bluuebunny/crossref_metadata_2025 huggingface dataset:
Perceptual space for musical structures
Authors: Carterette E. C. , Miller J. R.
Published: October 2005

Ideally one desires a physical representation of the critical parameters which distinguish one musical instrument from another in its perceptual qualities. To this end 27 musical sounds were synthesized in all combinations of three parameters. The seven harmonics of each of three fundamental frequencies—200, 400, and 800 Hz—descreased 5 dB per step from the most intense, which was either the first, second, or third harmonic. Each of these nine structures was contained in each of three envelope—G, gradual onset (20 msec) and decay (40 msec) for full intensity; H, horn; and P, plucked string. Nine listeners, of whom four were musicians, heard n(n−1)/2=351 sound pairs in each of four sessions. Each pair was rated on a nine-point similarity scale—1 = very similar, 9 = very dissimilar. Results were that (1) fundamental frequency was more salient than envelope and amplitude did not appear as a dimension in the multidimensional scaling solutions; (2) the correlation between response latency and the number of dimensions was high (0.46) though not statistically significant; (3) a quadratic curve related latency and similarity; and (4) the perceptual spaces of nonmusicians were at least as stable as those of musicians, based on correlations between third and fourth sessions on latency (p <0.05) and similarity (p <0.01).
Signal detection: poststimulus change effects
Authors: Pastore R. E. , MacLatchy C. S.
Published: October 2005

We recently reported [J. Acoust. Soc. Am. 53, 376–377(A) (1973)] that a decrease in the spectrum level of an otherwise continuous masking noise (300–3300 Hz) interfered with the detectability of a signal (1000 Hz, 20 msec), if the decrease was limited to the frequency region clearly outside the critical band of the signal (i.e., outside 700 to 1300 Hz) and the change was initiated within approximately 200 msec following the observation interval. With a similar poststimulus decrease confined to the frequency region of the signal (i.e., 750–1400 Hz), the detectability of the signal was improved for short change delays (0 to ∼25 msec) and was hindered for longer delays (25 to 350 msec). This paper reports on the effects of poststimulus spectral decreases which either (1) encompass all frequencies, or (2) involve more restricted frequency regions (i.e., below 700 and 1400 Hz, etc.). [This research was supported by a grant from the National Institute of Mental Health.]
Study of hearing-aid fitting parameters with a manikin
Authors: Burkhard M. D.
Published: October 2005

The traditional methods of characterizing hearing-aid gain as a function of frequency inadequately represent the performance of an aid when it is worn on an individual. Romanow (1942) showed how the body diffraction must be properly accounted for to describe hearing-aid acoustic gain. Hearing-aid audiologists have, for many years, been impressed with the apparent subjective discrepancy between the pressure generated by typical hearing aid in a wearer's ear and the observed response in Standard ANSI S3.3 and IEC measuring schemes. These differences, together with the various legislative pressures for maximizing the utility of the hearing aid for the user, have made the use of additional input to the specification and design of hearing aids essential. The manikin, KEMAR (Knowles Electronics Manikin for Acoustical Research), provides a basis for evaluating many of the parameters which are otherwise difficult or impossible to obtain, but which critically affect the performance of a hearing aid on a typical wearer. Such things as a preferred reference response for a hearing aid that will produce a “subjectively” flat listening stimulus, i.e., a transparent hearing aid, the numerous diffraction effects, the influence of reflection of sound from the torso on a hear mounted hearing aid, the importance of location of the hearing-aid microphone on the head, proper simulation of the ear canal, and a number of other variables can all be studied. These parameters, the directionality of the headworn hearing aid compared to the usual free-field gain measurement and several hearing-aid fitting types, are discussed and typical information is presented. Many of the resulting attributes and benefits from these studies will be more readily implemented in new hearing aids through the use of new generations of microphones and receivers that are available. The evolution of the KEMAR manikin and its acoustic similarity to a median human adult are discussed.
Tactile speech-reception aids for the hearing impaired
Authors: Miller James D. , Engebretson A. Maynard , DeFilippo Carol L.
Published: October 2005

Attempts to transmit speech to the hearing impaired through the skin are briefly reviewed. Major emphasis is on recent research by the authors demonstrating that certain phonetic features can be well recognized on the skin (voicing, nasality, and plosion) at least in isolated syllables and words. Possible directions for relevant psychophysical research and engineering development are discussed. [Supported by NIH Grant No. NS 03856 to Central Institute for the Deaf.]
Computing method for sound propagation through a non-uniform jet stream
Authors: Padula S. L. , Liu C. H.
Published: October 2005

