| 摘要 |
The present invention relates to a safety device for emitting a substantially tonal acoustic alarm signal, the device comprising:-a sound source for generating an acoustic alarm signal,-directing means for directing the alarm signal in substantially one or more preferred directions and attenuating the alarm signal in the other directions. The invention also relates to a method for emitting a substantially tonal acoustic alarm signal, comprising of:-generating an acoustic alarm signal,-directing the alarm signal in substantially one or more preferred directions and attenuating the alarm signal in the other directions.
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