bluuebunny/crossref_metadata_2025 huggingface dataset:
Real-ear responses of circumaural, supra-aural, and insert earphones
Authors: Kruger B. , Solomon B. , Cohen R. , Newton L. , Kaplan S.
Published: October 2005

Circumaural earphones provide improved coupling when compared with the standard supra-aural audiometric earphone (TDH 39, 49) [Kruger et al., J. Acoust. Soc. Am. 67, S91 (1980); Villchur, ibid. 48, 1387–1396 (1970); Erber, ibid. 44, 555–562 (1968); Shaw, ibid. 39, 471–479 (1966)]. The variability of real-ear responses of the TDH-49 earphone, audiometric circumaural earphones (Villchur-Telephonics Model 566, Beltone Auraldome & Audiocap), a hi-fi circumaural earphone (Sennheiser HD 430) and an insert phone (Knowles BP 1869) was assessed. Probe microphone frequency response measurements in the ear canal were used to evaluate intrasubject and intersubject variability with the above transducers (10Ss: 5♂, 5♀ 5 repetitions/condition: transducer, subject versus experimenter placement) and were referred to either the diffuse field or the tympanic membrane. Real-ear response variability is contrasted with KEMAR response variability [Kruger et al., (1980); Ciechanowski and Cooper, J. Am. Aud. Soc. 2, 88–94 (1976)] and with coupler calibration variability appropriate to the transducer (NBS 9-A coupler, Penn State flat plate coupler, Zwislocki coupler). The nature of the variations in real-ear responses with these supra-aural, circumaural, and insert earphones will be discussed in terms of calibration, probe microphone placement, coupling to the head, and earphone placement. [Work partially supported by AOS.]
To /b/ or not to /b/: The interaction of intervocalic silence and consonantal transitions
Authors: Samuel Arthur G. , Kat Donna , Tartter Vivien C.
Published: October 2005

The acoustic realization of a consonant depends upon its position in the syllable. For example in /bɑ/, there are rising transitions; in /ɑb/, there are falling transitions, and in/ɑbɑ/there may be either (/ɑb_ɑ/ or /ɑ_bɑ/), or both (/ɑbba/). The present study investigated the possible interaction of formant transitions (incoming, outgoing, both) and stop-gap duration in the perception of place of articulation in inter-vocalic position. Subjects identified tokens from 14 synthetic speech continua: /bɑ/—/dɑ/, its mirror image /ɑb/—/ɑd/, and 12 VCV continua. The VCV continua were constructed by preceding /bɑ/—/dɑ/ with /ɑ/ (/ɑ_bɑ/—/ɑ_dɑ/), following /ɑb/—/ɑd/ with /ɑ/ (/ɑb_ɑ/—/ɑd_ɑ/), and concatenating /ɑb/—/ɑd/ and /bɑ/—dd̥/ (/ɑbbɑ/— /ɑddɑ/); four silent intervals (0, 25, 50, and 100 msc) were used for each type of VCV series. Subjects labeled more tokens as /b/ in /ɑb/— /ɑd/ than in /bɑ/ɑ/dɑ/. Adding an /a/ to /ɑb/—/ɑd/ decreased /b/ reports, whereas adding it to /bɑ/—/dɑ/ increased such reports; these effects were very large with the 0-ms stop-gap, and decreased as gap duration increased. Labeling of the /ɑbbɑ/—/ɑddɑ/ continua was more similar to the /bɑ/—/dɑ/ derived series than the /ɑb/—/ɑd/ series.
Detection of frequency modulation (FM) following FM adaptation
Authors: Davidson Linda M. , Stebbins William C. , Moody David B. , Cole Dorothy M.
Published: October 2005

Recent evidence has suggested the existence of human auditory channels selectively organized to detect FM [R. B. Gardner and J. P. Wilson, J. Acoust. Soc. Am. 66, 704–709 (1979); B. W. Tansley and D. Regan, Sensory Processes 3, 132–140 (1979)]. In a systematic replication of those studies, thresholds for upward frequency sweeps were compared in four human subjects following adaptation by FM upsweeps, FM downsweeps, pulsed-pure- tones, continuous pure-tones and silence. Thresholds for FM-upsweeps were highest following adaptation by FM-upsweeps. The four other adapting conditions produced thresholds considerably below those following adaptation by upsweeps. Lowest thresholds followed adaptation by pulsed-pure-tones. Reaction time to upsweeps decreased as the amount of modulation of the test stimuli increased but there was no difference in latency as a function of the differing adapting conditions. The general findings were in agreement with previous research. However, different thresholds for the various non-sweep adapting conditions raises questions about the appropriate pre-adaptation baseline for the investigation of FM channels.
Discrimination of temporal jitter in tone burst sequences
Authors: Sorkin R. D. , Boggs G. J. , Brady S. L.
Published: October 2005

