Mic for noisey environments

Get any mic you like and put a long tube over it! Now you want to sound proof the tube with either rock-wool or cotton wool and put another tube around that for good measure! The more sound proofing the better, Don't forget behind the mic! Leave the other end open! Now you have a gun mic! Remember the more soundproofing the better! Go to the track and point with conviction! Use big, bold, brightly coloured electrical tape to add to the effect and not only will you be recording the sound of the cars but you will be catching the attention of all the promo girls who want to know what the large multicoloured truncheon is for!!

Google noise cancelling mics*...there are zillions of ceap mic inserts from the far east.
I can't specifically remember which are mest for noise cancelling it was a loooong time ago I worked in that field.

* Not to be confused with active noise reduction systems in headsets.... The mics themselves are pick up from front and rear ports and are effectively noise cancelling.

Del

I don't know race car ( I see it race only on TV screen) but in news gathering, reporter usually use super-directional mic which like a gun with a proof wind shield outside. you can take a try.

its about 30 --80cm length.

other method, you can use two mic together which pick up noise in opposite phase and can be cancelled each other, and remain useful sound.

sometimes we use this method for our test.

Thanks CN Power!

I've only used omni directional as I want to pick up voice before the car goes on track, and then engine sound on the track.

I could not find a mic with AGC - that's probably what I need given the range of SPW's

Cheers, Angus

you can use two mic together which pick up noise in opposite phase and can be cancelled each other.

This is unecessary... some mic inserts already have a port at the front and rear so 'ambient' sound is cancelled....

Don't s'pose anyone is bothering to actually read my posts today.

Don't worry Del, we love ya really!

It is actually termed off-axis rejection, what is often referred to as noise cancelling.

www.sweetwater.com they will have what you need and advice too.

wow, chankley, you must work in some studio. you are so familiar with mic type.

I thinka bidirectional mic at least will do better than omni one does at the moment. dynamic tyupe is a good idea which has lower sensitivity then condensors'. super directional is best bet. as the engine is large volume at sound, so one side keep a long distance or use some shield material on it to reduce sound pressure.

most of such material will absorb high frequency strongly, but the sound of engine will concentrate at low frequency power part. Taking acount of Doppler effect in the site of race, you can still use them.

I know this neumann component. they produce very good mic for studio, in fact almost studio in the world now use them indoor. they are famous with their MOSFETs condenser mic series.

colored effect is mostly depend on room condition, especially in not good normal vibration room. and more regular shape room. strong lower frequency audio absorb may cancel the situation.

recordist like to use different mic for their recording, this is out of my depth.

You can use the suggested microphone-in-a-tube. These are called "gun microphones" or "rifle microphones". These days, however, I wouldn't advise possessing one of these as you may be mistaken for a sniper!

If you're not too far from the track, you can try using a flashlight or torch.

Yes, that's right. Get one of those torches that have a large reflector. In place of the bulb, you put a small condenser microphone. You may have to adjust the position of the mic to get it into the sweet spot but once you get it, you won't need to adjust further.

Note that the quality might not be very good because of the small reflector. If you want better quality, try to look for a parabolic dish, an 18" to 24" will work fine. Maybe an old satellite dish may be lying around just waiting for you to pick it up.

If you can get a plastic/transparent parabolic dish, that would be better since you can aim through the dish, making accurate long-range pick up easier.

The mic's will be used in race cars, not on track side.

Need voice when stationary and engine when moving (did I say that already?!). Recording on a video data logger

Possible solution looks like: Omni direction amplified mic element from Knowles, designed for extreme conditions (temp, shock , vibration) - along with the "dead kitten" wind screen from Rode (through sweetwater) (no relation to the drowned cat in the pic above - sorry Cat!)

I made up a proto this a.m. and it sounds nice, even hanging out of the window of me Jeep! Will try it on race cars very soon, and then build a board batch in volume. Let me know if you want one!

Cheers for all the answers and info - I learned from you guys!

Er, no, you didn't say, exactly, how you wanted to use it. I assumed (and it seems everyone as well) that it would be used on the track side.

Recording voice and engine sounds requires two mics (unless the driver just makes engine sounds with his lips ).

One mic will be in his helmet where most of the outside noise will be attenuated by the helmet's padding and you can use a lower gain setting due to the close proximity to the driver's mouth. That ensures that outside noise will not be picked up or will be at such a low level that it won't matter very much.

The other mic can be in the engine compartment. Here, the sound level from the engine means that you can also lower the mic's gain such that outside noise will not be an issue.

It's so easy. The type of mic is not that important because the sound you want to record is so much louder than any "enviromental" noise. Athough I would suggest a very directional type. You should avoid a omnidirectional mic, because it will also record the sounds in wich you are not interested. (omni-directional = from ALL directions).

Then I suggest to record with a device that does NOT use AVR (Automatic Volume Control) because it will automaticly amplify the envirement noises when there are no cars passing. Make sure that the recordings NEVER go in the red (overload)

So : a simple directional mic, and a recorder without AVR are the things you need.

Do not just start recording when the car is passing, but start recording when there's no cars in sight, so that you'll have a nice part of only enviromental noise.

Later you feed the recording into a computer that runs e.g. Cool Edit Pro or any other "serious" music/sound program. In most of these programs there is a noise reduction feature. How does this work ? You take a "sample" of the noise (the part that has NO car sounds) and the program will substract this noise sample from your whole recording. You will have to experiment with the amount of reduction and the other parameters of the noise reduction, but I guarantee that you will be able to "fish out" a nice sound of your race car.

Easy, huh ?

Here's one I designed earlier (well my design team really)...note noise cancelling electret mic.

Del

Surely you had a paw in too...

Hi, Cat, you are not simple to design a mic!

I always think that deigning mic or speaker is an arduous journey! so much math formulas to deal with. only a film vibration equation will make your head spinning. initial condition, boundary condition etc. my god.

you must know much acoustics. I like to discuss and will learn from you later.

I didn't design the acoustics...we had an old guy with loads of experience in a little lab with a propper 'dummy head' set up and he did it mostly by experience and experimentation.
I was 'Chief Designer' at the time, I generally just let 'em get on with it as they were a good team...
I'd throw in the odd suggestion and brainstorm with them, offer encouragement or honest criticism if necessary...we had some problems with 'snap fits' on the plastic housing as I recall, but I expect most snap fits need some tweaking.
Of course things change...and the 'good team' only lasted a few years.
Then we went our separate ways.... still bump into 'em now and again, and play golf with one of the guys (maybe I should use a club_{?....<bad English joke>} )
Del

acoustics is mostly an experience subject in practice. English and Germany are good at it.

can you explain me what is " snap fits"?

---maybe I should use a club_{?....<bad English joke>} )

what is its meaning? why is bad joke? I'm curious
(hope learn more joke.

Snap fit... two plastic components which are assembled together without any aditional fixings, one part has small protrusions which 'snap' or 'click' into slots or recesses in the other part thus fixing the two together.

'I play golf with one of the guys'... it is slightly ambigous...I also play golf with clubs and a ball...I am deliiberately confusing to two...implying that I may be using one of the guys to strike the ball rather than using a club....
Just a bit of silliness.

Del

oh, now I see what is smap fit.

thanks Del.