Proc. 1977 IEEE Int. Conf. ASSP, p. 219 (1977)], and the other two were fixed-rate systems, one of which had its transmission frame rate equal to the average frame rate of the VFR system (about 30/sec), and the other had its frame rate equal to the peak frame rate of the VFR system (100/sec). Stimulus materials were six phoneme-specific sentences read by each of six speakers, three male and three female [see Proc. 1977 Int. Conf. ASSP, p. 413 (1977)]. Unprocessed speech was also included as an anchor. The results show that the VFR system's quality approximates that of the 100-frames-per-second fixed-rate system, and in some cases even surpasses it. Reasons for this rather surprising result will be discussed. [Work sponsored by ARPA-IPTO.)
Scattering at a rough boundary to an inhomogeneous ocean
Authors: McCoy John J.
Published: October 2005

The development of randomly rough boundary interaction models formulated in terms of the (averaged) acoustic intensity angular spectral density is considered. The principal advantage of these models is that they are completely compatible with a previously presented propagation model, which in turn is applicable for a general inhomogeneous medium and is well suited for numerical computation. Thus, taken together, the boundary interaction models and the propagation model provide a general wave theoretic approach to experiments containing both a rough boundary and an inhomogeneous sound-speed profile. Heretofore, such a general approach has been limited either to geometric theory analysis on to a perturbation analysis that is suitable for slightly rough boundaries. Two specific boundary interaction models are considered in some detail; one being a phenomenological model that can be termed a linear filter model, and one being a structural model based on Kirchhoff scattering theory. Any originality in these specific models is limited to the field measure in terms of which they are formulated although the derivation of the Kirchhoff model is thought to provide further insight on the applicability of the theory as it applies to inhomogeneous media. The phenomenological model is shown to be a natural extension of the ray theory approach to scattering at a rough boundary; i.e., the rise of reflection coefficients. The extension is required in order to incorporate some effects of diffraction. Finally, an idealized, but somewhat typical, experimental geometry is considered for which the combined application of the propagation and boundary interaction models is possible.
Basin reverberation measurements in Frenchman's Bay
Authors: Shepard G. W. , Zittel J. D.
Published: October 2005

As a preliminary to planned basin reverberation measurements in the Arctic Ocean, data were acquired in Frenchman's Bay, Maine, to test the experimental concepts and to provide some early physical insights into the relevant phenomena. The Bay is about 8 km across, 50 m deep, and had a downward refracting profile during the measurement period. Reverberation records were obtained using a pneumatic air gun as a source and three hydrophones located near the source. Typical records will be presented and discussed. Reverberation persisting as long as 10 sec was observed including both bottom and basin boundary scattering. Assistance was provided in the experiments by the U.S. Geological Survey, by the Woods Hole Oceanographic Institution, and by several other individuals from M.I.T. [Work supported by ONR.]
Acoustic sidebands from cw sources towed at long ranges in the deep ocean
Authors: Ramsdale Dan J.
Published: October 2005

Three cw sources (9.8, 110, and 262 Hz) were towed at approximately 7 knots along a track from Antigua, West Indies, to the Grand Banks of Newfoundland. Acoustic data from each were recorded on a bottom-mounted hydrophone near Antigua, providing source-to-receiver distances of from 100 to 2800 km. High-resolution spectral analysis centered at each frequency showed that while no acoustic sidebands were discernible at 9.8 Hz, they were observable over the entire track for both the higher frequencies. Except for expected statistical fluctuations, the right and left sidebands were of equal amplitude and symmetrically placed about the carrier frequency. The 110- and 262-Hz sidebands were separated from the carrier by a like amount with this separation decreasing noticeably with increasing range. In regions of strong convergence zone activity the sideband level displayed the similar peak-to-null variations as the carrier, although the peak-to-null ratio was smaller than for the carrier. Detailed environmental data were available only near the sources. A high degree of correlation was observed between the sideband levels and the wave and swell heights when the sources were towed through a storm which occurred some 2000 km from the receiver.
Comparison between plate and shell models for scattering from a framed elastic cyclinder
Authors: Ellison W. T. , Garrelick J. M.
Published: October 2005

Two mathematical models are used to calculate monostatic backscattering from a framed cylinder immersed in an acoustic medium. A comparison is made between the results obtained with an analytical model based on thin-shell theory, and the corresponding results obtained from a planar model. With the planar model the finite curvature of the cylinder is accounted for with a correction factor based on the geometric theory of diffraction. The frames are treated in both models as a periodic array of simple supports. The results from the two models are compared as a function of frequency, structural damping, fluid loading, and frame spacing.
New and general expansion for differential cross section of sound scattered from impedance cylinders
Authors: George Jacob , Überall H.
Published: October 2005

