Have you ever tried this? This is similar to what you are asking about.
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Category: Flight Simulator 2004 - Utilities[/FONT] [FONT=verdana, sans-serif]
Sounds For FS Scenery [/FONT]
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File Description:
This program implements sounds in the FS. There are two sound sets: One for night flying with owls etc and one for day flying with birds. The Sounds are activated by stopping the engine. This program uses FSUIPC and the necessary key is provided by the program. [/FONT]
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Filename:[/FONT] [FONT=verdana, sans-serif]
sounds.zip[/FONT] [FONT=verdana, sans-serif]
License:[/FONT] [FONT=verdana, sans-serif]
Freeware, limited distribution[/FONT] [FONT=verdana, sans-serif]
Added:[/FONT] [FONT=verdana, sans-serif]
1st November 2003[/FONT] [FONT=verdana, sans-serif]
Downloads:[/FONT] [FONT=verdana, sans-serif]
4531[/FONT] [FONT=verdana, sans-serif]
Author:[/FONT] [FONT=verdana, sans-serif]
José Oliveira, Jorge Filipe[/FONT] [FONT=verdana, sans-serif]
Size:[/FONT] [FONT=verdana, sans-serif]
3460kb[/FONT]
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It works by starting the program before you launch Flightsim. Start with engines off. That triggers the program to play a loop of ambient environment. Birds, traffic, over head planes. Total submersion. I actually recorded and mixed together my own set of day/night ambient sounds in very wide stereo.[/FONT] It's awesome to land somewhere and taxi to parking, shutdown and listen to the outdoor sounds, and AI coming in and leaving. It's found at Avsim.