Understanding the principles of jet noise propagation is an essential ingredient of systematic noise reduction research. High-speed computer methods offer a unique potential for dealing with complex real-life physical systems, whereas analytical solutions are restricted to sophisticated idealized models. The classical formulation of sound propagation through a jet flow was found to be inadequate for computer solutions, and a more suitable approach was needed. Previous investigations selected the phase and amplitude of the acoustic pressure as dependent variables requiring the solution of a system of nonlinear algebraic equations. The nonlinearities complicated both the analysis and the computation. A reformulation of the convective wave equation in terms of a new set of dependent variables is developed, with special emphasis on its suitability for numerical solutions on fast computers. The technique is very attractive because the resulting equations are linear in nonwaving variables. The computer solution to such a linear system of algebraic equations may be obtained by well-defined and direct means which are conservative of computer time and storage space. Typical examples are illustrated and computational results are compared with available numerical and experimental data.
Variations in bone-conduction responses with contact area (further experiments)
Authors: Khanna S. M. , Tonndorf J. , Queller J.
Published: October 2005

Bone-conduction (BC) thresholds measured in terms of acceleration had shown large systematic variations, mainly with contact area [J. Acoust. Soc. Am. 55, S62 (1974)]. Sound pressures generated in the occluded ear canal by BC signals of threshold strength were now found to be independent of contact area and, below 2 kHz, equal to those required for AC thresholds. Air/bone cancellation experiments revealed that, below 2 kHz and with the ear canal occluded, the BC stimulus is really given by the sound pressure generated in the ear canal, i.e., one measures the response to an air signal instead of that to a bone signal. [Essentially the same conclusion was reached for the cat; cf. Acta Otolaryng. Suppl. 132 (1966).] The cancellation experiments permitted the assessment of BC components unaffected by the sound pressure in the ear canal. These true inner-ear BC responses also varied with the contact area, demonstrating once more that acceleration is a poor indicator of BC responses. Experiments now in progress will determine if the above findings apply also to the unoccluded ear canal. [Supported by NIH and DRF grants.]
Long-range propagation of sound generated at the ice-water boundary
Authors: Diachok O. I. , Long G. K.
Published: October 2005

In order to investigate long-range spatial affects of high ambient-noise levels generated at the ice-water boundary by the interaction of ocean waves with sea ice [O. I. Diachok and R. S. Winokur, J. Acoust. Sec. Am. 55, 750–53 (1974)], coincident measurements of the spatial variability of ambient noise, transmission loss, and thermal structure were made along several 300-NM open water tracks normal to the boundary. The measurements were made from two aircraft with sonobuoys and expendable bathythermographs deployed and monitored every 20 NM, and explosive signals, deployed every 4 NM from one aircraft. The signals were detected on modified sonobuoys, which were monitored from a second aircraft. The resultant transmission loss data were corrected for cylindrical spreading and the attenuation coefficient was computed for comparison with the rate of change of the ambient noise versus distance measurements. An analysis of the results indicates that the ice-water boundary may be considered as a line source of sound and that the observed variations of ambient-noise signals with range may be quantitatively related to the computed attenuation coefficient.
Reflection and transmission at a randomly rough two-fluid interface
Authors: Kuperman W. A.
Published: October 2005

The specular reflection and transmission of an acoustic plane wave at a randomly rough two-fluid interface is studied. The perturbation method of Bass [Izv. Vyssh. Uchebn. Zaved. Radiofiz. 4, 476 (1961); (JPRS: 10223)] is used to derive a new set of boundary conditions to replace the unperturbed boundary conditions. The new conditions are valid for surfaces characterized by arbitrary anisotropic correlation functions. Using these new boundary conditions, reflection and transmission coefficients are derived. It is shown that in the Kirchhoff approximation, the reflection and transmission coefficients reduce to those obtained earlier by Eckart, Clay, Hagy, and Medwin. In the limit of the density of one of the fluids going to zero, the reflection coefficient for a rough pressure-release surface is obtained. Results are presented using ocean surface models in terms of wind speed and direction.
Interaural-intensive differences and dichotic listening
Authors: Speaks Charles , Bissonette Linda
Published: October 2005

Interaural-intensive differences were introduced in a dichotic-listening experiment with CV syllables. Six listeners with a right-ear advantage (REA) were tested. In one condition, speech level in the right ear was attenuated in 8-dB steps re each of four reference levels for the left ear: 50, 60, 70, and 80 dB SPL. In a second condition, speech level in the left ear was amplified (8-dB steps) re the same four reference levels for speech in the right ear. Attenuation of the right-ear signal overcame the REA, but the amount of attenuation required to cancel REA decrease as reference intensity decreased. REA was cancelled with amplification of the left-ear signal only for the 50-dB reference. At higher reference levels for speech in the right ear, amplification in the left ear did not affect scores for either ear throughout a 24-dB range. The differences between outcomes for attenuation and amplification during dichotic stimulation will be reconciled by reference to a “critical” region of intensity on the performance-intensity function for monotic stimulation.
Context effects on silent interval estimation in speech and nonspeech environments
Authors: Rupf John A. , Ruder Kenneth F. , Rowson Stephen V.
Published: October 2005

