The practical calculations of the first reflections from elements comprising the boundaries of an auditorium (such as a rigid plane panel, a rigid curved panel, and a panel having reflection coefficient other than unity) have reported. Multiple reflections between two rigid plane panels, two rigid convex panels, two plane panels with reflection coefficients different from unity, and those inside a rigid concave panel have also reported, based on the calculation of the first reflection. In this report, Terai's boundary integralequation is transformed by the successive substitution where early terms correspond to the early reflections. For each term, the equivalent result reported previously is applied. Finally, the calculated pulse response of the early reflections in a scale model auditorium, which is the convolution of the calculated impulse response and the direct sound simultaneously obtained, is compared with the measured result. It is shown that the sum of the reflections in a several orders correspond well to the measured early reflections and that the details of the formation of the sound field can be discussed on this method.

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Input impulse responses of several bassoons are presented. The impulse responses are obtained by the inverse Fourier transform of measured input impedances of the bassoons as seen from the bocal entrance. Method of input impedance determination are outlined. Comparison of the impulse responses shows such differences between a particular bas-soon and the others as can be found only by test blowing.

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In this report, a new functional evaluation method for predicting the output cumulative probability distribution of a sound insulation system is theoretically proposed, by intro-ducing few functional parameters supported by many physically structural factors directly connected with the statistical energy analysis method. These functional parameters are identified by practically introducing the entropy criterion. The proposed method was experimentally confirmed by applying it to the actually observed noisy data.

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The main purpose of this report is to provide a deeper and more adequate understanding of active noise control (ANC). ANC is now developed in many directions; many ex-periments have been done, proving that several kinds of noise and vibration can be at-tenuated substantially by active devices. One of the authors recalls the origins of his own method, which had been applied and developed in acoustics by G. Mangiante and G. Canevet becoming then the “JMC theory.” This theory has been recently reformulated in a set of three theorems on “field reshaping.” The first theorem of Field Reshaping is analyzed. It leads to a very general “designer's equation” which can be considered as the key of most active control systems.

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