I have never seen an ambulance with this device installed
I worked as an EMT in Virginia. We have little boxes with narrow tubes on their faces, pointed at oncoming traffic. These are <em>sound</em>-activated, and we had to use a specific siren setting when approaching an intersection with one of these devices. The tube on the traffic signal box was basically a waveguide, to reduce sound from other directions.
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I have never seen an ambulance with this device installed
I worked as an EMT in Virginia. We have little boxes with narrow tubes on their faces, pointed at oncoming traffic. These are <em>sound</em>-activated, and we had to use a specific siren setting when approaching an intersection with one of these devices. The tube on the traffic signal box was basically a waveguide, to reduce sound from other directions.