Patent attributes
An acoustic warning or alerting system for directing an audible warning signal to at least one intended recipient, while reducing the chance that the warning signal will be heard by others within the proximity of the system. The system includes a modulator for modulating an ultrasonic carrier signal with a processed audio signal, a driver amplifier for amplifying the modulated carrier signal, and a parametric array of acoustic transducers for projecting the modulated and amplified carrier signal through a propagation medium for subsequent regeneration of the audio signal along a pre-selected projection path. The parametric array of audio transducers operates by employing the nonlinear interaction between high frequency sound components and the propagation medium to generate at least one highly directional beam of lower frequency sounds within the propagation medium. The directional acoustic alerting system may be employed as a replacement for conventional alerting systems such as horns, whistles, and bells to assure that primarily only those people and/or animals intended to hear the warning signal actually hear the sound.