We asked subjects to discriminate (2ATFC) between two sequences of tone bursts; in one sequence the time interval between the bursts was jittered, in the other sequence it was constant. Discrimination was studied as a function of the jitter variance, the number of tone bursts, the mean time between tone bursts, and the serial pattern of tone burst frequencies in each sequence. Different rules for generating the serial patterns included: tones of fixed frequency (LLLLLL), tones alternating in frequency (LHLHLH), double alternating frequency tones (LLHHLL), random frequency tones (LLHLHH), and a random-repeated condition (LLLHHL, LLLHHL) in which the same random pattern was repeated in both sequences of a trial. The results support a model of temporal discrimination that is very sensitive to uncertainty about signal frequency and somewhat less sensitive to the frequency pattern of the tone sequence.
Confinement of vibration by structural irregularity
Authors: Hodges C. H. , Woodhouse J.
Published: October 2005

The propagation of vibrations in extended structures with some degree of disorder, i.e., departure from regularity or strict periodicity, is discussed. An account is given of the phenomenon of normal mode localization, caused under certain circumstances by the disorder. This phenomenon means that vibrational energy injected into the structure by an external source cannot propagate to arbitrarily large distances, but is instead substantially confined to a region close to the source. Specifically, it is shown that the steady-state response of the structure decays exponentially away from the source. This phenomenon, predicted by P. W. Anderson in 1958 with applications in solid-state physics in mind, has been of great importance in understanding electrical conduction processes in disordered solids and may turn out to be very important in many acoustical problems as well. We illustrate the phenomenon in terms of two simple mechanical models, a system of coupled pendula and a vibrating string with mass and spring constraints. We present experimental results for the latter system which demonstrate the confinement effect very clearly. [Work supported by the Ministry of Defence (Procurement Executive) U.K.]
Upper bound to coupling loss factor for coupling via a generalized point coupling
Authors: Smith P. W.
Published: October 2005

In Statistical Energy Analysis (SEA) the coupling loss factor equals the power of energy flux out of one subsystem into another subsystem coupled to it, nondimensionalized by the product of angular frequency and energy stored in the source subsystem. “Generalized point coupling” indicates any coupling mechanism whose dynamic displacement can be characterized by a single generalized coordinate, in the sense of classical mechanics. Without any other specification of the coupling, an upper bound is found for the sum of power dissipated in the coupling, if any, and power delivered to the other subsystem. The maximum loss factor is given by nmax−1 = 2πωn(ω = 2πfn(f), where ω = 2πf, f is frequency in Hz, and n(f) = 2πn(ω) is the modal density of the source subsystem— i.e., the density in f of modal resonance frequencies. The formula for nmax−1 equals 27.3 times the number of resonances in a tenth-decade (⅓-octave) hand. The upper bound is achieved in the case of two parallel thin plates of the same thickness, connected by a rigid, massless, point connection.
Diffraction by absorbent wide barriers
Authors: Hayek Sabih I. , Nobile Matthew A. , Kendig Robert P.
Published: October 2005

Wide barriers of a trapezoidal shape are investigated analytically and experimentally. The analytic model for the diffracted pressure is basedon the geometrical theory of diffraction. The incident ray is considered to undergo double diffraction, once at each of the edges of the two back-to-back wedges of the trapezoidal barrier. Thus, the second ray from first wedge to the second must graze the upper surface of the wide barrier. For the double diffraction calculations, the analytic solution for the diffraction by an absorbent single wedge, as originally developed by Malyuzhinets, is used. However, his solution breaks down on the surfaces of absorbent wedges. A correction solution was thus developed for rays that graze the surface of an absorbent wedge, facilitating a model for an absorbent wide barrier. Experiments on ⅕ scale models of hard and absorbent wide barriers were also conducted inside a gymnasium, where harmonic point sources as well as incoherent A-weighted line noise sources were used. The prediction of the analytic models and the experimental data compare favorably for point to point propagation. [Work supported by National Cooperative Highway Research Program—National Research Council.]
A layered ground impedance model for excess attenuation calculations
Authors: Soom Andres , Honda Budd S.
Published: October 2005

Two ground impedance models have been used to compare calculated and measured excess attenuation during outdoor sound propagation over various ground surfaces. A single parameter model uses available semi-empirical relationships between the specific flow resistance and the characteristic impedance of fibrous materials to estimate the normal impedance of ground surfaces assuming the medium to be of semi-infinite extent. A three-parameter model is based on the specific flow resistance and thickness of a layer of porous material situated over a semi-infinite finite impedance backing also characterized by its specific flow resistance. While the single parameter model was found adequate for modelling lawn grass and asphalt surfaces, the layered model provided significant improvement for exposed earth and thin snow layers over ground. For snow layers, low flow resistance layers over higher a flow resistance backing gave good agreement. For the exposed ground, a thin, high flow resistance layer over a more permeable backing proved to be most suitable. [Work supported by NSF.]
Classification of atmospheric turbulence and its effect on sound propagation
Authors: Roth S. David
Published: October 2005

Field measurements of sound propagation over a 90-m path during periods of moderate to strong insolation and slow (<2 m/s) to fast (8–12 m/s) winds have shown that the combined effects of strong ground heating and high wind shear cause the greatest fluctuations in the acoustic signal. Various methods of classifying the atmospheric conditions have been considered. Included are those standard in diffusion meteorology (Pasquill's stability classes). These have been found to be insufficient in the prediction of large acoustic fluctuations. Some data from simultaneous acoustical and meteorological measurements are presented. Elements necessary for a classification system to relate atmospheric conditions to acoustical stability is also discussed and related to the data. [Work supported by USDA Forest Service through the consortium for Environmental Forestry Studies.]
Variability of interaural loudness comparisons
Authors: Uchanski Rosalie M. , Braida Louis D. , Durlach Nathaniel I.
Published: October 2005

Roving-level intensity discrimination tests were performed using pure and partially masked tones of the same frequency (1000 Hz) over relatively large intensity ranges whose endpoints were matched in loudness. Five experiments have been conducted: two monaural experiments involving comparisons between the same stimulus types, two involving interaural comparisons of the same stimulus types, and one involving interaural comparisons of different stimulus types. Preliminary results indicate that the variance introduced by the interaural comparison is roughly independent of stimulus type. The size of this variance is slightly larger than the sum of the sensation and memory trace variances found in monaural comparisons. [Work supported by NSF.]
Time course of adaptation and recovery of human auditory channels selectively sensitive to amplitude and frequency modulation
Authors: Suffield J. Braxton , Tansley Brian W.
Published: October 2005

Psychophysical evidence for channels in the human auditory system selectively sensitive to Amplitude or Frequency Modulation (AM or FM) has been reported by Regan and Tansley [J. Acoust. Soc. Am. 65, 1249–1257 (1979)] and Tansley and Regan [Sensory Processes 3, 132–140 (1979)]. We investigated the time course of channel adaptation and recovery-from-adaptation. In experiment 1 we determined the rate of adaptation growth to sinusoidally amplitude or frequency-modulated 500 Hz pure tones over a 30-min period. Stimuli were modulated at tex times subjects' preadaptation thresholds, measured at the beginning of each session at modulation rates of 2, 4, 8, 16, or 32 Hz. Exposure to AM adaptation tones always elevated thresholds for Am more than this exposure elevated thresholds for FM. FM stimuli always elevated FM thresholds more than AM thresholds. Logarithmic functions describe the differential adaptation of the AM channel by AM tones, and the FM channel by FM tones. Recovery from adaptation to AM or FM tones (experiment 2) is best described by an exponential equation. Our evidence suggests a common neural substrate underlying adaptation characteristics of both AM and FM channels at different modulation rates.
Ultrasonic attenuation and propagation speed in normal human brain
Authors: Kremkau Frederick W. , Barnes Ralph W. , McGraw C. Patrick
Published: October 2005

Attenuation and propagation speed in the 1- to 5-MHz frequency range were measured in vitro in 22 tissue samples from six anatomic sites in five normal human brains obtained unfixed at autopsy. Two methods were used to measure attenuation: (1) received amplitude reduction resulting from insertion of tissue sample between a pair of transducers, and (2) radiation force reduction resulting from insertion of tissue sample between a transducer and a reflector. The piezoelectric transducer method gave attenuation values −10% to +90% higher than the radiation force method. Attenuation (by transducer method) was a function of frequency to the 1.08 power with a value of 0.87 dB ⋅ cm−1 at 1 MHz. Propagation speed was measured by observing signal arrival time change resulting from insertion of the tissue sample between the transducer pair. Propagation speed was 1562 m ⋅ s−1 at 1 MHz with a dispersion of 1.2 m ⋅ s−1  ⋅  MHz−1 over the 1- to 5-MHz frequency range. Ages at death were 3 days, 20, 21, 42, and 72 years. Results were similar in the 20- to 72-year range but attenuation for the 3-day case was about one-third that for adult. Formalin fixing decreased propagation speed by 10 m ⋅ s−1. One-day aging of unfixed tissue resulted in up to a 21% decrease in attenuation and up to a 10 m ⋅ s−1 decrease in propagation speed. White matter (corna radiata, medulla, pons) had attenuation 1.5 times that for gray (Island of Riel, cerebellum) with mixed (basal ganglia) having an intermediate value. Attenuation decreased with increasing temperature. Propagation speed as a function of temperature exhibited a minimum at about 15 °C.
Interactions of masker bandwidth with signal duration and delay in forward masking
Authors: Moore Brian C. J.
Published: October 2005

Forward-masked thresholds for 1-kHz sinusoidal signals were measured as a function of the bandwidth of a noise masker centered at 1 kHz, using a two-interval forced-choice technique. The noise spectrum level was 40 dB SPL/Hz, and noise bandwidth was varied from 50 to 1600 Hz. In experiment I signal duration was varied, with a fixed offset–onset time of 5 ms between masker and signal. For the shortest signal (5 ms) threshold at first increased with increasing bandwidth and then decreased. As signal duration increased, the bandwidth at which maximum masking occurred (the rollover bandwidth) decreased, and for the longest signal (45 ms) maximum masking occurred for the narrowest bandwith tested. In experiment II the silent interval between masker and signal was varied, for a signal of 5-ms duration. Again threshold at first increased with noise bandwidth, and then decreased. However, the rollover bandwidth decreased with increasing silent interval, and threshold varied less with bandwidth. In experiment III signal duration was varied for a fixed offset–offset time of 50 ms between masker and signal. Changes in threshold with noise bandwidth were small, except for the longest signal (45 ms) for which threshold increased markedly at the narrowest bandwidth used. For the wider noise bandwidths, threshold decreased gradually with increasing signal duration, whereas for the narrowest noise bandwidth, threshold increased with increasing duration. It is argued that interactions of excitation and suppression within the internal representation of the masker influence the results, but at least two other factors, detection of energy splatter in the spectrum of the signal and the presence or absence of quality differences between masker and signal, have a powerful influence.
Two procedures for estimating internal noise
Authors: Spiegel Murray F. , Green David M.
Published: October 2005

