Tedd wrote:

I think a direct comparison between the engine noise of an A350 & B787 is slightly unfair due to the power outputs. GEnx/Trent 1000 (B787) 75, 000lbs thrust approx, RR XWB-84, 84,000 thrust, true the XWB is later tech, but 10,000 lbs ish extra would be a stretch to make quieter. A case in point would be everyone's displeasure at B77W noise, but at 115, 000lbs each those GE's just can't compete the lower powered RR & PW B772 versions let alone what seem to be better insulated carbon-fibre frames of A350/B787. I think a much fairer comparison would be between GEnx & Trent 1000 varients of the B787, two very different sounding engines from outside on take-off at least, but very similar in power output.

This makes sense and provides the context I was looking for — thank you.

Channex757 wrote:

That's also why the baggage bins actually float rather than have hard bolting points. They run on rails that allow flexing.

Every day's a school day on here

Please post dB readings on same phone and same app, and where you sat, and where did you point your dB meter app. Then I might believe you.

jubguy3 wrote:

The posters here need to understand that the noise in the aircraft is highly dependant on your location in the plane. If you sat in the front of a 787 and just behind the engine of an A350, the A350 is going to sound louder.

Very true! Plus the human ears are the very best measuring instrument. However, very subjective and personal. Each set of ears / brains have different sensitivity in different frequency ranges. Plus bias plays an important role. https://en.wikipedia.org/wiki/List_of_cognitive_biases Therefore the ear cannot be used as a subjective comparison tool. My ears tell me the A350 is quite a bit more silent than the 787 (comparing C-cabin to C-cabin).

Why are we discussing a fact? You can just measure the in-flight noise in a controlled manner.

I flew both the 787 and the A350 days apart and I have to say the A350 was definitely quieter.

Thank you for your inputs.
I've taken about 20 longhaul flights in the past 2 years or so, of which 6 on A350XWB (all AY), 1 on B772ER (BA), 10 on B787 and a couple on B77W(JL/TK)/B77L(QR) and A330.

My quietness ranking is as follows:
1. B787
2. A350
3. A330
4. B777 all variants

I really can't figure out how the B787 is louder to so many of you guys compared to the A350.
To me the difference is so big that I need to wear earplugs on the A350 while the B787 always baffles me by how quiet it is, no matter where I sit on it.
Granted, comparing the front cabins is a bit more complicated, but in economy class, the difference is more marked.
Someone above pointed out that AY has chosen cheap cabin furnishings, which could explain it, as I've ever only been on AY A350's.

I disagree that measuring decibels is the right process to compare aircraft cabin noise.
A microphone measures sound waves in a much wider frequency range than the audible range.
Also, our brains do not perceive all frequencies in the same way. High frequncy sound is much more of a nuisance at same decibel levels as low frequency sound.
Sure, there is also a difference between an aisle seat and a window seat. I've once been sat in a window seat on a B77W where the window panneling was driving me nuts but my neighbor couldn't even perceive it and a flight attendant who came to check on it, was looking at me from the aisle like I was making it up.

Does the B787 have active noise reduction?
The Boeing lists a lot of noise reduction features. http://www.boeing.com/commercial/787/by ... lmer-cabin
I'm not trying to advertise for Boeing, I'm not known to be a Boeing fan. But I think that they really did an awesome job on this matter.

For those who don't know, I have worked in maintenance on several aircraft types, including Airbus, Boeing and others.
You know, remove/install overhead bins, sidewall panels, ceiling panels. Engines, APU, etc...
So I'm pretty sure that I know why it happens and how to stop a panel from buzzing at me for 12 hours.
Usually the buzzing is caused by a poor fit of the panels, courtesy of poor manufacturing and poor design.
Some click into place, some need fastening but the holes rarely seem to align. Very often, those panels need to be forced into place and fastened while keeping force applied on them. The first time that I worked on overhead boxes (the ones for O2, video, air vents), I couldn't believe that all that was keeping them from sagging down was the rubber lining. A bit shameful for such expensive equipment.

