Pronunciation of ワンマン運転

Question

I hear ワンマン運転　as ワンマウンテン, with the ん　of マン dissapearing, or perhaps being very soft.

Here's an example:http://youtu.be/DZnuH1XkE7s?t=49s

Another question shows that there can be something phonetically special about ん＋vowel words. This suggests the 'u' sound might be nasalized, but I don't hear the 'u' sound being different from a normal う in this example.

How do I pronounce ワンマン運転? Is this different from ワンマウンテン? Is there a rule that applies to some other words? Or is it a special case like 雰囲気?

Answer 1

Intervocalic ん is usually pronounced as a nasalized version of the preceding vowel, so in this case [ã]. This would lead to a pronunciation of ワンマン運転を (I'm adding the を from the clip, since otherwise I wouldn't be able to determine the pronunciation of the last ん in 運転) sounding something like

[wa.m.ma.ã.u.n.te.ẽ.o]

(dots between morae, tilde over a vowel means nasalization)

The nasalization on the intervocalic ん tends to spread to surrounding vowels, so it might even sound like this

[wa.m.mã.ã.ũ.n.tẽ.ẽ.õ]

or, if you prefer:

[wam:ã:ũntẽ:õ]

I believe the nasalization of intervocalic ん, and the spreading to surrounding vowels depends on how clearly the speaker articulates, and probably also the speaker.

ワンマン運転 would not sound like ワンマウンテン, since the latter lacks a mora, but I find it quite likely that ワンマン運転を could be mistaken for ワンマーうんてーを, especially with reduced sound quality like this where the nasality can be hard to determine.