Internal noise was measured in two paradigms simultaneously. In one method the listener’s agreement in choosing the same masker as the one in a pair that sounds most signal-like is used to estimate internal noise [D. M. Green, Psych. Rev. 71, 392–407 (1964)]. In the other the increment in detection performance on those trials having identical as opposed to different maskers is used to estimate internal noise [R. A. Siegel, unpublished Master’s thesis, M.I.T. (1979)]. Most results place the estimate of additive internal noise as nearly equal to the external noise variability. The estimates from the agreement method can be adversely affected by uncertainty regarding the observation interval and interval biases, whereas the estimates obtained with the detection method are highly sensitive to measurement errors.
The thin, spherical shell as the prototype of a vibrator with coupled modes, exact solution, modal response, and mean-value prediction
Authors: Skudrzyk Eugen J.
Published: October 2005

The velocity amplitude of a thin, sperical shell can be rigorously described by a two-mesh electrical circuit, and a considerable amount of information can be obtained from this circuit without computations. The exact solutions for the radial and tangential velocity components for point excitation of the shell are represented by two oscillator terms with frequency-independent coefficients and are interpreted physically. It is proved that by confining the computations to resonance vibration (using only one generalized coordinate to represent the ’’two-resonance-frequencies’’ modes) the coefficients of the exact solution can be derived with the aid of the Hamilton principle. The resonance frequencies can be approximated with relatively high accuracy by a simple expression, and the mean-value solution and the envelopes through the resonance peaks and the anti-resonance minima are easily derived. The shell turns out to be very stiff at low frequencies; resonances occur only at relatively high frequencies, i.e., near and above the ring resonance frequency. As the frequency enters the resonance range, the shell becomes very soft but, with increasing frequency, it stiffens up again, and its impedance approaches that of an infinite plate of the same thickness.
Acoustic radiation force on a fused silica sphere of large k
a
Authors: Hasegawa Takahi , Ochi Masayuki , Matsuzawa Kiichiro
Published: October 2005

The acoustic radiation force on a fused silica sphere of the size parameter ka up to 100 is investigated experimentally with a view to complete a previous work [T. Hasegawa and K. Yosioka, J. Acoust. Soc. Am. 58, 581–585 (1975)] and to develop an accurate method for determining the acoustic intensity in the high megahertz range. It is shown that the radiation force function Yp for a fused silica sphere in water is regarded as substantially equal to 0.90±0.04 over a wide range of ka greater than 30.
Absorption material mounted on a moving wall—Fluid/wall boundary condition
Authors: Dowell Earl H. , Chao Chen-Fu , Bliss Donald B.
Published: October 2005

The case of a structural (elastic) wall on which is mounted an absorptive material does not appear to have a self-consistent derivation of a physically correct boundary condition. Such a derivation is our goal.
Phase calibration of hydrophones
Authors: Luker L. D. , Van Buren A. L.
Published: October 2005

In order to determine the waveform of an acoustic signal by analyzing the electrical output of the receiving hydrophone, the phase angle as well as the amplitude of the receiving hydrophone sensitivity must be known as a function of frequency. Unless the frequency is well below the lowest hydrophone resonance, this phase angle varies considerably with frequency. This paper describes the extension of conventional amplitude reciprocity calibration to include phase. It also describes a unique measurement configuration that eliminates phase errors resulting from uncertainties in measurement distances and sound speed. Several hydrophones are calibrated using the new procedure. Measured phase-angle results are in good agreement with theoretical results based on diffraction-constant calculations.
Consistent coupled mode theory of sound propagation for a class of nonseparable problems
Authors: Rutherford Steven R. , Hawker Kenneth E.
Published: October 2005

This article examines the effects of boundary condition approximations that arise whenever the coupled mode theories of A. D. Pierce [J. Acoust. Soc. Am. 37, 19–27 (1965)] and D. M. Milder [J. Acoust. Soc. Am. 46, 1259–1263 (1969)], are applied to propagation problems involving range dependent boundaries. This boundary condition approximation requires that the depth derivative, rather than the normal derivative of the field, be continuous across a sloping interface. The approximation is necessary in order to carry out the partial separation of depth and range variables effected in the mathematical formulation of the theory. This article will show that a consequence of this approximation is that conventional coupled mode theory applied to dissipationless media with nonhorizontal boundaries does not conserve energy. It is shown that a correction to coupled mode theory can be derived such that the proper boundary conditions are satisfied and energy is conserved to first order in the local bottom slope. Moreover, the corrections are not prohibitive in terms of added computational complexity. Numerical examples are presented which illustrate the nonconservation of energy effect and the corrections to the theory.
Transition matrix in acoustic scattering by a strip
Authors: van den Berg Peter M.
Published: October 2005