We report a new expansion for differential cross section of sound geometrically scattered from a cylinder with impedance boundary conditions. The cross section is given in inverse integer powers of ka and is derived from the normal-mode solution for the sound field by the application of Watson transformation techniques and a generalized saddle point formula. Explicit expressions for terms up to (ka)−5 are given and the relative importance of the terms for values of ka from 2 to 8 is numerically illustrated. [Supported in part by ONR.]
Asymptotic grazing field on a point-force-excited, fluid-loaded cylindrical shell below critical frequency
Authors: Sachs D. A. , Smith P. W.
Published: October 2005

An asymptotic high-frequency solution is developed for the near-sonic grazing (“creeping”) pressure wave on a cylindrical shell lightly loaded by an external fluid and excited by a point force at frequencies below the critical frequency. The grazing waves travel along helical paths from the source, and the amplitude falls off cylindrically (R−1/2) with the geodesic distance R and exponentially as f1/3R/ρ2/3, where f is the frequency and ρ is the radius of curvature along the helix. The amplitude of the wave is path dependent, varying inversely as ρ1/3. The parametric dependence of the current result is, to first order, equivalent to that for the creeping wave solution for an appropriately chosen volume velocity source on a rigid cylinder, previously derived by other authors. The relationship to the grazing field solution for an infinite flat plate will be discussed.
Acoustic pulse distortion of wide-band plane waves by a plate
Authors: Stepanishen P. R.
Published: October 2005

The transmission and scattering of acoustic wide-band planar pulses by a fluid-loaded plate is investigated using Fourier transform and Timoshenko-Mindlin plate theory. It was shown that the transmitted and scattered time-dependent pressure fields can be expressed as a convolution of the time history of the acoustic pulse with an appropriate time-dependent impulse response which is also a function of the incident angle of the pulsed wavefront relative to the plate. The impulse responses for the transmitted and scattered fields are simply related and can be expressed as the inverse Fourier transforms of the associated angle-dependent harmonic responses. An investigation of the pole zero structure of the transform as a function of the incident angle indicates that the impulse response, and hence pulse distortion, exhibits a significantly different behavior for different angles of incidence. Normalized impulse responses are then presented to illustrate the various characteristics of the impulse responses as a function of angle. In particular the occurrences of different types of precursors, i.e., oscillatory and nonoscillatory, are noted as a function of angle. Finally, the impulse responses are based on the use of Timoshenko-Mindlin plate theory are compared to those based on classical plate theory.
Measurement and development of sound exposure level (SEL) versus distance curves for rotary-wing aircraft
Authors: Schomer Paul D. , Homans Brian
Published: October 2005

Systematic measurements, similar to FAR Part 36, were made on eight models of Army rotary-wing aircraft (OH-58, AH-1G, UH-1M, UH-1B, UH-1H, CH47B, CH54, TH-55). The aircraft performed dynamic operations consisting of level flyovers, ascents, descents, turns, takeoffs, and landings; and static operations including in-ground and out-of-ground effect hovers. SEL versus distance curves were developed for these operations. Results are grouped according to model and type of operation and are suitable for use in manual or computerized programs for predicting noise impact for rotary-wing aircraft. Type of maneuver was not found to be a significant factor. The largest level differences are from one type of aircraft to another.
Multidimensional analysis of auditory and visual perception among the profoundly hearing impaired
Authors: Sims D. G. , Montgomery A. A.
Published: October 2005

Fifteen profoundly deaf subjects' responses on the Phoneme Identification Test Series were studied via HI CLUS and KYST multidimensional analysis techniques in order to determine whether meaningful perceptual dimensions were utilized by subjects in spite of very low scores for exact phoneme identification. Results suggested that this group of subjects tended to categorize their responses along a single feature for auditory perception. In a second experiment, deaf subjects' speechread responses to the Phoneme Identification Test were analyzed via HYCLUS. Results were like that of previous studies with normal or mildly hearing impaired, but an interesting visual dimension was discovered which allowed discrimination between the back consonants (k) and (g) for some S's. [Supported by HEW.]
Measures of effectiveness of nonauditory aids for pre-school deaf children
Authors: Stark R. E.
Published: October 2005

