Suggestion - Jet engine sound

[pilot53]

After trying xplane for the first time a few weeks ago one of the shortcomings of P3D/FSX became apparent to me, at high altitude jet engines make very little noise, there should be no jet whine or "buzz", xplane and the ixeg 737 simulate this very well, above a certain altitude the engines are quiet, but in fsx the engines are just as loud during cruise as they are on the ground, although muffled by wind noise.  Im not sure if the capability already exists within fsuipc, but if not a welcome feature would be for fsuipc to have an option to gradually turn down the volume of the engines when flying jet aircraft, as altitude increases.  Does anyone know if anything like this is planned, or already exists?

Edited May 26, 2016 by pilot53

[Pete Dowson]

It wouldn't be an FSUIPC option, but possibly a project for an application. FSUIPC is really a tool to enable applications.

Are you sure none of the more sophisticated add-on aircraft don't get the sounds right? And isn't the main reason they are quieter in cruise because the engines aren't working as hard? It's the climbing which takes most of the fuel, after all. Surely pretty much all aircraft have lower engine noise for lower throttle / thrust settings?

There are some separate add-on sound packages too. Have you investigated those?

If you stopped the FS engine sounds you could have your own played by a Lua plug-in and vary the volume according to altitude. The Lua sound function library implemented in FSUIPC would be capable of doing that, in just a few lines. Of course it would need to take into account thrust settings too.

Pete

 

[pilot53]

I fly with the pmdg 737 and 777, and while the sounds are perfect at low altitude, some of the best I have ever experienced in an fs addon, they are innacurate at high altitude, this is a limitation of the esp platform which does not take air density into consideration with sound, the reason jet engines make that whining and buzzing sound is because of the high density low altitude air, at high altitude the sound is not there.  It doesnt have anything to do with power output, during climb at the higher flight levels engine N1 is sometimes higher than takeoff N1, but the sound is completely different.  The best fix for this would be for the sim to load separate sound files for high altitude, that eliminate the whining and buzzing sound, but keep the "whoosh" if you know what I mean.  For now I think the simplest fix would be for a script or fsuipc itself to be able to adjust the simulators engine sound volume level on the fly, in reference to altitude.  As if you were slowly dragging the engine sound slider closer to 0 as the aircraft climbed.  It doesn't seem like it would be that difficult, but I dont know much about programming.  If anyone can implement such a  feature, besides Lockheed Martin, I would think it would be yourself, or anyone familiar with writing .lua scripts.

 

Edited May 27, 2016 by pilot53

[Pete Dowson]

6 hours ago, pilot53 said:

For now I think the simplest fix would be for a script or fsuipc itself to be able to adjust the simulators engine sound volume level on the fly, in reference to altitude.

To do hat you'd need to either pull down the menus and operate the slider, or hack into the code to see where to change it. If you can do that then I can put in a link so you can program it anyway you wish in Lua or an application. I'm way past my hacking days.

If you use Prepar3D, then whilst it is still under development perhaps this proper way of doing it should be requested as a future enhancenent? The sound files for SimObjects do have different sounds for engines, but they are related to different engine modes not altitude. You would want one of them split into altitude related settings instead. Then it would be part of the SOUND.CFG file to determine when which was used.

For the present the only way I know would be to turn off the sim's engine sounds and play them in an Application like pmSounds (which does have its own engine sounds but at present I don't think related to altitude) or ProsimAudio (which only works with ProSim avionics), or a Lua plug-in -- which you cculd write as well as anyone else, once you have the right sounds recorded.

Pete

 

[alaxus]

I will just add to this conversation as I had the same issue a while ago. What I ended up doing is writing a app that uses a number of inputs from fsuipc and then alters the system volume using the Core Audio Api. The only issue with this is you need another sound source (different pc) for all the other sounds like wind noise etc. Its a bit clunky but on the whole it works, no noticeable engine noise once your above 200Kts.

[ammarmalhas]

So, can u pls share your app?

Does your app lower the engine sounds only or all the "Environment" sounds?

Do we need another PC for a sound source? Can't we use ProsimAudio or PMsound?

[alaxus]

It lowers the system master volume, so that's all volumes in the PC. If you want other sounds you need a second pc with PMSounds or equivalent. I have a full size sim so having a another pc to run sounds is not a problem.

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So, can u pls share your app?

Cant see why not.

Look here:

http://forum.simflight.com/topic/81553-fs-set-volume/

Edited May 28, 2016 by alaxus
Additional info

[ammarmalhas]

8 hours ago, alaxus said:

Cant see why not.

Many thanks. :-)

I will look into it but what I would rather have something that lowers the engine sounds only as what Pilot53 wants. ;-)

[Pete Dowson]

I asks some other folks about this "reduction in engine noise at altitude", and I think that you are not correct about quieter engines at altitude, at least with aircraft we are familiar with.. Here's what I am told. This does accord with what I can recall from the days when I used to be able to ride in the cockpits.

Pete

The user talks about jets like the 738 and in this case the statement is wrong, because a "typical" climb-N1 to FL is usually in the range of 92-96, whereas while cruising at M0.72-77, N1 is usually in the range of 86-89.

Nowadays I'm in the jump-seat in every week or two weeks or so for long time now, and even if I wouldn't know anything about the N1 part, I could easily say that at FL the engine-noise is simply slightly weaker, just because of the N1 difference.

One thing I can tell with confidence, namely that the average noise level in the 737 cockpit is between 74 and 78 db. I have measured that several times, just out of curiosity.

In the cockpit what the pilots hear is mostly the wind-noise which could even be higher due to the higher velocity compared to the climb-phase.