The transition matrix describing the scalar scattering by a strip has been obtained using a boundary-integral-equation technique. It avoids the procedure of the extended boundary condition, taking the strip as the limit of an elliptic cylinder. Our final results confirm the known results obtained from the extended-boundary-condition technique. The method presented in this paper seems to be very attractive to similar problems in elastodynamic scattering.
Practically perfect pitch
Authors: Lockhead Gregory R. , Byrd Robert
Published: October 2005

People who can identify piano notes with essentially no errors (perfect pitch) are much less capable in identifying musical notes produced by sine waves. Thus, frequency is not the only information these people use to identify musical notes; piano notes are complex waveforms or patterns, sine waves are not complex. Musically trained people who do not have perfect pitch ability have considerable difficulty identifying either sine waves or piano notes. As well as this quantitative difference, these two groups of musicians also differ qualitatively. The people in both groups are about equally able to judge octave levels, but people with perfect pitch are excellent in identifying the particular note, e.g., E, independent of its octave, while people without perfect pitch ability are not.
Temporary threshold shifts produced by wideband noise
Authors: Mills John H. , Adkins Warren Y. , Gilbert Robert M.
Published: October 2005

Groups of human subjects were exposed in a sound field to a wideband noise for 24 or for 8 h on consecutive days. The wideband noise was composed of octave bands centered at 0.5, 1, 2, and 4 kHz. For the 24-h exposure, temporary threshold shift (TTS) increased for about 8 h and then reached a plateau or asymptote. TTS’s at asymptote (ATS) increased about 1.7 dB/dB increase in noise level above about 78 dBA. TTS produced by single-octave band exposures were used to predict the TTS produced by the wideband exposures. Predictions were based on the ’’Intensity Rule’’ [W. D. Ward, A. Glorig, and D. L. Sklar, ’’Temporary threshold shift from octave-band noise: Applications to DRC’s,’’ J. Acoust. Soc. Am. 31, 522–528 (1959)]. Predictions were acceptably accurate and the validity of the ’’Intensity Rule’’ for 24-h exposures or 8-h exposures is supported. There is a remarkable coincidence between the relation which describes ATS and noise level, and the relation which describes noise-induced permanent threshold shift (in industrial workers) and noise level. This coincidence and animal data are used to support the hypothesis that TTS grows to an asymptote rather than a plateau, and that TTS at asymptote (ATS) produced by a given sound is an upper bound on any permanent threshold shift that can be produced by that sound.
Acoustic analysis of the Sonic Guide
Authors: Goldstein Beverly A. , Wiener William R.
Published: October 2005

The Sonic Guide is an eyeglass configured sonar-type device available for the orientation and mobility of blind individuals. It operates by emitting toward and receiving from target objects modulated stimuli whose intensity and frequency components directly result from the distance and physical properties of the target. This investigation measured the sound pressure level output, via a sound level meter, of four Sonic Guide temples, at three volume control settings, for six octave frequencies (250–8000 Hz), at six distances (35.6 cm–4.6 m) for a total of 432 measurements. Means, standard deviations, and an ANOVA were computed to investigate the consistency of output across temples and the interactions among frequencies with volume control setting and with distance. Across temples, the Sonic Guide devices were found consistent at each volume control setting, at each frequency, and for each distance measured. Higher volume control settings produced proportionally greater output in the higher frequencies than in the lower frequencies. As distance increased, the peak of the response shifted upward in frequency, although overall, targets at shorter distances produced greater intensity at lower frequencies than did the more distant targets at higher frequencies. Implications for use of the Sonic Guide by hearing-impaired individuals are discussed.
Comparison of backscattering of short pulses by solid spheres and cylinders at large k
a
Authors: Quentin Gérard J. , de Billy M. , Hayman A.
Published: October 2005

Backscattering measurements from solid aluminum spheres and cylinders have been performed at large ka using short ultrasonic pulses. A geometrical theory is developed in order to calculate the arrival times and the amplitudes of the echoes. The theoretical arrival times are the same for a sphere and cylinder of the same material and same radius, but there are important differences in the echo amplitudes. A focusing effect which prevents geometrical analysis is predicted for one type of echo from the sphere. The experimental arrival times for spheres and cylinders of the same radius are compared, and the echo amplitudes at different ranges and target sizes are compared with theory. Very good agreement is obtained between theory and experiment.
Comments on ’’Foliage as a low-pass filter: Experiments with model forests in an anechoic chamber’’ [J. Acoust. Soc. Am. 67, 66–72 (1980)]
Authors: Aylor Donald E.
Published: October 2005

In a recent article by M. J. M. Martens [J. Acoust. Soc. Am. 67, 66–72 (1980)] the measured attenuation of sound by small trees appears to disagree with earlier studies by D. E. Aylor.
Active adaptive sound control in a duct: A computer simulation
Authors: Burgess J. C.
Published: October 2005

