take a look at soundio for audio output

[vampirefrog]

https://github.com/andrewrk/libsoundio

[tobybear]

I can also recommend the following simple to use C/C++ cross-platform audio engines:

miniaudio:
https://github.com/mackron/miniaudio

sokol_audio:
https://github.com/floooh/sokol/blob/master/sokol_audio.h

minisdl_audio:
https://github.com/schellingb/TinySoundFont/blob/main/examples/minisdl_audio.h

All of these work as header-only single file libraries. In fact I have fmtoy running under all of these engines right now, cross-platform on Windows, Linux and MacOS.