What sound signifies a distress call on a radio?

In maritime communication, the sound that signifies a distress call is a warbling sound, often associated with specific distress signals like the International Distress Signal on VHF radios. This warbling tone indicates an emergency situation and is crucial for alerting other vessels and shore stations to the presence of a distress call.

The warbling sound is distinctive and easily recognized by trained operators. It's designed to cut through other ambient noises and grab the attention of anyone monitoring the radio frequencies. This sound carries a sense of urgency and invokes immediate action, prompting listeners to assist or acknowledge the distress call.

In contrast, a beeping sound is typically used for routine alerts and notifications, while a continuous tone can signify different types of warnings rather than a direct distress signal. Static interference does not convey any message; rather, it indicates poor signal reception or frequency congestion. Therefore, the warbling sound is the correct and designated audio signal used to communicate distress in maritime radio operations.