Most active sound cancellation systems reported in the literature use open-loop control, depend on near-zero phase delay in control system elements, and require constant acoustic signal transit time from a signal pickup (microphone) to a control sound source (loudspeaker). The applicability of such systems can be significantly enhanced by using closed-loop control. This study concerns a digital computer simulation of adaptive closed-loop control for a specific application, sound cancellation in a duct. The key element is an extension of Sondhi’s adaptive echo canceler and Widrow’s adaptive noise canceler from signal processing to control. The adaptive algorithm is thus based on the LMS gradient search method. The simulation shows that one or more pure tones can be canceled down to the computer bit noise level (−120 dB). In the presence of additive white noise, pure tones can be canceled to at least 10 dB below the noise spectrum level for SNR’s down to at least 0 dB. The underlying theory implies that the algorithm allows tracking tones with amplitudes and frequencies that change more slowly with time than the adaptive filter adaptation rate. The theory implies also that the method can cancel narrow-band sound in the presence of spectrally overlapping broadband sound. The method can be applied more widely, particularly to control systems that involve transport delay.
An aspect-independent sonar target recognition method
Authors: Chestnut Paul C. , Floyd Robert W.
Published: October 2005

A method for sonar target recognition is extended to include target echoes from an arbitrary aspect. The features used for target recognition are the sampled frequency responses of the targets. Since the feature vector varies strongly with aspect angle, a method for extracting linear combinations of features which tend to be aspect independent is applied. The method was tested on experimental echoes using a variety of recognition parameters. The probability of misrecognition ranged from 0.035 to 0.2.
Ultrasonic attenuation caused by Rayleigh scattering by graphite nodules in nodular cast iron
Authors: Papadakis Emmanuel P.
Published: October 2005

Longitudinal ultrasonic attenuation has been measured in a series of specimens of nodular cast iron. The frequency range used was in the Rayleigh region for scattering by the metal grains and the graphite spheroids. Rayleigh scattering proportional to the fourth power of the frequency was observed. When interpreted in terms of present scattering theories, the attenuation was found to be caused predominantly by the graphite particles. Quantitative agreement was achieved between theory and experiment.
Target detection in noise by echolocating Atlantic bottlenose dolphins
Authors: Au Whitlow W. L. , Penner Ralph H.
Published: October 2005

The capability of two echolocating Atlantic bottlenose dolphin (Tursiops truncatus) to detect a target in the presence of white noise was investigated. The target was a 7.62-cm-diam water-filled sphere located at a range of 16.5 m. A spherical transducer located 4 m from the animal directly in line with the target was used to project noise into the water; the spectrum of the projected noise was relatively flat from 40 to 160 kHz. The dolphins’ target detection performance as a function of noise level was determined. At the 75% correct response threshold, which was estimated by interpolation, the echo signal-to-noise ratio was 7.4 dB for one animal and 12.8 dB for the other. The response of an ideal energy detector was found to match the behavioral results as a function of the echo signal-to-noise ratio. It was observed that the dolphins’ response bias departed from the Neyman–Pearson criterion generally associated with dolphin echolocation experiments.
Free vibration of membranes and plates with four curved edges
Authors: Irie Toshihiro , Yamada Gen , Yoda Kaneo
Published: October 2005

An analysis is presented for the free vibration of membranes and plates with four curved edges. For this purpose, a membrane or a plate is transformed into a square membrane or a square plate, respectively, of unit length by the transformation of variables. The transverse deflection of transformed membrane or plate is expressed in a series of the deflection functions of strings (strips of membrane) or of beams parallel to the edges of the square, and the frequency equations are derived by the Ritz method. The elements of the equations are calculated by numerical integration, since they cannot be expressed analytically. By the application of the method, the natural frequencies and the mode shapes are calculated numerically up to higher modes for the membranes and plates symmetrical with respect to the center lines.
Signal and masker uncertainty in intensity discrimination
Authors: Spiegel Murray F. , Picardi Maria C. , Green David M.
Published: October 2005

Intensity discrimination thresholds were assessed in a series of experiments. Signals were in-phase increments in the level of one component of a multitone masker. The main parameters of interest were the effects of signal uncertainty (which frequency is tested on a given trial) and masker uncertainty (which components were selected as the multitone masker on a given trial). Thresholds were measured as a function of signal frequency, number of components, and amount of overall change in masker level. The results suggest a form of profile processing, in which the signal is detected by comparing levels in adjacent critical bands. Such a mechanism will account for the relatively small effects generally observed with signal uncertainty, for masker uncertainty showing larger effects on thresholds than signal uncertainty, and for the near constancy of signal threshold despite large (60 dB) fluctuations in overall level of the stimulus in the two intervals of the forced-choice trial.
Stimuli producing conflicting temporal and spectral cues to frequency
Authors: Warren Richard M. , Wrightson John M.
Published: October 2005

A waveform (A0) was excised from noise and alternated with its polarity inverted form (Aπ) to produce the periodic stimulus A0, Aπ, A0, ... . At infrapitch and low pitch repetition frequencies (2 through 30 Hz) the apparent frequency was twice the fundamental frequency, at 200 Hz and above, the apparent frequency equaled the fundamental frequency, and between 30- and 200-Hz ambiguous pitches were heard. Similar observations had been reported by Flanagan and Guttman [J. Acoust. Soc. Am. 32, 1308–1328 (1960)] for alternating polarity pulse trains at repetition frequencies producing pitch. Their model attributed low-pitch polarity insensitivity to special pulsate characteristics. We suggest rather that, for pulsate and for nonpulsate stimuli, the neural analysis of temporal patterns dominant at infrapitch and low pitch frequencies is insensitive to polarity inversions, so that apparent frequency is twice the waveform repetition rate. The neural place analysis dominant at higher frequencies is spectrally based so that apparent frequency is equal to the waveform repetition rate. It appears that complex waveforms with alternating polarity can be used to separate the results of periodicity analysis from place analysis.
Spatial coherence of wind-generated noise in a shallow ocean channel
Authors: Buckingham M. J.
Published: October 2005

