Enrichment for zoo elephants

So I work at a zoo and I'm trying to use the arduino to enrich the animal's lives as much as possible. The goal of the project is to encourage physical activity in African Elephants.

In a perfect world there will be 5+ speakers scattered around the exhibit. At random times throughout the day, one of the speakers will begin playing music. If the elephant walks near the speaker, a motion detector will see them and trigger a sequence of events. First, the motion detector will activate some sort of feeder that drops food in front of the elephant, rewarding the Elephant for moving towards the music. Second, the motion detector will turn off the current speaker and activate a different randomly selected speaker. This process will repeat for a predetermined amount of time so that the elephants are encouraged to walk around the exhibit.

I broke the project into a few parts but the one I'm currently focused on is playing music. I've seen a ton of examples using an SD card to play small files on small speakers but I need to hook the SD card up to decent sized waterproof speakers.

Does anyone know the best (and cheapest) way of doing this? The Elephants thank you!

I've seen a ton of examples using an SD card to play small files on small speakers

Just put longer samples on the SD card and feed the output into an amplifier that will drive your speakers.

Grumpy_Mike:
Just put longer samples on the SD card and feed the output into an amplifier that will drive your speakers.

Thanks! I'm super new to all of this so are there any rookie mistakes I should avoid or is it pretty idiot-proof?

Not sure their are any but then rookies can always supprise you. It just sounds like a normal project bet with a big amplifier and speakers stuck on the end.

Use Arduino to control an MP3/SDcard module.
Run the output thru an amplifier, then thru 5 DPDT relays out to the various speakers.
Arduino controls the song/file being played and the relay that get energized.