There really isn't a great solution here. Microphones at any distance are going to pick up all sound in the room as they can't differentiate between air conditioner noise and voices. No microphone, even a shotgun, is particularly directional at low frequencies. You must get the microphone as close to the voice as possible in order to maximize the signal (voice) to noise (air conditioner) ratio.

I realize that our instinct as videographers documenting an event is to be as unobtrusive as possible, but being completely unobtrusive at the event can often produce a video with problems that are very obtrusive to the viewer later. In situations like you're describing, I use at least one handheld wireless mic and enlist someone else in the room to either take the microphone to each person that has a question or simply pass it around. There is normally some admin assistant that has to simply be there but otherwise has nothing else to do. They usually jump at the chance to do something, anything. In other instances, I have set up a mic on a stand and people have to get up, stand in line and ask their question from this central location.

I have found that most people actually enjoy being a part of the "television making" process and will gladly do pretty much anything you ask of them.

PZMs work remarkably well however they will pickup everything apart from room tone.
One method I've had some success with is a wireless hand held mic. If you can get the MC on board it can work well with a "If you're not holding the mic you cannot speak" approach. Having a body to pass the mic around really helps. Having a "Mic Nazi" has made a big difference for me but that does mean tying up an extra person. Thankfully for me the event organisers or venue take care of that.

Bob.

Bob and John: I agree; passing the mic would be the ideal. Unfortunately the docs and nurses often want to hold a conversation. Last time I shot one of these sessions the eight people in the room interrupted the speaker and got into an animated discussion about passing a scope up someone's nose! The time before that three experts in the room (besides the speaker) volunteered information to the 30 some physicians in the room.

Trying to organize this lot is a bit like herding cats and I'm afraid Noise Reduction and some nasty audio may be the only "solution." It's not a question of my trying to maintain low visibility but rather a case of not having much control over how the event is set up and run and a desire to give the best product possible.

Thanks, as always, for your suggestions.

Jack

Unobtrusive? Moi? This sounds like a job requiring multiple mikes on separate channels, preferably with at least one boom swinger.

Given what you've just said I'd say this.
You're there to do a job, do not be intimidated. If what you're being paid to do is failing because of what others are doing then make yourself known, loudly if need be.
I've had one presenter turn off ALL the lights in the room and smile at me. Another refused to wear a mic etc. Clients don't want excuses, they want to see and hear what they paid you to deliver.
Get the MC to introduce you, meet with all the participants before the show. Most people think cameras and mics can perform magic so you need to educate them, politely, before the show rolls. If things go pear shaped during the show do whatever it takes to get it on tape e.g. "Ladies and gentleman this sounds like a very valuable discussion that will be of value to others outside this room but I need you to hold those thoughts while I move my camera / mics / lights."

The times I haven't intervened when things went south I ended up loosing the client. Everyone where I have I still have the client.

Bob.

I've used PZMs mounted on clear plastic backboards in other situations but I'm afraid they will just pick up the AC as well.

Maybe ... but it would only be when someone from the audience is speaking. If you, run it into a mixer .. or better yet, run it into a seperate digital recorder .. you can have the clean sound of the MC untouched. Running a seperate recorder "dual system sound" isn't all that hard. Get something good like a Zoom H2 or H4 and it will work just fine. Syncing the audio isn't all that hard.

If you can get a frequency analyzer in the room to find the freqs that the air system puts out .. you can use an EQ in post to knock it down. (you can try that anyway .. but it's easier to know ahead of time what freqs to work with)

Another option, (you didn't say if you've considered this), is to shut off the air contitioning for the duration of the shoot. But that means that the room must have a control .. not likely in big buildings.

Bob: Let me give you the scenario --
11:58 a.m., surgeon comes into the room, fresh out of open heart surgery.
11:59 a.m., wireless mic on surgeon
12:00 a.m., surgeon begins PowerPoint presentation
12:55 p.m., surgeon says "Any questions?"
1:00 p.m., exit surgeon, back to operating room

Under most circumstances, I'd be quick to stop the action, reposition camera and mics, etc. In this situation this isn't possible. Many of these shoots are lunch time information sessions for hospital staff -- 12-1, period. So I've got to come up with a solution that doesn't involve stopping, moving, etc., yet still satisfies the client and, perhaps more importantly, satisfies me.

Brighterside's suggestion, while it doesn't address the AC noise issue directly, is helpful. I've got an H4 and a mini disc recorder that could be used with mics placed around the room. This won't solve the problem, but at least will avoid having to run cables during a very limited set up time. And the suggestion to determine the frequency of the AC seems solid, too, helpful in addressing this in post.

Serena's suggestion of using a boom also has possibilities, although keeping it out of the shot will be difficult.

You've all give me some good ideas. I'll let you know how it works out as I've got a couple of more shoots in the save room coming up next week.

Thanks.

Jack

I know you siad that you tried noise reduction software, but depending on how loud the air conditioner is compared to the voices, with the right settings, the Sony NR2 noise-reduction plugin might work just fine. Choose as long a sample as you can that contains just the air conditioner at a steady volume*, choose "Mode 3" and an FFT size of 1024 or 2048. This will keep the artifacts to a minimum. While it may not be possible to completely eliminate the AC noise, it can probably be reduced by a significant amount. Also, "Izotope RX" may be able to do an even better job.

