Today’s invention is a way to encourage cars to move out of the way of an ambulance approaching from behind.
Everyone knows the Doppler effect causes the ambulance siren to appear to increase in frequency as it approaches.
It’s therefore a relatively simple matter to take a normal siren and electronically process it so as to raise all its frequency components in proportion to the distance between ambulance and car.
This would give the nearest car driver ahead the auditory impression that the emergency vehicle was approaching much faster than in reality -and thus cause him to pull out of the way more urgently.
