Audio In A Chopper

22nd February 2005

Hello wise people,

Wondering if anyone has any experience shooting in a helicopter, and if they had any helpful pointers as to getting the cleanest audio. Probably will be shooting on a DSR-570 with a PSC MKII M4 4-channel mixer, Lectrosonic 210 system with Sonotrim lavs, and a Sennheiser 416 on a K-Tek fishpole.

I was watching the latest Survivor and the host was in a helicopter, they got some decent audio and it just got me to wondering how'd they do that.

Thanks for your help.

Jeffrey Bloom
Pie Town Prods.
Director of Technical Operations

>I was watching the latest Survivor and the host was in a helicopter, they >got some decent audio and it just got me to wondering how'd they do >that

Ether tap into the communication rig for iffy sound or do sync later.

Other options : studio rigged helicopter with blue screen and rotors by a silent electric-motor. That's the most probable setup as it is difficult to carry a cameraman and soundman with the actors in the heli.

Robert Rouveroy csc
The Hague, Holland

>Wondering if anyone has any experience shooting in a helicopter, and if >they had any helpful pointers as to getting the cleanest audio

Jeff

My experience shooting in a helicopter was to stick a lav in my ear phone of the headset. it worked pretty well. With the right cabling you should be able to tap directly into the communication system.

All the best,

Michael Sheridan
Sheridan Pictures
Filmmaking and Photography
Boston, MA

Jeffrey Bloom asks:

>I was watching the latest Survivor and the host was in a helicopter, they >got some decent audio and it just got me to wondering how'd they do >that.

I found the best way to get usable audio in a helicopter or small plane is to tape a lav in the earpiece of the flight headsets and your good to go.

Now the audio will sound pretty much like you would hear it if you were wearing the headset but you will in fact hear it and usually pretty well!

Allen S. Facemire
DP/Director
SaltRun Productions,inc.
Atlanta

What kind of Helo? Some are as quiet as airliners, quiet enough inside to hold a normal conversation thus simplifying your problem. Others require headsets and noise cancelling mikes.

Hueys and similar helos with the doors open or off are very loud.

Do you want to record one individual or all of the conversation taking place in the helo?

If the latter, it is fairly simple to plug directly into an open intercom station. If the former, you can still plug in to the intercom and isolate the pilot -- if he has to talk on the radio to Air traffic control, etc.. Most commercial helicopters intercoms have provision for isolating the pilot from the passengers.

Alternatively many pilot shops sell an adaptor to connect a headset to a cassette recorder as kind of "a poor man's cockpit voice recorder."

For higher quality recording, noise cancelling headset mikes are available in different impedances to record directly, without going through the intercom, or you can use an impedance matching transformer.

Brian Heller
IA 600 DP

In my Cessna 182 I have a stereo output (tip. ring, sleeve) on my com system. They should have pretty close to the same thing in the Heli.

Marten Benatar
Rio Media Services
Northern California

I seem to remember this shot as a program opening--ship to ship, with a gyrostabilized video mount. The talent was standing on the port side skid looking directly at camera for dialogue and then the ship banked away.

I'm sure that they were pulling sound from the intercom. It didn't sound any different than standard VOX communications with the door off.

Kent Hughes
DoP
SoCal

Like several of the postings I tape a lav mike in one of the head sets. A spare headset is the easiest. Put the Lav between the two headsets and tape them together. If that isn't available I stick em in the producers ear piece.

Bob Hayes

Anti-phase

2 identical microphones, 1 closer to the mouth than the other.

Mix them together out of phase.

Anything going into both at the same level is much reduced in level.

Old rock and roll technique to reduce feedback.

Works well with any noisy environment.

Cheers

Geoff Boyle FBKS
Director of Photography
EU Based
www.cinematography.net

They use Dave Clark (or similar) noise cancelling headsets and microphones. The mike is right next to the announcer's mouth. (There may be another type of mike that picks up right off the speaker's throat?)

Lew Comenetz
HD Video Engineer

Stereo Adapter

Now use your stereo music headphones in your airplane. An impedance matching device that adapts any eight ohm stereo headphone for use with standard 500-600 ohm aircraft radios. Radio reception is provided to both stereo earphones without degradation in sound quality. No aircraft or headphone rewiring is necessary—just plug in.

Might just make it plug-n-play as it gets the 'goofy' headphone jack that I've found in most helicopters and aircraft down to a normal 1/4 jack. hope it helps...

http://www.sportys.com/acb/showdetl.cfm?DID=19&Product_

ID=1356&CATID=94

Brian Young
Flaca Productions
Miami Beach, FL

Geoff Boyle writes :

>2 identical microphones..........Anything going into both at the same level >is much reduced in level. Old rock and roll technique to reduce >feedback.

Can work well but does have the effect of rolling off the low end of the audio spectrum. Don't know if you can ever get back to "normal' sounding audio in post.

Randy "not a soundman" Miller

Lew Comenetz writes:

>They use Dave Clark (or similar) noise cancelling headsets and >microphones. The mike is right next to the announcer's mouth. (There >may be another type of mike that picks up right off the speaker's throat?)

That would be a throat mike. I know it's available from Motorola as n accessory for Walkie Talkies, but I've not seen one in the Clark listings.

Helicopter intercoms normally use military style single plug (U-174/U). "Y" adaptors are readily available to adapt general aviation headsets to helo, these adaptors split the mic channel from the Audio. The audio channel on GA aircraft uses a standard 1/4" phono plug. Then phono to XLR, or RCA, or Mini or whatever and you're all set.

Brian Heller
IA 600 DP

Randy Miller writes :

[Re: phasing two identical mics to cancel noise]

>Can work well but does have the effect of rolling off the low end of the >audio spectrum. Don't know if you can ever get back to "normal' >sounding audio in post.

Low-frequency rolloff is one of the things you usually want in this sort of situation anyway. In fact, most documentary sound can be improved by chopping the low end to one extent or another.

Normally you want to make just the right trade off between intelligibility and vocal warmth -- mainly by cutting the LOWER bass frequencies. But where your noise is extreme you'll just have to be a bit more ruthless... then maybe chop some of the high end so the result ends up sounding more balanced and less brittle.

Gently boosting the frequencies around 4KHz is another way to make voices pop out of a grungy sonic morass. But you DON'T want to overdo that or you'll get all kinds of ear-splitting distortion when your audio goes back out to analog(ue) and is reproduced on cheap systems.

Dan "lend me your ears" Drasin
Producer/DP/Audiogeek
Marin County, CA