Ubuntu – frescobaldi midi player seems to be working fine but doesnt produce any sound

I'm pretty new to ubuntu. I bought an acer aspire v5 laptop and installed Ubuntu. So far everything worked in the way I want it, except frescobaldi.

It's an editor for lilypond files. There's a midi-player included. I installed timidity and followed the instructions, however the midi player doesn't produce any sound. There's no error message or anything but it's pretty clear that it doesn't work. Every other sound application worked fine so far and I am able to use the timidity midi player to play my midi-files. Its just the built-in midi player in frescobaldi that doesnt work.

How to solve this?

I googled it for hours now and there doesn't seem to be anyone else with a similar problem.