masi1157 wrote:

trauha wrote:

Distance makes a big difference as dB decrease logarithmically with distance.

They don't. In a freefield environment they drop by 6 dB per doubling the distance, further away friom the source in the reverberant field they stay more or less constant. But that will take us too far off.

The important part was given by Thomas much earlier: Conversations from the next table or the next seat row might draw your conscious attention, but they are completely irrelevant for fatigue. The masking noise that you seem to desire on an aircraft (which is usually well above 70 dB(A)!) doesn't draw your attention, buit basically ruins your health and especially that of the crew working in that environment.


Gruß, masi1157

I thought dB is a logarithmic scale? In my experience someone talking two rows behind me is way more quieter than half as quiet, compared to someone talking in the row directly behind me? Please educate me.

As to the other point, my experience with irritating noise, no matter how quiet, e.g. 50dB talk leaking from neighbouring hotel room at night is very fatiguing. I would rather have the noisy air conditioner at a steady 70dB mask the noise.

In my 16 years of having my dB meter on flights, the biggest surprises have been the amount of hours that have exceeded 85dB which in my country is illegal, and how much noisier window seats and exits and some toilets are on some planes compared to aisle seats.

keesje wrote:

The db meter installed on smartphone, there is a calibration function. I will see if I can calibrate it somewhere. It takes at least 10-data points per second. I will try walk up and down the aisle and take the average after 5 munites / a few thousands measurements. So peeks are averaged out. And do that a few times at cruise level. Over the next 2 weeks I will fly A333 (PW), MD90, 753 (PW), 738 and 772ER (GE). Lets see if this works.

Smartphones are built to quite tight specs for this purpose and variances within the same model will be small. The app developer will give info as to variances between Samsung and Apple models. Then of course there are meters used by law enforcement for occupational hazard and safety that give numbers admissible in courts of law. In my experience they are however not much better than phones.

Heinkel wrote:

PlymSpotter wrote:

The differences in the noise levels shown above are so small, that an untrained obersever won't hear the difference. Normal people don't hear a difference of 3 dB (dB(A)?)

3 dB can comfortably be heard, although the difference is nearer to 5dB depending on engine type.

PlymSpotter wrote:

Heinkel wrote:

PlymSpotter wrote:

The differences in the noise levels shown above are so small, that an untrained obersever won't hear the difference. Normal people don't hear a difference of 3 dB (dB(A)?)

3 dB can comfortably be heard, although the difference is nearer to 5dB depending on engine type.

The dB unit was initially introduced in the belief that 1dB is an increment that is noticeable. Professionals work with units of 0.1dB in broadcasting and music for relevant results.

PlymSpotter wrote:

3 dB can comfortably be heard, although the difference is nearer to 5dB depending on engine type.

3 dB can easily be distinguished in direct A-B comparison. But you will not be able to hear the difference when you hear one aircraft now and the other one 1/2 hour later. And that is for continuous noise, but the numbers here are EPNdB, which is a completely different story.

Gruß, masi1157

masi1157 wrote:

PlymSpotter wrote:

3 dB can comfortably be heard, although the difference is nearer to 5dB depending on engine type.

3 dB can easily be distinguished in direct A-B comparison. But you will not be able to hear the difference when you hear one aircraft now and the other one 1/2 hour later. And that is for continuous noise, but the numbers here are EPNdB, which is a completely different story.

Gruß, masi1157

This claim of audio memory is interesting. Do you mean you can not remember, or are there studies on this subject?

trauha wrote:

I thought dB is a logarithmic scale? In my experience someone talking two rows behind me is way more quieter than half as quiet, compared to someone talking in the row directly behind me? Please educate me.

dB is a logarithmic scale and the distance law can as well be written in dB. The effect is that somebody 2 rows away will be 6 dB less noisy than somebody 1 row away (if they both speak at the same volume). That is not "half as loud". The larger the distance the smaller gets the difference in dB, until it eventually transits to constant in the reverberant field.

trauha wrote:

As to the other point, my experience with irritating noise, no matter how quiet, e.g. 50dB talk leaking from neighbouring hotel room at night is very fatiguing. I would rather have the noisy air conditioner at a steady 70dB mask the noise.

I could probably fatigue you easily by keeping you awake all night with tiny little sounds that draw your attention. But that is something completely different than fatigue by continuous high noise levels, that is not consciuously perceived.


Gruß, masi1157

trauha wrote:

In my 16 years of having my dB meter on flights, the biggest surprises have been the amount of hours that have exceeded 85dB which in my country is illegal, and how much noisier window seats and exits and some toilets are on some planes compared to aisle seats.

