Abstract: A plurality of actuators are provided at predetermined intervals on the reverse surface of a predetermined side wall of a swimming pool. When an electric signal corresponding to a sound to be propagated in the water is given to the actuators, the electric signal is converted by the actuators into a mechanical vibration signal to cause vibrations. The actuators are secured directly to the reverse surface of the predetermined side wall by an adhesive or otherwise, and thus the vibrations of the actuators are radiated as a sound in the water of the pool through the side wall.

Abstract: A method is provided for designing an acoustic correction filter applicable to a stringed instrument, which is composed of a string member operable to undergo a vibration, a support member for supporting the string member, a body member responsive to the vibration transmitted through the support member for generating a natural sound and a mute attachment for muting the natural sound. The acoustic correction filter is operable when the natural sound is muted by the mute attachment for filtering a signal derived from the vibration so as to create an artificial sound instead of the muted natural sound.

Abstract: A method is provided for designing an acoustic correction filter applicable to a stringed instrument, which is composed of a string member operable to undergo a vibration, a support member for supporting the string member, a body member responsive to the vibration transmitted through the support member for generating a natural sound and a mute attachment for muting the natural sound. The acoustic correction filter is operable when the natural sound is muted by the mute attachment for filtering a signal derived from the vibration so as to create an artificial sound instead of the muted natural sound.

Abstract: A plurality of actuators are provided at predetermined intervals on the reverse surface of a predetermined side wall of a swimming pool. When an electric signal corresponding to a sound to be propagated in the water is given to the actuators, the electric signal is converted by the actuators into a mechanical vibration signal to cause vibrations. The actuators are secured directly to the reverse surface of the predetermined side wall by an adhesive or otherwise, and thus the vibrations of the actuators are radiated as a sound in the water of the pool through the side wall.

Abstract: A reverberation generating system stores parameter data representative of a series of timings and a series of sound intensities for an initial part of reverberation, and calculates a series of parameter data for the later part of reverberation by using a return map of the proportional constant for time intervals of the initial part inversely proportional to the square of lapse of time so that the reverberation generating system stores the parameter data for the initial part only.

Abstract: A system for controlling the second field in auditorium having the feature that stage and audience seating areas are different acoustically, which includes a first assisted acoustics system whereby acoustical energy from the stage area is input, and then controlled acoustic energy is supplied to the audience seating area, and a second assisted acoustics which is provided independently of the first electronic acoustical augmentation system, whereby acoustical energy from the audience seating area is input, and then controlled acoustic energy is supplied to the stage area. Each assisted acoustics system includes acoustic energy input devices and acoustic energy output devices whereby a uniform rate of power decay coefficient can be effected throughout the hall, including spaces under balconies and the like. Significantly improved the degree of acoustic similarity between the stage area and audience seating area is achieved by controlling reverberation characteristics.