Physical measurements and a subjective evaluation have been performed for four analog type compact-cassette tape decks. From analysis of the correlations between different domain measurements, static phase difference between two channels and amplitude fluctuation in the high frequency range closely correlate with the subjective evaluation. In addition, 2nd and 3rd harmonics tend to correlate with the subjective evaluation. Therefore, an improvement in sound quality will probably be perceived with digital compact cassette decks, because amplitude fluctuation and nonlinear distortion have been reduced to negligible values.

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In this work the design and evaluation of the recognition performance of context dependentHidden Markov Models (HMMs) for the intervocalic voiced and unvoiced stops is described. The phoneme HMMs are context-dependent in order to account for coarticulatory effects. Continuous probability density functions are used for the out putvectors. Initial model parameter estimates are obtained by means of an automatic segmentation procedure for careful modeling of relevant pho etic features. The model structure and the training scheme are directed to associate the most acoustically dis criminativesegments of the consonants with a sequence of states in every consonant model. The speech data base consisted of a total of 2, 592 productions of the Spanish Stops /p, t, k, b, d, g/ in intervocalic positions with the vowels /a, i, u/ embedded in VCVCVCV nonsense utterances. The speech data has been produced by two male Argentine Spanish speakers. Phoneme recognition is accomplished finding the state sequence with highest likelihood in an ergodic model formed by the linking of all the context-dependent phoneme models allowing only the phonotactically valid state transi tions.A comparative study of the recognition performance under different degrees of context dependence, and the alternative use of spectral dynamic and energy related pa rametersis presented.

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This paper describes an investigation into the variation with humidity and carbon dioxide content in air of the speed of sound, characteristic impedance, specific heats, the ratio of specific heats, air density and the molar mass. The theoretical model is an approximation, which is based on standard air over a temperature range of 0 to 30 degrees Celsius and at a barometric pressure of 101.325kPa. Empirical equations for the computation of the above physical properties are provided together with uncertainty estimations.

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Split of sound image is an auditory phenomenon which must be avoided in designing and controlling sound fields such as concert halls, auditoria and theaters. This paper pro posesa practical chart to predict the degree of split of sound image for speech. The chart was obtained from the results of a psychoacoustical experiment in which a direct sound and a single reflection were presented to a large number of subjects. The chart should be utilized to predict the degree of split of sound image, which is a different phenomenon from echo threshold and echo disturbance.

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The mathematical analysis of non-axisymmetric vibration of a piezoelectric annular plate and its application to an ultrasonic motor had previously been reported. In this paper, analysis of the annular plate clamped on its inside or outside circumferences is stated from the view point of its application to an ultrasonic motor. Calculated results reveal the potential usage of the vibration modes for a thin-type ultrasonic motor.

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An adaptive lattice modeling method for speech processing is proposed. It is a device made of a refined ARMA lattice model. The refined ARMA lattice model is designed as a minimum realization stochastic model. In addition, this paper shows that it is not difficult to determine ARMA orders of the model because of lattice structure. Since the model is identified by using an adaptive approach, the estimation accuracy and the time resolution on the analysis procedure become high enough. Relationship between the refined lattice model and Richards circuits which include loss-less transmission lines is also pointed out. From this association, it is revealed that all ARMA lattice parameters can be transferred to characteristic admittances of transmission lines. Since all admit tanceparameters are physical values, the stability of an estimation model can be checked by observing them directly. From some experimental results, this paper shows that the above properties are suitable for speech processing.

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A new series expansion of the velocity potential in cylindrical coordinates is derived first. Although this expansion holds for an arbitrary piston, the detailed analysis is performed for a cylindrical shell piston. The expansion is used to calculate the velocity potential in the near field of the cylindrical shell piston.

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A number of experiments have been carried out in order to research how to design the interior of a four-channel sound control room for so called “Hi-Vision” (high-definition televison). In this four-channel sound reproduction form, the three main channels are reproduced from the three front loudspeakers, and the surrounding sound of the fourth channel is reproduced from the two rear ones. In these experiments, interiors of the test rooms were varied in accordance with five measuring conditions. However, room shapes were not varied. The experimental items were:(1) static transfer frequency re sponse, (2) mean frequency spectrum of music sound, (3) questionnaire, (4) subjective estimation. The results from the following three viewpoints were analyzed:(1) less coloration, (2) the width of the listening area, (3) the amenities of the sound production room. It was found that when treating the front walls, ceiling, and floor with absorbent materials and providing the rear with a diffusive and reflective surface, the results were superior in all experimental items. It was also confirmed that this concept is applicable to ordinary two-channel sound control rooms. Experimental results in actual twochannel sound control rooms are also mentioned.

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