I think that there is more to it on the B787.
Perhaps it's the lack of bleed air and the electric airco system? I once worked on finding a leak in the leading edge anti-ice system of an aircraft and you wouldn't believe how hard those joints and pipes were buzzing and screaming. We were running the air off the APU but it felt like we were cruising at altitude.
They did an awesome job on the panels, that I can confirm. I don't have the panel issues on the B787 that I have on most of the A350 or B777. It has never really bothered me on the A330.
The A350's hydraulic system is also very loud compared to the B787. On the B787 it's more like background noise, but on the A350 you are forced to hear it.

A 6 dB difference means that the B787's cabin noise is 4 times that of the A350. I really really doubt it.

I think that the only meaningful comparison is to record the sound on the same equipment at different locations in the aircraft and compare the recordings with our own ears.

You can in fact get an objective measurement that corresponds to subjective loudness, that's what the various weightings (A, B, C, Z) are for.

And no, a 6 dB difference in sound pressure level (SPL) is not 4 times louder. 3 dB is usually taken as the smallest easily perceived sound level difference, and a perceived 2x difference is 10 dB. You have to be careful with dB to specify whether you're talking about SPL, amplifier power output, or whatever; fundamentally, dB by itself is just a log ratio and you have to say what quantity you're talking about.

Flown the A350 twice, both times in business class, it seemed exceptionally quiet. One of those flights was a 16 hour direct from SFO-SIN. This was an extremely comfortable and pleasant flight.
Flew the 787 only once from LAX-SIN (also in business class). I thought the 787 was quite noisy. However, I felt like perhaps the air had a bit more moisture, and overall it was still a very comfortable flight.

Neither 787 or A350 are noisy at all relative to almost all types, If you travel more than say twice a year and are as sensitive to sound as you seem to be you should get a set of Bose noise cancelling headphones - I have the in-ear type., they make even a CR9/Q400 or 732 near the back quiet (to my surprise in my last few days of travel). I can test the decibel meter back to back in 3 weeks as I am flying BRU-BKK-AKL on TG 359/789 and ET 788/789 in relatively similar positions onboard. A bit of quantifiable data is always important to the discussion.

Waterbomber wrote:

A 6 dB difference means that the B787's cabin noise is 4 times that of the A350. I really really doubt it.

I think that the only meaningful comparison is to record the sound on the same equipment at different locations in the aircraft and compare the recordings with our own ears.

While 10dB is 10 times the power, it is only twice as loud as the perceived sound level. The ear is non-linear.

http://www.noisehelp.com/decibel-scale.html

Then there are also frequency effects and the effects of aging. My father-in-law can only hear the men in my family but not the women: not because he is sexist (ok, he still believes that women belong in the kitchen) but because he is deaf at higher frequencies but can hear lower frequencies.

Location in the plane is also very important. Last week I flew in an A330 (Trent 700). On the way out in row 40 (above back of the wing) and on return in row 32 (in front of the wing). The difference was big. For A380 and 747, upper deck is much better than lower deck. Then there is wind noise. Last year I flew an A350 through severe turbulence above the Bay of Bengal and it was extremely loud.

The worst I have experienced was an old NW DC-9 seated at the last row between the engines. That was actually physically painful....

grbauc wrote:

Easy to down load a app for measuring decibel level.

...and close to impossible to measure correct and useful noise levels with them. It is even hard enough to do that with professional equipment (which I did the last 35 years).


Gruß, masi1157

Interesting how much opinions can differ. While one forum member needs earplugs for the A350, the other describes the same aircraft type as exceptionally quiet.

I think it also depends where in the cabin you're sitting. I'd say they were pretty comparable when seated in J, and are much quieter than the 777/747 by a long shot!

The A350 is not quiet in the cockpit when you put the gear down, that's for sure, can barely hear ATC. As for the 787, as someone said, I think the electric pack motors are the problem, which could be fixed in the future, maybe.

jubguy3 wrote:

The posters here need to understand that the noise in the aircraft is highly dependant on your location in the plane. If you sat in the front of a 787 and just behind the engine of an A350, the A350 is going to sound louder. Obviously Airbus would take the time to standardize their testing methods.

