We are about to develop a realistic train simulator so its sound should be realistic (not a game for everybody, for only machinists). We’ll use FMOD library for sound processing. It has lots of capabilities and works fine. But my question is how to collect real sounds. We have opportunities to record on a train but we don’t know how to collect sound in a professional way analyze them. Main sound sources are: • Two train engine sounds in different locations, • 3 different brake system sounds • The environment and rail sounds • Wind whistle • Lots of fans(ventilators) • Warning sounds • Horn • Other trains The first problem is we can’t collect sounds in separate parts. At the same time engine is running and railway sound is heard. So engine and railway sound is overlapped. As I know, to separate sounds, one should make n channel recording where n is the sound source number. In a train there are 5-6 sound sources and that is too costly. After the separation in matlab program, the sound quality decreases. How are you doing sound collection? Secondly, which hardware is used to collect sounds? There are lots of kinds of recorders which differ in quality and price. What do you advice for recorder and recording methods? Another issue is dynamic sounds such as engines. Engines are affected by engine rpm and consumed current (as the velocity increases or). How can we analyze the sound behavior on these effects so that we can integrate with fmod. Also the train is interacting with the environment. There are tunnels, bridges, bends etc. In simulators how do you collect such sounds and bind them to fmod. Thanks

I'm going to move this over to the Music and Sound forum, since those guys will have a better idea of this sort of thing.

I do think you might want to post this in a specialized sound recording forum. Or hire a professional sound recorder. Most recording hardware is extremely expensive, though.

Well this is a tough one! i dont know much about dynamic sound manipulation, but i know alot about recording and editing. the way i would capture would be to use one mic, preferably a condensor that can handle extreme dynamics. you might be able to rent one. i would record each sound from as close as possible, recording a few seconds before or after the desired sound. now for noise removing, i use adobe audition. if you have an alert sound playing over a noisy engine in one file, you can select a part of the file where the alert sound is innaudible, then the software attempts to examine the selected piece and remove that sound from the entire file. it obviously reduces the quality a little, but thats the only way, unless you have full control of the train. i have no idea how you would would manipulate the sounds in realtime, like rpms, speed or tunnel reverberation.

the best way to seperate all these sounds if there is overlap like your talking about would be once recorded to get a spectrogram editor and rip the audio apart that way. can i ask why you are using matlab? for granted its awesome but for editing audio which is essentially what you are trying to do is overkill using a spectrogram editor for example something like the new izotope software (gui friendly) you could analyze the pants off all your rpm shifts and tunnel entries and exits, isolate and seperate the segments and mix them back together from separate wave files.

We can not separate all of the sounds, that are recorded at the same time, with a spectogram editor. Because, their frequencies may be overlapping. In that case how could we seperate them? The only way seems to be useful is the independent component analysis technique. We are planning to use matlab for this reason. With the help of the independent component analysis, we will separate the sounds that are overlapping. After that we can use the other softwares to denoise the sound signals.Further info you can look http://www.cis.hut.fi/projects/ica/fastica/

Sounds like the first thing you're going to have to do, exhaustiveresearcher, is find yourself a train. There are a variety of train enthusiast organizations throughout the US and Canada that run "1:1 scale" railways, buying up old engines and track to build their own circular railways. The only one with which I've dealt personally is the Halton Circular Railway, but I doubt they're what you're looking for since they focus entirely on electric streetcars.

As far as mics and recording, the gear budget can get out of hand pretty quickly, and gear designed for the rigors of field recording can be hard to find. However, the good news is that most film and television production rental houses can get you exactly what you're looking for at reasonable day-rates. If you can't find a rental place near you, give Trew Audio a call. They specialize in location sound, and will probably just ship the gear to you.

Here's a quick list of portable stereo recorders that'd do a bang-up job: Marantz PMD 620, 671, Tascam HD-P2, Fostex FR-2 LE, Zoom H4, and Sound Devices 702. If you can swing the extra money for a multi-channel recorder, take a look at these: Sound Devices 744t (4-tracks, but you really ought to put the SD 442 mixer on the front-end), Sound Devices 788t (8-tracks, just hit the market), Zaxcom Deva (4-track, 6-track, and 8-track models). All the recorder's I've listed are built for over-the-shoulder field recording, and most of them will roll 24-bit 192 kHz *.WAV files. A bit of a caveat: the lower-priced entry-level recorders tend to have fairly low-quality mic preamps, so if you're using one of them you should budget a few extra bucks to put a portable mixer on the front-end (SD mixpre, Shure FP-33, Wendt X3, PSC DVpromix 3).

Mic-wise, you're going to need at least two different mics to cover the wide variety of sounds you need. The best all-around mic for field recording is probably the Sennheiser MKH416. Its a short-shotgun condensor mic (available in both 48V phantom and T-12, more on that later) that's very clean and detailed, yet still built like a tank. Its also exceptionally resistant to RF interference and environmental issues (eg. humidity, dust). They're also the defacto standard for film and television production sound, so any decently stocked production rental house will have a few on hand. Be sure to also rent a zepplin-style shock-mount and windshield (eg. Rycote), or you'll be swamped with handling noise and wind gusting. If you wish to record stereo, just pop an MKH30 into the zepplin and you can record M-S. You may also want to take a look at the MKH418s, which is basically a `416 with a built-in back-electret figure-8 capsule, making it a convenient stereo mic (although I'm not that impressed by the figure-8 capsule they use).

If you're recording an electric train, especially one powered by overhead lines, try to get your mitts on an MKH416t (the "t" means its wired for T-12 power). T-12 is an obscure mic powering system rarely seen outside of old-school film mixers. Its incompatible with Phantom power, although PSC makes a barrel adapter to convert phantom power to T-12. The advantage is that T-12 powered mics are almost impervious to the RF pops and buzzes to which electric trains and street cars are prone.

To round out the kit, you'll need a dynamic mic or two. The `416 has troubles with excessively loud sounds (especially transient-heavy things like the scream of a train's breaks), and is best positioned a couple of feet from a sound source. To get in closer to very loud effects, I prefer an Electrovoice 635a(b), which is an omni dynamic mic popular with radio and TV journalists. The 635's mic-within-a-mic design makes it very resistant to gusting and handling noise, and its hands-down the toughest mic on the market. Bring along an "Ultra Clamp" and a Rycote Softie shockmount, and you can clamp that mic onto just about anything.

Throw in a pair of Remote Audio HN-7506 high-noise headphones, and you're ready to rock.