B738 cockpit db levels
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B738 cockpit db levels
Would anybody happen to know what the noise levels are in a B737-800 cockpit?
If anybody has any links to documentation about this it would be much appreciated.
Fly safe!
If anybody has any links to documentation about this it would be much appreciated.
Fly safe!
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Hmm, I can't give you any absolute values - but its not quiet 
One thing is for certain - older birds without vortex generators in front of the windshield and without redesigned ducting are a lot louder than the old ones, I remember reading something about 6db reduction with the modifications in place.
One thing is for certain - older birds without vortex generators in front of the windshield and without redesigned ducting are a lot louder than the old ones, I remember reading something about 6db reduction with the modifications in place.
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I saw a Boeing presentation some time ago that discussed the Flight Deck Noise Reduction program on the 737NG... you know the BS that added vortex generators to the base of the forward windows, allegedly changed the routing of ECS piping and mufflers? There were no concrete FACTS on the actual noise level (just a bunch of colored squiggly lines in a chart with no dB values), but a summary slide mentioned the "potential" for 73dB. I think they're off by 10dB. The noise reduction program was supposed to reduce the noise by 3 points, so a "baseline" of 76?
The reduction is supposed to be 1dB from ECS modifications, and 2dB from the boundary layer noise (vortex generators, insulation, etc). In my experience, the modified aircraft are just as bloody noisy as the unmodified ones so I think it's a crock!!
If anyone is active in the Bluecoat forum, I believe Bill Bulfer made some notes on flight deck noise by using a Radio Shack measuring device in the 737-300, 500 and -800 6 or 7 years ago. It has been some time, but I seem to remember at Mach .80, the -500 was quietest at 86 dB, and the -800 was noisier still at 87 db? I may be remembering incorrectly, but I am damn sure the -500 was quieter because it surprised me. You might try contacting him, he may have some more definitive numbers for you.
And to hell with the bloody Steve Jobs product already.
The reduction is supposed to be 1dB from ECS modifications, and 2dB from the boundary layer noise (vortex generators, insulation, etc). In my experience, the modified aircraft are just as bloody noisy as the unmodified ones so I think it's a crock!!
If anyone is active in the Bluecoat forum, I believe Bill Bulfer made some notes on flight deck noise by using a Radio Shack measuring device in the 737-300, 500 and -800 6 or 7 years ago. It has been some time, but I seem to remember at Mach .80, the -500 was quietest at 86 dB, and the -800 was noisier still at 87 db? I may be remembering incorrectly, but I am damn sure the -500 was quieter because it surprised me. You might try contacting him, he may have some more definitive numbers for you.
And to hell with the bloody Steve Jobs product already.
Absolutely I can, mate!
I work for a company providing digital sound and communications systems for use in Level D flight sims... the sound level varies depending on the aircraft operating state (yeah, that's obvious...
), so you name it!
The Boeing simulation data package includes octave band SPL levels for many operating conditions, with the 63Hz band generally being the loudest... for example the peak level at 63Hz for an on-ground engine acceleration from idle to take-off power is about 90dB SPL, during take-off the peak (again 63Hz band) is around 98dB, while in cruise (FL350, 0.78M) the level drops to about 80dB SPL, while application of full thrust reverse gets you to just about 100dB SPL in the 63Hz band.
The 63Hz band is a good guide for the overall SPL, since the overall sound level is the integral of all energy in the audible range (and recognizing the energy at low frequency is much great than at higher frequencies).
Cheers, GY
I work for a company providing digital sound and communications systems for use in Level D flight sims... the sound level varies depending on the aircraft operating state (yeah, that's obvious...
), so you name it!The Boeing simulation data package includes octave band SPL levels for many operating conditions, with the 63Hz band generally being the loudest... for example the peak level at 63Hz for an on-ground engine acceleration from idle to take-off power is about 90dB SPL, during take-off the peak (again 63Hz band) is around 98dB, while in cruise (FL350, 0.78M) the level drops to about 80dB SPL, while application of full thrust reverse gets you to just about 100dB SPL in the 63Hz band.
The 63Hz band is a good guide for the overall SPL, since the overall sound level is the integral of all energy in the audible range (and recognizing the energy at low frequency is much great than at higher frequencies).
Cheers, GY
Would you happen to know the overall SPL in dB(A)?
- GY
Indeed I do have Airbus cockpit levels - those are easier since the dBA overall SPLs are included in the Airbus data package for sound.
For now all have access to is for the A320 w/ CFM engines:
Ground idle = 67.8dBA
Engines max pwr on-ground w/brakes (71.5%N1) = 73.4dBA
Typical climb profile = 73.4dBA
Cruise FL330 M0.78 = 70.5dBA
Cheers, GY
For now all have access to is for the A320 w/ CFM engines:
Ground idle = 67.8dBA
Engines max pwr on-ground w/brakes (71.5%N1) = 73.4dBA
Typical climb profile = 73.4dBA
Cruise FL330 M0.78 = 70.5dBA
Cheers, GY
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A bit of thread drift, but for those of you concerned about hearing damage the following may be of interest. During my miss spent youth I trained on T6 Harvards, B35 twins, and a whole host of very noisy aircraft. Now back then, few if any used ear protection, I just found them so bloody loud I was one of the few who used plugs and full cover ear phones, recently at an "Old Farts" gathering I noticed I was one of the very few without a hearing aid to cope with low freq hearing loss, I woluld like to tell you I protected my hearing cause I was smarter than most, in fact this was not the case, but Im bloody glad I did, so take heed ,protect your ears at all costs . By the way I do have selective hearing loss, "take out the trash" is one of many things I just dont seem to hear.
Last edited by clunckdriver; 23rd Jul 2010 at 17:12.
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From my own experience The SPLs levels (outbd ear level) on older in service A320a aircraft generally hover between 74-77 (plus or minus 1 or 2 dBa) across different hulls and you can reliably maintain 78-80dBA with the right side vent and pack configurations. That cabin chime goes to 82 dba
