| 摘要 |
A toroidal shaped closed chamber whistle produces a warning signal capable of being easily heard at relatively great distances from the whistle. The toroidal whistle emits a bidirectional sound which is phase-locked to a particular pitch. The toroidal whistle has a circular plate positioned within a hollow cylinder to form an air passage leading to an annular air slit. Incoming air under pressure flows through the air passage and out of the annular air slit into a toroidal chamber. Within the toroidal chamber, a sound wave is formed which passes out of the toroidal chamber through a chamber mouth. Optionally, two toroidal chambers can be used in combination to produce a dual-tone sound. Additionally, a tremulant device can be used to produce a warbling effect in the emitted sound.
|
