Flight Simulation Audio

By Aaron Swindle/Skysong Soundworks

I would like to start off by naming some of the people that have pioneered and contributed to simulation audio through the years: Vance Dylan (Sonic Solutions), Mike Hambly (BASF), Christoffer Peterson (TSS), Ted Tufun Wolfgang, Benoit Plamondon and myself.

Let's talk a bit about hearing. For the most part people have a normal measurable base-line of hearing sound. As we age our hearing changes, depending on how much we've been exposed to elongated periods of loud noises; high pitched noise can be especially hard on our inner ear. I myself have suffered from tinnitus for most of my life. Tinnitus comes in many forms--high pitched ringing, cricket noises, low diesel engine rumble sounds, and other odd hearing anomalies. Mine was mostly caused by damge I sustained as an infant from two bouts of meningitis. Tinnitus is a condition caused by damage to the tiny hair cells in the inner ear. Once these cells are damaged the sound is not processed as it should be, and the brain is constantly looking for a signal that is not there. It's like the feedback from a hot amplifier. I wear a hearing aid in my left ear with a built in tone generator, it provides feedback to the brain and eases the symptoms. No matter your age I sincerely caution you to wear ear protection around loud noise; once you incur hearing damage it can not be regained. I include a Sound Warning in all of my sound sets to alert people about protecting their hearing.

Sound Memory

We all have sound memory. When we pick up the phone we know who it is by the sound of the person's voice. Those of us that work on cars, trucks, aircraft, farm equipment, can recognize when an engine is not hitting on all the cylinders. Engine sound has a particular rhythm and lope. We know when a lifter is not properly adjusted, it ticks to let us now it needs attention. The same applies to electric motors, we instinctively know when the brushes are worn or the main shaft bearings have had it. We use our sound memory to intuit and diagnose these type of issues.

What Makes Sound Interesting?

Why does a particular song make it to number one, and others stay farther down on the charts? The content of the lyrics, guitar riffs, the bass line? Yes, it's all of these combined. Music has the ability to evoke emotions, life memories, good feelings in most of us. Aircraft sounds have this same essence. Almost all us aviation enthusiasts know the sound of a Pratt & Whitney radial engine. Nothing else in the world of sound comes close to the rumble of all those cylinders firing in a timed sequence. There are so many recognizable layers as you listen to those enormous aircraft engines. The twill and whispering of the prop tips, the rich bass of the exhaust, the whine of the turbo-chargers, the chest rumbling bass as she flies by at 250 knots. That cacophony of sounds does something to me that I can't quite explain to the people standing around watching with me. To the people reading this article I don't have to try and explain it to you...it's an unspoken shared experience, and you know what I am talking about here.

Flight Simulator Sound Engine Beginnings

I first encountered Microsoft Flight Simulation back in 1986. I went to my brother's house before I deployed in the military. He pulled up a wire frame Flight Simulator that really caught my attention. Somewhere around 1994 I enrolled in a community college here in Virginia, and one day that same old 486 computer showed up Fedex on my door step. Back then it was all Prompt and DOS commands, 12 megs of RAM! Between bouts of studying I would pull up the simulator and fiddle around with it. In a few years a newer version of Flight Simulator hit the market. I immediately noticed a vast improvement in the sound of the aircraft and enviornment. Somehow I found FlightSim.Com and began trading e-mails with Mike Hambly. He was already editing and making improvements to the sounds in the simulator. He told me where to download a freebie sound editor, we were off to the races from there. Mike and I traded tips and sound files for many years.

Making It All Come Together

As far as I can intuit there are three parts to the sound engine in Microsoft Flight Simulator: The Edlin Language (Sound Config) Sound Source (Wav files) and the Base Code that knits these elements together to create the looping audio we hear when we fire up the program. As the simulator evolved the sound configuration became more complex and added more tools to work with. The sound engine now has the ability to produce a morphed (stereo effect) for multi-engine aircraft and other simulation vehicles. Producing sound packages with rich realistic character is not just a matter of slapping a bunch of sound files together and calling it good. Due to the nature of the sound engine you have to learn to create actual work arounds to produce work that is accurate and pleasing to the end user.

The advent of sound cones is a good example of this process. To employ this tool you have to create a volume and sound type differential. As you rotate around the aircraft the sound engine has to be able to read and identify the differential you created with the sound files. It can be a daunting task. Chris of TSS came along and really perfected this with his vast catalogue of jet aircraft sound packages. He has an impeccable ear, and the editing skills to make it all work together in a seamless fashion. Chris did teach this old sound dog some new tricks!

Sound Cards And Polish

There are many different sound cards on the market to choose from. I have always used Sound Blaster. Their cards have a built in amplifier plus crisp accurate sound reproduction. It used to be we sound guys were always fighting with the looping pop issue. It was a fly in the ointment for a very long time. Most of this issue was caused by deep bass sounds that would make a popping sound as they cycled from the beginning of the file to the end. The newer sound cards eventually solved this editing anomaly for us.

Before I release an audio package I spend many hours beta testing it and listening for anything undesireable. Since there are many complex layers in aircraft sounds I check them in multiple situations, views, and at many different volume levels. Once I've done all that I adjust the final release volume to accomodate the average PC sound system. If you do run a Bass Kicker on your sound system you will find that I've left in plenty of wall rattling sound for you. As for sound systems I recommend any of the Logitech surround systems. They generally run less than $75.00 and produce excellent sound.

If you run your simulator for hours on end you might begin to notice some audio degredation is occurring. Even with a high end system this can occur after lenghthy sessions. A system reboot almost always cures this as it replenishes the available memory and system resources.

Closing

Can you make a bunch of money producing audio packages? No! Back when I was working with multiple development groups we sometimes could make some decent profits. Those days have long since passed and a lot of the folks I worked with have closed their development companies. These days the expenses of production actually outpace any profit I might make on the end. We all have jobs, most pay us by the hour. When you buy one of my sound packages you are really just paying an expense for web-space or a new piece of editing software. I spend more on add-on aircraft than I'll ever make back. That is okay by me, I still enjoy what I do and plan to keep producing work for as long as possible.

I hope this article sheds a little light on some murky corners. It's been many years since I've written about my little peice of the FS world. I hope you enjoyed reading it.

Blue Skies To My Fellow Pilots.

And thank you Nels for the space you provide to all of us here at FlightSim.Com.

Sincerely,
Aaron Swindle
Skysong Soundworks

Editor's Note: For nearly twenty years now Aaron has been supplying the flightsim community with improved sounds, as part of larger design teams and on his own, both as freeware and payware.

View Aaron's Freeware Sounds