1. Field of the Invention
This invention relates to the production of sound using a toroidal shaped closed chamber whistle, more particularly the sound output from the toroidal shaped closed chamber whistle can be used as a warning signal of impending natural and man-made disasters such as tornadoes, storms, nuclear power plant failures, among many others. The whistle can either produce the sound of a single tone or a dual tone depending upon the number of toroidal chambers used. A circular plate within a hollow cylinder forms an air passage through which the entering air under pressure flows to an annular air slit. The sound output of the whistle is produced by passing air under relatively low pressure through the annular air slit into a toroidal shaped closed chamber. The sound output is formed within the chamber and is thereby released to the atmosphere through the mouth of the chamber. The sound output is bidirectional with a phase-locked tonal pitch. The sound output is greater for a given pressure than that of a single chamber whistle. Optionally, two toroidal chambers can be used in combination to produce a dual-tone bidirectional sound output with each tone being phase locked.
2. Brief Description of the Prior Art
Warning signals produced by a whistle provide to the listener a valuable cautionary indication of an impending dangerous situation. Warning signals are needed to alert the surrounding community to various imminent dangers such as tornadoes, floodings, accidents, nuclear power plant failures, plus many others. The whistle or warning device used must be capable of producing a very audible sound which can be heard clearly and easily at relatively large distances away from the whistle. The whistle or warning device must also be able to provide an unique and easily distinguishable sound so that the listener can immediately recognize and understand the signal. If the whistle does not have a powerful output and strong sound level, then many individuals who depend upon the warning device will fail to hear the signal. The lives and properties of these individuals could be in danger due to the inadequacies of the warning system.
A formerly used warning system consists of a single chamber device which produced a nondirectional sound output. The single chamber whistle fails to formulate a sound output which is sufficiently audible at relatively large distances of approximately 3 miles. Each single chamber whistle contains only one chamber through which air pressure can pass to form sound waves and, hence, the sound output of the whistle is limited by the capacity of the single chamber. To improve the output from the single chamber whistle, some prior devices combined many different single chamber whistles into one system. Such a system, however, can produce neither a single tone sound nor a directional output. Instead of an easily distinguishable unique sound, the combination of many single chamber whistles produces a multi-pitch sound which merely confuses the listener as to the meaning of the signal. A combination of single chamber whistles cannot be phase-locked to produce a single pitch. The individual whistles of the combination wander out of phase with each other and as a result cancel out each other's output. When the combination of whistles is out of phase, the efficiency and output of the system is reduced.
The present invention obviates these disadvantages by providing a single pitched unique sound output which is readily audible at relatively large distances of approximately 3 miles from the whistle. In contrast to prior warning devices, the toroidal whistle produces a bidirectional sound output. With the present invention, a greater sound output than that of the single chamber whistle can be created while using significantly less air pressure to achieve that output. The present invention allows every point in the toroidal whistle to vibrate in phase with each other and thereby provide a phase-locked sound.
By using an additional toroidal chamber, the present invention can yield a dual-tone bidirectional sound which can be easily heard within a large range of distances of approximately 4 miles from the whistle. The dual-tone toroidal shaped closed chamber whistle permits one whistle to be used as a warning device for a number of various situations by altering the signal emanating from the whistle. The dual-tone toroidal whistle can yield a number of distinct sounds, each of which can serve as a warning signal to a particular danger. The dual-tone whistle eliminates the need of installing a number of single chamber whistles, each of which is used to warn the listener of a particular danger. Optionally, a tremulant device can be used with the toroidal whistle to create an unique warbling effect by altering the air pressure.