Audiveris is an open source (free) music OCR software. It takes PDF files as input and generates MusicXML files as output.

I don't think that BiaB currently supports MusicXML imports (I could be wrong), but you can probably find another open source software that can read and translate MusicXML to MIDI so you can listen to it.

Audiveris: https://audiveris.kenai.com/

Jordan