The speech stimuli for this experiment were derived from two sentences, each containing the words free criminals. In one sentence, the words free criminals occurred intraphrase and in the other sentence they occurred interphrase. The vowel duration in free and the silent interval preceding criminals were systematically and independently varied. Vowel durations of 100, 200, 300, 400, 500, and 600 msec were paired with silent intervals of 0, 50, 100, 150, 250, and 500 msec. Subjects were asked to make direct magnitude estimates of the silent interval duration between free and criminals. Power-law scaling exponents for judgments versus vowel duration and silent interval duration were 0.29 and 0.48, respectively. The above experimental procedure was repeated in two experiments using nonspeech stimuli with temporal characteristics similar to the two sentences. In particular, the silent interval to be estimated occurred between two 1000-Hz tones. In Experiment 1 the duration of the tone preceding the silent interval was varied, while in Experiment 2 the tone following the silent interval was varied. Power-law scaling exponents for judgments versus tone duration and silent interval duration were 0.45 and 0.36, respectively, for Experiment 1 and 0.24 and 0.45, respectively, for Experiment 2.
Binaural masking-level differences for interaurally delayed and for jittered pulse-train signals
Authors: Pohlmann Lawrence D. , Sorkin Robert D.
Published: October 2005

Two experiments were conducted to investigate the effects of interaural signal delay and temporal jitter on the MLD for pulse-train signals. A two-interval forced-choice detection task was employed with the level of the masking noise (No) controlled by a PEST program. In all conditions the signal in one ear was a pulse train composed of 100-μsec positive or negative polarity pulses with an interpulse period of 2 msec. The signal in the opposite ear was either an identical but temporally delayed pulse train (Experiment 1) or was a pulse train in which the interpulse interval was perturbed (jittered) for some proportion of the pulses (Experiment 2). In both experiments conditions were run in which pulse polarity was either fixed or was a random variable. All signals were low-pass filtered at 5 kHz. In Experiment 1 the magnitude of the MLD was found to be a function of the interaural signal delay and the polarity pattern. In Experiment 2 the MLD was found to be a function of both the amount of temporal displacement and the proportion of pulses which were jittered. Results are interpreted with respect to the spectral properties of the signals. Relationships to previous MLD research and implications for correlation-type MLD models are discussed.
Earphone calibration based on the threshold of the stapedius reflex
Authors: Yonovitz A. , Campbell I. , Robinson C.
Published: October 2005

The MX 41/AR cushion mounted on the TDH-39 earphone has been the standard receiver arrangement for both laboratory and clinical work in audition. In certain applications, however, the substitution of circumaural earphones or earphone cushions may provide better attenuation of ambient environment noise or greater comfort to the wearer. Various psychoacoustic techniques requiring voluntary judgments by a subject have been devised for the calibration of nonstandard earphones. In this study ten subjects tracked auditory thresholds using five different earphone arrangements at eight frequencies (500–4000 Hz). These earphones included a TDH-39 earphone mounted with an MX 41/AR cushion, “doughnut” cushion (NAF)48490-1), Zwislocki (CZW-6) cushion, Tracor “Otocup,” and a Sansui circumaural earphone. Following this procedure, the threshold of the stapedium reflex was also obtained on the same subject under each earphone. The data were analyzed using multivariate statistical techniques and indicate the stapedius reflex threshold is highly useful in calibrating non-standard earphones.
Vibrotactile spatial summation: effects of vibration amplitude and static force
Authors: Green Barry G. , Craig James C.
Published: October 2005

Vibrotactile spatial summation was investigated at suprathreshold amplitudes using a matching task. Previous work [R. T. Verrillo, J. Acoust. Soc. Am. 35, 1962–1966 (1963)] at threshold amplitudes has shown that spatial summation occurred only at frequencies greater than 60 Hz. Three frequencies, 25, 40, and 160 Hz, were tested at several intensity levels above threshold. The change in perceived magnitude between two contactor sizes (static pressure on the contactors held constant) was measured to determine if summation would occur at vibration frequencies below 60 Hz. The results showed that spatial summation occurred at 25 and 40 Hz in amounts which varied directly with vibration amplitude. At 160 Hz, spatial summation was present but independent of amplitude. The data are consistent with the hypothesis that spatial summation is mediated by deep-lying receptors which are more sensitive to high frequencies but which can be stimulated by strong, low-frequency signals. A second experiment investigated an earlier finding by Craig and Sherrick [Percept. Psychophys. 6, 97–101 (1969)] that static force rather than static pressure, penetration, or contactor area was the mechanical coupling factor most responsible for spatial summation effects. Changes in sensory magnitude comparable to those found in the first experiment were found in the second experiment when static force rather than contactor area was varied. The results suggest that changes in static force which accompanied changes in contactor area in the first experiment may have been responsible for the summation effect. [This research was supported by an NIH grant.]
Acoustical characteristics of a side branch resonator in a duct with flow
Authors: Singhal Vijay K. , Ingard Uno
Published: October 2005

