Audacity will batch normalize wave files:

1.Open your first wav file.

2.Project/Import

3.Audio Import all of the other wave files that you want to normalize as a batch.

4.Edit/Select/All

5.Effect/Normalize

6.File/Export Multiple

Be sure to select a different folder when exporting & make sure to select .wav

If you don't select a different folder Audacity will over write the current folder files. Your choice. But you may want to try before over writing.