Need advice - Projector noise

J

ja_swaer

Member
Hello.

I have recorded a couple services for a newly found church. The venue is a small hall, seats 40 people maybe. This past service we just started to use a projector during the service.

Problem is, the projector's fan is being picked up by the microphone. It does not interfere with the speech or singing, but is very audible. I looked at moving the projector but there isn't really anywhere further away.

I use a noise filter in Audition to take some of it out, but it then introduced a couple of strange artifacts. Most notable, about 3 to 4 times it sounds, just for a second, as if the speech is coming through a can.

Any suggestions ?
 
How are you recording the services? I hope you aren't using the camera onboard mic to record.

Normally folks would take a feed from an available output of the sound console; one of the Aux sends, Matrix, Group outs, or a duplicate of the Masters. We know the hall is small and anything remotely loud is going to be over-exaggerated by the reflections and buildup of soundwaves in the room. With a feed from the console you'll be getting almost every microphone that's being amplified into the room, or not.

Assuming that there aren't any sound reinforcement equipments used during the service, you must move your microphones closer to the desired sound sources or put a microphone in front of everything you're trying to record.
 
Noise removal, such as a fan is pretty tough to do in post. You could create a filter from the fan noise by getting good room tone, but complete elimination of it in post is pretty much an impossibility. Because many times a fan is basically white noise or pink noise. Which is impossible to remove completely, because it has a presence across the entire audio spectrum.

Depending on the room itself, it may be a situation of no matter what mic you use, you will face the problem. The room may be too "live" to be able to avoid it.

So, if this is going to be an ongoing project, you have a couple of options:

Enclose the projector with a "quiet" enclosure (can be built).
or
Live with the sound, filter it as best you can like you have been doing. I am going to ask also......how are you capturing the audio? Feed or on-board camera mic. A feed may be a bit quieter if you are using the on-board mic. or best case......record separate audio. Resync in post. Talk to the pastor about the situation, and make sure he understands that a pause every couple of minutes will help you fix any drift issues. Have material to cut to to get rid of any weird transitions. Like a scripture, or bullet point of the sermon.

As to the artifacts, you may need to be more selective with your filtering. When using a "blanket filter" you need to adjust it so the vocals do not fall within the EQ parameters of the filter. You might get more noise, but it leaves the vocals intact.

Just my .10, as I used to film at my church when I first got in to filming.
 
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Yes, as Doc pointed out, you have to decide which you hate more-- the fan noise or the artifacts on the source material (that come from trying to get rid of the fan noise).

GJ
 
Oh, and also, and this might be hard to do, but gently coach the speakers to use proper mic technique. Pulling off the mic when speaking decreases the signal, and makes it more subject to your filtering.

LOL, it took me 3 months of coaching the ministry at my last church about how much this affects the end result.
 
Hi, sorry left out that bit. I am recording the audio via 2 sound sources. the first is a Sure Mic at the pulpit. The other is an azden omni mic. The second is for the singing etc. They both feed into a behringer mixer that feeds into a zoom h2 recorder. The azden is only used when there is singing etc, the rest of the time it is turned down on the mixer. The pulpit is about 8 feet away from the projector. That mic (the Sure) is picking up the fan noise.

I have been thinking of making a sound barrier, maybe a piece of plywood with foam on the inside and placing it between the projector and mic, just a thought. Or I could try a lav mic, but I don't have a wireless, only a wired lav. The preacher does move around a lot and the Sure has done a good job of picking up the audio.
 
ja_swaer said:
Hi, sorry left out that bit. I am recording the audio via 2 sound sources. the first is a Sure Mic at the pulpit. The other is an azden omni mic. The second is for the singing etc. They both feed into a behringer mixer that feeds into a zoom h2 recorder. The azden is only used when there is singing etc, the rest of the time it is turned down on the mixer. The pulpit is about 8 feet away from the projector. That mic (the Sure) is picking up the fan noise. ...
Click to expand...

You didn't say WHICH Shure mic you have on the pulpit but it sounds like there's a combination of factors at work here. I'll bet that you have an omni mic up there while a cardioid would be a much better choice for this application - you could aim it so the projector is in the low sensitivity back part of the pattern. Then you need to look at the mic distance - if the speaker moves to far away from the mic, more than about 18 inches, his voice won't be much louder than the surrounding background sounds. With him moving around you need to increase the gain on the mic to get a good recording level but that also increases the level of all the other sounds in the room as well. A podium-mounted mic such as the one on your pulpit generally assumes the speaker is going to position his head about a foot from the mic, directly in-line with it, and keeps it there. If he's a dynamic speaker, moving around a lot behind the pulpit or even stepping away from it from time to time, you need to consider alternatives to a fixed podium mic such as wireless on the speaker.

Take a look at the Shure web site - their support library http://www.shure.com/americas/support/downloads/index.htm has a booklet for free download that discusses extensively the considerations involved with audio for Houses of Worship.
 
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