Field Report: Diesel Train Sound Effects with Microphone Comparison

2011/07/26

Courtesy of Buddahbless

Train Sound Effects

Train sound effects are one of my favorite field recordings to capture. Whether they are subway sounds, monorail sound clips, trams or streetcars, high-speed trains or electric train sound effects, I find that trains or “rolling stock” offer endless different sounds to record.

Similar to construction vehicles (like the drilling rig sound effects I posted), trains are mechanically specialized and incredibly complex. This means that they have potential for unique and interesting sound effects.

Some things I like to think about when field recording trains are:

  • power source – electric, steam or diesel
  • rail type – age of track, location of track (turned, straight, bridge, tunnel, etc.)
  • cargo – passenger cars, freight or solo engine
  • motion – speed, static position or direction

From my travels around the globe, I’ve noticed that recording trains are a great way to evoke a country’s character.

Spain, for example, uses four types of rail gauge different from the rest of Europe. In most cases this means passengers traveling from France to Spain must disembark and reboard, meaning different trains and distinct sounds.

Futuristic high-speed trains, sleeper trains and commuter trains all have individual voices. Recording these sound effects well will bring out characteristics of the type of train itself and evoke the country and spirit of where the train was recorded.

I’d love to record the bullet trains in Japan, but for now I may have to be satisfied with recording North America’s only high-speed line: Amtrak’s Acela Express trains. Both are on my field recording wish list.

Background

I was visiting a small town in Ontario a few weeks ago. I happened to be passing by the local train station with my recording gear on my shoulder. A diesel train was idling on the tracks for an unusually long time. Typically the trains stop only briefly in smaller towns before rushing away to larger cities. The train was obviously delayed.

In Canada, our federal government manages our train lines. This “Crown Corporation,” Via Rail, primarily uses General Electric diesel engines. The train idling on the track was a GE Genesis P42DC diesel engine pulling 5 or 6 passenger cars.

This train has 4,250 horsepower and a top speed of 110 mph (177 kph). Besides being used in Canada’s Québec City-Windsor rail corridor, it’s also used for Amtrak’s long-haul and high-speed service.

I approached and noticed that the environment was surprisingly good. I couldn’t hear birds, cicadas or traffic. This had potential to be a very clean recording.

The shoot

The train could depart at any time. I knew I had only seconds to start recording.

It’s easy in these situations to become excited at a golden opportunity. It’s important to remain calm. Becoming panicked, or rushing things can mean you’ll overlook a critical aspect of setting up gear or a problem with the environment that has to be accommodated.

I calmly set up the gear and punched in with two recorders. Rushing things would only make recording worse. A quick but botched set up wouldn’t be worth the poor sound effects I would capture by not taking time.

Other challenges:

  • accurately predicting the increase in engine noise when the train departs and setting levels appropriately
  • staying a safe distance from the track
  • not being disturbed by security
  • setting up equipment with limited time
  • isolating the microphones to minimize extraneous sounds such as traffic, birds, insects and curious people

Results

I ended up having more time than I thought. I managed to capture long section of the idle with various air releases before the train departed. The sound clips below are a portion of what I recorded and the most eventful part. A bell rings as the train departs slowly to the right. This is followed by the passenger cars scraping and squealing lightly on the metal rails.

The the samples were edited in sync. The first sample is from the H4n recorder. The next is the Neumann 191 microphone, powered by Sound Devices’ MixPre and the 722 recorder.

I placed the microphones at the same location. The H4n is recording at a 120° pattern. The Neumann is recording at a 100° pattern.

For reference purposes I haven’t equalized, processed or no-noised the recordings.

H4n:

Neumann RSM 191-i:

I found it interesting to compare the microphones. It may be unfair to compare microphones with such a difference in quality and price. I did find it makes me appreciate the expensive Neumann microphone, and reminds me of the limitations of the cheaper, but more portable, H4n.