I know of no country in the world where more than 85 dB(A) would be illegal, when passengers are exposed to those levels for a certain period of time. The laws that I know of have an average of 85 dB(A) over an 8 hour working day as "upper action limit", that requires your employer to take actions and provide hearing protection, that you, as employee, would have to use.


Gruß, masi1157

I will include engine type.

I looked at various db tests on youtube. Decibel x appears to be one the best in various tests. Still it is free. I'll probably use that one.

Demo: https://youtu.be/cbPoNMEg4xw

Article on the topic: http://thenewyorkhearingcenter.com/2018/01/sound-level-apps-for-smartphones/

The db meter: http://skypaw.com/decibel10.html

masi1157 wrote:

PlymSpotter wrote:

3 dB can comfortably be heard, although the difference is nearer to 5dB depending on engine type.

3 dB can easily be distinguished in direct A-B comparison. But you will not be able to hear the difference when you hear one aircraft now and the other one 1/2 hour later. And that is for continuous noise, but the numbers here are EPNdB, which is a completely different story.

Gruß, masi1157

This is LGW we're talking about, it's often less than five minutes between A359 and B789 overflights, and other heavies, so I'd consider it a very close comparison, if not a direct A-B test held seconds apart. There are also other environmental factors; as the house has been built over time, certain outbuildings/rooms in the property have much greater insulation/noise shielding, meaning quieter aircraft are inaudible in them, whilst louder ones are. The altitudes and flight paths tend to be very regular too.

Airbus also claims that the A380 makes 300 flights per day... Which is absolutely ridiculous. LOL

Heinkel wrote:

The differences in the noise levels shown above are so small, that an untrained obersever won't hear the difference. Normal people don't hear a difference of 3 dB (dB(A)?)
The difference can be measured but it is hardly audible.

Though they may form the basis of noise-related landing and take off charges at some airports.

masi1157 wrote:

trauha wrote:

In my 16 years of having my dB meter on flights, the biggest surprises have been the amount of hours that have exceeded 85dB which in my country is illegal, and how much noisier window seats and exits and some toilets are on some planes compared to aisle seats.

I know of no country in the world where more than 85 dB(A) would be illegal, when passengers are exposed to those levels for a certain period of time. The laws that I know of have an average of 85 dB(A) over an 8 hour working day as "upper action limit", that requires your employer to take actions and provide hearing protection, that you, as employee, would have to use.


Gruß, masi1157

Here you have it: http://www.legislation.gov.uk/uksi/2005 ... ion/4/made
Many flights are longer than eight hours.

It seems like Boeing could market this advantage by showing sound range at key areas of the 787 to stuff you really dont want to hear and how much greater your exposure is to passing wind and drunk conversations in the 350 and 380. I must be a dinosaur enjoying the white noise of flight.

trauha wrote:

Here you have it: http://www.legislation.gov.uk/uksi/2005 ... ion/4/made
Many flights are longer than eight hours.

That is exactly what I said earlier. Are you passenger or crew? Passenger? That law doesn't apply. Crew? Did you use a dosimeter to measure your daily/weekly exposure level? That is basically a level energetically averaged over the given period of time. Is that exposure level above 85 dB(A)? And does your employer not have an action plan in place how to reduce your exposure (that could even be rotating you through noisy and less noisy workspaces) and doesn't provide hearing protection? Then that is the illegal part (on his side), not the noise level being locally and temporarily above 85 dB(A).


Gruß, masi1157

I sat right by the wing on a SQ a359 and I felt that it was just slightly quiter than a 773 er. I read that some people said that 788/9 are quiter and some said they are noisier than the A359, could the difference be due to the RR and GE engine?

While I haven’t been on the 787 (may have a flight coming up soon), I have been on the A350 and found it to be quieter than all other twinjets I’ve been on (all in the window seat behind the engine) and I couldn’t notice the cabin rattling at all, maybe SQ has different panels. Interestingly, I found a RR A333 much much quieter than the A359 when sitting in the middle seat of the middle section (you know, the 4 in the 2-4-2) just behind the wing. A380 is the undisputed quietest in my opinion.

Not related to the topic, but one thing I think is overhyped is the lower air pressure on the A350 and 787, I couldn’t notice a difference between the air on the A350, the airport, and a B738 I went on a few hours after.

Cblk wrote:

...could the difference be due to the RR and GE engine?

