In vehicle audio recording

[Larrie Easterly]

Thanks for the clarification. I realize I will not be getting pristine sound. With the information and ideas you all have suggested I should be able to get what I need. Will be running tests with different microphones and their placement the beginning of December.

[Greg Miller]

Also be sure to record some road noise immediately before and after each take. That will give you noise spectrum samples, in the event that you want to use some spectral noise reduction software.

[Bob Hart]

You might try a Rode NT2a studio mike switched to figure 8 inside of a good shockmount or piece of foam with a hole in it placed on the console between the seats just below image frame edge. Also stuff as much old clothes in rubbish bags and blankets on the floor and rear seats as you can to suck up in-cab reverb and road noise. The sound was not pretty but of sort of worked.

[Greg Miller]

Larrie,

I quickly skimmed through a couple of your videos. I did not hear any objectionable road noise, with the exception of one short stretch that was obviously highway driving. I didn't try to extract the audio from the video, and I don't recall exactly where that was. But the off-road footage IMHO did *not* have objectionable noise. In fact if it had sounded like a quiet studio it would have seemed hokey.

PS: Gawd, that's a rocky road. I would have hated to make that trip in my '71 Land Rover.

[Larrie Easterly]

Thanks Greg.

Yes, I do get to pretty out of the way places.

[Greg Miller]

If you want to give me a link to an existing file (and approximate time within the file) that concerns you, I'd be interested in hearing what sort of issues you've having.

I recorded a really informal test earlier today, but haven't had time to analyze the tracks yet. I'll post a brief report on what I find out.

[Greg Miller]

As promised, here's a brief summary of some non-rigorous testing. The aim of the test was not to evaluate a specific mic, it's to compare pickup of [essentially] the same mic in two different locations.

I used two off-brand lav mics (the kind marketed to amateur videographers), both small diaphragm cardioids, both the same model, but not claiming to be a matched pair. A side-by-side test shows that their performance is similar.

I mounted one mic on the sun visor (in its usual "up" position) sandwiched inside a larger SM-58 size foam windscreen, to isolate the mic from the car's vibration. I clipped the other mic to a headset boom arm (with no other mic attached).

Results:

With gain on both mics the same, the visor mic picked up much more low frequency rumble from engine & exhaust, even with the car stationary. This makes sense when I remember that LF from a loudspeaker is boosted when the cabinet is located on one room boundary (wall or floor), boosted more at the intersection of two boundaries, boosted even more at the intersection of three boundaries. The visor mic mounted roughly an inch from the roof couples more LF from the car, compared to the boom mic which was roughly 10" from the roof.

With gain on both mics the same, and the vehicle in motion, the visor mic picked up at least 10-12 dB more overall noise, sometimes much more than that.

With the engine off and the car stationary, the visor mic (~ 10" from my mouth) picked up my voice ~14dB lower level than the boom mic (~ 1.5" from my mouth). Of course a difference was expected, and this test gives us an approximate numerical amount.

Conclusion:

If I raise gain on the visor mic channel, so the voice level is similar to the boom mic channel, then noise level on the visor mic is ~24 dB or more louder than on the boom mic.

Of course I expected the boom mic to be a better choice, but I didn't expect the difference to be this drastic, so this was a worthwhile experiment. It also opens up some other questions for possible future tests. I hope this is helpful to folks like Larrie who might be planning to record in a moving vehicle.

[David Peterson]

I've shared lots of videos demonstrating car rigs on my YouTube channel:

https://www.youtube.com/c/SoundSpeed...arch?query=car

[Andrew Smith]

Originally Posted by David Peterson

I've shared lots of videos demonstrating car rigs on my YouTube channel

David, mate, it's so good to see you here. Love the videos on your channel when I come across them.

Andrew

PS. Is it true you were a stand-in on LOTR?

[David Peterson]

Originally Posted by Andrew Smith

PS. Is it true you were a stand-in on LOTR?

ha! No.

But I did get rung up by a line producer on Amazon's LotR to be a Production Sound Mixer for them on one of their units. Sadly I could not :-( As I was already busy working on Cowboy Bebop. That's ok though, I could always end up working on them next season instead?

oops

LotR left NZ :-( :-/ No more filming here!