Nonauditory aids are now being used in the training of profoundly deaf preschool children. Wearable nonauditory aids may soon be available to such children. It is important to obtain valid measures of the effectiveness of these aids. Measures of vocal output are useful but difficult to obtain from children at a prespeech developmental level. A number of such measures were developed in a study designed to assess the effectiveness of training by means of visual and vibrotactile (Optacon) displays. In this study children were trained to produce reduplicated babbling of /ba/, /da/, and /ma/ syllables [M.H. Goldstein, Jr. and R.E. Stark, J. Acoust. Soc. Am. 59, 1477–1481 (1976)]. The children's output before, during, and after training was assessed from phonetic transcriptions. Total number of syllables was not found to be a useful measure. The ratio of CV syllables to the total number of syllables produced (CV/CV+V) did show group differences. However, it may be objected that vowel and CV syllables vary independently and should not be combined in a ratio. Mean syllable duration also showed group differences. Syllable duration is known to decrease in reduplicated babbling as compared with earlier types of vocalization. Problems in the use of this measurement are discussed. [Work supported by NINCDS.]
Development of a prediction of the equivalent sound level due to traffic noise in residential areas
Authors: Kelsall J. T. , Friedman O.
Published: October 2005

A series of 80 short-term measurements of A-weighted equivalent sound level (Leq) and the results from twenty-three 24-h community noise measurements are presented. These measurements, from communities with populations as low as 200 and as high as 2 000 000 provide the data base for an empirical prediction of Leq due to traffic noise applicable to most locations in residential areas. A major area of concentration of both the measurements and the prediction is the background urban hum which gives fairly uniform results for backyard measurements of Leq across most communities. The variation of Leq with respect to time as well as location has been examined.
Acoustic modeling of “close-proximity” rail transit noise barriers
Authors: Cann R. G. , Tocci G. , Cavanaugh W. J.
Published: October 2005

In connection with the development of prototype close-proximity noise barriers for railroad and rapid transit applications, an acoustic modeling study was undertaken to determine the effectiveness of various barrier cross-sectional geometries and the effect of acoustical absorption. Barriers studied included flat vertical walls and various “Z” shape and “C” shape cross sections. The flat-top surface has been designed to allow these structures to be utilized as both a noise barrier and as safety walks for passenger emergency egress. The chief conclusions are that “C” and “Z” cross-sectional shapes are nearly equal in performance as noise barriers, and slightly better than an equivalently located flat vertical wall. It was also determined that track bed absorption (ballast) and barrier absorptive treatment appear to have significant effects in improving the performance of close-proximity rail transit noise barriers in reducing transmission of wheel/rail noise to wayside areas. [Studies supported by Fanwall, Inc., Framingham, MA.]
Indoor simulation of SAE J366b—heavy truck noise measurements
Authors: Witwer R. K. , Sullivan J. W.
Published: October 2005

The SAE J366b test for heavy truck noise was simulated by moving a vertical microphone array past a stationary operating truck in a semianechoic chamber. The microphone boom was moved linearly at a distance of 15 ft from the truck center line. The engine was operated at full throttle and loaded with a water brake dynamometer. By decreasing the water flow rate, the engine speed was made to increase thus simulating vehicle acceleration. The subsequent increase in the engine tachometer signal was used to automatically position the microphone boom. The data extrapolated to 50 ft shows good correlation with measurements made outdoors on the same truck using the SAE J366b procedure. [Work supported by Motor Vehicle Manufacturers Association of the United States, Inc.]
Comparison of various techniques for the determination of the random incidence response of microphones and sound level meters
Authors: Sorbyn Myroslav R. , Magrab Edward B.
Published: October 2005

The measurements necessary for the determination of the random incidence responses of microphones and sound level meters were made from 500–20 000 Hz in an anechoic chamber using both single-frequency tenes and 1/3-octave bands of noise. The random incidence responses were computed from these data using formulas given in the relevant IEC and ANSI standards documents and according to a Gaussian-type numerical integration formula. This Gaussian formula appears to introduce less numerical error due to the approximation procedure used to compute the random incidence response than either the IEC or ANSI formulas. The random incidence responses of the microphones and sound level meters tested in the anechoic room were also measured in two reverberation rooms using both discrete sampling of the reverberant field and two types of continuous sampling: linear and circular. The results from the various methods and procedures are compared to the exact values (determined by a numerical procedure that used at least 30 points) and the minimum number of points (angles) necessary to achieve a prescribed level of accuracy in the random incidence responses are determined.
Phase shift due to scattering by a microphone
Authors: Cook Richard K. , Proctor Thomas M.
Published: October 2005

