Turbojets are truly that much louder than the turbofans we're now used to. At the time it was only a bit louder than contemporary aircraft, but everything else got far quieter. Concorde is more comparable in engine noise to a modern fighter jet than it is to most commercial aircraft.
At the time it was built, it was a little bit noisier than the 707. The only issue is that while planes got much quieter (as the 707 was retired for example and new ones appeared), Concorde kept on flying...
It's always been seen to me as a supreme irony that a country that sells two-stroke leaf blowers and line trimmers by the chinese-container load was worried about a 4-times-day distant thunder-like rumble.
Much more is understood about the noise footprint now than in the '60s.
I used to live under the Concorde flight path in and out of Heathrow, and yes, it was noisy (even travelling subsonic). Every day at about 1000 there'd be this deep-throated roar and the windows would start rattling[ * ], I'd look up, and there'd be this beautiful delta-winged shape sliding through the sky.
It was completely unlike the noise a normal jet makes, more like a rocket engine than anything else. I can't say it particularly annoyed me; I liked knowing it came from Concorde.
Yep, it is a problem (though not on the ocean flight obviously). I'm pretty sure Boeing would have liked to sell a SST given what they spent back in the day and their teaming with NASA to figure out a way to reduce the sonic boom. http://www.nasa.gov/aero/centers_tackle_sonic_boom.html