It could be any combination of the altitude, the speed, the thrust of the engines in that moment (which again depends also on current A/C weight and outside temperature), your exact seat position, the seat layout and cabin arrangement, the seats themselves (leather or fabric over opencelled foam?), the number of pax around you and what they wear, how ECS was adjusted to the pax count, the loading of the overhead bins, the carpet, your airline's cabin and system configuration, your personal constitution, your sensitivity to certain noise signatures, ..and...and...and...the engine type and manufacturer.


Gruß, masi1157

Non scientific observation but having flown in business class on both A350(Qatar) and B787(ANA&JAL), I could hardly tell the difference in cabin noise. Both aircraft were noticeably quieter than previous generation WB twins i.e, A330 and B777.

For me one of the noisiest aircraft ive been on was AY's A333 LTO and LTN to ICN. Those GE CF6s are damn noisy and as one person wrote, the cabin materials do rattle. However we do have to take into consideration that we were flying against 100km/h winds. The 747s for me are a quiet and happy place. As for the 787 vs a350 i can't comment as i haven't flown a a350 yet.

planecane wrote:

Without data this debate is a waste of time.

... Without data this debate is just ... noise?

I do agree data would be useful. And thank you for those who have provided. Of course, the measurements aren't easy, so there's plenty of room for intepretation.

AirlineCritic wrote:

I do agree data would be useful. And thank you for those who have provided.

Did anybody provide useful data to answer the initial question? I must have missed that. The numbers provided might be useful to say how noisy it may have been in the moment somebody looked at his "dB meter" in flight. But it is a very long way from there to a useful comparison of cabin noise in aircraft types.

Gruß, masi1157

I think what Masi is sort of telling you, and I, as a professional in the field of sound would support is that there are lies, damned lies, statistics and sound measurement data.

It is virtually impossible to get any truely meaningful out of it on this scale.
It is the easiest thing in the world to produce data that shows one cabin is 3dB quieter than another. Saying you have then cut the noise by half is grossly misleading, but strictly speaking not wrong.

Using smartphones for measurement is likewise useless, while the microphone element itself is probably good enough within 1-2dB within a useable frequency range, there are tons of other variables.
The A/D, the dust stuck in the holes for the microphone, the way it is held, handling noise, wind from breathing, the jacket tge person holding it is wearing on a cold day, there are thousands of parameters to control to get a meaningful sound measurement. It is almost only possible in an anehonic chamber or in a strictly static and controlled environment.
Measuring airplanes in movement and their enviromental impact is meaningless unless you have a HUGE dataset with extremely tight control on weather(wind, temperature, pressure, percipitation, humidity) positions, speed, road traffic, people, extremely tightly calibrated test equipment.

All these variations also exist in a cabin.
Speed, altitude, people, interior details, microphone placement, microphone direction, weather(engine power, humidity affecting hi-freq response)

Are you guys getting the picture?

Hey, good to see people here who not only pretend they know everything about "dB".

What I would add, and said before: Even if you could control all those parameters or would at least know them (which is impossible for somebody flying as a passenger), what would be equivalent parameters an another aircraft type that would produce results for a meaningful comparison? For example: You measure on type X flying at M=0.82. Should type Y then also be tested at M=0.82, even when it normally flies and is designed for M=0.85? (and that ignores that noise depends not on Mach but on TAS).


Gruß, masi1157

Ok, here I have my latest personal non-scientific opinion, based on my most recent chunk of flights... And I am one of those who are pretty much obsessed by quietness and 'noise quality'!!
A350 is slightly but consistently quieter than the 787, especially starting from the wing back (up front both are seriously impressive). The 787 is very quiet, but more so when equipped with the Genx engine. The RR has more of a hum-rumble at the back and on take-off.
The A380 remains the quietest jet IMHO. A346 is also very quiet (almost on a par with the new twins) particularly up front, and the A330 is close behind the new twins, with older RR variants being the noisiest ones perhaps, and PW the quietest.
Looking forward to healthy discussions!

I think that I have resolved this one.
I have recently been on ANA B789 flights and JAL B788 flights for similar stage lengths, and found the ANA flights to be quite a bit noisier, perhaps on par with the AY A350 flights.

The ANA are equipped with RR engines, would take off with higher take-off weight being a B789 and configured 9-abreast in economy, have about 50 additional seats.

The JAL B788 are equipped with GEnx and would take-off with lower take off weight if carrying less payload and fuel.

I think that while the weight plays a role, the amount of noise does not really vary that much in terms of weight as can be compared at various stages of flight/weight, but the GEnx vs RR Trent 1000 is the key factor here.
My personal conclusion is that the GEnx B787's are quieter than the RR Trent 1000 B787's and the A350.

A family member who also flew both a lot agrees that the JL B787 is markedly quieter than the AY A350.

