Here are some of the past giveaways. I created a sound wallet and uploaded them. Inside the audio is an unecrypted private key. The people then decoded the audio and used the private key to claim their bounty and confirmed the proof of concept.
Try out a sound wallet for yourself. Once someone gets the private key out of the audio the coins are GONE, so be fast and come back often. In the meantime support the project over at startjoin
Setting for audacity to get the private key
Or you can use androspectro on your android device.
Then you need to import your private key into your wallet to get the coins