Some questions about car pass by techniques

Question

Hi there! I'm moving my first steps into sfx recording and I have some questions about car pass by recording techniques.

I saw in many videos people pointing their pistol grips at car arriving (let's say left) and then following it with the mic to the right, doing a fast movement with the arm.

• Now, if they're using a stereo mic to capture that pass by, why they need to move the mic? I wouldn't sound better with the mic still pointing at the centre of the road (between left and right)?

• If they're using a mono mic it would make sense moving it following the source of the sound, but why recording a car pass by in mono? Maybe to automatize the pan in post and make recording fit with various footage?

• Last question: recording a car pass by using a stereo recorder with no XY position, but just with the two mics pointing one left and one right (like olympus LS-100), would cause some spatial listening isssue?

Thanks for answering ;)

Answer 1

Moving the mic vs. holding it steady also changes the perceived speed/intensity of the car by. If you pan with the car you get a longer and less extreme by; holding the mic steady gives you more of a zip by, especially at higher speeds. For really extreme zip bys you can even move the mic in the opposite direction right when the car passes you.

Answer 2

Hi, the recordists would have been using a mono microphone following the source of the sound as I would do with most passes of vehicles or aircraft. The Olympus you mention as far as I know from my LS11 essentially is an xy position mic placement and whilst fine for quick recordings on the go, the built in mics are not really of a great quality if you are planning to record sfx for a library.

Answer 3

Now, if they're using a stereo mic to capture that pass by, why they need to move the mic? I wouldn't sound better with the mic still pointing at the centre of the road (between left and right)?

Perhaps, unless one would be capturing the sound as it would be captured with a mono microphone, but wants added liveliness/naturalness to the recording by using a stereo microphone or perhaps a Mid-Side configuration. Mono tends to sound too dead on many sources.

If they're using a mono mic it would make sense moving it following the source of the sound, but why recording a car pass by in mono? Maybe to automatize the pan in post and make recording fit with various footage?

Yes.

Last question: recording a car pass by using a stereo recorder with no XY position, but just with the two mics pointing one left and one right (like olympus LS-100), would cause some spatial listening isssue?

Not necessarily, but the spacing of the microphones in pocket recorders is so small that it's impossible to get a good stereo image.

Answer 4

I think a mono car pass, following the source, makes for a better editing material later. Not only can you pan it any way you like,but you also have more "full" sound to take away from, when attenuating for distance and movement. If it needs a bit of extra "speed" and doppler effect, stereo material will already have much more of the dynamics "baked in" .

Some issues with stereo mics are not apparent until you actually grab the mic and try to record broadband sound sources such as car passbys, water/waves, etc. There's complex filtering (mics are not ears), and the difference in the capsules' angles on a stereo recording makes that more apparent.

Vehicle passbys may need compression and that brings out noise, be it system or ambient. Hence the directional microphones, hence the need to follow..