Abstract: A four-dimensional acoustical audio system utilizes both spatial and temporal signal processing to provide uniform sound throughout a range of ear levels in an enclosure and combines the output of loudspeakers above and below the desired level to substantially eliminate the perceived direction and location of the sound sources and effectively creates a phantom sound source at the desired level

Abstract: A bass audio circuit includes a first filter network which receives left and right channel input signals and produces two filtered signals by attenuating frequencies in the input signals above a first cutoff frequency. The two filtered signals are summed to create a first monophonic signal. A second filter network produces attenuated frequencies in either the input signals or in the first monophonic signal that are above a second cutoff frequency which is lower than the first cutoff frequency. The signals from the second filter network are combined and passed through a phase inverter to derive a second monophonic signal. An output stage individually amplifies the two monophonic signals which then either are applied to a dual voice coil woofer, or are electrically summed and applied to a single voice coil woofer. Alternatively, the two monophonic signals are first summed and applied to a single channel amplifier which drives a single voice coil woofer.

Abstract: A compact full-range loudspeaker system includes an elongated enclosure having two open ends joined by a hollow interior, which enclosure may be of fixed dimension or telescoping, and has a full-range speaker mounted at each end of the cylindrical enclosure. The enclosure length is set in a range governed by the small speaker size to maximize the system response, particularly in the lower frequency range, and a dampening material is provided to construct the enclosure to minimize the structural acoustic response of the enclosure when being driven. A pair of miniature sound boards may be flat, polymer surfaces mounted to a base and positioned at each end of the cylindrical enclosure at an angle facing each speaker for reflecting sound waves emanating from the speaker in accordance with the positioning of the cylindrical enclosure to create an effective sound stage and control directionality.