GG, the decibel level inside a cabin without a single soul in it is going to be somewhere between the low 70s and high 80s depending on the make of plane, how close you are to the engines you're sat and so on. That's as loud as a busy office, or being in the same room as someone using a hoover. You're just not going to hear someone nattering on their cell phone two or three aisles forward or behind. Sure, if everyone in your row, and the rows immediately in front and behind you suddenly decided to make a telephone call at the same time, then I concede that might be irritating for at least, oooh, 5 whole minutes of an [x] hour flight - but how likely is that, really