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Old July 13th, 2007, 11:41 PM   #16
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I just threw the file into ProTools and looked a frequency analyzer. It seems to be a modulated signal of 6349 HZ, There is also a steady tone of 16,000 HZ that is in audible. L and R channel are slightly out of phase.

To me it sounds like some sort of Radio Frequency telemetry interference.
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Old July 14th, 2007, 12:05 AM   #17
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sounds like some sort of Radio Frequency telemetry interference.
I like this one. Makes me feel like I'm on board the Enterprise. :)
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Old July 14th, 2007, 12:10 AM   #18
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I just threw the file into ProTools and looked a frequency analyzer. It seems to be a modulated signal of 6349 HZ, There is also a steady tone of 16,000 HZ that is in audible. L and R channel are slightly out of phase.

To me it sounds like some sort of Radio Frequency telemetry interference.
Does that mean the mics picked them up, or that they corrupted the audio in the XLR cables? The latter makes more sense to me, otherwise we should have heard the beeping too.
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Old July 14th, 2007, 12:30 AM   #19
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I wonder if everyone is hearing the same thing in this. I hear two clicks, the first slightly higher in pitch than the other, immediately followed by 'hooop' sound with a slight upward glissando, "cleeek...cliiiik......whooooeeeep, while running faintly under it in the background is a continuous ringing that sounds almost like a burlgar alarm bell ringing far far away.
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Old July 14th, 2007, 12:31 AM   #20
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The noise is below the room tone. I think it is mostly audible due to its high frequency compared to the room tone. So I would not be surprised if a sound guy with headphones did not hear it during the take. The approx 16 khz bump I am seeing might be the horizontal sync frequency from a monitor in the room. If that is the case, the XLR runs are probably picking up some crap.

Or then again, it could be a squeeky office chair :)
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Old July 14th, 2007, 12:39 AM   #21
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We posted at the same time. Emre, how long does the noise last? The sample we are listening to is very short.

Last edited by Glenn Davidson; July 14th, 2007 at 02:15 AM.
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Old July 14th, 2007, 12:45 AM   #22
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Steve,

A while back you gave me some excellent step by step advice on syncing my Tascam to three cameras. The information you provided was detailed and written with patience. It really cleared up a confusing situation. Thanks.

OK...back to the mystery noise...
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Old July 14th, 2007, 06:44 AM   #23
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Spaces are full of noise. Most people never listen.

That sort of noise could be from anything plugged in.

I heard something like it in a conference room at the Dirksen Office building in DC last week. It was a plug in air purifier. I heard it in my cans, twisted the mic boom to find it and took my cans. Instantly it was a lot more obvious.

Also video lighting on dimmers can cause a mechanical vibration in some light fixtures that can sound soundthing like this.

There is good resaon to ask for quiet on the set. It allows the sound person to hear these sorts of sounds and hopefully deal with them.

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Old July 14th, 2007, 09:06 AM   #24
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Hmmm... Sounds like an outside low frequency (traffic) is causing and interior mechanical high frequency rattle.

Sounds like a spoon in an empty glass.
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Old July 14th, 2007, 09:42 AM   #25
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Glenn - you beat me to it! I was going to do the same thing today.

Short pulses of a highly coherent tone (i.e., the 16kHz tone) will sound like a click. Indeed, as the pulse gets shorter, it becomes more like white noise.

Trekkie-wise, it's an example of the Heisenberg Uncertainty Principle. As the duration of the tone gets smaller, the certainty of its frequency becomes less, too. Instead of a beep, you hear a click.

An application for the mythical Heisenberg Compensator Coils, perhaps.
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Old July 14th, 2007, 10:00 AM   #26
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The noise is below the room tone. I think it is mostly audible due to its high frequency compared to the room tone. So I would not be surprised if a sound guy with headphones did not hear it during the take. The approx 16 khz bump I am seeing might be the horizontal sync frequency from a monitor in the room. If that is the case, the XLR runs are probably picking up some crap.
There was a monitor in close proximity in both scenes! It sounded pretty quiet to me :(
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Old July 14th, 2007, 10:01 AM   #27
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If you listen carefully it sounds like the "Ode to Joy" played backwards. Perhaps it's the faint sound of Beethoven decomposing.
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Old July 14th, 2007, 12:37 PM   #28
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Here is a screensot that shows what I think is the video sync at about 16 kHz. I do not think that this is what you are hearing, but it does indicate that your mic line is picking up a signal.

To me the noise still sounds like two modulated tones one around 3000 and one around 6000. In fact you can see them as the smaller blips on the screenshot.

A 6000 Hz tone is pretty directional. If that was in the room I think someone would have noticed it when they got in a 'sweet spot'.
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Old July 14th, 2007, 12:50 PM   #29
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If you listen carefully it sounds like the "Ode to Joy" played backwards. Perhaps it's the faint sound of Beethoven decomposing.
LOL! Upon further review with headphones on...the beeps sound more electronic and seem to move around in the stereo image. Unidentified Flying beeps.

Reminds me of a metal detector.

Not sure if a mixer is being used. It would be better to power the mic from quality mixer than from the camera input.
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Old July 14th, 2007, 03:09 PM   #30
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I just listened to it in headphones and it does sound electronic. I wonder if there might have been something on the tape before you used it? Play a new blank from the same batch. Then record something on the tape. That'll tell you whether the sound is coming from your equipment, or was present on the tape before you started.

If I had to describe the sound I would say it sounds like the capstan roller in the tape mechanism, but how you are getting it recorded to tape I don't know.

I love a good mystery ...

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