The electrical output of a microphone in a plane wave of sound in air, harmonic in time, will have its phase shifted relative to the phase of the sound wave. Part of the phase shift is due to scattering by the finite bulk of the microphone, and part may occur in its electronic circuit. Information on the amounts of the phase shifts is needed whenever the outputs of an array of microphones are used to measure such quantities as cross-correlation coefficients, the Umov (intensity) vector, the local phase velocities for various directions, etc., in a sound wave field. We present the theoretical analysis and some experimental results for the phase shift due to scattering. The theoretical analysis leads to the concept of a “phase plane” associated with the electrical output of a microphone. Results will be presented, mainly at long wavelengths, (1) for a solid spherical microphone, (2) for a probe-tube microphone, and (3) for a Helmholtz resonator at low frequencies.
Electroacoustic sensitivity of ceramic cylinders
Authors: Wilder W. D.
Published: October 2005

The low-frequency voltage/pressure sensitivity of piezoelectric right circular cylinders is derived for three common polarization schemes. The acoustic pressure on the three major surfaces is considered variable, thereby allowing for any configuration of shielding. Derived sensitivities are illustrated for a common piezoelectric ceramic material (Clevite PZT4).
Acoustical compound reflex resonator system
Authors: Sebesta G. J. , Hofer A. , Carlisle R. W.
Published: October 2005

A miniature paging-tone loudspeaker is described. The reproducing range is centered around 2 kHz and the size is 18-mm cube (just over 58 in.). The structure utilizes a conventional button earphone, loaded acoustically by a structure resembling a folded horn having two traverses. There is a first-traverse chamber, a second-traverse chamber which functions as a conical frustum horn, and suitable orifices coupling the chambers. The analysis requires the use of both resonator and conical horn theory. Mass (inertance) and compliance elements are calculated relative to a diaphragm of definite area, in both MKS and cgs units. The ratio of impedance in the two systems is shown to be exactly 10, demonstrating the feasibility of facilitated transformation. The nickname is “Beeper Cube” and current applications are concerned with paging intercoms for medical or service personnel.
Optical fiber hydrophone
Authors: Bucaro J. A. , Carome E. F. , Layton M. R.
Published: October 2005

Recent studies [J.A. Bucaro, H.D. Dardy, and E.F. Carome, Appl. Opt. 16, 1761 (1977); J.H. Cole, R.L. Johnson, and P.G. Bhuta, J. Acoust. Soc. Am. to be published] have shown the viability of obtaining sensitive, versatile acoustic sensors utilizing long, low-loss optical fibers. In such devices an optical beam propagating in a length of optical fiber which is immersed in a fluid is modulated by the presence of a sound field in that fluid. We have studied such effects in a variety of fiber systems and have quantified various coupling mechanisms which lead to the optical modulation. Examples include phase retardation, acoustically induced birefringence, and intermode beating effects. These results will be discussed and future directions will be indicated. [This work has been supported in part by the Office of Naval Research.]
Optical hydrophone
Authors: Shajenko P. , Flatley J. P.
Published: October 2005

Progress on optical hydrophone operating in conjunction with 2-km-long optical fiber is reported. The hydrophone is a pressure-sensing light modulation device, where the Doppler frequency shift is multiplied by multireflections increasing the hydrophone's sensitivity. The light beam to and from the hydrophone is guided along optical fibers. Coherent detection is made by employing homodyne or heterodyne detection technique. Experimentally tested sensitivity and signal-to-noise ratio of the optical hydrophone are comparable to the piezoelectric hydrophone. Using a multiple-interference technique, successful operation of the optical hydrophone with 2-km-long multimode optical fiber was obtained. Test results are presented. [Work supported by CNM and NAVSEA.]
Review of seismic design and testing
Authors: Pusey H. C.
Published: October 2005

It is well known that earthquakes can be devastating in terms of life and property. Along with the preservation of life, one of the more important concerns during these natural disasters is the survival of vital power and communications equipment. Over the past several years significant progress has been made in seismic design and analysis, and in techniques for simulation of seismic loads for purposes of equipment qualification. A review of the present state of the technology is presented with particular emphasis on seismic design approaches and test capabilities.
Seismic qualification of equipment by generic testing
Authors: Shipway G. D.
Published: October 2005

