The thermodynamics-like theory (an analogue theory of the ideal gas) of annoyance coupled with a power law hypothesis is studied, particularly on the behavior of the constant γ in the theory. It is found that magnitude of the constant γ should depend on the energy of the external stimulus of noise under the power law hypothesis. Further, numerical values of the parameters of the power law are discussed.

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The rates of chemical dissolution of spherical gypsum were measured in aqueous solutions of several kinds of chelating agents, such as EDTA, CyDTA, DTPA, GEDTA, and EDTA-OH. Particularly in EDTA solution, the relation between the power of ultrasound and the rate of chemical dissolution accelerated by ultrasonic irradiation was investigated in details. The investigation has revealed that the mechanism of the chemical dissolution of the gypsum and how ultrasound acts on the acceleration of the dissolution. These dissolution mechanisms are also applied to the chelating agents other than EDTA. Considering also the chemical properties of the agents, it has been deduced that the rate of chemical dissolution of calcium salt in crystal state seemed to be dependent on the concentration of chelating agent ions, i.e. ligands, having more than four uncoordinated donor groups and the values of the effective stability constant.

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There are various effects of environmental noise on our daily life, but there are few investigations of the effects of noise on performing some tasks. This study aimed atobtaining the evaluation of the noise with context in situations similar to daily life. In order to realize this situation, the subjects were instructed to suppose that theywere listening to the broadcast in the living room. And they were told to evaluate the noises with context which is presented with the broadcast program. The results showed that the annoyance of the noise with context is almost evaluated by L_eq. Investigated in detail, however, the interruptive sounds with context, are more annoying than the steady and meaningless noise with the same energy. This fact seems to be related to the effect that the attention is scattered when signal sound and interruptive sound can be heard at the same time.

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In this paper, the principle of the active control of noise in duct is analyzed bymeans of impedance. It is shown that the principle is equivalent to making a short circuit on a transmission line by the equivalent impedance of the active system. From the result of the analysis, general equations and their equivalent circuits of multi-microphone and multi-loudspeaker system are deduced, and also general requirements for control without acoustical feedback which makes the system unstable, are made clear. For the practical use, some suitable combinations of microphones and loudspeakers which control the noise without acoustical feedback are shown. In addition, an electrical method by which the acoustical feedback is canceled is proposed.

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