Abstract: A sound reproduction system comprises a left and right speakers located in close proximity, and a sound processor which provides audio signals to the pair of speakers. The sound processor preferably derives a cancellation signal from the difference between the left and right channels. The resulting difference signal is scaled, delayed (if necessary), and spectrally modified before being added to the left channel and, in opposite polarity, to the right channel. The spectral modification to the difference channel preferably takes the form of a low-frequency boost over a specified frequency range, in order to restore the correct timbral balance after the differencing process. Additional phase-compensating all-pass networks may be inserted in the difference channel to correct for any extra phase shift contributed by the spectral modifying circuit. The technique may be used in a surround sound system.

Abstract: Spectral imbalance (alteration in timbre) when playing home video versions of motion pictures having soundtrack equalized for playback in a room whose room-loudspeaker system is aligned to the standard motion picture theater X-curve is overcome by timbre correction which compensates for the X-curve equalization. Surround-sound home playback of motion pictures is enhanced by employing main channel loudspeakers that produce generally direct sound fields and surround channel loudspeakers that produce generally diffuse sound fields. In addition, the reproduced surround-sound channel is further enhanced by decreasing the interaural cross-correlation of the surround-sound channel sound field and by reducing comb filtering effects in the surround-sound channel at listening positions within the room, preferably by introducing slight pitch shifting in the signals applied to multiple surround loudspeakers.

Abstract: A method and system for recording and playing back from a bulk digital data storage medium having unequal access time, such as a rotating magnetic disk, data of a plurality of separate files, such as multi-channel sound information. Blocks of the digital data streams are stored in physically non-sequential scattered positions on a disk. The starting sectors of each recording track of the disk are not made the same but rather at least two different starting sectors are provided on alternating tracks in order to reduce the amount of access time between blocks of data. The blocks of data are read from the disk into a buffer memory in accordance with a disk read head scheduling technique that causes the next block of data with the shortest access time to be transferred unless there is an urgency to maintain balance in the various channels, in which case a block of data for the channel having the least buffered data is transferred next.

Abstract: A motion picture loudspeaker system is described in which the loudspeaker elements are integral with an acoustical boundary wall such that the characteristics of the vented box woofers are optimized. In order to overcome high reflection problems as sound from the tweeters is reflected by the motion picture screen and the acoustical boundary wall, frequency dependent acoustical absorptive material is attached to the wall to inhibit high frequency reflections with minimal effect on the bass optimization. The system includes the use of a steep slope crossover netowrk having a crossover frequency such that there is a first order match of the woofer and tweeter dispersion at the crossover.

Abstract: A universal multilayer circuit prototyping board is provided having a predefined universal pattern of socket pin perforations which accommodates all standard DIP integrated circuit packages at virtually any position on the board. The universal board allows high density circuit packing while maintaining excellent electrical performance with high speed circuits.

Abstract: One or more high speed programmable digital signal processors, particularly for audio processing such as mixing, sound effects and synthesizing, are supported by one or more slower speed computers that provide timed and untimed update commands to the high speed processors. Untimed commands are originated as by real-time operator gestures. Timed commands are originated by a master support computer. A queue of update commands is maintained in the high speed processor such that untimed commands are placed at the head of the queue for immediate execution and timed commands are placed at the end of the list. New timed commands are interleaved in time order with timed commands already in the queue.