Generic testing has evolved as a very popular approach to seismic qualification of equipment for nuclear power plants. Generic testing is where equipment is tested to a high-level seismic environment which is arbitrarily selected to encompass all, or nearly all, present and future requirements. This approch has presented uncertain areas of potential over conservatism, since beats superimposed on background random, difficult to handle OBE testing, and test levels which tax the capacity of testing machines. Other questions not yet answered by guides or standards are the appropriate accuracy for measuring and controlling the Test Response Spectrum and for measuring and controlling the zero-period acceleration. The display of the TRS is not yet sufficiently standardized. How to perform seismic testing for line- (pipe) mounted equipment is an area begging a solution for which there is no current concensus. The solution will require in part a better definition of the pipe environment. The paper will present the details behind these areas of uncertainty and will offer suggested approaches and testing techniques towards standardized methods.
Algorithm development for signal-selective seismic field recorders
Authors: Adams Wm. Mansfield
Published: October 2005

A seismic field recorder has been developed based on the MC6800 microprocessor [W.M. Adams, Geophys. Prospect. (to be published, 1977)]. This allows the real-time implementation of algorithms for selecting the signals from the microseismic background and hence for recording primarily signals. The advantages are the greatly reduced amount of recording media that must be processed at the central data-processing depot and the reduction in the amount of data processing that must be done later; the current disadvantages are the battery requirements, the complexity of the equipment, and the lack of effective algorithms. The first two defects will be solved by component evolution; here we discuss the last factor. The present system is not self-adapting. Instead, continuously recorded data are processed by heuristic procedures to find an improved method of selecting the signals from the background. Because of spurious impulsive noise, an energy-content discriminator followed by a zero-crossing (frequency) discriminator is found to be superior to the usual threshold trigger, such as used to turn on the strong motion accelerographs for earthquake engineering research. The algorithm used by the Seismic Research Observatory (SRO) of the USGS is compared with the energy-content + zero-crossing processing. [Work supported by NSF.]
Effect of contralateral and ipsilateral noise on the quality of monaural speech
Authors: Pierce Linda , Pavel Michael
Published: October 2005

This study was carried out to examine certain effects of ambient noise on the quality of speech communication over telephone channels. The stimuli consisted of monaurally presented speech and accompanying circuit noise and binaurally presented background noise. The background noise and the circuit noise had identical spectral characteristics. The stimuli were presented over headphones for good stimulus control. The ambient noise was represented by background noise which remained constant over a block of trials. The variables manipulated over trials were speech level, circuit noise level, and the ipsilateral and contralateral background noise. On each trial subjects heard two phonetically balanced sentences and were asked to respond on a ten-point quality rating scale. The data were analyzed in terms of averages of the ratings. This analysis indicates that the circuit noise is more detrimental to the quality judgments than the identical level of ipsilateral background noise although the two noises have identical physical characteristics. In addition, as expected from contralateral masking studies, the contralateral background noise has only minimal effect on the ratings compared to the ipsilateral noise.
Real-time synthesis of optical lip patterns from vowel sounds
Authors: Erber N. P.
Published: October 2005

An analog circuit has been constructed to convert speech (vowels) to Lissajous-type oscilloscope patterns in real time. The method is like that described by D. W. Boston [Br. J. Audiol. 7, 95–101 (1973)], but includes important circuit modifications to improve naturalness of lip outline and articulatory change. The speech signal receives pre-emphasis resembling ear canal resonance and is split into two channels. Two voltages, one proportional to 200–1000-Hz energy (F1) and the other proportional to 200–3000-Hz energy (F2 in front vowels; F1 in back vowels), are generated to control a multiplier and divider, respectively, which vary levels of sinusoidal signals to form the height and width of the lip outline. Resulting patterns are comparable to lip shapes of vowels in natural speech. Vowel-confusion matrices obtained by lipreading the oscilloscope display (for speech input) are similar to those obtained by lipreading the talker's face directly. The device has been employed in studies of auditory-visual speech perception, and has potential as a telephone communication aid for the deaf. [Work supported by NINCDS.]
Response bias account of selective adaptation
Authors: Elman Jeffrey L.
Published: October 2005

A number of investigators have hypothesized the existence of specialized neurolinguistic mechanisms—feature detectors—as playing a role in the perception of speech. One of the strongest sources of support for feature detectors has come from the selective adaptation paradigm, in which it is supposed that adaptation causes neural fatigue in a feature detector. In this study, a signal detection theory model was developed for phoneme identification tests. Results from identifications of three series of stimuli (/abə-abə/, /bæ-dæ/, /bæ-pæ/) were analyzed using this model to answer two questions: (1) Is increased discriminability of stimuli near the phoneme boundary due to response bias? (2) Does the phoneme boundary shift after adaptation result from criterion movement, or from sensory changes consistent with a feature detector account? Findings indicate that while the phoneme boundary effect does not seem to be due to response bias, selective adaptation is accomplished by a criterion shift, rather than changes at a more basic level of perception. These results suggest that the adaptation effect thus provides no evidence for feature detectors. [Work supported by NSF.]
Recovery from selective adaptation to a voiceless VOT stimulus
Authors: Sharf Donald J. , Ohde R.
Published: October 2005

