Batch tool for merging wav files including length detector (batch can use existing tools like Sox)

Hello! In a folder I have about 800 wav files. They are always in pairs like this: [login to view URL] [login to view URL] [login to view URL] [login to view URL] [login to view URL] [login to view URL] ... and so on All files have different length. They are all between 2 and 4 seconds. I need a tool that merge this files together in this way: [login to view URL] + [login to view URL] + [login to view URL] (save as [login to view URL]) [login to view URL] + [login to view URL] + [login to view URL] (save as [login to view URL]) [login to view URL] + [login to view URL] + [login to view URL] (save as [login to view URL]) The only a little bit tricky thing in this project is the [login to view URL] What is this? [login to view URL] is a wav file containing a silence passage. The length must be set from your tool dynamically and depends on the length of the other two wav files. What the tool should do lastly is to give all merged files the same length. This length should be a parameter which I can set and should be scalable with a minimum of 0.02 seconds. Example: I set the parameter to 11.24 seconds. [login to view URL] has a length of 2.44 seconds and albert2 has a length of 3.82 seconds. Together both files count 6.26 seconds. So the [login to view URL] must have a length of 11.24 - 6.26 = 4.98 seconds. So your tool should add a silence passage between [login to view URL] and [login to view URL] with a length of 4.98 seconds. Attached you can find some sample files. If you have any questions please ask me. Best regards Marc