which plane make less noise boeing 777 or airbus 340?

both those aircraft have high by-pass turbo fan engines.

This means most of the air going into the engine is not compressed and ignited. It is by-passed around the combustion chamber. Simply, what it does is quiet down the engines, and increase efficiency.

the 777 commonly uses GE90-77B. they also use PW 4077 RR 877. All three of these engines are super high bypass, and very large in diameter. (11 feet)

the 340 typically uses smaller diameter but also hi bypass RR or CFM engines.

the previous answerer is right in his estimation but there is actually no relation the size of the turbofan and the noise it generates. larger engines could be quieter but it all depends on the tech used and the amount of air bypassed.

in this case though, I would say both are loud but the 777 is quieter.I have both aircraft types flying over my house regularly, I live right under the departure path of 24R at CYUL.

Actual decibel level would probably yield very close readings. However, the sound signature of the 777 just seems quieter. As it approaches, you get mostly a long whine that varies in pitch, as it passes, the you get the thunderous but even roar that lasts about 5 seconds, then it fades very quickly. you get a whisper of the whine again

the 340 with CFM engines has a high pitched roar when you initially hear it, and then it becomes are loud pulsing roar that continues until the airplane becomes a speck in the sky while decreasing in loudness as the airplane gets further

it sounds like the 737s with CFM engines but louder because of the 4 engines instead of 2.

PS: in terms of being inside the plane, both of those planes are both pretty quiet. the 777 sounds like a A330 from the inside in terms of sound intensity while the A340 sounds like a A310. I think the A340 is quieter inside during cruise because I've only been on it once and I was in front of the wings & engines. on the 777 i was nearer or behind the engines.

Regarding safety, ETOPS (which stands for Extended-range Twin-engine Operational Performance Standards). All United States registered twinjets can fly virtually anywhere in the world, except for small pactches in the south pacific and over Antarctica. Being a twinjet does not make the plane any less safe than a 747 or Airbus A340. If by "best" you mean economics, the 777, if by "best" you mean comfort, it is dependent on airline, but the A340 is quietest. The best of all these criteria is likely the Airbus A330-200 or the next generation of jetliners, like the Boeing 787 and Airbus A350XWB.

Why wouldn't they both make a lot of noise? Its a jet engine, they aren't going to be quiet.

Typically speaking, the larger the jet engine (we're talking turbo fans here, not turbo jets by the way) the quieter it is. The larger engines spin at a slower rpm and that results in less noise. If you don't believe me go stand in front of a Citation 525 or CJ1 that is starting up, they are incredibly loud, at least at frequencies that we hear and perceive to be loud.

the A340 has smaller engines, but not much smaller, and not enough smaller to make them much louder. But it does have 4 engines, which means it will be louder.

When it gets right down to it, they are both loud. Loud enough that without hearing protection (assuming you are close to them on the ground) you'll get a ringing in your ear. With hearing protection they are both going to be just as loud.

If you're talking about inside as a passenger, they will both be about the same. I have never flown in either of those two planes, but it has been my experience that airbus is usually a little quieter.

If you really want to see loud look for a Lear 23 with a small turbojet, even with hearing protection I don't like getting too close to those. Or just about anything military, they are rarely quiet.

I've been in both for 10+ hours (Dallas-Tel Aviv in a 777 and Boston-Sydney in an A340), and the 777 was much quieter. However, pitchwise, the A340's engine noise was slightly less obtrusive/obvious.

Buy some noise canceling headsets, and forget all the long-winded answers. There's probably less than 1db of difference between the two at best. Every 3db doubles the sound level.

well i flew on the 777 300ER in 2006 Sydney - London and back and i didn't think it was very loud. I found it quite easy to get to sleep

Also the boeing 777 200LR is apparently the quietest airplane in operation

In response to Dennis. True, stand in front of a small jet. The loudest plane I have heard on the ground in a MU-2

The A340 is probably slightly louder, but I can't imagine you'd notice it over the sounds of passengers screaming and crying as they plummet to their deaths.

I would say the A340