Recovery from selective adaptation to a voiceless VOT stimulus was determined by having a group of subjects identify stimuli varying in VOT duration as /p/ or /b/ before adaptation, immediately following each of a series of 1 min adaptation trials, and at 1-, 4-, and 7-min intervals following adaptation. Shifts in phonetic boundary loci (in milliseconds) were obtained between preadaptation and adaptation conditions and between adapatation and postadaptation conditions; recovery was measured in percentage of postadaptation shift. Mean recovery was above 50% in the first minute, above 75% at 4 rain, and tended to level off from 4 to 7 min. By 7 min, more than half the subjects achieved at least 75% recovery and more than three-quarters achieved at least 50% recovery. The prevailing recovery patterns for subjects reflected either considerable recovery in the first minute with more gradual recovery thereafter or gradual recovery over the entire time interval. No correlation was found between the amount of boundary shift and the degree of recovery for any of the recovery intervals. For the three time conditions, mean pre-adaptation boundary loci differed by about 1 msec and mean adaptation shifts differed by about 2 msec.
Some relations between duration of silence and duration of friction noise as joint cues for fricatives, affricates, and stops
Authors: Liberman A. M. , Repp Bruno H. , Eccardt T. , Pesetsky D.
Published: October 2005

As is well known, introducing a short interval of silence between the words SAY and SHOP causes the listener to hear SAY CHOP. In isolation, SHOP may be turned into CHOP by reducing the duration of the friction noise. Now, varying both cues orthogonally in a sentence context, we find that, within limits, they are perceived in relation to each other: The shorter the duration of the noise, the shorter the silence necessary to convert the fricatives into an affricate. On the other hand, when the rate of articulation of the sentence frame is increased while holding noise duration constant, a longer silent interval is needed to hear an affricate, as if the noise duration, but not the silence duration, were subjectively longer in the faster sentence. In a separate experiment, varying noise and silence durations in GRAY SHIP, we find that, given sufficent silence, listeners report GRAY CHIP when the noise is short, but GREAT SHIP when it is long. Thus, the long noise in the second syllable disposes the listeners to displace the stop to the first syllable, so that they hear not a syllable-initial affricate (i.e., stop-initiated fricative) but a syllable-final stop (followed by a syllable-initial fricative). [Work supported by NICHD.]
Phonetic context effects on the identification of stop consonants
Authors: Diehl Randy L. , Elman Jeffrey L. , Buchwald Susan
Published: October 2005

Changes in the identification of speech sounds following selective adaptation are usually attributed to a reduction in sensitivity of auditory feature detectors. An alternative explanation of these effects is based on the notion of response contrast. In several experiments, subjects identified the initial segment of synthetic CV syllables as either the voiced stop /b/ or the voiceless stop /p/. Each test syllable had a value of VOT which placed it near the English voiced-voiceless boundary. When the test syllables were preceded by a single clear /b/ (VOT=−100 msec), subjects tended to identify them as /p/, whereas when they were preceded by an unambiguous /p/ (VOT=+100 msec), the syllables were predominantly labeled /b/. This contrast effect occurred even when the contextual stimuli were velar and the test stimuli were bilabial, suggesting a featural rather than a phonemic basis for the effect. To discount the possibility that these might be instances of single-trial sensory adaptation, we conducted a similar experiment in which the contextual stimuli followed the test items. Reliable contrast effects were still obtained. In view of these results, it appears likely that response contrast accounts for at least some component of the adaptation effects reported in the literature.
Phoneme recognition system based on auditory perception
Authors: Searle C. L. , Jacobson J. Z. , Rayment S. G. , Dockendorf D.
Published: October 2005