The spatial coherence of wind-generated noise in an isovelocity channel is discussed on the basis of a recent analytical model [M. J. Buckingham, J. Acoust. Soc. Am. 67, 1186–1192 (1980)] of shallow-water noise. An expression, consisting of a summation of Bessel functions, is derived for the coherence function between the noise fluctuations at two horizontally separated sensors. This expression is shown to be virtually indistinguishable from the corresponding result for a similar environmental situation predicted from a more general, computer-evaluated model [W. A. Kuperman and F. Ingenito, J. Acoust. Soc. Am. 67, 1988–1996 (1980)]. The analytical noise model is then employed to investigate the noise gain of a long, horizontal line array in shallow water. In the angular region around endfire, the fine structure on the curve of noise gain versus steering angle is interpreted in terms of the modal structure of the noise field.
Elastic wave propagation in hexagonal honeycombs: II. High-frequency characteristics
Authors: Park S. K. , Bertoni H. L.
Published: October 2005

Based on the methods developed in the companion paper, computations are made of the propagation characteristics of waves in hexagonal honeycomb structures. We investigate the dispersive character of the propagation induced by the periodic nature of the honeycomb. The dispersion is found to have three aspects, one being the variation of wave velocity with frequency. A second aspect is the variation of wave velocity with propagation direction in the x–y plane. Finally, the polarization type of the waves is found to depend on the direction of propagation relative to the cell axes.
On the elastic profiles of a layered medium from reflection data. Part II: Impulsive point source
Authors: Coen Shimon
Published: October 2005

It is shown that the density and the two Lamé profiles of a layered elastic half-space are uniquely determined from the surface displacement due to an impulsive point source. Two different inversion algorithms are developed which construct these profiles in a direct (noniterative) manner from the surface data. The first algorithm transforms the surface data due to the point source into three reflection coefficients due to SH plane waves at two precritical angles and a P plane wave at normal incidence. From these reflection coefficients, the density and the two Lamé profiles are uniquely determined by the procedure developed in Part I of this series. The second algorithm is based on the modification of Weidelt’s theory to apply to the Radon transform of the surface particle velocity. Although the second algorithm is conceptually similar to the first algorithm it provided the necessary conditions for the existence of the solution.
Concerning the numerical constant 0.16...
Authors: Bernfeld Benjamin
Published: October 2005

The numerical constant used in the reverberation time formulae, as given in different papers, books, and standards, shows variations from 0.16 to 0.164, i.e., an error up to 2.5% in the evaluation of T60.
Diffraction of dipole sound by the edge of a rigid baffle
Authors: Meecham W. C. , Bui T. D. , Miller W. R.
Published: October 2005

The theory of the diffraction of dipole radiation by a half-plane has been much used in aeroacoustics work. This letter describes an experiment which directly confirms the predicted diffraction effects.
Plasma angiotensin II changes with noise exposure at three levels of ambient temperature
Authors: Wright John W. , Dengerink Harold A. , Thompson Pamela , Morseth Sandra
Published: October 2005

Significant plasma elevations of the powerful vasoconstrictor angiotensin II (AII) were measured in rats following exposure to either 100-dB or 20-dB SPL white noise in three environmental temperatures (5°, 21°, and 38 °C). Loud noise exposure in the normal temperature condition (21 °C) and both temperature extremes with soft noise exposure resulted in marked plasma AII elevations. The two extreme temperatures combined with loud noise exposure resulted in plasma AII concentrations not different from the levels observed following 20-dB noise at normal temperature. These results indicate that separately administered noise and temperature extremes stimulate the production of AII and thus vasoconstriction. Simultaneous exposure to multiple stressors including noise and temperature extremes may result in severely elevated plasma catecholamines and reduce renal responsiveness to β-adrenergic stimulation thus reducing plasma AII levels.
Directivity patterns of laser-generated ultrasound in aluminum
Authors: Hutchins D. A. , Dewhurst R. J. , Palmer S. B.
Published: October 2005

Directivity patterns of laser-generated longitudinal and shear waves in aluminum have been determined experimentally, for laser power densities both above and below the threshold for plasma formation on the target’s surface. Comparison of experimental results with theory has allowed generation mechanisms to be identified. Thermoelastic mechanisms predominate in the absence of a plasma, where stresses parallel to the surface are a dominant source characteristic. At higher power densities, momentum transfer from ablating material becomes more important, leading to a source with normal drive components.
Absorption of sound in water fog
Authors: Wei Rong-jue , Wu Jun-ru
Published: October 2005

