bluuebunny/crossref_metadata_2025 huggingface dataset:
The effects of impulse noise level on the magnitude of asymptotic threshold shift (ATS) in the chinchilla
Authors: Hamernik R. P. , Henderson D. , Salvi R.
Published: October 2005

Four groups of monaural chinchillas were exposed to either 99, 106, 113, or 120 dB peak SPL reverberant impulse noise for 10 days. The impulses had a “B” duration of approximately 160 ms and were presented at the rate of 1 impulse/s. Hearing thresholds were monitored before, during, and for 40 days after exposure. After 24 h in noise, all four levels produced a stable ATS. The level of ATS at 0.5, 2.0, and 8.0 kHz grew at the rate of 2.5 dB for each dB increase in the impulse noise level. The PTS function at these frequencies suggests a threshold effect, i.e., the two lowest levels produced no PTS, while at the two highest levels PTS began to increase rapidly. The relation between ATS and PTS is complex. Both the 106 and 113 dB exposures produced similar levels of ATS but the 106 dB group showed no PTS while the 113 dB group developed as much as 30 dB PTS at 2.0 kHz. Although the data are limited, it appears that after some criterion level has been reached, PTS also grows at the rate of 2.5 dB/dB. The cochleograms for the four groups of animals show an orderly increase in the severity of damage. However, an orderly relation between individual cochleograms and audiograms was not found. [Work supported by NIOSH and NIEHS.]
Threshold shifts in chinchillas exposed to octave-band noise centered at 125 Hz for three days
Authors: Burdick Charles K.
Published: October 2005

Maximum threshold shifts for exposures to octave bands of noise having center frequencies of 500–4000 Hz are found one-half to one octave above the exposure-band center frequency (Carder and Miller, J. Speech Hear. Res. 15, 603–623). Maximum threshold shifts produced by exposure to octave-band noise centered at 63 Hz are found four to five octaves above the exposure-band center frequency. The question arises as to the frequency at which the maximum threshold shifts occur to octave bands of noise with center frequencies between 63 and 500 Hz. The present experiment was conducted to provide such information. A group of four monaural chinchillas was exposed for three days to an octave band of noise centered at 125 Hz at an intensity level of 110 dB SPL (94 dBA). Maximum threshold shifts occurred at four and four and one-half octaves above the center frequency of the exposure band, i.e., at 2000 and 2800 Hz.
An environmental stimulus for sudden death in infancy
Authors: Dickinson Philip
Published: October 2005

The results of a detailed examination of the circumstances surrounding all cases of Sudden Infant Death (Crib Death) in Utah over a 3-yr period, strongly suggest the influence of an environmental stimulus or trigger. Of the parameters investigated the leading candidate at the moment appears to be low-frequency noise—either naturally occurring in some sizes of family home, or produced in a moving automobile.
How loud are television commercials in comparison with the programs
Authors: Potter Richard C. , Potter John F.
Published: October 2005

The loudness of prime-time television programs and commercials was measured by obtaining 30-s Leq sound levels at a typical viewer location in a representative living area. Preliminary results suggest that the overall sound levels are similar for both the commercials and the programs. However, the range of sound levels is much greater from the programs in comparison with the commercials, which all tend to be at the same higher sound level. The subjective differences are presented in terms of the statistical descriptions and frequency content of the sounds.
Estimation of short-time spectral envelope of voiced speech using maximum entropy method of spectral analysis
Authors: Paliwal K. K. , Rao P. V. S.
Published: October 2005

The Burg maximum entropy (ME) method of spectral analysis is used to estimate the short-time spectral envelope of the voiced speech signal. A number of vowel segments from continuous speech are analyzed using this method. The Burg ME method is compared with the autocorrelation and covariance methods of linear prediction using normalized linear prediction error and accuracy in estimating the speech spectrum as criteria. It is shown that the Burg ME method consistently gives better results than the autocorrelation method of linear prediction for both pitch-synchronous and pitch-asynchronous analyses. For pitch-synchronous analysis, this method performs slightly better than the covariance method, while for pitch-asynchronous analysis, its performance is marginally inferior to that of the covariance method.
Evaluation of the effects of aperiodic components on a periodicity measure of voiced speech
Authors: Bancroft J. C.
Published: October 2005

A measure for quantifying the periodicity of normal and abnormal voiced speech was developed using the modified short time auto-correlation function. [J. C. Bancroft, J. Acoust. Soc. Am. Suppl. 1 65, S67 (1978)]. The aperiodic components within the voiced waveform are not evaluated with equal weighting when processed by this periodicity measure. The effects of shimmer, jitter, additive noise, and additive periodic noise were identified and their influence and contribution to the overall periodicity measure were evaluated. These results will be presented along with the effects of anti-aliasing filters on the measure.
The intrinsic pitch of vowels in sentence context
Authors: Shadle Christine H. , Pierrehumbert Janet B. , Liberman Mark Y.
Published: October 2005

