Voice recorder, silent / invisible mode all the time

Hello folks,

I need a voice recorder app, that will activate on any sound and starts recording, preferably in invisible mode or something.

Just for clarification, no intent of spying or anything. DS has autism and has extremely limited communication skills. We are traveling to another country, where we can not use our GPS tracker that we use here in the US. Plus, he does not even understand the language of the country, we are traveling to. He will have his ID bracelet but it is in English. So we plan to keep a android phone in his pocket with child tracker or cell tracker application installed. These precautions are just for worst case scenario.
This voice recording app will hopefully upload recordings to Dropbox or something so that they are accessible to us, in case if something goes wrong.

Many thanks in advance.

 

This is a good idea, but I don't think it will be in invisible mode.

You would wonder why I want it in invisible mode, because DS tempts to play on the phone many a times and I do not want him to notice that app. He will not lose it for sure. Hence, I would prefer something that is running ALL The Time, just in invisible mode.

If I come to conclusion that this is the best method, I will make a new thread there after giving a try myself first. Thanks for the offer.