Forte notation software uses .fnf files to saving notations and also allows users to export them to few audio formats, including .wav files. It doesn't look like other programs support .fnf notations, so using the original tool seems like the only way how to achieve this conversion.
Convert Forte notation file to WAVe PCM Sound, standard Windows sound format.
We have found one software suitable in our database for this conversion.
Microsoft Windows software - convert fnf to wav on Windows
FORTE has been developed over several years with a strong focus on usability and abandons thus the prejudice that “musical notation on a computer is drawn-out and complicated”. Used by people and institutions from more than 40 countries.
Convert from fnf file
to wav file
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.