One iteration of the acoustic bouy system is the Homerus Autonomous Sailing System was developed by students at Olin College. A brief article describing the system can be found by clicking here.
The following video, from Sailing Education Association Sheboygan (SEAS), explains how visually impaired sailors use sound technology in blind match racing,
Further explanation of how sound technology works can be found in the video below, from the WIM Series Youtube page. The video will start at a point that explains how the blind sailors use sounds to identify makrs, and what those marks sound like, but is an overall interesting video to watch as it highlights the difficulty and skillset required to be successful at using sound technology,