It has long been accepted that high vowels have a higher intrinsic pitch than low vowels. First noted by J. W. Black [J. Speech Hear. Disorders 14, 216–221 (1949)], this effect has been verified for different consonantal environments and in several languages. However, all studies of intrinsic pitch of vowels have used nonsense words, either in isolation or bearing the main phrasal stress in a carrier sentence. As a first step towards an understanding of how the intrinsic pitch of vowels interacts with intonation in running speech, this study examined the F0 of the vowels in “reed,” “rod,” and “rude” in sentence context. Results for four speakers are reported, for four locations in sentences matched for length and stress pattern. A statistically significant effect of vowel height was found for all speakers in all positions. In addition, /u/ was generally higher than /i/, confirming results reported by Lehiste and Peterson [J. Acoust. Soc. Am. 33, 419–425 (1961)]. Possible explanations for these results will be discussed. [Work supported by NIH and Bell Laboratories.]
Acoustic characteristics of first week infant cries and their relationship to sudden infant death syndrome
Authors: Colton R. H. , Steinschneider A.
Published: October 2005

Several acoustic characteristics of cries produced in the first week of life by normal full term, premature, and SIDS sibling infants were analyzed using a sound spectrograph and a graphic sound level recorder. The characteristics analyzed were fundamental frequency, overall sound pressure level, duration, F1, F2, F3, energy in the range from 0.05–4 kHz (spectral band ♯ 1), energy in range 4–8 kHz (spectral band ♯2), and energy in the band 8–16 kHz (spectral band ♯3). Of the three infant groups, normal newborn infants (N = 66) exhibited the highest average f0, shortest duration and lowest center frequency of the first three formants. In addition, most of the energy in their cries was below 8000 Hz. The premature infant group (N = 58) exhibited greater variability among the measures and tended to produce greater energy in the higher frequencies. The group of SIDS siblings (N = 22) exhibited the lowest f0, highest f0, and greatest energy in the higher frequencies of the cry. With respect to the cry variables, a multiple regression analysis revealed that the center frequency of the first formant was significantly related to the distinction between normal full terms and premature infants whereas fundamental frequency and the energy in the frequency band from 4–8 kHz were both significantly related to the normal full term/SIDS SIB distinction.
Numerical method for calculating input impedances of organ reed pipes
Authors: Plitnik George R.
Published: October 2005

The physical dimensions of organ reed pipe resonators are used to compute the input impedance as a function of frequency for each resonator. The numerically computed input impedances are compared to experimentally measured curves and some discussion of the tone color resulting from the interaction of a coupled reed-air column system is provided.
Organ reed and air column regenerative relations: Tools of the voicer's trade
Authors: Benade A. H.
Published: October 2005

There is a sharp dynamical distinction to be drawn between an orchestral woodwind (in which the flow controlling reed is almost totally dominated by the resonances of its air column), and the human speech mechanism (where the frequency of the oscillating vocal folds is little affected by vocal tract resonances). The lip reed-air column interaction of the brass instruments has an intermediate position, but fairly close to that of the woodwinds. In the pipe organ one finds reed-air column combinations having all degrees of mutual influence, and problems sometimes arise when one member of the collaboration “escapes” from the instruction of the other. Over two decades ago work with Bruce Schantz to solve some pipe design problems, and to systematize voicing procedures (to control pitch, loudness, and tone color), introduced your speaker to a wide variety of easily reproduced, highly nonlinear, multidegree of freedom oscillations. Some of these will be discussed, and attention drawn to the way that they guided the development of our current understanding of orchestral wind instruments. [Work assisted by NSF.]
Effects of finite aperture and nearfield oscillations in a parametric acoustic array
Authors: Tjötta Jacqueline Naze , Tjötta Sigve
Published: October 2005

On the basis of a simplified analytical expression for the linearized sound field from a baffled piston source (see Paper GG2, by the same authors, in this Program), we calculate the effects of nearfield oscillations on the generated difference frequency wave in a parametric acoustic array. We also derive a generalized aperture factor which is valid for short and long ranges. [Work supported in part by the Office of Naval Research.]
Axisymmetric propagation of a spherical N wave in a cylindrical tube
Authors: Essert Robert D. , Blackstock David T.
Published: October 2005

Measurements have been made in air of the transient sound produced by a point source (an electric spark) inside a tube. Source and receiver are located on the tube axis, a distance L apart. In the received waveform the direct sound, an N wave, is followed by a sequence of reflected signals, the first representing a single reflection (at 12L), the second a double reflection (at 14L and 34L), and so on. The first reflected signal resembles an N wave, but the second is a U-shaped pulse, the third an upside down N, the fourth an upside down U, and the fifth an N wave again. The four-waveform cycle is repeated indefinitely. The sequential change in waveform is attributed to the two-dimensional focusing (which causes a 90° phase shift) that occurs each time reflected rays cross the tube axis. Nonlinear behavior has also been measured: when the source amplitude is increased, the phase shift of the reflected signals changes. Theoretical work, in which absorption is accounted for, is in progress. [Research supported by ONR.]
Phase insensitive frequency tracked tone-hurst spectroscopy
Authors: Cantrell John H. , Heyman Joseph S. , Winfree William P.
Published: October 2005