Here are some diferences I noticed:

  • the Neumann sounds wider, and has more depth despite the pattern being narrower. The H4n is flatter, like a wall of sound
  • the Neumann captures more high-end, and a breathy aspect of the engine
  • while the ringing bell seems buried within the idle of the H4n recording, it seems to jump out a bit more in the Neumann recording. Additionally, the bell is placed slightly to the right in the Neumann recording
  • the Neumann seems to bring out more of the metallic aspect of the rail scrapes, as well as tighter low-end thumps as the cars pass over seams in the rails
  • the Neumann recording generally sounds more powerful
  • the Neumann appears to have more “soundstage” or available stereo imaging

Find more diesel train sound effects at my website airbornesound.com. Here are some more quick links to train sound effects on airbornesound.com:

  • general train sound effects
  • steam train sound effects
  • monorail train sound effects
  • streetcar, trolley or tram sound clips
  • some electric train sounds, recorded in South Africa
  • subway, Metro or underground train sound effects, recorded in various places around the world

Some thoughts

One of the tricky things about recording trains is the significant difference in level between the engine passing and the cars passing.

The engine with its heavy and oppressive motor will carry most of the power as well as the sensation of movement. It is incredibly loud, especially when passing at high speed.

The passing cars make little noise themselves, which makes them very valuable for capturing rail screeching sound effects.

Normally the rail sounds are buried beneath the power of the engine. However, freight trains can have endless lines of cars. After the engine has passed into the distance, you’ll have the opportunity to capture isolated metal screeches, grinds and groans without the diesel engine interfering.

Since the dynamic between these two sounds is significant, you’ll have to make a choice:

  • ride the gain after the engine has passed to capture the quieter cars at an optimum level
  • establish a fixed gain for either the engine or cars
  • record with two microphones, one set with the level attenuated for the engine, the other for the rails

Let me know in the comments below which technique you prefer.

Notes

Equipment used:

  • Neumann RSM-191i with Sound Devices MixPre and 722
  • Zoom H4n




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10 responses to Field Report: Diesel Train Sound Effects with Microphone Comparison

  1. It’s interesting that the engine sound (pitch or volume) doesn’t change as the train starts moving. It just idles away.

    • Do you sense that on both recordings?

      In the Neumann recording in particular, I can sense a shift as the engine passes to the right at around 0:51, then transitions as the engine fades and is replaced by the rails.

      Listen for the engine’s bell. It follows the engine departing to the right.

      Let me know what you think.

      • I clearly hear the engine moving, shifting from left to right with the diesel sound fading. What I don’t hear is the speed of the diesel engine (RPMs) changing. Nor do I hear the exhaust note changing as if the diesel engine is taking up the strain of moving the train.

        It is like the sound of an automobile with an automatic transmission moving away if the driver simply removes his foot from the brake without pressing on the accelerator. The engine simply continues to idle.

        There is nothing wrong with the recording, it is just how short trains work. A long freight train would require that the engineer advance the throttle to accelerate from a start. Long freights also have the sound of the couplers as slack is taken up.

        I’m often surprised at how badly TV and movie sound of things like helicopters (especially helicopters) and airplanes matches real life. As a helicopter lands the pilot adds power so the engine becomes louder and the sounds of the rotor blades (both main and tail) also get louder. The speed of blade rotation (RPMs) doesn’t change. However in TV and many movies the sound that normally comes after touching down (reduced engine volume, reduced engine speed) is heard as the helicopter approaches the ground.

        I’ve seen turbine airplanes with piston engine sounds.

        • Ah, I understand what you’re saying now, and that makes perfect sense! And you are exactly right about the sound. Now that you mention it, it is peculiar that the RPM of the engine remains constant.

          It is fascinating to read what you mention about the differences between short trains, freight trains, and the coupler moves.

          Excellent points about the detail needed to portray these machines accurately, and the breath of character and sound effects possible in these types of recordings.

