I've never got on a train outside of Japan, so i don't know how it is like in foreign countries, but Japanese trains during rush hours are extremely crowded. For example, if I suceed to raise my hand to touch my hair, then there will be no space to put it down. It's really crowded in a train so you won't fall down even if you sleep while standing. Japanese rush hour is like that.
By the way, I found a reasech about disturbances in a train.
http://www.mintetsu.or.jp/enquete/archives/syousai7.html
The overall ranking is:
1. Unmannered way of sitting on seats (12.9%)
2. Using cell phones in a train (*I think it means talking) (12.2%)
3. Noise leaking from headphones (11.3%)
4. Unmannered way of getting on/off a train (10.2%)
5. How people hold their bagpacks (9.6%)
6. Loud and noisy people (7.8%)
7. Women getting their makeup on a train (6.9%)
8. Sitting down directly on a floor of a train (4.7%)
9. Eating and drinking in a train (4.5%)
10. Leaving trash or cans in a train (4.5%)
I've seen all of these disturbances -_-;
To me, i don't like hearing people talking on their cell phones in a train because they usually speak very loud. It's louder than their normal conversation, but it's hard to notice.