What is the purpose of sound signals in maritime navigation?

The purpose of sound signals in maritime navigation is primarily to communicate the vessel's presence or actions in poor visibility. When visibility is impaired due to fog, rain, or darkness, visual signals such as lights or flags may not be effective or reliable. Sound signals, which include whistles and horns, serve to inform nearby vessels of a ship's movements and intentions, thereby helping to prevent collisions. It is crucial for vessels to be aware of each other's location and navigation status, especially in challenging conditions where visual cues are absent.

Sound signals are standardized under the International Regulations for Preventing Collisions at Sea (COLREGs), which define specific sound patterns that indicate various maneuvers, such as "I am altering my course to starboard" or "I am at anchor." These signals are vital for maintaining maritime safety and ensuring that all vessels can navigate within shared waters effectively.

The other options do not accurately reflect the primary function of sound signals in maritime navigation. For instance, while sound could potentially alert crews of certain environmental changes, it is not primarily used for weather notifications or for distance measurement between vessels. Additionally, sound signals do not serve an entertainment purpose and are strictly functional tools essential for safe navigation.