Which type of tone should be used to indicate presence without alarming others?

The choice of a short tone, often described as a "machine gun" sound, is effective for indicating presence without causing unnecessary alarm. This type of tone is characterized by its rapid and repetitive nature, which can capture attention without invoking the urgent and often anxiety-inducing response of drivers and pedestrians that a long wailing tone might create.

In emergency scenarios, it's essential to balance the need to alert others to your presence while minimizing panic or disruption. A short tone provides a clear signal of approach while allowing people to remain calm and not overreact. This is particularly important in situations where an ambulance needs to navigate through traffic or crowded areas, as it promotes awareness without escalating the situation into panic.

Other tones, such as a continuous tone or long wail, could overwhelm by invoking a sense of urgency that isn't necessary in all contexts. High-pitched tones might also be startling rather than simply informative. Thus, the short tone is the most suitable option for non-alarming presence indication.