Use dir with several files/extensions:
dir "C:\Folder-A\File-1.txt" "D:\Folder-B\File-2.log" ...
Also use for loop to gets all the logical drivers on your system, try:
rem :: In command Line :
for /F %i in ('wmic logicaldisk get deviceID^|find ":"')do echo\ dir /s /b %i\*.mp3 %i\*.mp4 %i\*.wav
rem :: In .bat/.cmd file :
for /F %%i in ('wmic logicaldisk get deviceID^|find ":"')do echo\ dir /s /b %%i\*.mp3 %%i\*.mp4 %%i\*.wav
After testing the output, remove:
echo \
em :: To omit "file not found", if there are no files on the drive
)do... 2>nul dir /s %i\ *.mp3 *.mp4 *.wav
If necessary, add the full path (recommendable):
%__APPDIR__%wbem\wmic.exe