The acoustical characteristics of a single side branch resonator in a duct with flow have been studied. These studies include measurement of reflection and transmission coefficients as a function of frequency and flow velocity, investigation of conditions for flow excitation of the resonator, and the acoustic response of the resonator to an external sound field under conditions of self-oscillation. These response characteristics are compared with the results of an earlier experiment involving a moving resonator cavity exposed to an external sound field. The experimental results are compared with the theoretical analysis of the problem. [This work was supported in part by the U. S. Navy (Office of Naval Research) under Contract N00014-67-A-0204-0019.]
Method for computing acoustic mode properties in uniformly treated ducts with sheared flow
Authors: Dean L. Wallace
Published: October 2005

A numerical method is presented to model the propagation of acoustic waves in treated ducts with a uniform flow profile. This method provides numerical solutions for modes using a computational procedure equivalent to a variational principle to calculate eigenvalues. The method has been found to converge more rapidly and for a wider range of duct parameters compared to other methods tried, and is easily adapted to all duct geometries for which separation of variables can be applied to solve the wave equation. Also included is an exact solution of the wave equation for a duct having an abrupt drop to zero in flow velocity near the walls. Solutions then can be obtained for a duct having a specified wall impedance and an infinitely thin shear layer at the walls. The solution across this infinitely thin shear layer is found to agree with approximate solutions presented by other authors.
Noisiness of low-frequency bands of noise
Authors: Lawton Ben William
Published: October 2005

A study was performed to examine the relative noisiness of low-frequency one-third octave bands of noise. The frequency range investigated was bounded by the bands centered at 25 and 200 Hz, with intensities ranging from 50 to 95 dB SPL Thirty-two subjects used a method-of-adjustment technique, producing comparison band intensities as noisy as 100- and 200-Hz standard bands at 60 and 72 dB. The work resulted in contours of equal noisiness for one-third octave bands, ranging in intensity from approximately 58 to 86 dB SPL. These contours were compared with the standard equal noisiness contours; in the region of overlap, between 50 and 200 Hz, the agreement was good.
Calibration for digital spectrum analysis
Authors: Burgess John C.
Published: October 2005

Two interesting kinds of error are possible when spectra are obtained using digital data-processing techniques. The first can arise when a periodic calibration signal is used and the sample length is not an integer multiple of the calibration signal period. The maximum value of the corresponding discrete (line) spectrum can then be incorrect by as much as −3.9 dB. The error can be avoided by observing the peak value of the calibration signal in the time domain or by adjusting the maximum displayed discrete spectrum value. The adjustment is easily calculated using the two discrete spectrum values that lie on each side of the true frequency position. The second kind of error arises when a data window is used and the signal being analyzed has both periodic and random components. The spectrum can be calibrated for either the periodic or the random components, but not simultaneously for both. For example, if a Hanning data window is used and the spectrum is calibrated for an ideal random process, the spectrum levels displayed for periodic components will be between −1.7 and −3.1 dB in error.
Noise generation in pneumatic blow-off guns
Authors: Cudworth A. L. , Hanson W. J.
Published: October 2005

The relation between noise level, force (thrust), and inlet pressure has been investigated for 20 different blow-gun nozzles or ejectors. This variety of design was a result of an Occupational Safety and Health Administration ruling that all hand-held blow guns must be provided with pressure regulation and relief such that the maximum blocked static pressure could not exceed 30 psig. At a supply pressure of 100 psig a noise level variation of 63 dBA was found between the quietest and noisiest guns. Nearly the same degree of variation was demonstrated when the supply pressure was adjusted for each gun to yield equal force downstream. Guide lines will be given for the selection of nozzle design to yield minimum noise exposure consistent with downstream force requirements.
Some monaural and binaural facets of median plane localization
Authors: Gardner Mark B.
Published: October 2005

Recent studies, together with others dating back as far as 1851, leave little doubt that the cavities and convolutions of the pinnae play an important role in the localization of signals that originate in the median plane. Less clearly understood, however, is the nature of the clues that are utilized in arriving at a localization decision. Results of the present study indicate that, insofar as localization in the anterior sector of the median plane is concerned, clues associated with the cavities of the pinna have an important monaural component. Binaural reception also plays a significant role including confining the apparent location of the resultant image within, or near, the median plane. Such a centralizing influence is an essential requirement for optimizing this type of localization. Clues of a secondary nature were found to be associated with the range of frequencies between about 0.7 and 3.5 kHz.
Recovery of detection probability following sound exposure: comparison of physiology and psychophysics
Authors: Young Eric , Sachs Murray B.
Published: October 2005

Detection probability for 1-kHz test tone-bursts was estimated at 1-sec intervals following exposure of subjects to a 1-kHz continuous tone. Immediately after the exposure tone, detection probability is depressed. Recovery to preexposure probability is well fit by a single rising exponential function. These psychophysical data are compared with the recovery of discharge rate in single fibers of the cat's auditory nerve following similar exposures. For both sets of data the time constant of recovery decreases with increasing test tone-burst level; the decrease is significantly faster for detection probability recovery than for recovery of discharge rate. This difference can be accounted for by a simple model relating discharge rate in ensembles of auditory-nerve fibers to detection probability. Whereas the recovery time constant of discharge rate increases monotonically with exposure level, the recovery time constant of detection probability increases up to about 40 dB SPL and then decreases as exposure level is increased. We could not explain this difference on the basis of existing data.
Generalized radiation impedances and reflection coefficients of circular and annular ducts
Authors: Zorumski William E.
Published: October 2005

