Many experimental data suggest that a listener who focuses attention on a specific spectral region (or regions) becomes more sensitive to sounds falling there than elsewhere. Most often, the subject's task has been to detect a pure tone in noise. For example, in a two-interval, forced-choice paradigm, scores were around 90% when the signal was at an expected target frequency (0.5, 1, 2, or 4kHz) and were near chance, 50%, when the signal was at an unexpected frequency more than a half critical band away. In other tests, subjects detected unexpected temporal patterns (repeated tone bursts) just as well as expected patterns, provided spectral frequencies were the same. It has also been shown that when listening to a sequence of tone bursts that rise (or fall) in frequency, subjects miss a burst at a frequency significantly different from the value it normally has in the sequence. Other data suggest similar spectral specificity in the discriminationof complex sounds, including speech. Just what mechanism improves performance remains unclear. Nevertheless, some measurements of evoked physiological responses leave open the possibility that spectral specificity is achieved by efferent input to the auditory periphery, perhaps even to the cochlea.

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The time-averaged intensity spectral density function of the acoustic radiation from rotating blades is theoretically derived by replacing the blades with rotating dipoles. Dimensional analysis reveals two non-dimensional parameters which play an important role in generating the blade-passing frequency tone and its multiples. Increasing the number of rotor blades widens the peak under the condition that the non-dimensional parameter of the rotational speed is fixed. Moreover, the acoustic spectral density function is not stationary even if the inflow turbulence is homogeneous and isotropic. Further, the time variation of the propagation path due to the rotation should be considered in the computation of the spectral density function. For instance, in the rotor specifications of the present study, the rotor radius is approximately 0.3m and the rotational speed Mach number is approximately 0.2.

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This paper describes new experimental results on equal-loudness level contours and the minimum audible sound field (MAF) as well as a supplementary consideration on experimental procedures. Our equal-loudness level contours for 20 phon or greater are close to those obtained by Fletcher and Munson rather than to those by Robinson and Dadson. On the other hand, the minimum audible sound field reported herein is similar to that in ISO 226 which was obtained by Robinson and Dadson. Supplementary experiments to clarify the discrepancies among various research studies suggested that the experimental condition, e.g., whether the level of the standard tone or the level of the test tone is varied, could be a possible cause to explain a part of the discrepancies.

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The effect of noise events of railway noise has been found in earlier researches. But this is inconclusive problems. The number effect of ordinary railway noise in Tokyo was examined for sixteen different reactions. Analyses were conducted for individual and grouped data of Likert's scales and highly disturbed responses. Further analsyis was conducted by Hayashi's quantification method 2 and the number effects were obtained from trade-off method. Conventional assumption that reactions are related to the logarithmic number effect of the events is supported with this data, but additive model cannot be rejected. The decibel equivalent number effect (k) ranged widely among different reactions in different methods of analyses. As for annoyance, the number effect was estimated to be equal to or larger than k=20.

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The purpose of the paper is to find out the instant of the glottal opening/closure from the speech signal by a recursive algorithm, and to accurately estimate the characteristics of a vocal tract by using glottal closure covariance analysis. The identification of the glottal closure/opening was achieved by estimating the waveform of the glottal volume flow. A recursive estimation of the glottal volume flow was realized by using a timevarying AR model with an unknown nonwhite input (u-input). In the applications to synthetic vowels generated by the two-mass model, it is shown that the phase of the estimated u-input corresponds to that of the glottal volume flow. It is also shown in the experiment for real vowels uttered by male adults that the phase of the estimated uinput corresponds to that of the glottal movements which can be confirmed by observing the Electroglottograph (EGG). The glottal closure intervals are determined from the estimated u-input, and stable formant frequencies are estimated by covariance analysis which utilizes only the speech during glottal closure intervals. The estimates are compared to the conventional autocorrelation LP analysis. As results of some experiments, we show that the proposed method is effective for the identification of the glottal closure intervals.

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A practical method for estimating the headway distribution based on the experimentally observed data of the number of vehicles passing in a certain time interval is theoretically considered in the general case of gamma-type headway distribution model. Concretely, an explicit expression of a generalized probability function for the number of vehicles is newly derived in the expansion form. The probability expression proposed in this study includes as special case the weighted sums of Poisson due to F. A. Haight. The unknown parameteres contained in the headway distribution function are estimated by using the method of maximum likelihood. The validity of the theory is experimentally confirmed by use of a digital simulation technique.

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