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lessening mystery noise

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Ruby Gold
lessening mystery noise
on Aug 14, 2006 at 10:06:26 pm

I usually do my own audio for interviews using wired lavs recorded onto mini-dv tape, but I had a crew shoot an interview for me and they used a wireless lav. The audio on the tape is riddled with a mystery noise while the interview speaks that sounds like the interviewee is breathy, e.g like there's wind on the tape at certain points, and her plosives (p sounds, etc) produce this noise too. I can't understand what created the problem, mic placement seems okay, level too, but... The thing that's strange is that's it's not consistent--not all p-words produce the sound, nor is the breathy/wind sound consistent. Sucks, but I'm stuck with it.

I'm at a loss to try and clean this up so it's not so distracting--have tried the pop-click eliminator and de-noising in Audition 1.5, but no improvment resulted.

I have PPro 1.5 and Audition 1.5. Any suggestions greatly appreciated.
thanks-



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Will Salley
Re: lessening mystery noise
on Aug 15, 2006 at 2:29:00 pm

That could be overmodulation of the wireless. Many budget level systems will have a transmitter side gain adjustment that is designed for a wide range of mic impedances, so it's easy to overdrive the RF link. The level you see on tape (or on camera meters) would not show any unusually high levels. The overmodulation occurs on parts of audio that reveal it most - low and high end. Midrange is more forgiving and, if it's borderline over, would not have the problem. These systems also have suspect compander circuits that could contribute to the "swooshy" effect. The best way to prevent this from occuring again is to wear good, over-the-ear, headphones during th entire take.

You said mic placement seems ok - is it within 12 inches of the mouth? If so, does it have some wind protection (windscreen, rycote, etc.)? Some speakers can produce downward plosives that could hit the mic and produce the results you described. Again, the best way to prevent this from occuring again is to wear good, over-the-ear, headphones during the entire take.

As for fixing the problem, it's probably safe to say that you can't eliminate it, but that type of noise usually occurs at a lower frequency than your average female voice, so try a shelving filter (lo cut) starting around 180hz and go up until you hear improvement. Also try a de-esser. It is used to reduce silibance and may be able to help the "breathy" portions. Most de-essers are available as plug-ins for DAWs.

If you paid the crew, the soundperson should be held responsible. This is one of those businesses where one persons actions, or inaction, can negate the efforts of everyone else on the crew.
I don't know why they were using a wireless - a wired, overhead boom is best - unless frame composition make it impossible.


System Info - G5/Dual 2 - 10.4.7 - QT v7.1.2 - 8GB ram - Radeon 9800Pro - External SATA Raid - Decklink Extreme - Wacom 6x8


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Ruby Gold
Re: lessening mystery noise
on Aug 15, 2006 at 7:53:26 pm

Thanks for your response. Yes, we paid the crew. They set things up and then left an operator who was not very experienced to do the shoot. He had headphones on--told me about the noise he was hearing and we adjusted the mic several times, but, because I was not in control of the shoot and didn't know what was producing the noise (which he said got better over time, but nonetheless is still on the tape in numerous places throughout), I was dependent on him to let me know what was going on. At any rate--I will try the fixes you mentioned. Thanks again for your thoughts.




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Ty Ford
Re: lessening mystery noise
on Aug 16, 2006 at 10:27:12 pm

Tough one. The op told you of the noise. That was their responsibility. That you didn't act on it puts it on you, unfortunately.

It wasn't his/her rig. I get antsy when someone wants me to use THEIR sound gear for this very reason. I also know my gear is better than the average kit.

The noise could be due to many different things, interference, a blackberry on the set, a nearby DTV station, Nextel walkie talkie phones, nose snorts from the person speaking.

It's about communication. At the end of each take, you either ask the sound person or they know to tell you whether orr not the take was good.

An added option is to get a split from the camera headphone jack so you can hear what's going into the camera. It won't tell you if the sound acctually went to tape with most camcorders, but it's as good as you get.

Regards,

Ty Ford



Ty Ford's "Audio Bootcamp Field Guide" was written for video people who want better audio. Find out more at http://www.tyford.com


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