The reverberator is used today to add reverberation (mainly musical and panoramic sound etc. . )to signal. But there still remains the question how to add reverberation to signal. To resolve this question, a sound field which is similar to three dimensional room was brought into being by the electro-acoustical devices in an anechoic room. Using this sound field, experiment was carried out with the view of finding the relation between subjective evaluation and components of fundamental acoustical characteristics in a room. This paper describes the synthetic way of sound and the experiment conducted on the relation between the delay time amongst the fundamental acoustical characteristics in a room and its subjective evaluation. From the experimental results, it may be concluded that the traits are connected with the delay time, and especially some of them are effective to the delay time up to 50m sec whereas they are not effective for subjective effects when the delay time exceeds the above value.

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A new method of controlling the directivity of synthesized directive output in receiving system is described. This method, abbreviated as the TD (time difference) method, is different from the other usual methods in its principle. The information on the time difference between outputs of separated hydrophones was utilized to synthesize the directive output. The signals from hydrophones were transformed into pulse trains, maintaining the initial time difference, and then the controlled relative delay and pulse widths were given. After that, the coincidence of each pulse in pulse trains was discriminated in order to trigger the final output stage. The bearing and the width of receiving beam were controlled by relative delay and pulse widths respectively. Controlling characteristics and the limitation for speed of bearing-scanning were theoretically analysed, and experimentally confirmed. The effects of noise were also discussed. The receivine beam was electronically controlled and high-speed scanning was easily attained. The result of the reduced scale test on the experimental sonar with sector scanning by TD method is shown.

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