What is required of emergency vehicles regarding audible signals?

The requirement for emergency vehicles regarding audible signals is that they must be approved by the secretary of transportation. This means that the specific type of siren or audible signal used must meet certain standards set forth by the regulatory authority, ensuring that they are effective for alerting the public and other drivers in emergency situations.

This approval is crucial to maintain consistency and safety standards across all emergency services. It ensures that all emergency vehicles utilize equipment that has been evaluated for its effectiveness and sound levels, providing necessary alerts to an appropriate distance. This is important not only for the safety of emergency responders but also for the public, as it facilitates a quicker and more organized response to emergencies.

The other choices point toward practices or assumptions that do not reflect the regulatory requirements or standards enforced for the use of audible signals in emergency vehicles, which is why they do not hold up in the context of established law and regulations.