          • A final comment. When a long freight train starts, it first backs enough to compress all the couplers. Then it starts moving forward. This way it starts moving one car at a time. The first car moves, takes up the slack to the next and so on until the whole thing is moving. Once you’re aware of this it is interesting to hear.

            A few years ago I took an Amtrak from Cleveland, Ohio to Seattle, WA. In the sort of half sleep that you get sitting up on a train at night I was aware of the horn blowing at each and every grade crossing. A distant but distinct sound — a detail any good movie sound designer would work into his product.

            • Thanks, Speed.

              Your comment is a good example how complex and varied the sounds from these machines can be. Your description in particular is evocative. Including details like the ones you mentioned I think have great potential to drive home a strong emotional impact through sound design.

          • ObscureRobot 2011/08/04 at 01:04

            Diesel trains don’t directly drive their wheels. The diesel engines (turbines?) drive generators, which drive electric motors. The electric motors drive the wheels. So it makes sense that a low power start does not require a change in RPMs.

            • @obscurerobot I had no idea that was how the diesel engines worked. But it definitely explains @speed’s observations about the RPMs. Thanks for the info.

              It occurs to me that field recordists can benefit from a good general knowledge about machinery and physics to inform their recordings. Having a deeper knowledge about what you record, like you point out, will make the recordings richer, more detailed and, in my opinion, therefore more evocative and powerful.

              I wrote a bit about this in an earlier post about investing yourself in your recordings.

  2. SonicFields 2011/07/27 at 18:16

    Hi Paul, an interesting post and pleased to hear that I’m not alone in trying to determine the best method of recording moving locomotives with rolling stock. I believe the method depends on the type of sound required, whether it be the detailed sound of locomotive, rolling stock and track or merely the general ambient sound of the passing train. The general ambient recording is of course the easiest to achieve by setting up at quite a distance from the track (100m or more) with suitable recording levels set and just hope the driver does not operate the air horns or steam whistle when its nearby, as that can seriously clip the recording from more than 500m away. With this method the recording will not contain the detailed squeaks, clanks, clonks etc of track ambience, but a less dynamic, more smoother stereo transition of the passing train.
    These recordings can sound good, but they lack that dynamic explosion experienced when standing trackside to a passing locomotive. This is the difficult one to record, as one minute the gain levels need to be set to record track ambience (approx 35dB) as the train approaches in the distance, complete with metallic twanging sounds from the rails and other natural ambience present; then in a short space of time there is an explosion of sound (depending on the locomotive type and power, horn operation etc. up to approx. 125dB)as the locomotive passes, then back down to approx. 35dB as it disappears into the distance. You quite rightly indicated the need to ride the gain controls to be able to capture this type of recording without excessive clipping, this is the method I prefer. Personally I do not support the use of multi-channel mixing with lots of post-processing to achieve the desired result – I try where possible to capture the actual raw recording with minimal post-processing.
    This leads me on to Speed’s comment about poor TV and movie audio – which is one of my pet hates, especially where it concerns documentary films. It may be due to the fact that there appears to be a rash of videographers currently swanning around the world capturing anything that moves, with automatic point and shoot HD digital video cameras. Unfortunately many have a complete lack of understanding when it comes to audio recording. This results in farming out the audio to foley companies who basically search their sound archives for suitable sound clips to dub onto the video. We then end up with films and documentaries having sound which bears little or no relation to the video captured. My arguement is that viewers are being conned into believing they are watching and listening to factual documentaries, when often they are not – I rest my case!

    • Thank you for the vivid description of recording locomotives at various distances.

      The range of sounds you describe are exactly why I enjoy recording trains, construction vehicles and other complex machinery. They have endless vocabularies. I find it incredibly satisfying if I can capture their various inflections and character in the recordings.

      I also agree with you and Speed. I prefer realism over loosely-fitting TV and movie audio, not just for the accuracy, but I also believe when sound is represented properly and accurately, the viewer experiences the film more deeply.

      It is also important to me because I feel the sounds have the capacity, when fully realized, to create an evocative experience in the listener.