"Scientifically" speaking there's one factor that may play a role in the scenario, that the air is less dense at FL, so theoretically the wind-noise should be a bit less, but I seriously doubt the human ear could figure out that minor difference and the speed difference adds enough to that.

As in FS the jet-whine sounds are designed to be Rpm dependent, anyone could design a sound-set that suits his taste and the jet-whine is much lower at high rpm, but there's no reason for those sounds to be altitude-dependent.

[alaxus]

My sim is a CRJ700 so it has a similar layout to the MD80 with the engines at the back. So above 200kts you barely even hear the engines.

Watch this clip from 6:15. The pilot mentions how quiet it is. (like flying in a glider)

https://www.youtube.com/watch?v=7R0CViDUBFs

 

In FS/P3D however, at cruise, the engines sound like they are right next to my head. :(

 

My understanding is when the aircraft is stationary the sound that comes from the engines travels at M 1.0 .When you are at cruise (M 0.80) the sound is traveling at you at M 0.2 (M1.0 - M 0.8) this is if the engines are behind you. This results in the sound energy being dissipated quicker hence the perceived reduction of engine volume.

Maybe someone who understands fluid mechanics can give us a better explanation.

 

My understanding is that most of the engine noise heard at cruise is engine vibration traveling through the airframe.

 

[Pete Dowson]

2 hours ago, alaxus said:

In FS/P3D however, at cruise, the engines sound like they are right next to my head. :(

Well you certainly need to adjust that. Even during takeoff and climb they'd be a lot quieter from the cockpit. There will be parameters controlling the engine volume levels, maybe in your aircraft's "Sound.CFG"?

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My understanding is when the aircraft is stationary the sound that comes from the engines travels at M 1.0 .When you are at cruise (M 0.80) the sound is traveling at you at M 0.2 (M1.0 - M 0.8) this is if the engines are behind you. This results in the sound energy being dissipated quicker hence the perceived reduction of engine volume.

But the engine sound is so diminished in the cockpit that you'd probably need Superman's hearing to tell the difference, especially over all the wind noise.

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My understanding is that most of the engine noise heard at cruise is engine vibration traveling through the airframe.

That's possibly true, but then your previous paragraphs are rather irrelevant, aren't they? Any way, even with airframe transmitted sounds, I think you'd find that, in the cockpit (not necessarily in the passenger cabin of course) ,the wind noise overshadows all that.

Pete

 

[Lapi]

11 hours ago, alaxus said:

In FS/P3D however, at cruise, the engines sound like they are right next to my head. :(

It is not FS/P3D, it's not the FS sound-engine, it rather means your sound-set is simply badly done...

FS uses a quite refined method for the sound locations, it is directX's DirectSound engine, which defines the "cone" of the sounds 360 degrees around you.
If you are inside that cone and cone angle, it is that defined location & angle within which the sound is at its normal volume (to be found in the sound.cfg file, for each sound).
There are variables, like the ConeHeading, ConePitch, OutsideConeVolume, full_scale_distance, etc. for each sound which determine what you hear - in relation to the source position of the particular sound.

As in FS jet-whine sounds are usually comprised of several lower and higher sounds, it is the designer's task to place them into the right "place" inside the cone, of course depending on where the engines are.

If your sound-set has not been done carefully in this regard, perhaps the best is to study this DirectSound system a bit and modify the properties of your sounds in the cone. Takes some time and has a tiny learning curve, but still easier and better than trying to "solve" a problem by external utilities, which has been readily available for those who designed the sounds for that particular aircraft.
(Or even more obviously to ask the designer of the sound-set to place the sounds at their right places...)

Lapi

Edited May 30, 2016 by Lapi

[alaxus]

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It is not FS/P3D, it's not the FS sound-engine, it rather means your sound-set is simply badly done...

That is most likely the case. I did look into modifying the sounds in the sound set but didn't get very far. The sound set that I use is done by a company that does engine sounds for FS.

Do you have any documentation on altering the sounds? I might give it another go. It will certainly be better than using a external app.

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Any way, even with airframe transmitted sounds, I think you'd find that, in the cockpit (not necessarily in the passenger cabin of course) ,the wind noise overshadows all that.

Most of the flights I have done in the cockpit there does not seem to be much wind noise, at least to me. However a lot of noise can come from the windows not being sealed properly which creates a pressurization leak. Worst case you get a annoying loud whistling noise in the cockpit.

Cheers

[Lapi]

22 hours ago, alaxus said:

Do you have any documentation on altering the sounds? I might give it another go. It will certainly be better than using a external app.

The FSX/P3D SDKs give a brief description of the parameters. Unfortunately I have no knowledge of any utility which could really help you in that. There's a nice little payware prg named FSSound Studio, but it's a bit old and although good for putting together and combining sounds, the DS positioning part was not done for it.
Once you understand the DirectSound concept, it is probably easy to modify the sound locations, as most commercial packs use 5-7 stereo sounds altogether for jet-whine, so you can modify the parameters by hand and it's not a complicated matter at all.
(In case you did a good left channel positioning for the sounds, for the right one you simply need to define diametrically opposing values.)

Edit: I do hope you were not serious when did the " windows not being sealed properly which creates a pressurization leak" comment...

Lapi

Edited May 31, 2016 by Lapi

[alaxus]

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Edit: I do hope you were not serious when did the " windows not being sealed properly which creates a pressurization leak" comment...

Its common for cockpit windows. Passenger windows are installed differently, however they are all checked with a pressurization run. Pump the plane up on the ground and check the windows for any whistling noises.

Here is what happens when a run goes bad : http://discity.com/kc135/

 

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FSSound Studio

I had a look at that previously and noted that it seemed to only support stereo sound and not positional sound ie DS.

I will have another re-read of the SDK again and see what I can come up with.

Cheers