Dear Editor ,
On the swimming pool public address problem; I noticed many years ago in Kuala Lumpur (we were all younger then) a system where all the seats in the auditorium had small speakers in the upright back facing the seat behind.
It did not matter where you moved, you could hear everything being announced very clearly, even though the levels were individually low and not invasive.
I also noticed this effect at an Australia Day Skyshow where almost everybody sitting on the lawns had a small radio tuned to the fireworks music and all at a low level of sound, but it appeared like the very trees were carrying the sound. The same might be the answer for the swimming pool; a host of small horn speakers focussed downward around the target areas being operated at, individually, low audio levels. Your ‘local’ sound engineers should be canvassed and, to monitor costs, a view of Altronics.com.au site will show you pricing for public address 100volt line speakers, From memory less than $100 each for a weather-proof unit.
Ian Brown might even stump up the money, or perhaps even the good citizens whom are disturbed might contribute??