Morse's equation for the radiation impedance of a vibrating rigid piston is extended to give the generalized radiation impedances Zmnl of all modes in circular and annular ducts which have arbitrary wall admittance β and which terminate in an infinite baffle. The equation for Zmnl is reduced to a single infinite integral which is a function of the mode radiation directivity factors. An infinite matrix equation is derived which relates the generalized mode reflection coefficients Rmnl to the radiation impedances. Results are presented which show that the duct-wall admittance is a significant parameter in the effect of duct-termination reflections and that mode-coupling reflection effects may be more important than direct-mode reflection effects.
Erratum: “High-speed method for computing the exact solution for the pressure variations in the nearfield of a baffled piston” [J. C. Lockwood and J. G. Willette, J. Acoust. Soc. Am. 53, 735–74 (973)]
Authors: Lockwood J. C. , Willette J. G.
Published: October 2005

A corrected version of Fig. 6 of the subject article [J. C. Lockwood and J. G. Willette, J. Acoust. Soc. Am. 53, 735–741 (1973)] is presented.
Infrasonic and low-frequency ambient noise measurements on the Grand Banks
Authors: Perrone Anthony J.
Published: October 2005

Infrasonic and low-frequency ambient noises were investigated using a bottom-mounted omnidirectional hydrophone located in 614 fm of water on the Grand Banks. Data were recorded continuously on magnetic tape from 20 to 28 July. Ten-second average levels for 25 contiguous 1/3-octave bands between 1 and 250 Hz were computed for the entire eight-day period. Hourly averages were then computed from the 10-sec values. Autocorrelations of ambient-noise level and wind speed, as well as cross correlation of ambient-noise level with wind speed, are presented. In the 4–250-Hz range, the measured ambient-noise spectra are produced predominantly by large fishing vessels in the general area of the hydrophone; in the 1–4-Hz range, a relatively strong wind-speed dependence is observed. The high values of standard deviation (as a function of frequency) are suspected to be caused by the varying proximity of the few ships in the area to the hydrophone. The correlation coefficient of wind speed to sea noise is variable and directly dependent on the wind-speed distribution and the amount, type, and location of shipping during the measurement period.
Determination of electron mobilities in thin metal films from the attenuation of elastic surface waves
Authors: Bierbaum P.
Published: October 2005

An elastic surface wave propagating on a piezoelectric substrate on which a metal film is being deposited is attenuated as a result of the interaction between the wave and charge carriers in the film. This attenuation was measured for various metals and substrate temperatures. It was shown that the experiments agree closely with a theoretical model if an electron diffusion term is retained and related to the Fermi energy of the metal under consideration. It thus becomes possible to determine the product of electron mobility and Fermi energy from the measured maximum attenuation. The assumption that bulk Fermi energy would apply to the films proved correct except in the case of the semi-metals tin and bismuth, and electron mobilities were obtained which agreed with published values.
Ultrasonic spectroscopy applied to double refraction in worked metals
Authors: Papadakis Emmanuel P.
Published: October 2005

An experiment has been performed showing that ultrasonic spectroscopy can be used to study texture in worked metals and other textured polycrystals. Echoes from a broadband shear transducer polarized at 45° between two characteristic directions in a rolled aluminum specimen showed nulls in their spectrum corresponding to differences of (2 n − 1)π in phase between the components of the wave amplitude resolved along the characteristic directions. From the frequencies of the nulls, the fractional velocity difference Δv/v was computed to be 0.021, a reasonable value for aluminum with moderate texture. Ultrasonic spectroscopy is particularly useful to study texture when the first echo contains several nulls, i.e., n > 1 in the phase difference (2n − 1)π.
Effect of sliding on lateral seismic forces of a building structure
Authors: Raftopoulos D. D. , Scavuzzo R. J.
Published: October 2005

The effect on maximum lateral seismic inertia forces of sliding between the foundation of a heavy-stiff building structure and the soil is studied. The lateral inertia force acting on the structure is limited to a value FD, which is determined by multiplying a prescribed coefficient of friction times the total structural weight. Effects of rocking of the structure are not considered. The soil is modeled as a two-dimensional elastic half space. Results are evaluated by comparing the effect of increased sliding on the spectrum response of the lateral motion of the foundation mass.
Dependence of reverberation time on stage-enclosure configuration in the Philadelphia Academy of Music
Authors: West J. E. , Sessler G. M. , Flanagan J. L.
Published: October 2005