Ultrasonic spectra obtained by conventional Fourier-transformed pulse spectrum analysis techniques are influenced (1) by the shape of the electrical drive pulses used to generate the ultrasonic waveform and (2) by the sensitivity of the receiving transducer to phase front variations of the incident wave across its face. A new method of ultrasonic frequency analysis is introduced which combines the newly developed phase insensitive acoustoelectric transducer (AET) with a frequency tracked tone-burst spectroscopy (TBS) technique. TBS eliminates pulse shape artifacts in the ultrasonic spectrum by generating spectra equivalent to exciting the transducer with a true delta function shock excitation. Spectra from the AET-TBS combination are shown to produce clean spectral information even when sample inhomogeneity and geometrical irregularity severely degrades the spectral output obtained with conventional methods.
Atmospheric finestructure in an arctic valley
Authors: Kerman B. R. , Mickle R. E.
Published: October 2005

Multiple layers of turbulence were observed by an acoustic sounder in the Shakwak Valley of the southern Yukon. The layers, extending in time for more than five days, were found to correlate highly with temperature steps observed by a tethered balloon system. During the period of the observation, the wind was virtually calm and the skies clear, suggesting a radiational cause for the phenomenon. Various mechanisms are discussed with particular attention to the possibility of a dynamic instability of katabatic (Stewartson) sidewall layers. Order of magnitude estimates suggest that the lateral turbulent heat flux of such eddies is comparable to the radiational heat losses of the valley walls.
Monitoring the diffusivity of the atmospheric boundary layer by acoustic sounding
Authors: Kerman B. R.
Published: October 2005

The concept of asymptotic diffusion states is extended to the outer boundary layer. Various models are introduced for the determination of maximum ground level concentration based on classical similarity arguments for plume rise, equilibration, and downwash. An analysis is offered for the estimation of the controlling mean and turbulent parameters (surface heat flux and stress, mixing depth, wind speed and outer flow stability) by acoustic sounding. Further developments are outlined for the estimation of internal turbulent parameters based on revision of the classical Monin-Obukhov similarity theory in terms of acoustic scattering observables.
Psychoacoustic measures of hearing impairment
Authors: Wightman Frederic L. , Raz Israel
Published: October 2005

Several laboratories have used psychophysical methods to study various aspects of hearing impairment in the belief that rigorous stimulus and response control would lead to stable and revealing results. Unfortunately, the data obtained thus far in our laboratory are disappointing. In spite of efforts to obtain homogeneous groups of subjects (using audiometric profiles), to practice them thoroughly, and to conduct rigorous, well-controlled research, the results of most of our experiments have been just as variable as the previous work. We feel this is probably due to the failure of standard audiometric measures to classify hearing-impaired listeners in terms of their basic auditory abilities. Current work in our laboratory is directed at developing alternative means for classifying hearing-impaired listeners, based on cluster analysis of performance on a large number of psychoacoustic tests. [Work supported by NIH Grant No. NS12045 and NS07108.]
Measurement and analysis of the dynamics of mechanical structure
Authors: Litz James O.
Published: October 2005

Modern methods for testing, modeling, and analyzing the dynamics of mechanical structures are given. Modes of vibration are shown to be the link between a model developed using finite-element methods and a transfer-function model, the elements of which can be measured in the laboratory. Testing techniques are reviewed with emphasis on the transfer function method.
Electromagnetic noise in large induction motors
Authors: Koizumi Takayuki , Narita Masao
Published: October 2005

An approach to prevent noises of large induction motors which are subjected to various forms of vibration caused by electromagnetic exciting forces is presented. From the results obtained in experimental investigations for many actual large motors, it has become clear that all the components of the noise and vibration paths from exciting point to radiational sound field must be taken into consideration for avoiding typical peak noise and vibration. A substructural system analysis is adopted to comprehend the vibrational behavior of all components by using FFT (fast Fourier transform) analysis and the transfer function method. The combined system simulation is done in a digital computer by using modal parameters to estimate the frequency response of the total structure. It means that the contributions of each component to the total noise and vibration are predicted without actual motors. Now, through this investigation, it is considered possible to predict quantitatively the effects of each component al least on vibration.
A propagator matrix method for periodically stratified media
Authors: Gilbert Kenneth E.
Published: October 2005

The propagator matrix formalism is a convenient method for treating horizontally stratified media [F. Gilbert and G. E. Backus, Geophysics 31, 326 (1966)]. Until now, however, it apparently has not been applied to periodic media. This paper shows how the propagator formalism can be used in conjunction with Sylvester's theorem to obtain an extract solution for the propagation of waves in a periodically stratified layer of arbitrary thickness. Explicit expressions are derived for the simple case of a periodically layered fluid. These expressions are used to investigate several interesting limiting cases. Application of the method to more complicated cases is discussed.
The uniform asymptotic expansion with concave caustics
Authors: Floyd Edward R.
Published: October 2005