Let's face it, Boeing is out selling Airbus on the B787-A350. There's No dispute about that and it doesn't matter why.
If airlines get a better deal from Boeing than Airbus? It's worth their money to purchase from Boeing.
Nothing any Know-nothing Fanboy is going to say on this board means much when None of YOUR money is going to pay for any airplane.
I retired from United and worked primarily with the A320/A319 fleet. We had pretty good stats with those airplanes because we knew what we were doing.
And I believe we'll have pretty good stats with the A350 when it comes on line. Will they outshine the B787's? I doubt it.
Airbus (the company) has other flaws that hinder them. Their Engineering dept is as slow as molasses in getting Technical issues resolved.
I can't speak to Rolls Royce as I've never had to work with their Tech Reps.
So? It remains to be seen whether they have a superior product or even a comparable product when operated Side by Side.
But? Where the rubber meets the Road? WE shall SEE !! Until then? This is all "Academic".. What you can do?
See the airlines who operate Both models and see how they stack up in performance..

masi1157 wrote:

grbauc wrote:

Easy to down load a app for measuring decibel level.

...and close to impossible to measure correct and useful noise levels with them. It is even hard enough to do that with professional equipment (which I did the last 35 years).


Gruß, masi1157

You musn't forget that most smartphones are very good at cancelling out continuous noise - like jet engines, airflow. Making these apps even more unreliable.

i have flown B787 from QR and TG
also flown A350 with SQ, QR, TG and AY
for some reason the AY 350 is the absolutly most noisy so my ranking will be:
A350 SQ
A350 QR
B787 QR
A350 TG
B787 TG
A350 AY

in the AY planes there are so many diffenrent noises you dont hear in the other

fessor wrote:

i have flown B787 from QR and TG
also flown A350 with SQ, QR, TG and AY
for some reason the AY 350 is the absolutly most noisy so my ranking will be:
A350 SQ
A350 QR
B787 QR
A350 TG
B787 TG
A350 AY

in the AY planes there are so many diffenrent noises you dont hear in the other

Agree. I fly regularly between LHR and DOH and usually end up on a B787 in one leg and a A350 on the other (usually QR1 is a A350). usually I end up either on Business or on a economy seat as close to the exit door as I can because of tight schedule... depends what is available when I buy my ticket.

Last time (a couple of weeks or so ago), it was on a Business Class on their brand new A350-1000. I would say that the noise (and actually the smell of fuel) was, to say the least, richer...

But, again, it might depend on the configuration of the cabin, engines being used, etc., etc. etc... I lost a chance to fly a LATAM A350 last DEC because I changed my flights to a non-stop from LHR meaning a trip on their B77W (which was a good plane but actually much louder than QR's one).

Also, Airbus statement seems to be on the same grounds as VW stating in the past that their diesel cars were fuel efficient or Ferrari saying that their cars do 20 miles/gallon - they might do on testing conditions but, on a day to day it is a completely different story.

Ive flown both A350 and B787 few times in different classes. In general 350 is quieter and the flight was smooth - I didn't even need my noise canceling headphone when I was sleeping. Also in general I had less jet lag with A350 but 787 is also a very good airplane.

However if traveling in economy I would avoid 787. The space just feels very limited.

Interesting debate....

I'll be able to make my own subjective comparison next week when I fly MAN-DOH on a QR788, DOH-BKK on a QR A346 and BKK-CNX on a TG A359...

DarkSnowyNight wrote:

eamondzhang wrote:

Having flown on both planes, no I disagree to the statement. 787 is simply noisier, but that's my view. And surely I know someone will bash me before I realise.

Michael

They shouldn't, since you're right. In my experiences, yes, 787 is just a little noisier that the 350s. But even then, I still find the 787 about comparable to any A330 with RR powerplants. This is all to say that they there are all very adequate for noise issues, especially compared to anything else made in the past 40 years. Not seeing what the fuss is about.

I still have to fly the A350, but I fully agree that the 787 -although quiet- is not any quieter than a well maintained A330. Actually, I wasn't terribly impressed with my latest 787 flight, and on the immediately following flight (on an A330) I had the distinct feeling that this RR powered example was ever so slightly quieter than the newer Boeing jet?..

The A380 instead really takes things onto another level. Or for that matter, so did the sleek and mighty VC10.

The 777 can be a bit of a disaster, especially at the back.

Fiend wrote:

Interesting debate....

I'll be able to make my own subjective comparison next week when I fly MAN-DOH on a QR788, DOH-BKK on a QR A346 and BKK-CNX on a TG A359...

My bet is on the 346

strfyr51 wrote:

Let's face it, Boeing is out selling Airbus on the B787-A350. There's No dispute about that and it doesn't matter why.

