Multiple fadeIn/fadeOut effects in one audio file with ffmpeg -

i have problem add several fade effects 1 audio file. when try use command this:

ffmpeg -y -i /home/user/video/test/sound.mp3 -af "afade=t=in:ss=0:d=3,afade=t=out:st=7:d=3,afade=t=in:st=10:d=3,afade=t=out:st=17:d=3,afade=t=in:st=20:d=3,afade=t=out:st=27:d=3" /tmp/test.mp3 

then output audio file has fadein , fadeout applied once. next effects don't applied. there possible way apply several fade effects same audio file? also, difference between ss , st parameter in command?

take here: ffmpeg volume filters

volume='if(lt(t,10),1,max(1-(t-10)/5,0))':eval=frame 

complete command:

ffmpeg -i movie.wav -filter volume='if(lt(t,10),1,max(1-(t-10)/5,0))':eval=frame modified-movie.wav