While the uniform asymptotic expansion had been developed for smooth convex caustics [D. Ludwig, Commun. Pure Appl. Math. 19, 215–250 (1966)], its validity to concave caustics has been tacitly assumed by the underwater acoustics community. A counter example based upon deriving the ansatz quantities from ray-tracing wavefronts for a concave caustic exhibits both a domain on the ensonified side of the caustic where the uniform asymptotic expansion is valid and the domain's complement where the uniform asymptotic expansion is degraded monotonically with penetration into this complement.
Range-dependent propagation in coastal waters
Authors: Kuperman W. A. , Jensen F. B.
Published: October 2005

The parabolic equation (PE) is used to study sound interaction with a sloping ocean bottom and some of the results are compared to a model tank experiment. The bottom, as inputted in the PE model, is characterized by sound speed, density, and attenuation. Practical running times have been achieved for these coastal water studies by utilizing a real time computer system with an array processor. Up and down slope propagation is studied demonstrating mode conversion and mode cutoff. For the upslope propagation we find that each mode cuts off by radiating a discrete beam into the ocean bottom and that there is very little conversion into the next lower mode. Mode cutoff occurs at approximately the depths predicted by normal mode theory but the cutoff takes place over a finite distance which essentially provides an aperture of many wavelengths for radiation of the beam into the bottom. An important conclusion that one can draw from this study is that mode-coupling theories should also include the coupling into the local continuous modes which would then provide the description of the radiation into the bottom.
A different … view … of attenuation … Part III, Conclusion
Authors: Maples Louis C
Published: October 2005

“A Different Point of View on the Role of Attenuation as a Component of Total Propagation Loss in Underwater Acoustics,” a paper given at the 96th Meeting of the Acoustical Society, and its sequel, Part II, presented at the 97th Meeting, presented a mathematical model for propagation on the axis of a sound channel which proposed simple random-phase addition of multipath signals as the mechanism determining spreading loss, rather than the usually accepted cylindrical spreading. Interpretation of experimental attenuation data using the new expression results in lower coefficient values that those of Thorp, Browning et al., based on the same data. Earlier studies involved eye-fitting to published plots, and least-squares fits to calculated propagation data produced by Weinberg's generic model. The present paper compares “old and new” attenuation model analyses of actual raw data, as planned for Part II, but made possible only in July 1979, with obtaining of the original records. [Work supported by the Naval Underwater Systems Center.]
Propagation of sound from water into a sloping fast bottom
Authors: Coppens A. B. , Sanders J. V. , Bradshaw N. , Kawamura M. , Ioannou I.
Published: October 2005

When sound is propagated from large distances toward the apex of a fluid wedge overlying a fluid bottom in which the speed of sound is greater, acoustical energy must be transmitted into the bottom as the various normal modes in the wedge are cut off. (Alternatively, we can say that the rays of sound, because of the continual increase in their grazing angles of incidence on the wedge-bottom interface resulting from successive reflections between the wedge surfaces, will eventually obtain angles of incidence greater than critical, at which time they will begin to be refracted into the bottom; this simple view is qualitative only.) In our approach we use the method of images to calculate the distribution of pressure and its phase at the interface, and then treat the interface as a distribution of sources and calculate the field radiated into the bottom by the Green's function integral. Both calculations require a high-speed digital computer. Preliminary results and comparisons with experiments will be discussed. [Work supported by ONR and NOSC.]
Optical simulation of acoustic propagation through deterministic and internal wave sound speed variations
Authors: Estes L. E. , Fain G.
Published: October 2005

We make use of an argon-ion laser operating at 4880/ Å to model portions of the 406-Hz MIMI experiments. Our simulation covers a range of 250 km. The Garret-Munk internal wave model is used to construct two-dimensional sound speed profiles at 15-rain intervals. Each profile is recorded as a separate photographic plate. The plates are imaged using a high-intensity ruby laser beam to differentially heat a fluid. The argon-ion laser beam propagates through the light speed variations caused by the heating. The modeled rms sound speed fluctuation at the sound channel is approximately 0.01%. Phase and intensity measurements are made. Our results are compared with numerical models and extrapolated experimental results. Using the deterministic sound speed profiles reported by Clark and Kronengold, [J. Acoust. Soc. 56, 171–1083 (1974)], we present measurements of intensity as a function of range and depth. [Work supported by the Office of Naval Research.]
Shadowing by seamounts
Authors: Medwin H. , Spaulding R.
Published: October 2005

