Optimum listening levels and Sound quality evaluation of 3-1 surround Sound in Hi-vision HDTV system were studies. A hundred non-professionai listeners were attended to the experiment as subjects. AS for the listening levels, meam level that listeners judged optimum was 83.9 dB(C-weighted) for the classical music, and 79.8 dB for Japanese populer music. Those values are 8〜10 dB lower than that of the professonal studio mixing engineers. Difference will be presumably come from the difference of experience between professional studio engineers and non-professional listeners. As for the sound quality evaluation, most of listeners highly evaluated 3-1 surround sound rather than conventional 2 channel stereo sound. Using the factor analysis method, subjective evaluations of 3-1 surround sound are classified to three independent factors, i.e. the first factor "Ambience", the second "Surround" and the third "Sound volume". Results of this study will be useful for the standardization of HDTV multichannel sound system.

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It is so complicated to produce HDTV program in the conventional post-production studio due to the different synchronizing frequency and time-code format between HDTV and NTSC. Therefore the sound post-production studio specially designed for HDTV (HVD520) has been constructed in NHK. This studio featured by several specifications such as large screen with low acoustical loss (156 inches), full digital processing system with digital mixing console, DAW and several digital equipments. It is expected to produce new surround sound program for HDTV using computer-aided system.

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We have recently developed a new digital audio signal frame synchronizer. This equipment, when digital audio signals from outside broadcasting are input into a digital system of broadcasting station, reduces audio distortions caused by the difference of frequency accuracy between transmitted Sampling signals and an in-station reference signal. The new equipment uses an over-sampling method of a high degree and a 16-bit digital signal processor and operates the low-pass filter with a newly developed algorithm. These innovations have resulted in a high-Performance audio equipment operated in real time with minimized Sound deterioration.

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This "Support system" has an interactive Knowledge Base(KB). Interactive KB makes simple to construct and adapt KB (without knowledge engineer and computer expert). "Support system" easily gathers knowledge which each operator has, and it presents gathered knowledge by human-machine interface using Hypermedia.

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KDD in cooperation with AT&T and BT launched the first international ISDN service in the world on June 1, 1989. The network growth since the inauguration of international ISDN service includes the interconnection with NTT's domestic INS-Net and the overseas expansion to 20 regions as of June 1993. Regarding international ISDN applications, the use of videoconferencing has been steadily increasing in Japanese businesses as well as foreign based ones and high-bandwidth audio codec has been accepted by broadcasting businesses.

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We, Tokyo Broadcasting System Inc. (TBS), have brought in a computer Booking System, which enabled us to link the booking conditions instantly with the Press Section, Circuit Office, Overseas Bureaus, and other related places. Also, we have set up a digital exclusive line between New York Bureau and Tokyo, which made it much easier to carry on the transmissions.

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Fuji Television Network has introduced into its production technology base the ADX-7000 broadcast-use digital audio console it developed and manufactured in cooperation with the Tamura Corporation. With 48 BUS capabilities, ADX- 7000 responds to present-day audio demands, providing both multi-recording and surround broadcast audio. The console itself, moreover, has storage and replay capacity for up to 90 parameter patterns.

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