A phoneme recognizer for stop consonants has been constructed using a system design derived from studies of auditory physiology and psychophysics. The system consists of a case 13-octave filter bank as a reasonable approximation to auditory tuning curves and critical bands, a bank of high speed, wide dynamic range envelope detectors, a logarithmic amplifier, and a digital computer for analysis and display. The detector outputs can be displayed as a type of “spectrum” which we believe is similar in information content to the signals passing along the eighth nerve from the cochlea to the brain. Certain features of these measured “spectra” are then abstracted, such as voice onset time and spectral peaks. The features are chosen to correspond to probable features in the human auditory system, as revealed by psychophysical experiments. These features are then analyzed by methods of statistical decision theory (specifically discriminant analysis) to decide on the most probable phoneme. Examples of running spectra (the equivalent of spectrograms in this analysis method) and results of discrimination trials will be presented.
Categorical perception of /b/ and /w/ during changes in rate of utterance
Authors: Minifie F. D. , Kuhl P. K. , Stecher E. M.
Published: October 2005

Normal sentences containing the sound /w/ were tape recorded and digitized. A normal and a “fast” token of each sentence was stored in a PDP 11-10 computer. The “fast” tokens were created via a pitch-synchronous segmentation program wherein segmentation lines were interactively applied at the zero axis crossing at the beginning of each periodic waveform, and at similar periodic intervals during voiceless speech sounds. Deletion of every third interval resulted in a token of the sentence, increased in rate by one-third. The test consonants plus following vocalic transitions were similarly segmented (11 segments approximately 9 msec each). A recursively applied deletion program allowed alteration of the slope of the CV transitions in 11 steps in both normal and fast utterances. Listeners randomly heard ten presentations of each slope condition for each test sentence at each rate of utterance. Rapid slope changes were heard by listeners as /b/ and more gradual slope changes as /w/. During changes in rate of utterance, the categorical boundary between /b/ and /w/ was shifted toward a steeper slope. The results of this study are discussed in regard to the temporal relativity of categorical boundaries.
Binaural processing of dichotic CV's in a split brain child
Authors: Lenhardt M. L.
Published: October 2005

The subject was a 7-year-old Caucasian female who in May 1977 underwent a section of the corpus callosum for removal of a third ventricular teratoma. CV's (kindly provided by Kresge, L.S.U.) were presented dichotically and at asynchronies of 30, 60, 90, and 150 msec. A strong right-ear advantage was found. The left ear did not perform above chance for single correct identification. There was, however, significant correct identification in the left ear if the CV in the right ear was also correctly identified. In all lead/lag conditions, double corrects occurred above chance levels. Performance at various CV asynchronies appeared to be a function of the number of different CV pairs processed correctly. At the 30-msec interval only DA, TA, and BA were identified. At the 60-msec interval KA, PA, GA, and BA were identified. At the 90-msec interval KA, PA, GA, BA, and TA and at 150 msec PA, GA, BA, TA, and DA were correctly identified. At zero lag all six stop consonants were identified. After commissuratomy, the right ear is superior in the dichotic task to the left ear. However, it should be stated that the left ear is still a viable channel, but subservient to the right.
Response of people to noise—an analysis of a local government's experience
Authors: Peppin Richard J. , Ferrara Gloria J. , Manns Basil H.
Published: October 2005

Montgomery County, an affluent, suburban, and rural county neighboring Washington, DC, has received numerous noise complaints before and after the Noise Control Ordinance became effective (October 1976). A program was initiated to develop an approach to categorize and analyze citizen complaints so that a broad rational statement as to the effectiveness of the ordinance could be made. This paper presents only a part of the results of the program that was developed to analyze the effectiveness of the ordinance and deals only with noise problems that were serious enough to lead to “official” complaints by the citizens. All complaints were tabulated into categories that include the type and location of complaints, the action taken, and the long-term effects of the action. Complaints are plotted as a function of various parameters to show the factors influencing complaints. The analysis will be updated and refined periodically.
Generation of acoustic tones by flow through multiholed plates
Authors: De Metz F. C. , Taylor David W.
Published: October 2005

The mechanisms and scaling laws for acoustic tone generation by gas and liquid flow through multiholed plates have been studied experimentally. Rigid and compliant multiholed plates were tested in quiet air and water flow facilities to determine hydroacoustic and hydroelastic resonance frequencies as a function of hole diameter, length and spacing, and flow conditions. The resonance frequencies are expressed as a Strouhal number based on hole dimensions and flow velocity and presented as a function of Reynolds number, hole shape, and Mach number. The scaling laws for predicting upper bounds for the tone pressure amplitudes are also presented.
Transfer matrix method for sound transmission in acoustically lined horns
Authors: Beckemeyer Roy J.
Published: October 2005

