I think that it would be a bad idea to use speech ads. No matter what.
If you must use ads that track you, make sure that no one sees the information, and that it is fully erased when done with. If the information needs to be submitted anywhere, make sure the connection is secure and that it cannot be intercepted at any levels. Any traces of the information should be erased. And seeing as this can be very difficult, I think it would be a better idea if you did not use this method if you do not want your programme to be classified as adware/spyware.
-Julien