Major topographical features such as seamounts can cause large propagation losses which are functions of sound frequency and the type of interruption of the sound path. A 2 × 2 × 0.2-m high model of Dickens Seamount has been constructed of wood and plaster to a scale of 1:7874 and the sound shadowing in air has been studied for various source/receiver locations and for five octaves of laboratory frequencies. A new universal concept, the farfield “diffraction strength,” is defined. The diffraction strength obtained from laboratory measurements is used to predict the isovelocity, frequency-dependent diffraction loss at sea. This loss is added to predictions of ray refraction losses during propagation up to, and away from, the seamount. This sum agrees well with the total long-range ocean propagation loss measured beyond Dickens by G. R. Ebbeson, J. M. Thorleifson and R. G. Turner [J. Acoust. Soc. Am. 64, S76 (1978)]. The scale model is a relatively inexpensive device to aid in the prediction of shadowing losses at sea.
A time-dependent difference theory for sound propagation in ducts with shear flow
Authors: Baumeister K. J.
Published: October 2005

A time-dependent numerical formulation is derived for sound propagation in a two-dimensional straight soft wall duct with a sheared mean flow. The time-dependent continuity and momentum equations are developed along with the soft wall boundary conditions. The appropriate governing equations and boundary conditions are solved simultaneously by an explicit iteration procedure. The analysis begins with a harmonic noise source radiating into a quiescent duct. This explicit method calculates stepwise in real time to obtain the transient as well as the “steady” state solution of the acoustic field. The von Neuman method is used to develop relationships which describe how sound frequency and grid spacing effect numerical stability. The soft wall boundary conditions require special treatment to keep the iteration technique stable. Example calculations are presented for sound propagation in hard and soft wall ducts. The time-dependent analysis has been found to be superior to the steady finite difference and finite element techniques because of much shorter solution times and the elimination of matrix storage requirements.
Application of partial coherence methods for identification of interior noise sources in aircraft
Authors: Howlett James T.
Published: October 2005

Effective interior noise control procedures require identification of the noise sources and the noise transmission paths. Recent developments in computational procedures have led to increased interest in partial coherence analyses for source/path determination. The theoretical aspects of this method have been explored by Bendat and also by Dodds and Robson; however, only a few reports of applications to practical problems are available. Previous authors reported only partial success in identifying sources. Therefore, improvements of the approach are felt to be needed. This paper describes the latest results of an ongoing effort to develop partial coherence techniques for interior noise source/path determination in aircraft. The paper includes a summary of the computational techniques as developed by Bendat [J. Sound Vib. 49(3), 293–308 (1976)] and illustrates the application to a two-input, single-output system with coherence between the inputs. Solution of this system by previously used methods illustrates the occurrence of erroneous results (including negative psd) in the course of the calculation. New results are presented to suggest possible sources of the negative psd, and to suggest a procedure for avoiding this problem. The augmentation of the calculations on a digital computer interfaced with a two-channel real-time analyzer is also discussed. Future plans in the development of the partial coherence method includes application to experimental source identification in laboratory tests using simulated aircraft noise sources and fuselage transmission paths.
A comparison of acoustic sounder returns and C
T estimated from meteorological parameters
Authors: Smith D. A. , Hicks R. B. , Mathews T.
Published: October 2005

A vertically oriented monostatic acoustic sounder has been used in conjunction with a tethered balloon profiler for a series of observations on the stable atmospheric boundary layer immediately following sunrise. Estimates of relative average values of CT over the height range 60–220 m were derived from the acoustic backscatter results and were compared with predictions based on wind and temperature profiles using several different models. Our results show that reasonable correlation can be achieved using the temperature gradient as the sole meteorological parameter. Use of more sophisticated models based on similarity functions or atmospheric energy budget does not significantly improve the correlation obtained.
The detection of the temperature structure coefficient of atmospheric boundary layer by acoustic radar
Authors: Ming-yu Zhou , Nai-ping Lu , Yan-juan Cheu
Published: October 2005

The magnitude of temperature structure coefficient is computed by sounder echo data. The results showed that the magnitude of CT2 has an obvious fluctuation with time. It has a character of positive bias distribution, and fits the logarithmic normal distribution. The analysis of the spectra CT2 showed that, the spectrum F(k) of CT2 usually fits the k−4 rule in stable and unstable stratifications. There exists a peak range of energy on the frequency range 10−1 − 3 × 10−4 s−1. The analysis of CT2 on time-height counter section indicates that the distribution of Cr CT2 has horizontal stratum structure in stable stratification and it fits the rule CT2 ∝ z−4/3 in unstable stratification. These results measured by acoustic radar agree with earlier direct observations by airplanes [L. R. Tsvang, Radio Sci. 4(12) (1962)].
Internal noise measurements
Authors: Spiegel Murray , Green David M.
Published: October 2005

