Abstract: A process for evaluating spatial impression of an enclosed space includes the steps of generating output signals as a function of fluctuating sound pressure at two points spaced about one-quarter meter apart, band limiting the output signals to a pass band of less than about one octave, generating fluctuating signals that represent amplitude information of the band limited output signals, band limiting the fluctuating amplitude information signals to a pass band of about five hertz to thirty hertz, and comparing the band limited fluctuating amplitude information signals to provide an indication of the spatial impression of the enclosed space.

Abstract: A sound reproduction system for converting encoded stereo signals on input channels A and B into signals on left, supplemental left, right, and supplemental right output channels, respectively, that includes a left output channel for producing output signals intended to come from the left direction; a supplemental left output channel for producing output signals similar in level (intensity) to output signals of the left output channel and with reduced steered signal level for left direction signals; a right output channel for producing output signals intended to come from the right direction; and a supplemental right output channel for producing output signals similar in level (intensity) to output signals on the right output channel and with reduced steered signal level for right direction signals.

Abstract: An electroacoustic system for acoustic enhancement of a room that includes a sound source location. The electroacoustic system includes a microphone spaced from the sound source location, an array of loudspeakers arranged in at least four interleaved banks, each bank including at least one loudspeaker, and signal processing electronics connected between the microphone and the speaker banks that includes an input channel, circuitry connecting the microphone to the input channel, a plurality of output channels corresponding in number to the number of speaker banks, circuitry connecting each output channel to a corresponding speaker bank, and at least four statistically independent time-variant reverberation units responsive to input signals from the microphone for producing output signals on the output channels for driving the several banks of speakers.

Abstract: A directionality enhancement system for converting encoded stereo signals on input channels A and B into four signals on left, center, right and surround output channels.