I am not sure if this is 100% specific to PMDG, but so far I have only noticed it with the PMDG 747 and also the 737NG - all in FS9. So am posting here.I quite often get a kind of musical rising and falling note, like a low, slow sine wave, along with the engine sounds (can be spot or cockpit view). I thought it was the fault of the sound files themselves, but I notice on my FS PC (which is flying a 737-900 as I write this on my laptop) that the sine wave sound has just stopped (even though the a/c hasn't changed mode - on cruise all the time).Does anyone else get this (or even know what I am talking about!)? It's not a PC-specific thing, as I had it on my old FS rig, and get the same on the new one (with totally different hardware & O/S).Thanks,Martin

I think I know exactly what you're talking about but I've never been able to describe it in words. But I hear it in FSX and its worst with the Flight1 Mustang so I don't think I can be of much help.

You could make a video and post it here for PMDG to hear exactly what you're talking about.

Most of the time, the sine wave is associated with a relative difference in the power settings between the engines. It's why you have prop sync on prop aircraft, otherwise it would drive you up the wall. I'll try to find an example and post it later.Under what conditions are you flying? AP on/off? AT on/off?

What you're likely hearing is actually called "phasing" - it's a common problem in audio production when you have multiple versions of the same sound playing back simultaneously. FS9 is much worse with it than FSX is (using FS9 soundsets in FSX causes a bad phasing effect too - LDS767 for example)The technical explanation is that the waveforms are overlapping and cancelling or reinforcing each other, depending on where in the cycle it is.

What you're likely hearing is actually called "phasing" - it's a common problem in audio production when you have multiple versions of the same sound playing back simultaneously. FS9 is much worse with it than FSX is (using FS9 soundsets in FSX causes a bad phasing effect too - LDS767 for example)The technical explanation is that the waveforms are overlapping and cancelling or reinforcing each other, depending on where in the cycle it is.

It's really odd. There are several videos on YouTube showing default FSX aircraft where the audio "phases"... Whereas I've never experienced that problem. I've also googled this problem and there is no apparent solution..

Yep, I have the same phasing sound here too, depending on the plane..... it always has reminded me of the beginning of The Cars "Moving in Stereo".:)Chris Bremmer

I get it on certain aircraft, it really annoys me but I can't do anything about it. I notice it happens mostly when I cange from an interior to exterior view, at least on my Feelthere airbus. I'm thankful I've never had this phenomenon occur in a PMDG bird.

Sometimes you can cancel it by turning the sound off and then on (with Q key on your keyboard).Lmaire

Hi, thanks for the replies.Yes, phasing, exactly the term I should have used. Is it right/normal then that I have "multiple versions of the same sound playing back simultaneously"? The problem is a little annoying to get this sine wave tone (sounds so 'unrealistic'), though hardly the worst thing that could happen in FS, I'd be the first to admit! For the 747, I selected all a/c to use GE sounds, as I find this doesn't produce the phasing, whereas RR an PW do.. Getting it in the 737NG is new (and I have had those a/c since they were issued) - perhaps something to do with my change of PC.I can try turning sound on and off to see if that stops it for the duration.Martin

I had the same problem with the LD-767 engines giving a 'flanging' effect.This was solved under xp32 by dropping the directx sound slider a notch. Under Win7-64 I have not encountered the issue.