The purpose of this study is to compare two ways of estimating the ratio of internal noise variability to external noise variability (σ1/σE). One method [D. M. Green, Psychol. Rev. 71, 1392–1407 (1964)] infers internal noise from the consistency a listener shows in choosing between two different noise maskers when the same pair are repeated on another trial. The second method [R. A. Siegel, masters thesis, M.I.T. (January 1979)] infers internal noise from the difference in signal detectability between trials containing a pair of identical versus different maskers. The masker bandwidth (narrow = 100 Hz or wide = 2800 Hz) and mode of presentation (continuous, burst, or continuous with gaps surrounding the observation intervals) were varied. The observation interval was 10 ms. Both methods estimate the ratio (σ1/σE) to be within experimental error of unity for most conditions. Factors that influence the estimate will be discussed, such as temporal uncertainty, response bias, binomial variability in the estimate of detection performance, and incoherence between signal and masker. [Work supported in part by a grant from the National Institutes of Health, Public Health Service, U.S. Department of Health, Education and Welfare.]
Scattering of sound from a randomly rough solid-liquid interface
Authors: Numrich S. K.
Published: October 2005

Measurements have been made of sound scattered by submerged surfaces with Gaussian height and slope statistics. A wide range of roughness was spanned through the use of transient pulse analysis. In terms of the ratio of the rms surface height (σ) to sound wavelength (λ), the range included 0.03 < (σ/λ) < 5.0. Coherent and incoherent terms were separated digitally. In the region of small roughness, the coherent reflection coefficient was compared with two theoretical models. Comparisons with theory were also made using the incoherent term when large values of roughness were involved. At both extremes of the range, the experimental data agreed well with the theoretical predictions. Of particular interest in this experiment is the intermediate region in which the coherent and incoherent terms are explained in detail. Here the coherent term decreases rapidly and the incoherent term begins to dominate the scattering return. No adequate theoretical model exists for this transition region. [Work supported by ONR, Code 461, and NOSC, San Diego.]
Discrimination between random signals
Authors: Pollack Irwin
Published: October 2005

Random polarity pulse trains of two states (plus and minus polarity) and of three states (plus and minus polarity and no change at defined clock intervals) were constructed and presented to listeners within forced-choice discrimination tests. The pulse trains were either of the same average pulse density or were amplitude-compensated for different pulse densities. Since the long-term spectrum of such signals is uniform, the most likely discriminable feature is the short-term spectrum or the temporal patterning of the signals. Successful discrimination is obtained even for pulse trains of extremely high clock frequencies. [Work supported by NSF.]
Phase effects in pure tone central masking
Authors: Calder H. B.
Published: October 2005

Centrally masked threshold shifts were determined for 1000-Hz pure tone signals masked by a 200-ms, 1000-Hz masker with either 0° or 180° interaural phase disparity between the signal and the masker. Three signal durations of 20, 100, and 200 ms were employed in the study. Differences in the masked thresholds of 1.5 to 5.6 dB were occasioned by the phase reversal of the signal and masker with the greatest difference occurring for the 200-ms duration signal. These results support models which account for central masking on the basis of a physiological interaction at the level of the brainstem. [Work supported by Horace Rackham Graduate School.]
Acoustic cues in the identification of vowel sequences
Authors: Kerivan J. E. , Alfonso Peter J.
Published: October 2005

We have observed that at 30- and 60-ms durations some permuted orders of 4 synthetic vowels /i, æ, a, u/ were much more identifiable than others using a single sequence method [Kerivan, Alfonso, and Bornstein, J. Acoust. Soc. Am. Suppl. 1 65, S113(A) (1979)]. Also, significant improvements in identification of difficult sequences occurred when silent gaps were placed between selected vowels resulting in a rhythmic grouping of the sequence. These findings have been correlated to the various acoustic parameters used to synthesize the vowels. The results of these multiple correlations show that the identification of vowels in sequence follows the laws of pitch continuity established by numerous investigators using tonal sequences. The more monotonic pitch continuity displayed by adjacent first formants the better is sequence identification. A similar but weaker correlation was found between sequence identification and pitch proximity of fundamental frequencies. An interaction was also found between pitch and loudness of adjacent fundamental and formant frequencies. The relative intensity differences for all first formants were within 3 dB; however, those for fundamental frequencies were as disparate as 11 dB. It appears that the ear primarily tracks the first formant of each vowel complex in determining vowel identity in the sequence. [Work supported by an NINCDS NIH grant awarded to Haskins Laboratories and the University of Connecticut Research Foundation.]
Temporal and spectral cues to syllable stress
Authors: Smith Mary R.
Published: October 2005

The interaction of temporal and spectral information for judgments of syllable stress was studied using a formant pattern of each of the vowels /i/, /I/, and /ɝ/ of English. The patterns were arranged to form all nine possible disyllables in the nonsense frame /s-ds-d/. In all disyllables the duration of the first vowel varied in 10-ms steps from 50 to 150 ms while the duration of the second vowel was changed to keep the work length constant. Fundamental frequency and intensity were kept constant within and across the words. Eight subjects judged the stress, length, and phonetic identity of the target words in isolation. The 50% crossover points for the stress and length judgments as a function of vowel duration were obtained by PROBIT analysis and subjected to an analysis of variance with phonetic identity as the treatment. Further tests show a significant difference between the locations of stress boundaried for different vowel pairs. The results are not so clearly a function of the inherent duration of the phonemes involved as previous research suggests.
Masking of short probe sounds by tone bursts with a sweeping frequency
Authors: Coninx F. , Smoorenburg G. F.
Published: October 2005

