| 摘要 |
<p>An emergency vehicle audible warning system and method for improving emergency vehicle mission effectiveness and reducing the undesirable side effects or emergency vehicle audible warning systems. The audible warning system projects different selectable sound phrases that indicate varying levels of urgency. Periods of silence are included between sound phrases for, among other purposes, improving listener attentiveness and allowing operators of emergency vehicles to hear other approaching emergency vehicles. Urgency is further indicated by varying the duration of silent period between sound phrases with speed changes of the emergency vehicle. Higher and broader frequency spectrums compared to typical warning systems are utilized in order to better penetrate other vehicles and to project a less harsh, yet still effective warning. Forward-directional and rear-directed acoustic radiator (25, 26) projecting dissimilar sound phrases cue listeners to whether the emergency vehicle is approaching or departing the listener's vicinity.</p> |
