Audacity will do it fine and even can do some very advanced batch
processing too - took me a while to find it as they call it chains.

Look under [ File / Edit Chains ] to create your own conversion scheme
then go to [ File / Apply Chain ] to select a folder to convert and
the 'Chain' you wish to apply - puts all the processed files in a sub
folder called 'Cleaned'.

Yes it is a strange way of doing it, but it actually works very well
and I'm sure can be very powerful with a bit of investigation of the
command structure for chains.