Is there any reason you don’t use Chains (Audacity Batch) to load a sound file, send the cursor to the end and paste a pre-baked 3-second silent sound file?
Export and Repeat.
If that doesn’t work, Generate and make sure the Silent tool is set to 3 seconds so you don’t have to program it.
Free software called SoX will do that.
[ IIRC the command is “concatenate”* to add two files : one file from your batch and a silent audio file 3 seconds long ]
Thank you all! I’ll try all solutions and report back. As you can imagine, batch processing (and ways to automate it) is determinant with large amounts of files. I’ll come back detailing which method was the best. I appreciate your insights. Cheers!