The masked threshold of a short probe tone or a short one-third octave probe noise appears to increase if the frequency of a tonal masker is swept. Frequency sweeps were exponential (octave/s) and unidirectional. Probe sounds were presented in the time center of the masker at the center frequency of the masker. The sweep gradient appeared to be an important parameter, masker duration was much less important. For 10-ms probes, 100-ms maskers, and upward sweeps increase of the masked threshold appeared to be maximal at a sweep gradient of 30 octave/s and the masked threshold was 21 dB higher than the masked threshold found for the steady masker (0 octave/s). Above 30 octave/s the masked threshold decreased. For downward sweeps masking was maximal at 20 octave/s and the threshold was 15 dB higher. The results are inconsistent with current models of masking: sweeping the frequency, the masked threshold increases whereas the energy within the critical band at the probe frequency decreases. [Research supported by the Netherlands Organization for the Advancement of Pure Research, ZWO.]
Developmental reading and dichotic listening
Authors: Lenhardt M. L.
Published: October 2005

It has been observed that the relative size of the right ear advantage [REA] to CVs does not change from 5 years upward. In addition, children showing right or left hemispheric representations for speech can be distinguished by the way they read. Right ear dominants read relatively fast but inaccurately, while left ear dominants read slow but accurately. Left ear dominants exhibit right [visual-spatial] hemispheric strategies in initial learning to read. The better readers are characterized by shifting from left to right ear dominance by grade 5. One hundred poor readers in grades 1–5 were studied with dichotic CVs. The relative REA remained constant until grade 5 when it lowered with an increase in left ear scores. Double corrects [DC] increased while double errors decreased across all grades. Analysis of DC scores revealed a 22% order report effect with left ear CVs reported first for grade 1, afterwards the right ear CV was reported first. Poor readers at grade 5 had normal REAs, DCs, but had phonetic errors in DC like younger children. In fact the reading and phonic skills were also like children in first grade. Related listening and reading hemispheric strategies will be discussed.
A comparison of listener and speaker perception of nasality
Authors: Burzynski Cecile M. , Garber Sharon R.
Published: October 2005

The relationship between speaker and listener perception of nasality was investigated by having speakers judge their own productions as they vocalized. The productions were taped and played to listeners who judged the speaker's nasality. In part one, speakers used a magnitude production procedure and both speakers and listeners rated nasality, using a ratio scale. Output from an accelerometer placed on the speaker's nose provided a measure of nasalization. Self-perception grew approximately as the 4.4 power of nasalization. Listener perception grew as the 2.2 power of nasalization. Thus, self-perception of nasality grew twice as rapidly as listener perception for a given increase in nasalization. In part two, both listeners and speakers used a magnitude-estimation procedure. The exponents for the power functions for self and listener perception were 3.6 and 1.7, respectively. The 2 to 1 relationship between self and listener perception of nasality held when different procedures were used. The 2 to 1 ratio closely paralleled data on vocal loudness. [H. L. Lane, A. C. Catania, and S.S. Stevens, J. Acoust. Soc. Am. 33, 160–167 (1961)].
Real-time ADPCM coding on a digitat signal processing integrated circuit
Authors: Boddie James R. , Johnston James D. , McGonegal Carol A. , Upton John W.
Published: October 2005

An algorithm for adaptive differential pulse-code modulation (ADPCM) has been implemented in real time on a Bell Laboratories produced digital signal processing integrated circuit [J. S. Thompson and J. R. Boddie, IEEE ASSP Conference, Denver (April 1980)]. The algorithm demonstrates the flexibility and programability of the IC processor for doing medium-scale signal processing. The processor can decode an instruction, fetch data, and perform a 16-bit by 20-bit multiplication and a full 36-bit product accumulation in one machine cycle of 800 ns. An 8-kHz, 4-bit, ADPCM coder and decoder have been implemented for simultaneous operation, consuming approximately one-half of the processor's capability. General details of the IC architecture and the adaptation of the ADPCM algorithm to this architecture will be discussed.
Laboratory exercises in noise control engineering
Authors: Bradley J. S.
Published: October 2005

In the Faculty of Engineering at the University of Western Ontario, noise control engineering courses are taught to final year undergraduates and to graduate students in our Master of Engineering program. The M.Eng program is a one-year course work masters in noise control engineering and is the only program of this type in Canada. Laboratory exercises are seen to be an essential enhancement to lectures in noise control engineering, and are intended to not only reinforce concepts learned in lectures but also to give a better appreciation of the gaps between theory and the real world. Because of the applied nature of the subject most laboratory exercises have been planned so that they demonstrate the various fundamentals, but in realistic situations. A wide range of conventional acoustical instrumentation is used as well as several purpose build pieces of equipment. Physical measurements have been enhanced by a number of interactive computer programs that allow students to make more extensive measurements as well as to explore various relationships via the computer programs. A number of laboratory exercises are discussed with respect to their special features and purposes.
An undergraduate course in noise control engineering
Authors: Dunn Stanley E.
Published: October 2005

