VH-TJW - High levels of ambient noise?

[Actualise]

Is there an explanation why the noise level in the cabin of VH-TJW (a 737-400) at cruise is almost uncomfortably high? It makes one think you're back in a 707.

I don't seem to have noticed it in other 737-400s...

This was on a SYD-ADL flight which would have been into a headwind, and with a full pax load.

Cheers,
Andrew.

 

[docjames]

This was on a SYD-ADL flight which would have been into a headwind, and with a full pax load.


.

That may be your answer: higher thrust = louder.

 

[munitalP]

Maybe someone had a window open?


:shock: :shock: :shock:


Mr!

 

[Travel Guru]

Maybe someone had a window open?

LOL!

TG

 

[straitman]

That may be your answer: higher thrust = louder.

Yeah, right :!:

 

[NM]

That may be your answer: higher thrust = louder.

Yeah, right :!:

Makes sense in some circumstances. A P&W TF30 generates around 50,000 lb thrust and is louder than a CFM56 at around 30,000 lb. So in that example "higher thrust = louder"

 

[anat0l]

Maybe someone had a window open?


:shock: :shock: :shock:

I'm thinking what a nice riposte that was in conjunction with the ol' explosive decompression thing where people get sucked out of an aircraft like toothpaste coming out of its tube.

That may be your answer: higher thrust = louder.

That's just wrong on so many levels. And correct on only one.

 

[docjames]

I also love how everyone jumps down my reply but doesnt actually give the OP any decent response to the question asked!

 

[anat0l]

I also love how everyone jumps down my reply but doesnt actually give the OP any decent response to the question asked!

Well, OK I'll start the ball rolling.

Honestly, I don't know why.

I do know that the old aircraft tend to be quite a bit louder. For example, IME I find the Jetconnect 737-300s to be a bit louder than the 737-400s.

Now why does it seem that one particular 737-400 is louder than the others is really beyond me. But I do notice 737-400s tend be louder than say a 737-800.

 

[NM]

Now why does it seem that one particular 737-400 is louder than the others is really beyond me. But I do notice 737-400s tend be louder than say a 737-800.

I expect the variation in noise within in the same carriers versions of the same aircraft type (i.e. between different QF 734s) is likely more to do with seating position than anything else.
Many of QF's aircraft have individual air-conditioning vents that can case QF's aircraft to seem to be noisier than airline's that do not have individual air vents. This can also be noticed between the 767-338 and 767-336 aircraft in the QF fleet.

Apart from that, there is little physical difference between aircraft of similar models.

 

[anat0l]

I expect the variation in noise within in the same carriers versions of the same aircraft type (i.e. between different QF 734s) is likely more to do with seating position than anything else.

What would be a typical engine noise profile be like going from the front to the end of the aircraft?

Or to put it simply, in which seats would the engine noise be most heard and least heard?

 

[NM]

What would be a typical engine noise profile be like going from the front to the end of the aircraft?

Or to put it simply, in which seats would the engine noise be most heard and least heard?

Typically, the further forward the quieter. Sitting over the wings should be quieter than behind. But I really don't notice much difference on aircraft like 737 or 767. Newer aircraft seem to be quieter due to improved engine design and better insulation.

Try sitting in the last row of a MD80 or DC9 and you will know what engine noise it all about :shock:.

 

[anat0l]

Try sitting in the last row of a MD80 or DC9 and you will know what engine noise it all about :shock:.

I've had my time in tiny aircraft. Dash 8s are pretty loud to the uninitiated; Metro 23s and the like are pretty bad - I had to fly one out to a mine site and we were issued ear plugs upon boarding.

I had to fly a 717 back from the site and I think I was lucky that I got row 3 rather than being shoved at the back of the aircraft.

 

[oz_mark]

Try sitting in the last row of a MD80 or DC9 and you will know what engine noise it all about :shock:.

Never flown those, but used to score the last row or two in F28's and they were noisy little critters.

 

[NM]

Never flown those, but used to score the last row or two in F28's and they were noisy little critters.

Yes, very similar effect.

 

[Actualise]

Thanks for all your insights. VH-TJW is the only 737-4L7 in the QF fleet - it is looking rather aged internally, and it caused me to wonder if:

* it might have different engines to the other 734s
* it might have a different level of noise deadening internally - Air Nauru might not have had as high expectations/specs or it might have been built as cargo and bought at a discount by Air Nauru
* the noise deadening (is it in the airframe or fitout?) might have a life (airframe is 16 y.o) and now need replacing...

The flight attendants had trouble being heard in a way I had not seen since the MD80 days (or Dash 8-s in the regions) - noisier than some of Ansett's old 767's.

Finally, I was in 13F whereas usually I get rows 4-7 and aisles.

I'm guessing it was unusually heavy going was the principle cause - the flight time to Sydney from Adelaide was just 1 hour 20 min on the previous morning flight the other way, but was hoping some airliner-phile might just know the facts.

Cheers,
Actualise.

 

[oz_mark]

Finally, I was in 13F whereas usually I get rows 4-7 and aisles.

This may be part of it. I do remember years ago flying in an A300 airbus that seemed to be louder than the other A300's I had been in, and wondered much the same things back then. Was it the age, was there something different about it etc?

 

[Happy Dude]

As an acoustic consultant who has worked on more than a few aircraft noise projects, including ANEFs, I believe the answer could come from a variety of sources.

Firstly and most significantly, there is engine noise. When a plane is airborne, noise is produced as hot air from the engine mixes with the cold air at incredibly high velocity. Then there is speed/thrust. My experience of measuring noise associated with a British Hawker Harrier at a tie-down facility indicates that higher thrust equates to higher noise output. It's the single loudest thing I've ever heard and I've stood within 5m of underground coal mine exhaust systems. The faster the turbine spins, the more noise that comes off it.

Engine noise can and does vary even for the same type of plane. Variables include the age of the engine, whether it's been serviced etc, and when flying, the speed of the aircraft. The faster the plane travels, the more noise that comes off it.

Secondly, the "friction" type of noise caused by the aerodynamics. Wind rushing over the wings and fuselage produces significant noise. The level of this noise is again influenced by variables such as the speed of the plane, and also the position of the wing flaps and atmospheric conditions such as humidity, temperature, wind speed and direction etc.

To the observer inside the plane, seat location will be everything. In my experience, a seat close to but behind the engines will be the noisiest.

Actualise is also correct when suggesting "deadening" inside the plane (well not by deadening per se, but absorption). A plane with more people, newer carpet, cloth seats etc will result in more reverberant noise control which will "deaden" the space. So the fitout and load of the plane also plays a part.

Also, as a few have suggested, the age of the plane is also relevant. Planes are becoming quieter.

Based on what I know, I'd guess that Acualise experienced an older 737-400 that was being flogged into a chilly headwind and he had a seat close enough to the engine to cop an earful.

 

[Actualise]

Thanks so much happy dude. We'll see what the Q says to my "complaint"...

and I'll update you.

 

[NM]

Secondly, the "friction" type of noise caused by the aerodynamics. Wind rushing over the wings and fuselage produces significant noise. The level of this noise is again influenced by variables such as the speed of the plane, and also the position of the wing flaps and atmospheric conditions such as humidity, temperature, wind speed and direction etc.

As aircraft become older, they become less efficient due to little dents, bends, wrinkles, blemishes and dirt build up on the outer surfaces. so just as these variations can affect add drag to the frame, I expect the variations in "friction" can also result in different levels of noise . So perhaps the older frame also has more imperfections than some others resulting in different audible affects.