The reverberation time of the unoccupied Academy of Music in Philadelphia was measured utilizing the method of integrated tone-burst decays. Third-octave tone bursts covering the frequency range from 50 to 5000 Hz were used as test signals. The measurements were taken at 14 different microphone positions throughout the hall for two loudspeaker locations on stage. In addition, two different ceiling arrangements of the stage enclosure were implemented; namely, a flared tilt (normally used) and an experimental, horizontal configuration. The subjectively important initial reverberation time T1 (extrapolated from the decay over the first 10 dB of the integrated response) as well as the final reverberation time T2 (extrapolated from the decay over the range −10 to −30 dB) were evaluated on a digital computer. The results for the octave band centered at 500 Hz, averaged over positions are: T1=l.2 sec, T2=1.4 sec for the flared stage ceiling; and T1=l.3 sec, T2=1.5 sec for the horizontal ceiling.
Comments on “Vibrations of rectangular sandwich plates with mass attachments” [M. J. Jacobson, J. L. Malokoff, J. L. Preston, and V. I. Weingarten, J. Acoust. Soc. Am. 40, 677–683 (1966)]
Authors: Solecki Roman
Published: October 2005

Frequency equation derived by Jacobson, Malokoff, Preston, and Weingarten [J. Acoust. Soc. Am. 40, 677–683 (1966)] is analyzed. It is shown to be divergent in the case of a mass concentrated at a point.
Discrete relaxation processes as a model of the absorption of ultrasound in liver homogenate
Authors: Danckwerts H.-J.
Published: October 2005

The concept of molecular relaxation as a mechanism of the absorption of ultrasound in liver homogenate is discussed by the use of a special discrete distribution of relaxation times. The distribution is interpreted in terms of molecular activation processes. Assuming an exponential relationship between the relaxation time and the free energy of activation, it follows that neighboring activation energy levels are equidistant. The model leads to an interpretation of measurements of the absorption coefficient as a function of the frequency.
Acoustic scattering from a moving turbulent medium
Authors: Clifford S. F. , Brown E. H.
Published: October 2005

The scattering cross section of a homogeneous turbulent layer found in the existing theory assumes that the mean motion of that layer is zero. For acoustic sounding in the real, open atmosphere the most interesting experimental results are for the case of the turbulent medium moving with the mean flow. In this case the measured Doppler shift indicates the average velocity over the scattering volume, a technique currently being used to extract vertical profiles of wind velocity. We extend the theory to the case of moving scatterers and find a modified angular dependence that, unlike the zero-wind case, predicts a nonzero cross section at a 90° scattering angle. Interestingly, there is essentially no change in the form of the backscatter cross section, i.e., there remains no contribution from wind eddies.
Diffraction of sound around corners and over wide barriers
Authors: Pierce Allan D.
Published: October 2005

Formulas and procedures are described for the estimation of sound pressure amplitudes at locations partially shielded from the source by a barrier. The analytical development is based on the idealized models of a wave from a point or extended source incident on a rigid wedge or a three-sided semi-infinite barrier. Versions of the uniform asymptotic solution for the wedge problem which are convenient for numerical predictions are derived in terms of auxiliary Fresnel functions by means of complex variable techniques previously employed by Pauli from a generalization of the exact integral solution developed by Sommerfeld, MacDonald, Bromwich, and others and are interpreted within the spirit of Keller's geometrical theory of diffraction. The Kirchhoff approximation in terms of the Fresnel number is obtained in the limit of small angular deflections from shadow zone boundaries. An approximate and relatively simple expression for the double-edge diffraction by a thick three-sided barrier is given based on the single wedge diffraction solution and on concepts inherent to the geometrical theory of diffraction which reduces to finite and realistic limits when either source or listener are near the extended plane of the barrier's top. A simple approximation suggested by Maekawa based on the replacement of actual barriers by an equivalent thin screen with diffraction treated by the Kirchhoff approximation is discussed in terms of the present theory and it is concluded that in some instances this approximation may lead to sizeable errors. An alternate scheme is suggested whereby one approximates the actual barrier by a three-sided barrier wholly contained within the actual barrier.
Low-frequency fluctuations of a CW signal in the ocean
Authors: Stanford George E.
Published: October 2005

Amplitude and phase fluctuations of underwater acoustic signals measured during a series of CW experiments have been statistically analyzed in order to obtain a better understanding of long-range acoustic propagation. The signals were transmitted along a 1318-km path from Eleuthera to Bermuda that utilized a stationary projector and two stationary receivers. The analysis extends previous long-range propagation studies by examining phase fluctuations as well as amplitude fluctuations. The amplitude fluctuations were almost Gaussian in distribution and exhibited a coefficient of variation that ranged from 42% to 65%. Power spectrum levels for these fluctuations underwent their greatest change when the frequency f was between 5 and 20 cycle/h, where the spectrum level was proportionately varied between (1/f)2 and (1/f)4. In the region between 20 and 120 cycle/h, the spectra exhibited seasonal effects, showing a 9-dB difference in spectrum level between March and July. Correlation time for the phase fluctuations varied from 35 to 46 min, exceeding the amplitude fluctuation correlation time by a factor of seven. Power spectrum levels for the phase fluctuations decreased monotonically from 0.3 to 120 cycle/h and were approximately proportional to (1/f)5/2.
Nonlinear shock analysis problem: The inelastic annulus on a distributed foundation
Authors: Mays John R. , Nelson James E.
Published: October 2005

