Patent attributes
A whistle (1) has: a mouthpiece which includes an air inlet (4); a first and a second resonance chambers (5a, 5b) to which air is injected through the air inlet via a first and a second air passages (6a, 6b); a first and a second sound outlets (7a, 7b) in the form of openings formed between the air passages and the resonance chambers; and a first and a second air flow converters (9a, 9b) for varying the flow of air between the air passages and the sound outlets. The air flow converters (9a, 9b) are each part of the sound outlets, and have walls (10a, 10b) which are perpendicular to the air passages (6a, 6b). The air flow converters (9a, 9b) create extra higher harmonics, increase sound pressures in the resonance chambers, and shorten rising time of the whistle, so that the whistle quickly produces loud harmonious beats, which is effective to call attention of people.
