I once read an article on how people adopt the speech patterns of those around them to a greater degree than is generally believed. If you live somewhere other than the place you were raised, you pick up bits of the local dialect and accent fairly quickly, and if you spend a lot of time around a certain person, you pick up some of their "vocal mannerisms," if you will. I can't seem to find the article right now, but I'll keep looking.
I think it is common for Aspies to do this to a greater degree than most people. It's certainly true for myself and the one other Aspie I know, though not to the extent that you mention.
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"A flower falls, even though we love it; and a weed grows, even though we do not love it."