Waterbomber wrote:

I think that I have resolved this one.
I have recently been on ANA B789 flights and JAL B788 flights for similar stage lengths, and found the ANA flights to be quite a bit noisier, perhaps on par with the AY A350 flights.

The ANA are equipped with RR engines, would take off with higher take-off weight being a B789 and configured 9-abreast in economy, have about 50 additional seats.

The JAL B788 are equipped with GEnx and would take-off with lower take off weight if carrying less payload and fuel.

I think that while the weight plays a role, the amount of noise does not really vary that much in terms of weight as can be compared at various stages of flight/weight, but the GEnx vs RR Trent 1000 is the key factor here.
My personal conclusion is that the GEnx B787's are quieter than the RR Trent 1000 B787's and the A350.

A family member who also flew both a lot agrees that the JL B787 is markedly quieter than the AY A350.

Now that's what I call science. In truth only family members can confirm with any sort of scientific credibility that one aircraft is markedly quieter than another, and "markedly" being a more widely accepted unit of noise measurement than dB. Thanks for this WB.

I can bet you one thing and that Joe soap wouldn't know a Decibel from a barbell and even a poll will be inconclusive as each person would perceive noise differently, so wind your necks in and just accept that Airbus aircraft are generally quieter than Boeing. For interest sake, has Boeing ever said that their aircraft are quieter?

Having just flown both from North America to Asia, I have to give the credit to 350. Both are very modern planes, but the 350 is just so quiet that it's literally the first plane that I'm able to watch a movie comfortably (hear the conversations clearly) out of many planes I've been on, especially 77w. Now, being an aviationist, it's apparently a different story, everyone like GE90 but have to say it's not for traveling, especially for long-haul transoceanic flight.

I just flew a Qatar 788 and Lufthansa A359 and I can honestly say i think the 788 was more quiet and more comfortable ride. I sat over the wing and dead center both times.

My .02

Boeing clearly don’t seem to care about cabin noise. The Airbus equivalent models are consistently quieter (737 vs A320, A330 vs B777 etc). From my experience in many 787 and A350 flights is that both are much quieter than their predecessors, but the A350 does have a slight edge. This is usually sitting forward of the engines on both types.

Boeing has made a lot of progress with the 787, but interestingly enough I still find the older generation A340 to be a quieter ride. Not to mention the cathedral-like A380, and, to some extent, the A350. I am very curious about the upcoming 777X's noise Level, but I'm not very optimistic, with those thinner sidewalls.

If the manufacturers really cared about noise levels they'd fill in all the windows and replace with window strip TVs (like EKs fake window in its new F class centre seat).

Would allow for a lot more sound and temperature proofing and I suspect make a plane a lot lighter and simpler and cheaper to construct.

Was on my first A350 flight a month ago (MH) and to be honest it didn't feel noticeable quieter to me (cattle class aisle seat). I still struggled to hear the movie dialogue at times (with the rubbish headphones provided). Maybe my expectations were too high or I'm spoilt by the A380!

I've certainly never found on planes that they are so quiet that passenger noises (other than screaming babies) become really intrusive.

AirbusA6 wrote:

Was on my first A350 flight a month ago (MH) and to be honest it didn't feel noticeable quieter to me (cattle class aisle seat). I still struggled to hear the movie dialogue at times (with the rubbish headphones provided). Maybe my expectations were too high or I'm spoilt by the A380!

I've certainly never found on planes that they are so quiet that passenger noises (other than screaming babies) become really intrusive.

Well, actually this has recently happened to me both on the A380, as well as the A340-600. Wonderfully quiet cabins, and really noisy, annoying, intrusive stupid human beings intruding into your comfort zone with their high-pitched, meaningless conversations. On one long flight I was desperately trying to get some much-needed sleep when this big, bulky older woman was having a conversation with another lady sitting on the row behind about a mutual third friend. I could go on with the details for half an hour, it was so loud. Needless to say, silence was had by all for the remainder of the flight following my quick expletative blitz.

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

I believe there are roughly similar in noise. The Airbus probably seems quieter as it’s noise is a deeper lower frequency. Low-frequency noises are more easily ignored so they are perceived as being quieter. It’s just the way we are wired, even the best set of ears can’t hear sound evenly, and our brains also are wired to pay more attention to certain sounds and frequencies over others. For obvious reasons and is why we can’t ignore a screaming baby, even if it’s in the next room. Your mind is wired to give baby screams priority over other louder sounds.

Is why a 787 seems louder, it’s noisier in the mid and upper frequencies.

Is it true that the 787 that uses GE engine is quieter than RR's engine?