This report serves as a retrospect of the problem in question since the early forties when serious study of the effect of sound absorption due to mass transfer began. The progress in an understanding of this effect since then is discussed. Different theories and their relationships are examined. It is concluded that because of the scarcity of data a quantitative comparison between theory and experiment is still difficult. We reach the view that more intensive investigations concerning fog dynamics as well as more accurate measurements of fog constants by employing present-day laser and computer techniques are desirable.
A cross-language study of range of voice onset time in the perception of initial stop voicing
Authors: Keating Patricia A. , Mikoś Michael J. , Ganong William F.
Published: October 2005

A series of experiments was carried out to compare the extent of range effects in the phonetic categorization of voice onset time (VOT) by speakers of Polish and of English, two languages which contrast different VOT categories. Results indicate that Poles are more prone to range effects than are Americans. For acoustic continua with appreciable numbers of prevoiced stimuli, monolingual Polish speakers’ perceptual boundaries fall in the gap between their production categories. For ranges of VOT which include few prevoiced stimuli, their boundaries are substantially shifted. Americans show no shifts of this type, although they do show some small shifts. It was determined that the much smaller shifts shown by the American subjects were not due to expectations about the test. Results are interpreted in terms of the different VOT contrasts involved: their spacing along the VOT continuum, and their psychophysical basis.
Forward-masking AP tuning curves in normal and in acoustically traumatized ears
Authors: Gorga Michael P. , Abbas Paul J.
Published: October 2005

Compound action potential tuning curves (APTC’s) were developed in a series of normal and acoustically traumatized cats. Probe frequency was set to 4 kHz and probe level was set to 15–20 dB SL re: AP threshold for both normal and impaired ears. In addition, normal ears received the probe tone at a level of 70–75 dB SPL. Probe-elicited AP amplitude was measured in a forward-masking paradigm as a function of both masker level and frequency. Results indicated that the sharpness of the APTC’s (defined by Q10) was unaffected by acoustic trauma. The relative difference between required masker level on the tail and at the tip was reduced for the noise-damaged ears. Thus sharpness around the tip was essentially normal yet low-frequency energy was more effective at masking high-frequency regions in these impaired ears. When slope of the decrement in normalized, probe-elicited AP amplitude-versus-masker level functions are calculated for different frequency maskers, normal ears showed a frequency dependence such that low-frequency maskers resulted in the steepest slopes with progressively less steep slopes as masker frequency increased. Some of the noise-damaged ears did not show this same frequency dependence. Specifically, the slopes of these functions were not as different for low- and high-frequency maskers. These slope data may suggest that nonlinearities, present in the normal system, may be reduced as a consequence of this cochlear insult.
Elastic wave propagation in fluid-saturated porous media II
Authors: Berryman James G.
Published: October 2005

Recently, a new method of deriving the coefficients in the strain energy functional of Biot’s theory for elastic waves in fluid-saturated porous media was proposed. The results of this approach have been criticized as being unphysical in the limit K*/Kf → 0, where K* and Kf are the frame and fluid bulk moduli. We show that an error arose due to the literal interpretation of the term ef as the fluid dilatation whereas this term actually differs substantially from the fluid dilatation in some situations. We also show that by lumping part of the solid together with the fluid (conceptually) to form a fictitious fluid suspension, the corresponding fictitious ef may be correctly interpreted as the dilatation of the fluid suspension. This trick leads to a transformation which takes the recently published formulas into standard form. The standard formulas are found to be invariant under the same transformation. New insight into the significance of the standard formulas for the coefficients is obtained.
Wind generated noise in the Parece Vela Basin
Authors: Shooter Jack A. , Gentry Milton L.
Published: October 2005

A 24-h segment of noise level as a function of wind speed and frequency is presented for the frequency range 150–500 Hz. These data were measured in the Parece Vela Basin and represent one of the few (maybe the only) cases where the wind speed was measured in situ along with the noise level in the deep open ocean. The acoustic data show lower levels and a greater sensitivity to changes in wind speed than some other areas.
Wave propagation and resonance in piezoelectric materials
Authors: Auld B. A.
Published: October 2005

The two basic physical phenomena involved in all piezoelectric devices are wave propagation and resonance. A general review is first presented of the connection between piezoelectricity and crystal symmetry, noting that a recent arrival on the scene (ferroelasticity) is intimately related to crystal symmetry rules for piezoelectricity and promises to be applicable to new devices in the future. Special features peculiar to wave propagation in piezoelectric materials are noted and a brief sketch is given of methods used for solving piezoelectric boundary value problems.
Loudness (or annoyance) summation of combined community noises
Authors: Berglund Birgitta , Berglund Ulf , Goldstein Mikael , Lindvall Thomas
Published: October 2005

The purpose of the experiment was to study how the loudness (or annoyance) of the constituents in pairs of community noises combines into total loudness (or total annoyance). Three community noises (pile driving, jack hammering, street traffic) were combined pairwise at different sound levels. The observers judged the total loudness of the combined noises as well as the loudness of each component noise when heard alone. Three models of loudness (or annoyance) summation for noise were tested: a vector summation model, a model assuming that the loudnesses of the masked constituent noises add arithmetically, and a simple model stating that the total loudness equals the loudest of the component noises when heard alone. All three models fitted the data satisfactorily from a statistical point of view. The ’’loudest component’’ model was favored because it produced a prediction error of only 14% in the ’’worst case’’ and can, therefore, serve as a ’’rule of thumb’’ for many practical purposes.