Traffic **officers** use different means to give instructions to drivers, and it is mandatory to follow their signals. Among these means are **audible signals with a whistle**.

When a traffic officer wants to order the **stopping of vehicles**, they use **short and frequent whistle blasts**. This audible signal is clear and is specifically used to indicate to drivers that they must stop.

Therefore, when you hear **short and frequent whistle blasts**, you must stop your vehicle, as it is a direct order from the traffic officer that takes precedence over other traffic signals.