But they're differentiated products.

The 787 is smaller. The 787-8 replaces the ER 767s and A330-200s/A340-200s. The 787-9 is a longer-range A330-300/777-200ER and A340-300. The 787-10 replaces higher-density A330-300 and 777-200s.

A350s are a different animal. The A350-900 replaces 777-200ERs, and the A350-ULR replaces A340-500s and 777-200LRs. The A350-1000 replaces A340-600 and 777-300ERs.

There are very, very many airlines that could benefit from having both 787s and A350s. In a duopoly this kind of differentiation is what you'd expect, so both Boeing and Airbus could have their own slice of monopoly profits.

ba319-131 wrote:

All depends upon where you sit, but from my experience, the 350 is quieter than the 788 if sitting forward of the engines.

Is my experience too. Sat forward of the engines back to back 788 and 359 and the 359 was hands down quieter...

lots wrote:

You musn't forget that most smartphones are very good at cancelling out continuous noise...

I never heard of any problem like that and it would be quite strange not to use the unprocessed microphone signal with an app like that. The problems are rather the missing calibration, bad linearity over frequency and amplitude, unknown directivity, unknown stability vs. time, temperature, ambient pressure, variations from phone to phone, even of the same type and much more. But the biggest problem is the operator. And even if all that goes well, what exactly will you measure? How will you compare between different A/C types?


Gruß, masi1157

zeke wrote:

When manufacturers and regulators talk about sound levels that are talking about scientifically measured quantity, sound pressure and sound intensity. These decreases in inverse proportion to the distance, that is, with 1/r from the measuring point to the sound source, so that doubling of the distance decreases the sound pressure to a half of its initial value.

However us humans are not scientific instruments, the quietness of a cabin is a psychological correlate of the sound amplitude, and is also affected by parameters other than sound pressure, including frequency, bandwidth and duration.

If a manufacturer says an aircraft is 6 dB quieter, it is based upon scientific measurements, this is entirely logical as the A350 engines are further away from the fuselage. These are facts.

However every person has different perceptions on loudness, these perceptions are the valued personal opinions.

Also different frequencies can be precieved by humans as having different “loudness” even if they are at the same dB.

When manufacturers and regulators talk about sound levels that are talking about scientifically measured quantity, sound pressure and sound intensity. These decreases in inverse proportion to the distance, that is, with 1/r from the measuring point to the sound source, so that doubling of the distance decreases the sound pressure to a half of its initial value.

However us humans are not scientific instruments, the quietness of a cabin is a psychological correlate of the sound amplitude, and is also affected by parameters other than sound pressure, including frequency, bandwidth and duration.

If a manufacturer says an aircraft is 6 dB quieter, it is based upon scientific measurements, this is entirely logical as the A350 engines are further away from the fuselage. These are facts.

However every person has different perceptions on loudness, these perceptions are the valued personal opinions.

Let me post the last post of this topic : " Since the discussion has gone off topiv this thread will be locked ".

The very famous A.net post )

zeke wrote:

However every person has different perceptions on loudness, these perceptions are the valued personal opinions.

Yup. I flew a 788 and A359 a week apart and found the 788 way more pleasant (quieter).

Not sure if it matters, but I sat over the wing on the 788 and in the back of the A359.

737max8 wrote:

zeke wrote:

However every person has different perceptions on loudness, these perceptions are the valued personal opinions.

Yup. I flew a 788 and A359 a week apart and found the 788 way more pleasant (quieter).

Not sure if it matters, but I sat over the wing on the 788 and in the back of the A359.

Sitting at the back, you're going to get the noise of the thrust from the engines, whereas if you're over the wing you're not. So those 2 examples are not comparable.

strfyr51 wrote:

Let's face it, Boeing is out selling Airbus on the B787-A350. There's No dispute about that and it doesn't matter why.
If airlines get a better deal from Boeing than Airbus? It's worth their money to purchase from Boeing.
Nothing any Know-nothing Fanboy is going to say on this board means much when None of YOUR money is going to pay for any airplane.
I retired from United and worked primarily with the A320/A319 fleet. We had pretty good stats with those airplanes because we knew what we were doing.
And I believe we'll have pretty good stats with the A350 when it comes on line. Will they outshine the B787's? I doubt it.
Airbus (the company) has other flaws that hinder them. Their Engineering dept is as slow as molasses in getting Technical issues resolved.
I can't speak to Rolls Royce as I've never had to work with their Tech Reps.
So? It remains to be seen whether they have a superior product or even a comparable product when operated Side by Side.
But? Where the rubber meets the Road? WE shall SEE !! Until then? This is all "Academic".. What you can do?
See the airlines who operate Both models and see how they stack up in performance..

