Sabbath (Binaural Recording)

This tune is played by the synthesizer system using 20 channel speakers and recorded with a dummy-head microphone; therefore, its three-dimensional sound can be enjoyed by playing the tune back with headphones. The inner loudspeaker unit is arranged to form a rectangle that is 157 cm long and 148 cm wide, with eight channel speakers placed in the front and back. Four channel speakers are arranged on the left and right sides of the rectangle, two on each side, at a distance of 33 cm from each vertex, and a dummy-head microphone is placed at the rectangle's center of gravity. The sound source localization of the eight channel speakers is controlled using a mixer with a built-in amplifier. In this case, the sound source localization perceives the sound played back from the eight channel speakers. The loudspeaker is arranged so that the eight speakers may be adjoined, and the sound is transmitted using a mixer. The sound source localization of the four side channel speakers is controlled using an amplifier and a mixer, with the mixer allowing sound source localization to move to the left and right sides of the rectangle. The multiple synthesizer, state variable filters, all-pass filter, Sallen-Key circuit, and whitening filter are used for filtering the system. The two kinds of state variable filters used are called state variable filter 1 and state variable filter 2, and their circuits differ. A multiple synthesizer is connected with a computer synthesizer and can perform amplitude modulation and sound synthesis. The output signals of the multiple synthesizer and state variable filter 1 are input into the mixer that controls the eight channel speakers on the front side of the rectangle. The output signals of the Sallen-Key circuit and all-pass filter are input into the mixer that controls the eight channel speakers on the back of the rectangle. Finally, the output signals of the state variable filter 2 and whitening filter are input into the mixer that controls the four channel speakers on the left and right sides of the rectangle. Because each mixer can control two sound source localizations, this system's sound is unique. Thirty-two channel speakers used by the conventional system were changed into 20 channel speakers. Therefore, although an individual difference may be heard when playing back this tune by headphones, unlike the traditional system, this system's sound image is localized outside the head.