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Abstract

A system for suppressing the effects of undesirable noise from an annoying noise source contains a plurality of transformation sounds which, when combined with the noise form a sound that is pleasing to the ear. The transformation sounds are stored in the digital memory of the system or on a CD-ROM. The incident noise is detected and converted to signals which are dynamically analyzed, filtered and monitored to control the transformation sound selection process. The transformation sounds are modulated by a filtered signal derived from these noise signals that tracks the average energy in the noise. The transformation sounds include a primary transformation sound that is selected substantially continuously. The transformation sounds include also secondary transformation sounds that are selected for combination with the noise in periods when the primary transformation sound does not completely suppress the undesirable effects of the noise, and when the primary transformation sound is decreasing in volume. The system is especially effective in abating the traffic noise from freeways at nearby locations.

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First Claim