Different POI on same road

1. When a tour location is detected, the audio begins to play.  Instruct the user to mute or stop (it takes one click on a nuvi) the audio if they've already heard it.
2. Though it would take some fine-tuning, you could position the POI at just the right distance away from the road so the user is within the set proximity when traveling the road one direction but out of the proximity when coming the opposite direction.  Assuming a two-lane road with 10ft wide lanes, you would put the location exactly 490 feet from the side of the road you want the audio to trigger (assuming a 500 ft proximity has been set).  Thus, when the user travels one way, they will be within the 500 feet, but won't be when going the other way.  Of course, this also assumes that you have good GPS accuracy when passing the point going both directions.  Like I said, it would take some fine-tuning, but I think it's possible.

If using GeoTours Mobile and GeoTours iQue, locations are played only once.  When you hear the audio the first time, the program remembers that the location has been visited and if passed again, it does not play.