Firstly, your posts are so poorly written that they're really quite difficult to follow - they just seem to be a stream of verbal diarrhea. I don't know if it's because you're old, impaired, poorly educated, or just lazy.
Secondly, have you actually flown on either the 787 or A350? I have, extensively, and they are both great aircraft. The A350 definitely has an edge for economy passengers as it's a wider cabin width, but for J passengers, I don't think there's much in it. Boeing historically hasn't invested much effort in noise insulation, but the 787 is a vast improvement over their other models.

My personal opinion based on the flights I've taken is that the noise levels are so similar that I doubt there is any real difference. Both aircraft are vastly quieter than their predecessors, and that itself is a huge achievement.

zeke wrote:

When manufacturers and regulators talk about sound levels that are talking about scientifically measured quantity, sound pressure and sound intensity.

I hardly ever heard anybody talking about sound intensity, at least I know not a single regulation that would specify it.

But all this is useless as long as we don't even know if those "6dB" are for interior or exterior noise. And if it is exterior noise, it will be cumulated levels compared to their respective limits, nor with one another. If it is interior noise, how where and what was measured? However, the distance engine to fuselage that you mentioned, has rather little influence and is easily compensated or reversed by many other effects. And the engines are not the major noise source anyway, except in climb in the rear of the cabin.

Gruß, masi1157

I've flown in similar seat locations in both planes, and I think both planes are significant improvements over crappy old junk like the 777

I do think the 350 is a tad quieter than 787, but all in all, not worth starting a fight (or thread) over it

Another point:

zeke wrote:

...sound pressure and sound intensity. These decreases in inverse proportion to the distance, that is, with 1/r from the measuring point to the sound source, so that doubling of the distance decreases the sound pressure to a half of its initial value.

That distance law is only correct in the far field of point sources, not with line or area sources and not in the near field anyway. And even with a point source the sound pressure does drop to 1/2 at 2x the distance, but intensity drops to 1/4. But for both the level drops by 6dB.

Gruß, masi1157

And let’s not forget that the first batch of A350s, first 20 frames or so, had different cabin fixtures than later batches. That might explain some differences in cabin noise levels. AY has many first batch frames being one of the launch operators.

strfyr51 wrote:

jubguy3 wrote:

The posters here need to understand that the noise in the aircraft is highly dependant on your location in the plane. If you sat in the front of a 787 and just behind the engine of an A350, the A350 is going to sound louder. Obviously Airbus would take the time to standardize their testing methods.

Let's face it, Boeing is out selling Airbus on the B787-A350. There's No dispute about that and it doesn't matter why.

Way to completely go off topic?

Finn350 wrote:

And let’s not forget that the first batch of A350s, first 20 frames or so, had different cabin fixtures than later batches. That might explain some differences in cabin noise levels. AY has many first batch frames being one of the launch operators.

That explains it IMO. The AY A350's have very similar noise levels to the A330's and the whole cabin is cracking and squeaking at every maneuver, like on the goold old B747's. Now I can't wait to try a standard A350. If they can beat the B787 as most here seem to agree on, they must be super quiet.

Come to think of it, I found JL's B787 to be quieter than the QR and NH B787's.
I wonder if there is any difference in cabin furnishings?

I don't know if I will be able to make it to Farnborough, but it's definitely a question that I would like to ask at the Boeing and Airbus stands.

Here we go again AB playing the old my "schlong" is bigger than yours game. So a difference of 1 or 2 DB is a game changer is it from a pax point of view. Personally I prefer a bit OF noise, as planes get quieter more "human" noises come into play snoring, talking even passing wind !! etc. I find the 380 noisier in the QF Business cabin than I do on the economy section. Is this because Y is more dense and absorbs the engine/ airflow noise better than the cavernous J cabin ?? . As many have said , it depends on cabin furnishings, seat position etc .