One-dimensional sound propagation in a waveguide of continuously varying area is governed by Webster's equation. For certain axial variations in area and in locally reacting wall impedance, closed form solutions can be obtained. However, for arbitrary variations in these parameters as well as for more complicated forms of the equation, numerical solution techniques are required. In this paper, modified versions of Webster's equation are derived which allow consideration of horns with axial temperature gradients and with inserts of porous material. Numerical solutions to the equations are effected by means of a transfer matrix technique. The horn is segmented axially and the segment length is used as an expansion parameter with which to perform an asymptotic expansion of the governing differential equation. As a result the segment boundary value problem is replaced by a sequence of initial value problems. These are solved to yield a transfer matrix relating the acoustic pressure and particle velocity on the right end of the segment to those on the left. Transfer matrices are developed for each of the horn configurations for which governing equations are derived. Some sample numerical results are included.
Combustor fluctuating pressure measurements in engine and in a component test facility — a preliminary comparison
Authors: Reshotko Meyer , Karchmer Allen
Published: October 2005

As part of a program to investigate combustor noise, simultaneous measurements were made with a YF-102 engine of combustor internal fluctuating pressure and farfield noise. As the dependence of farfield noise on engine internal measurement becomes understood, an important question becomes the connection between combustor internal measurements obtained in an engine and those obtained in a component test facility. To explore this question, a YF-102 combustor, instrumented identically with that of the engine tests, was operated in a component test facility over a range of conditions encompassing engine operation, and the fluctuating internal measurements were repeated. A comparison of the directly measured spectra at corresponding locations in the two tests shows significant differences. However, the results of two-point signal analyses within each combustor such as coherence function, transfer function, and phase relationships are similar for both tests. This indicates that the internal dynamics of the combustor as an acoustic source are preserved in a component test facility.
Water-flow induced cavity resonances
Authors: Farabee T. M. , DeMetz F. C.
Published: October 2005

The mechanisms of water flow-excited acoustic resonances in simple cylindrical cavity systems with circular and slot openings were investigated experimentally. The resonance frequencies of the internal fluctuating pressure field were determined as a function of turbulent boundary-layer thickness, free-stream flow velocity, cavity structural parameters, and opening dimensions for flush-mounted cavities on a large self-propelled streamlined body of revolution. The scaling laws of the cavity resonance frequencies and peak forcing function amplitudes are considered in terms of feedback mechanisms between the shear layer instabilities in the cavity opening and the vibrations of the cavity structures. Predicted and measured results are reported for the amplitude of the pressure field radiated from the cavity openings.
Measurements of the low wave number components of turbulent boundary layer wall pressure fluctuations with zero and adverse pressure gradients
Authors: Moeller M. , Leehey P. , Martin N. C.
Published: October 2005

Two rectangular plates with approximately clamped boundary conditions were used as spatial filters to measure the low wave number components of the wall pressure fluctuations beneath a turbulent boundary layer. The plates were designed to provide low wave number measurements at higher frequencies and wave numbers than previous plate experiments in order to provide data comparable to measurements made using microphone arrays. Measurements were made in the lower test section wall of the MIT low turbulence subsonic wind tunnel under zero pressure gradient and adverse pressure gradient conditions. The zero pressure gradient data lies in the wave number frequency range 2.5 <ωδ*/U∞<10 and 0.5 <k1δ*<1.8 while the adverse gradient data lies in the range 4.5 <ωδ*/U∞<23 and 0.9 <k1δ*<4.6. Momentum thickness Reynolds numbers ranged from 6000 to 11 000 for the zero pressure gradient case and 11 000 to 16 000 for the adverse pressure gradient case. When normalized on outer variables the adverse gradient data do not exhibit increased levels from those of the zero pressure gradient data. [Work supported by the Sonar Technology Program, Office of Naval Research.]
Flexural wave baffling
Authors: Ko S. H. , Sherman C. H.
Published: October 2005

An effective baffle must have a high insertion loss which is usually measured with normally incident plane sound waves. In some applications the following question arises. Is a baffle which has a high acoustic insertion loss also effective when used in other situations where acoustic insertion loss is not the direct requirement? For example, can the pressure fluctuations produced in a fluid by flexural vibrations in a plate be effectively reduced by covering the plate with an acoustic baffle? A simple model has been used to investigate this question in which the baffle is taken to be a layer of lossless fluid. For evaluating flexural wave baffling this layer is in contact with a vibrating plate, and the reduction is pressure caused by the layer is calculated. The plane wave acoustic insertion loss is also calculated for the same layer and compared with the flexural wave insertion loss. It is found that the baffling achieved in these two situations is nearly the same for some types of plate vibrations, but quite different for other types. [Work supported by CNM.]