In this paper an analytical procedure is developed to calculate the response of an inelastic annular plate on a distributed foundation to shock-pulse excitation. The shock pulse is applied to the inner edge of the annulus. The dynamic system is expressed by a second-order nonlinear partial differential equation. For a more general approach, certain nondimensional parameters are used—a ratio of the pulse duration to the fundamental natural period of the system, the ratio of the stiffness of the plate to that of the foundation, the ratio of the critical yielding moment to the maximum amplitude of the shock pulse, and the ratio of the inner to outer radii of the system. The shock excitation used is a 12-sine pulse. The Tresca yield criterion is used to describe the inelastic behavior of the plate. The technique of solution for deflection and moments is verified by allowing the model to degenerate into well-known limiting cases. The response spectra for deflection and moments are presented for variations in parameters.
Ultrasonic holography free from phase turbulence
Authors: Ueda Mitsuhiro , Sato Takuso , Ikeda Osamu
Published: October 2005

It is well known in the field of ultrasonic holography that the formation of a hologram is affected seriously by the presence of turbulence inside the medium in which ultrasonic waves propagate; especially in case of large phase turbulence, it becomes almost impossible to reconstruct the image from the hologram. In this paper, a principle of a new method of reducing the effect of the fluctuation on the detected hologram by using a stochastic processing of the signal is proposed. The basic idea is to estimate the mean values of the phase and the amplitude of the ultrasonic signal separately and then combine these two averaged values to get the ultrasonic signal which would be obtained in the absence of turbulence. By constructing models of a turbulent medium, the effect of this processing is studied and the result of computer simulation which demonstrates the usefulness of this method is presented. In addition, such usefulness is shown by the experimental result obtained by using a device which was constructed to verify the principle.
Equal aversion levels for pure tones and 1/3-octave bands of noise
Authors: Molino John A.
Published: October 2005

College students tapped rapidly on a telegraph key to reduce the intensity of a continuous acoustic stimulus presented through earphones. Failure to respond resulted in an intensity increase of 1 dB every 4 sec. A group of 14 students responded during 10-min sessions to eight pure tones and eight 1/3-octave bands of noise at octave frequencies from 63 Hz to 8 kHz. The average SPL maintained by the subjects became stable after about 5 min. The different asymptotic levels observed from 5–10 min were taken as a measure of equal aversion levels for the stimuli. Equal aversion levels were compared with other subjective weighting contours: equal loudness level, A-weighted sound level, perceived noise level, etc. They were closest to an A-weighted sound level of 80–85 dB.
Binaural masking level differences for pulse train signals of differing interaural correlation
Authors: Pohlmann Lawrence D. , Sorkin Robert D.
Published: October 2005

Binaural masking level differences (BMLDs) were obtained for pulse train signals in a 2IFC task in which the noise (Nπ) level was controlled by a PEST program. The signal in one channel was a random polarity (+1, −1) pulse train composed of 60 100-μsec-duration pulses with an interpulse period of 2 msec. Signal correlation was varied by modifying the signal in the contralateral channel. The correlation was varied by (a) randomly inverting some of the pulses, (b) randomly deleting some of the pulses, (c) deleting or inverting some of the pulses contingent on their polarity, or (d) delaying the pulses by an integral number of pulse periods. The data were compared to predictions generated from Osman's correlation model. Performance was found to be accurately predicted by the model for conditions (a), (b), and (d). Differences between the model and the data for condition (c) were explained in terms of changes in the monaural detectability of the contralateral signal.
Signal/noise ratio and the critical band in fishes
Authors: Tavolga William N.
Published: October 2005

Auditory thresholds in the presence of masking noise and masking tones were measured in three species of teleost fishes: goldfish (Carassius auratus, family Cyprinidae); pin fish (Lagodon rhomboides, family Sparidae); African mouth-Breeder (Tilapia macrocephala, family Cichlidae). In the goldfish, the signal-to-noise ratio to broad-band noise was about 22 dB, and direct measurement of the critical band yielded a value between 100 and 200 Hz. Single-tone masking effects in the goldfish showed partial remote masking, and strong masking at frequencies within 5 to 20 Hz of the signal. The audiograms for pinfish and Tilapia were significantly higher than in the goldfish, but the signal-to-noise ratio values were in the same range. Provisionally, the evidence supports the existence of a critical band in the goldfish, but not in the other species tested. The question of the relationship of signal-to-noise ratio to the critical band was discussed in reference to the frequency-discrimination capacities and hearing mechanisms in fishes.
Effects of rotation on vibrations of circular cylindrical shells
Authors: Wang Shih-sen , Chen Yu
Published: October 2005

The effects of rotation due to centrifugal and Corliolis forces on the frequencies are analyzed on the basis of the Herrmann-Armenakas bending theory. Closed-form expressions for the frequency and the nodal rotational velocity of the flexural modes are discussed, and their accuracy is compared with previously published results.
Rebuttal to papers on aircraft noise by S. R. Lane at the 86th Meeting of the ASA
Authors: Callaway V. E.
Published: October 2005

