I'm curious what the relationship is between む and ん. I have the feeling that sometimes, む is pronounced more like ん:
- むむむ: is this really /mumumu/? Or does it become /mmm/?
- うむむ: is this really /umumu/? Or does it become /umm/?
I've spent more time reading than listening, and I'm not sure where I picked this idea up. I did see on Wikipedia that ん was formerly written む. Unfortunately, the article doesn't say anything about the two being related in modern Japanese.
I'm also aware of うむ, which is apparently an older version of うん. Perhaps this is an example of something similar?
Here is an example context for むむむ, in which I suspect it is not actually pronounced /mumumu/: