Sound Waveforms

There may be some, but according to the online description this doesn't have that capability. For instance there is no connection for an input signal, only power input.

 

I am not sure, exactly what you want but it sounds to me that you could be after a modulator which would modulate the programme material onto your generator output. That would give a possibly hideous output unless it's tastefully done. Or did you want to be able to transcribe the 'tune' of the MP3 file and programme the output of your signal generator. I believe there are midi processors that can dig out the melody of a recorded tune and produce a one- note version in midi code. That code could then be used to programme a suitable generator frequency and amplitude. But, as has been pointed out, the unit in your link has no electronic input for achieving this. If you really keen on this sort of thing then you would need to do a lot of homework, trawling around for a suitable unit (not as cheap as £13, I would think).
Otoh, you could go down the software route, if your PC is new and fast enough, to achieve the functions I have described. Doing it that way would ensure a certain amount of future proofing for your investment. There is a big scene in electronic music and loads of enthusiasts and 'experts' post their ideas on the Web.