An767

Waterbomber wrote:

I've flown the A350-900 and B788 back to back within 4 days on long haul flights and I'm not happy to read the Airbus claim that the A350 is 6 decibels quieter than the B787.
The B787 definitely is a lot quieter than the A350.

How did you calibrate the instrument you used to measure the noise?

The A359 engines will have more thrust than a 788 and probably more than a 789 depending on aircraft weight at any given time during cruise...but I imagine that the engines on the A350 are a bit farther away from the fuselage. The 787 also has a different air conditioning system with compressor motors in the aircraft. I don't know if the wing differences affect noise...I imagine a lower wing loading means less noise, but can't say for sure. So this all makes it reasonable to expect the 787 to be a bit noisier.

I agree the 777 is very noisy...mostly because of those huge engines. Interesting to see what the A350-1000 will sound like, it will have larger engines than the A359, similar in thrust to the 772 and 773 but still smaller than the 77W. I'm sure most passengers don't really care too much as you get acclimated to flight noise.

If you want a more comfortable 787, noise should not be the first priority...Convince airlines to give us 8-across Y-class. That, and reasonable pitch would make the 787 experience much better.

None of them are s good as the A380. I have flown on all three aircraft. Emirates A388, Thai B789 and Cathay A359.

QuarkFly wrote:

The A359 engines will have more thrust than a 788 and probably more than a 789 depending on aircraft weight at any given time during cruise...but I imagine that the engines on the A350 are a bit farther away from the fuselage. The 787 also has a different air conditioning system with compressor motors in the aircraft. I don't know if the wing differences affect noise...I imagine a lower wing loading means less noise, but can't say for sure. So this all makes it reasonable to expect the 787 to be a bit noisier.

You miss out on a major differentiator:
The design of the fuselage walls resp. buildup of hull, how is framing attached,
(thickness of) insulation blankets and their noise dampening properties finaly inner fairings and other details.

Historically Airbus puts more effort into a lower noise passenger environment.
( No idea if Boeing has no interest there or sees the weight advantage of a thinner lighter wall buildup.)

The perception of noise on the A350 is not an issue. The lack of engine options on the other hand, well, ...............

glideslope wrote:

The perception of noise on the A350 is not an issue. The lack of engine options on the other hand, well, ...............

It would appear that the era of engine choice is over.

The only ones with options now are the 787, 380 and the 320 families. I am ignoring the 330ceo.

Further it seems we have Boeing with GE and AB with RR on the widebodies.

I’ve never really understood this obsession with how quiet a plane is. I don’t really notice the difference and think all are similarly noisey other than the mad dog.

I have never been on an A350 but I remember my first 787 flight with BA. I did have high hopes and was looking forward to fly on it. Then reality hit me. First impression, it’s one noisy plane, especially during pushback and taxi. The ride on the ground felt as hard as when driving in a Mini. My overall impression was it feels and looks cheap, like it was build in a Peugeot factory. I prefer to fly on any other plane but the 787.

senatorflyer wrote:

I have never been on an A350 but I remember my first 787 flight with BA. I did have high hopes and was looking forward to fly on it. Then reality hit me. First impression, it’s one noisy plane, especially during pushback and taxi. The ride on the ground felt as hard as when driving in a Mini. My overall impression was it feels and looks cheap, like it was build in a Peugeot factory. I prefer to fly on any other plane but the 787.

Sure. Whatever you say. Shall we queue up a DeHavilland Comet for you, then?

glideslope wrote:

The perception of noise on the A350 is not an issue. The lack of engine options on the other hand, well, ...............

How is lack of engine option remotely relevant to this thread?

neutronstar73 wrote:

senatorflyer wrote:

I have never been on an A350 but I remember my first 787 flight with BA. I did have high hopes and was looking forward to fly on it. Then reality hit me. First impression, it’s one noisy plane, especially during pushback and taxi. The ride on the ground felt as hard as when driving in a Mini. My overall impression was it feels and looks cheap, like it was build in a Peugeot factory. I prefer to fly on any other plane but the 787.

Sure. Whatever you say. Shall we queue up a DeHavilland Comet for you, then?

Meant more the alternatives which are around today. I fly an awful lot and if I can avoid the 787, I’ll do. Sorry to hurt your feelings but that’s just my opinion.