People have a better response to sirens when they:

The effectiveness of sirens in eliciting a response from the public can be significantly enhanced when the siren or tone changes pitch frequently. This variability in sound captures attention more effectively because it breaks the monotony and draws the listener's focus to the noise. A changing pitch can create a sense of urgency and alert individuals that there is an emergency vehicle approaching, prompting them to react appropriately, such as yielding the right of way or pulling over.

While loudness and constant sound can also be effective, they may become less noticeable over time due to auditory desensitization. Similarly, using sirens sparingly can be practical in certain contexts, but it does not enhance the immediate response when an emergency vehicle is actually in need of a clear, responsive path. The use of flashing lights works in conjunction with sirens, but it is the variability in tone that can really draw attention and prompt a more immediate reaction from people on the road.