I had some auditory hallucinations during alcohol withdrawal too. Whenever I had a fan or an air conditioner running, I would hear what sounded like a radio playing at a volume just loud enough to be noticeable but too faint to make out the details. It was quite realistic -- at times I could
almost tell what song it was playing
Of course no one can say for sure except maybe your doctor, but I would bet it's much more likely to be related to alcohol withdrawal than Librium use. I gather it's not terribly uncommon and it should probably go away on its own within a few more days. If it doesn't, seek professional advice.