This paper is a reply to views on aircraft noise in the community and in the passenger cabin of modern jet aircraft presented in three papers at the 86th Meeting of the Acoustical Society in Los Angeles, Nov. 1973 (Papers MM1, MM3, and MM11). It is argued that procedures used by the author of paper MM-1 can result in EPNL values subject to errors of as much as 8 to 15 EPN dB. Recent measurements by Boeing are quoted that are substantially in agreement with those officially determined in 1971 for 727 aircraft on take-off. It is anticipated that landing noise will show similar agreement with published data. Other Boeing measurements using an aircraft in which engine noise was essentially eliminated indicate that it is technologically impossible to achieve the low community noise levels suggested in MM3 at the present time with a viable commerical airplane. Measurements together with widely accepted hearing conservation criteria indicate that travellers are not being exposed to hazardous noise levels inside passenger cabins of modern jets as claimed in paper MM11.
Interaction of flutter and random vibrations of a clamped-clamped beam
Authors: Elishakoff I.
Published: October 2005

The interaction of flutter and random vibrations of clamped-clamped beam is studied. The external loads are composed of pressure fluctuations in the field of random forces, which are assumed to be random space-time functions, and the pressure perturbation which depend on the beam deformations according to the “piston theory.” Corcos's concept of the cross-spectral density of turbulent fluctuations is used with Bull's correction for low-frequency range. The Galerkin's procedure with two- and three-mode approximations is used for solving the stochastic boundary-value problem.
Experimental verification of linear random vibration theory as applied to a four-wheeled vehicle traversing a random terrain
Authors: Chu M. L. , Doyle G. R.
Published: October 2005

The theory of linear random vibrations is used to analyze the response of a four-wheeled vehicle with an independent suspension system on each wheel. A scaled-down model of a vehicle and a simulated roadbed are constructed. The vehicle is assumed to have three degrees of freedom-vertical translation, pitch, and roll. Equations giving the power spectral density of each degree of freedom about the center of gravity of the vehicle are derived as a function of the vehicle parameters and the power spectral density of the vertical displacement of the four wheels. The displacement power spectral densities are found using experimental and numerical techniques. The test results of the power spectral density of the vertical displacement of the center of gravity are compared to the theoretical predictions as given by the linear random vibrations theory. At higher velocities and on rougher road conditions, very good agreement is achieved between theory and experiment.
Sources of unsteady flow in subsonic aircraft inlets
Authors: Clark L. T.
Published: October 2005

The paper presents the results of a study of turbulent flow typically found in subsonic inlets. Space-time correlations measured at the inlet-engine interface plane were used to represent the structure of the turbulent flow. The results have application in the analysis of rotor noise and performance. It was observed that turbulence which originated outside and was convected through the inlet had elongated shapes with stream correlation lengths much longer than those in transverse directions. However, when inlet originated turbulence was measured, the lengths were about the same in each direction. Thus, the contraction effect on the flow through the inlet strongly affects the shape of the turbulent eddies. The basis for the observations were high-frequency response total pressure transducers mounted on rakes in the inlet near the fan plane. The inlets used were representative of current technology in subsonic aircraft. 15-in.-diameter models were used in a 9 × 9-ft wind tunnel. Flow through the inlets was established using a downstream engine. Mach numbers studied were representative of the full-scale inlet. Conditions represented in the results are static, crosswind, and angle of attack.
Effects of nonuniform inflow on fan noise
Authors: Pickett G. F.
Published: October 2005

A prominant source of turbomachinery noise is due to high-speed unsteady flows interacting with blades and vanes. In particular, atmospheric turbulence, cross-wind effects, and the “ground vortex” apparent during most static test conditions can interact with the fan on turbofan engines to produce significant levels of noise. An analysis is presented that models this noise-generating mechanism and is capable of predicting propagating noise, accepting as input various inlet turbulence structures, temperature fluctuations, and flow distortions. Because of the random uature of most inflow disturbances, a statistical approach was used to develop the model which is a modification and extension of a previous analysis presented by Mani [“Noise Due to Interaction of Inlet Turbulence with Isolated Stators and Rotors,” J.S.V. 19 (1971)]. The analysis shows that the level of fan blade passing tone and harmonics and their relative forward and rearward radiated intensities are critically dependent on both the inlet turbulence intensity and correlation length scales in the axial, circumferential, and spanwise directions. This analysis is used in conjunction with measured fan noise data to infer the turbulence properties that would be required to account for levels of observed blade passage tone noise.
Diagnostic ultrasound: injury thresholds, mechanisms, and safety standards
Authors: Lele P. P.
Published: October 2005

With the extensive and ever-increasing use of ultrasound in clinical medicine and the development of progressively more sophisticated systems of tissue visualization, the importance and urgency of specifying the safety standards and the possible hazards of over-exposure to adult and embryonic tissues cannot be overemphasized. The implications of the results of several pertinent interaction studies and epidemiological surveys to the problem of realistic risk assessment are discussed.