How can I batch replace audio in .avi files without re-encoding?

Question

I have hundreds of .avi files that have two audio channels. One channel contains the audio from the original video footage, and the other channel contains speech-shaped noise that was added later.
I need to replace the speech-shaped noise with a different type of noise (multi-talker babble) without re-encoding the video and degrading its quality. I would like to be able to do this in a batch process if possible. Do any of you have an idea about how to approach this in Premiere Pro?
Some more details: each .avi file is about 2-3 seconds long, so I would need the replacement noise to be the same length as the original noise.
Any advice would be greatly appreciated.

Answer 1

Using -replace:
$strings = @(
"Karaoke A Spoonful Of Sugar - Mary Poppins -_fwCVHtOQUk",
"Karaoke Ain't No Stoppin' Us Now - McFadden & Whitehead -kzh0Df42vms",
"Karaoke Ain't Nobody - Chaka Khan -qDP3_jInyl0",
"Karaoke A Tisket, A Tasket - Ella Fitzgerald -amgeW6HqaVo"
$strings -replace 'Karaoke (.+) - (.+) -.+','$2 - $1'
Mary Poppins - A Spoonful Of Sugar
McFadden & Whitehead - Ain't No Stoppin' Us Now
Chaka Khan - Ain't Nobody
Ella Fitzgerald - A Tisket, A Tasket
[string](0..33|%{[char][int](46+("686552495351636652556262185355647068516270555358646562655775 0645570").substring(($_*2),2))})-replace " "