So basically, I know there are issues on this sort of topic but I think mine may be specific to my computer. 

There is this MD-80 sound pack developed by a guy named Adam Murphy. It sounds great in the videos, and here's the thing. I got it, and for the most part it sounded pretty good until I shut the engines off, changed views and returned to the cockpit. There's this really loud, ugly noise playing and resetting the "Q" key didn't solve it. There was still an annoying noise.

My friend, who has FSX:SE, also downloaded this sound pack. He does not have this problem, which leads me to believe it's something wrong with my system? I'll link you to the video on my YouTube so you can understand exactly what I'm talking about. Skip to about 1:00 minute in the video. 

 

My problem was similar, several years ago now, with a sound set by Emil Serafino.   The sounds themselves were a vast improvement from the default, but I couldn't get rid of what seemed like a residual sound after the engines were shut down.   I even tried turning down the Environment sounds, thinking that it could be a residual sound from a passing aircraft on the tarmac.  So I decided to hunt down the offending .wav file (if indeed that was the problem).

Finally, I nailed it to the "rumble" .wav file.   So I commented out each of those files, don't remove them (and there were quite a few of them on a four-engined aircraft), and that residual awful sound was at last removed.   Of course, I guess those files were probably there for the rumble sound of the wheels rapidly turning while on take off roll, so I lost that sound, which wasn't important for me.

So I don't know whether this description deals with your issue, though it may steer you in a possible cause.   All the best - I know how annoying that can be.

Chris

 

It's okay, I'm not sure if there's a way to close this thread but I found the new files on avsim updated for FSX. Apparently using FS2004 files for FSX isn't a good idea 😕