What's a phonetic device?

Answer 1

I think you may mean a mnemonic device. I have no idea what a phonetic device is and cannot find it anywhere as a phrase.

A mnemonic is a memory aid that generally serves an educational purpose. They are mostly verbal, e.g a word, each of whose letters help the user to remember the first letters of items in a list. However, there are also other types of mnemonics, such as visual mnemonics. Mnemonics rely on associations between something that is easy to remember, and something that is harder to remember. Sometimes mnemonics are chosen to directly relate to the target information, and othertimes they are arbitrary.

Answer 2

Maybe you mean phonetic stylistic devices/means. It's in linguistics. Those are things like alliteration, rhyme, etc.... stylistic devices which deal with sounds.