Room Ambience, Laughter, Clapping, etc...
 

When recording audio at a wedding reception, party, or any kind of event for that matter, I need to record room ambience when people are cheering on the person speaking for instance. I don't want to use my on cam mic because I want to try my best to keep room ambience seperate from the person speaking. So I was thinking about using a shotgun mic high on a mic stand, pointing towards the audience, with the low-cut filter on, facing away from the person speaking to capture just ambience. Does anyone use this method with good results?

Thanks,
Eric

Sounds good to me - that's what I do but I don't use the low pass filter as there's no point in doing that.

Jon

I mentioned turning on the low pass filter because some or all shotguns will capture low frequency sounds from the sides so turning on the low pass filter would most likely eliminate it.

That's something best left to post production unless you think it will swamp your desired audio. Like they say, "Better to have it and not need it than to need it and not have it".

-gb-

I guess you have a point there. :)

Why a shotgun? Room ambience is diffuse, sort of coming from all directions at once. I think of shotguns as being more suited to isolating point sources from their surroundings. How about a cardioid positioned somewhere in front of the speaker and pointed away from him toward the room? If you really want to isolate the speaker from the ambience, in post you can invert the phase of the speaker's track and mix it with the ambience track, thus cancelling out any of the speech that has bled over to the ambient mic and leaving only the room sounds themselves.

Does this method actually work?

I theory it would work but in reality it wouldn't and you would get weird phase cancellations. For something to cancel out completely because of the phase being inverted, the two tracks must be exactly the same. Anything other then that and it will sound phasy and hollow.

Can someone tell me exactly what I need to do to get this reverse phase thing working in Premiere Pro 1.5 or Adobe Audition? I can't seem to figure it out.

Thanks,
Eric

Check help in your application for an invert processing option. I'm pretty sure that both Audition and Premiere have it but I don't recall where in the menus you'll find it. I looked at a trial of Audition 2 and it's on the Effects menu. Make a copy of the track you want to invert, select it, and run the invert processing. When you mix the inverted copy back into the original the two should cancel out. In the case of the speech being picked up by the room ambient mic, invert the speech track and mix it into the ambient track. As Bennis pointed out, because of the arrival time differences of the sound at the two mics that have recorded it, you will have to experiment with slipping the inverted speech back and forth to line it up and fiddle with the amount of the signal to inject but with a little trial and error you should be able to reduce the bleed-through of the speech into the ambience to an acceptable level. People viewing the video would expect there to be a little echo of the speech in the room so it shouldn't be necessary to get it to cancel perfectly.