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What are the relative noise levels in various aviation scenarios for observers seated inside an aircraft? I'm sure the specifics depend on model but I'm curious if any general trends can be drawn that are model agnostic.

e.g. Let's consider the following cases for a start:

  1. Jet aircraft e.g. 747
  2. Jet aircraft gliding with all engines out
  3. Helicopter
  4. Glider
  5. Jet aircraft with noise insulation removed
  6. Piston driven prop. aircraft

We could rate on an arbitrary 1 to 100 (noisiest) scale. Even better, in case data is available, I'd love to see the dB values. (@vortaq7's comment below)

I suppose speed will matter so we can probably use their typical cruise conditions for each case?

One motivation is to tease apart contributions from engine vs aerodynamic noise. Another is to quantify the effectiveness of sound insulation.

I suppose most of us never get a chance to really hear an all engines out jet nor to fly in a jet with no sound proofing.

PS. This question was motivated by some comments here:

What are these green "bags" on the SSJ100?

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    $\begingroup$ If reliable sources could be found it would probably be best to rate the aircraft on a standard scale (Sound Pressure Level (SPL) in dB). This will make it easier to compare to other sound measurements people may come across. $\endgroup$ – voretaq7 Feb 12 '16 at 5:32
  • $\begingroup$ @voretaq7. Indeed. Great idea. I will change the question to reflect that. $\endgroup$ – curious_cat Feb 12 '16 at 6:21
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    $\begingroup$ "Jet aircraft gliding with all engines out" would probably be the most noisy cabin. More seriously, it'll depend on the seat location too. $\endgroup$ – mins Feb 12 '16 at 10:44
  • $\begingroup$ @mins Noises of human origin? Let's exclude those. :) $\endgroup$ – curious_cat Feb 12 '16 at 10:46
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    $\begingroup$ Entirely subjectively speaking, as someone who's been in 1, 3, 4, and 6 in your above list, I'd rank them glider < modern commercial aviation jet < your typical GA prop aircraft < helicopter. Helos are bloody loud, really quite uncomfortably so. It's hard to have a conversation in a prop plane, or a helo, without amplification. You can practically whisper in a fibreglass 2-seater glider and be heard by the other pilot. $\endgroup$ – Landak Feb 18 '16 at 22:11
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Let's start with the items for which hard data is easily available: Sound levels

This FAA chart gives relatively average noise levels for passenger jets, GA turbine aircraft, and helicopters. In addition, this chart should start to give an idea of how much noise is generated aerodynamically in aircraft: Sound levels aero

While this is older ground data and not cabin data, it still serves to show that the contribution of aerodynamic noise to total nose levels is not insignificant.

Based on this, I would say that a likely ranking of these environments, from loudest to quietest, is:

1/2: Helicopters and uninsulated jets. In both cases, the close proximity to large, powerful engines leads to extremely high noise levels.

3: General Aviation piston-engined planes. Again, these generally have little insulation,but smaller engines generating somewhat less sound.

4: Passenger jet cabin. Protective insulation reduces sound, but actual noise levels vary based on seat position.

5: Passenger jet cabin, gliding. As seen in the second chart, aerodynamic noise still contributes to a relatively loud environment.

6: Gliders. Slower speeds and cleaner aerodynamic profiles reduce aerodynamic noise, leading to a much quieter ride.

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