Originally Posted by
aidanf
... conversations taking place among fellow passengers...
I speak from experience in the TGV (high speed train).
Conversations between passengers are normally between people sitting next to each other. Barely intelligible in the next row, and beyond that they blend into the ambient noise level, as on aircraft (note I said conversations, not a screaming baby).
Bleating cell phones (with them funky ring tones) pierce right through the ambient noise and can be heard through most of the carriage / cabin. And I don't need to describe the habit of carrying on LOUD conversations on cellphones, even you must have experienced those. Again they tend to pierce right through the ambient noise for at least several rows.
I hope security will still allow me to take a box of those old-fashioned waxed earplugs on board. But maybe they look too much like small sticks of dynamite?