In this paper, how the output probability distribution form of sound energy is affected by the frequency width W of random input, the time constant T of sound level meter, the reverberation property of room and the existence of direct sound component is theoretically and experimentally considered, especially from the fundamental viewpoint by use of characteristic function method of probability. In two special cases with no signal component and a signal component of narrow frequency band, the proposed theory agrees with the well-known probability distribution expression derived previously in the field of room acoustics. Finally, by actually applying the above theory to the sound energy fluctuation observed in the diffused sound room, the legitimacy and the validity of theory are experimentally confirmed too.

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This paper proposes a new spark discharge pulse sound source model, and validity of the model is examined by comparison between the theoretically estimatedand experimentally obtained output pulse wave forms. This paper describes first the pulse spark discharge sound source model and an estimation method for directional dependency of the wave form. After a brief explanation of the pulse sound source structure, the experimentally obtained output pulse wave forms and directivity patterns are compared with the estimated ones and the good coincidence between them is shown. The model proposed in this paper explains well the experimental results.

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Schouten's temporal theory is revised by altering time intervals between peaks of fine structure waveform taken previously by Ritsma and Engel, and as a concrete model of the “revised fine structure theory” the interspike interval distribution of a mathematical model for firings is numerically investigated. It is shown that the “revised fine structure theory” is phase-insensitive. Hence, the chief objection against the fine structure theory on “phase-fine-structure problem” lodged by the majority of auditory investigators is unreasonable. Moreover, a new question in the fine structure theory including in most recent theories is raised.

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The input admittance measuring system for shakuhachis was constructed and its accuracy was examined in detail. Then basing on the comparison with input admittance measurement of various pipes by the use of this system, input admittance calculating method was improved for the purpose of obtaining sufficient validity to be used for design practice of the shakuhachi or any other woodwinds. The pipes used in the comparison were 4straight tubes with and without side holes and two real shakuhachis. The maximum error of the measuring system was estimated to be5.3cent in peak frequency and 2.2 dB in absolute level. The average differences of calculated frequency and level of input admittance peaks from those measured were less than3cent and3dB respectively. As for levels of higher peaks relative to the first peak as well as the levels at the multiples of the two lowest peak frequencies, the calculated values showed well coincidence with those measured.

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The calculating estimation of the initial impulse response at a receiving point within an auditorium through the computer simulation has developed as one of the effective measures to obtain design information for room acoustic designing. In simulating sound field in a room, it has generally been assumed to be a diffusive sound field. However, in analyzing the impulse response of a hall in terms of initial impulse response, which has a significant acoustic effect, the reflected sound from a wall surfaces reaches a receiving point discretely and not in a diffused state. Accordingly, such an assumption is not necessarily appropriate. This paper deals with the analysis of and experiments on the reflection response of finite rigid surfaces to acquire basic information for sound field simulation. In the analysis, the areal integrals on reflecting surfaces are found through the application of the sound ray tracing method, which has originally been developed on the basis of geometrical acoustics, for the approximation of impulse response incorporating the effect of the wave motion of sound. The appropriateness of the new finite sound ray integration simulation system is verified by proving the possibility of the approximation of a transfer function corresponding to the accuracy of simulation for the multiple reflection, through the comparative evaluation of the measured results and the results of simulation calculation regarding flat plate, diffusive plates and closed spaces.

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Sound propagation is considered in the rest atmosphere where the sound velocity varies linearly with height. With the results of the ray theory of refraction being introduced to the asymptotic solution of spherical wave propagating over a locally reacting ground surface, the approximated solution of the sound field is obtained. The results of calculation by this theory explains the measurements satisfactorily, as a result quantitative prediction of excess attenuation is available.

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Until now, the output probability distribution prediction for the sound insulation system was investigated by many researchers based on two contrastive structural and descriptive approaches especially from a methodological viewpoint. The descriptive method is certainly more suitable for the complicated stituation of actual sound insulation systems with an arbitrary distribution type random excitation. In this paper, especially by paying our attention to the effective information on the remainder fluctuation around the formally introduced linear regression, a simplified identification method for an arbitrary sound insulation system and then a simple prediction method for its output probability distribution have been proposed. More concretely, by introducing new types of linear and/or non-linear regression models between input and output fluctuations, their system parameters can be identified by use of the well-known least squares error method or its generalized error criterion. Furthermore, in an actual case with an existence of background noise, the effect and simple removal countermeasures of background noise are also discussed. The effectiveness of our identification and prediction methods is experimentally confirmed too by applying them to the actual living environment.

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