I think what you're asking is: can you include wildcards in file names in ffmpeg commands - i.e something like *.wav. I didn't think so, and a bit of googling seems to confirm that - but I'm not absolutely certain.

So you would need to use a script - which is what I assume you mean by a batch file. Something like Guest's bash script, which is just a loop that applies the ffmpeg command to every wav file - though I'm pretty sure that windows scripts have different syntax to bash scripts.

A .bat file doesn't have to contain any logic. It could be just a list of almost-identical ffmpeg commands, as Joe suggested. So once you've got a command working do a bit of copy/paste/editing of the filenames in notepad then run it. Google for how to run it. Tip: make your source files read-only before you run it ;)

It might interest those with somewhat newer computers that you can run bash scripts on Windows 10. I would guess that bash scripts are more often published on stackexchange and similar places than windows scripts.