The considerations of offering a course in noise and vibration control at the undergraduate level are presented. Based on several years of experience in an Ocean Engineering program environment, attention is given to goals and objectives of the course, the desirable prerequisites, program support and faculty requirements, the constraints and the accomplishments of the course. In particular, the organization of the course around the source-path-receiver model is discussed. Attention is also given to the design aspects of engineering and the way in which course material is selected to meet engineering design requirements, such as those set forth by the Engineering Council for Professional Development. The utilization of a full scale problem lasting the duration of the course is discussed, including the organization of the students into design teams. Finally, the use of the course as a measure of the effectiveness of the remainder of the Ocean Engineering program to provide necessary preparation is discussed.
Noise control education at Iowa State University
Authors: Holger D. K.
Published: October 2005

Noise control education for engineering students at Iowa State University consists of two formal courses devoted to the area of noise control, a number of supporting courses in related areas and research or design experience involving industrial noise control problems. The development of this educational package and the various levels of undergraduate and graduate student participation in the package are discussed. This highly informal program in noise control attempts to serve the needs of students who desire an introduction to the concepts of noise control as well as those of students who wish to informally specialize in the area of noise control. The core of noise control education for both groups is a senior level elective course which incorporates formal lecture-recitation instruction, text book problems, laboratory experience and actual industrial noise control design problems. The content and organization of this course will be discussed and examples of typical laboratory and project work will be presented. Supporting courses in related areas and an introductory graduate course in noise source analysis are also summarized.
Workshop on Using MEDLINE: Information Retrieval in Communicative Sciences and Disorders
Authors: Ludlow C. L. , Reiner B. J.
Published: October 2005

Participants will be introduced to MEDLINE, the major data base of the medical literature analysis and retrieval system of the National Library of Medicine (NLM). This computerized data base contains citations of articles drawn from 3000 journals worldwide. It can be searched online at computer terminals either independently or with the assistance of technical information specialists located at over 800 online centers in the United States. MEDLINE citations include author, title, source, and abstract which can be retrieved on a topic.

The Communicative Disorders Program, NINCDS, in cooperation with NLM, improved MEDLINE coverage of communicative disorders by increasing the number of journals and the specificity of indexing terms in these fields. A users' manual and thesaurus have been written to guide communicative disorders specialists in conducting searches on over 2000 topics.

Participants will learn how to use MEDLINE to meet their own literature retrieval needs. The workshop will demonstrate the design of accurate search statements, use of indexing terms, and procedures to find concepts not included in MEDLINE vocabulary. Basic protocols and conventions of the system will be demonstrated.

Experience with MEDLINE is not necessary for successful participation. The users' manual and thesaurus will be distributed to participants.
Pitch of whispered vowels
Authors: Oesterle E. C. , Feth L. L. , Burns E. M.
Published: October 2005

Previous research in which listeners matched a pure tone to the perceived pitch of tape recorded whispered vowel stimuli has suggested that the perceived pitch corresponds closely with the second formant frequency [Thomas, J. Acoust. Soc. Am. 46, 468–470 (1969); McGlone and Manning, Folia phoniat. 31, 9–14 (1979)]. We investigated the pitches of computer generated whispered vowels /i, u, a, Λ/. Five listeners were asked to match the pitch of an adjustable rippled noise stimulus to the perceived pitch of the whispered vowels. Rippled noise was selected as the matching stimulus because it is spectrally similar to whispered vowels, thus minimizing the well known problems involved in pitch matching pure tones to complex stimuli. Results indicate that the perceived pitch does not correspond with the second formant frequency. These findings will be discussed in light of current theories of pitch perception. [Work supported by NIH.]
The story of /r/
Authors: Lindau Mona
Published: October 2005

In describing sound changes, sound patterns and alternations in languages one clearly needs to refer to a natural class of r sounds, or rhotics. This phonological class encompasses sounds with a wide variety of manners and places of articulation, and it has been suggested that its “phonetic correlate” is acoustic in nature, namely a lowered F3. Acoustic properties of phonetically different /r/s were investigated in languages like American English, Yoruba, French, Southern Swedish, Hausa, and Edo, using several speakers of each language. The results do not show any single acoustic parameter underlying the phonological class of [+rhotic]. The third formant does not lower for all types of /r/s. There is often a decreased intensity associated with the rhotic, but this is by no means consistent. The natural class of [+rhotic] sounds is a phonologically convenient class, but it is not controlled by any single articulatory or acoustic correlate. Instead, this phonological class is associated with complex combinations of both articulatory and acoustic parameters. [Work supported by NSF.]