Accurate audio selection
This command, which used t reference for aselect, worked for me:

ffmpeg -i AV36_1.avi -vf "select=between(n\,200\,399),setpts=PTS-STARTPTS" -af "aselect=between(t\,(200/15)\,(399/15)),asetpts=PTS-STARTPTS" -y test.mkv


If you want to use n (frames), then you will need to know the frame size of the audio codec e.g. 1024 samples for AAC, variable for MP3..etc