(* I know Spot suggests a very small sample, but I have always had much better results with as large a sample as possible.)

I might have something for you. if I can find it!

There seems to be a range of new wireless mics intended mostly for video conferencing. I kind of looked and then gave up on them as the receiver units feed to USB however maybe they could solve your problem as they have PZMs that you just put down on a desk, no wires, a 'lapel' mic that you simply put in a pocket, no wires etc. RF comms is spread spectrum 127bit encription for the paranoid CEOs, multichannel receiver.

Now if only I can remember where I found the friggin link in the first place :)
{Edit] Found it:
http://www.revolabs.com/
No idea of price or any technical details but looks interesting.
Bob.

Professionally speaking... If a video contractor, is expected to deliver coherent (keyword: coherent) video and audio, from that situation, while working alone, then somehow the client has developed thoroughly unrealistic expectations of what can be done. IMO, the situation sets the video contractor up to fail.

Actually, Jim, the client's expectations are quite low. They're happy just to have an audible record of the talks. It's I who am dissatisfied and would like to improve the outcome if possible.

I can't do anything to change the shooting conditions -- can't get more time to work with speakers, can't change the venue -- so I'm looking for ways to improve either the acquisition or post. That's about all I have any control over.

Jack

I do think because of the time pressures you need someone looking after audio, although I appreciate that this adds to costs. Since the atmosphere is casual I wouldn't worry about boom-in-shot -- never worries the news guys and people are used to seeing this. Putting each mike on individual recording channels gives you a lot of flexibility in extracting good audio and subtracting unwanted noise. Timecode isn't essential if you record guide audio on the camera mike (the built-in one, even). If placing individual mikes is too time consuming I might consider hanging mikes from the ceiling so they cover the area -- can't say I've done that and it works!

The guys I regularly shoot stage shows for hang an array of tiny mics from the grid. Seems to work well except they've got a pretty big desk!

I'll look into the wireless mics I mentioned above some more.
There's an Australian agent but they're computer not audio people. I really like the idea of having a mic and transmitter all in one unit that could just be popped into a shirt or coat pcket instead of futzing around threading leads down shirts and bras.

Bob.

as an aside.....

i wouldn't worry about the boom in frame - you are doing an eng style shoot...... i mean, how many 'shows' do you see on tv with studio audiences that don't have the boom showing up in shot?

leslie

btw. when i've done this in the past i've hired a friends son / daughter, or someone wanting some experience. for them it can be fun....

Hello Jack,
depending on the budget for this project, I would consider getting a handful of digital recorders - locate them strategically around the room and record six or eight different tracks that can be entered later. . . use a cardioid mic on each recorder facing in the general direction of four or five people. . .
Get them all running before the meeting starts - use a loud clap of sound as a synch marker . . .
_ _ _
Alternately, get a small 6 or 8 input sound board - Mackie - or the like; and a handful of wireless mics ... once again this option depends on the budget...

A rental might also be an alternative until such time as the project begins to make a profit to permit you to invest in a set of your own. . .

Just a few passing thoughts - you're getting sound advice from others... just trying to help you solve the problem - honest...

Also, don't forget to come back and give us your final solution. . .

Until that time. . . Earl J.

Recenty did a series of shoots with 12 people seated at three tables.
Horseshoe affair.
Three camera shoot.
considered two booms, but too obtrusive.
Hired an audio guy who placed three Sanken mics, omni-diredtional little disc mics.
Sorry don't have a model number for you.
Audio guy rides levels.
Put a wireless lav on the presenter, and Bob's your uncle.
Good outcome.
Hope this helps.
If air conditioning noise is a problem process audio with iZetope RX..

Since you have painted a picture of having little control over the room, do what they do at football games . . .
http://shop.ebay.com/?_from=R40&_trksid=p0.m38.l1311&_nkw=parabolic+microphone&_sacat=See-All-Categories

If you have a bunch of mics scattered around a room and have the rental budget check out a Dan Dugan style automixer. Dan achieved some industry fame for providing an auto mixer to the Hollywood Squares TV show. The celebrities were too fast with their wise cracks for even a fast sound person.

Also each time you add an open mic the background noise in the mix goes up 3 db. A good sound guy can ride the faders but not as well as a good auto mixer.

Larry

http://www.dandugan.com/

Again, thanks for the suggestions. I'll keep you all posted on the outcome.

Since there isn't enough money involved to hire a sound person, boom operator, etc., for these quickie shoots, which is what I would normally do, I'll initially probably go with the PZMs I have on hand for small groups and rely on Sony and Audition NR software to clean things up as much as possible. For larger groups I'll try using a boom or even a hand-held mic and see how that works within the dynamics of the groups.

Dan: the mic you refer to is available at It's pricey but looks like a great improvement over most PZMs.

Jack

How about a small parabolic mic, similar to those used at football games from the sidelines (you know...a salad bowl with an inverted mic).

We've used one with great success outdoors, but never indoors. It may be worth a shot!