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Old January 4th, 2009, 03:28 PM   #1
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Identifying Frequency in S/F9

I am trying to notch out an annoying whistle on S's from a PA mic feed. As the bandwidth up here is pretty narrow, it is difficult to find the exact frequency by listening and then varying the notch filter. However, it is so pronounced that I can easily identify the offending waveform, so all I need to do is measure this frequency and put in the notch.

The help menu in S/F does not show anything.

Any suggestions please ?

RonC.
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Old January 4th, 2009, 04:02 PM   #2
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Start with a standard eq filter wide, then sweep freq while narrowing the Q. That said, if you mean you can we it in spectral view just lasso it and fade or delete it. At least in audition you can and flits pretty easy
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Old January 4th, 2009, 05:45 PM   #3
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You could also consider a multi-band compressor. No effect on audio when amplitude is below threshold. Set it up sort of like a parametric with notched bandwidth and experiment to find best ratio for transparency.
However if this is feedback, you would be better off with a parmetric EQ.
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Old January 4th, 2009, 06:15 PM   #4
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Thanks Steve & Rick.

No, the effect is not feedback, and I am using the parametric Eq. I think it's a peak in the mic's response being excited by this person's voice, almost a pure whistle ! It's quite easy to see in the waveform, so that's why I would like to identify its fo. and notch it out with a very narrow notch to minimize the overall effect. I am quite used to doing this sort of thing. Identifying HF down to a few hertz. is not easy so I thought in S/F with all its tools & gizmos it would be a breeze. I know Audition is good but I don't have it.

RonC.
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Old January 4th, 2009, 06:58 PM   #5
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What you are looking for is a 'de-esser.' In a recording studio, you used to have a dozen of 'em in a rack. Dunno what other software you have but check your audio filters and plugins for it. I'm sure they are available for download...

Otherwise, try this: don't start with cutting the frequency--boost it. Make it really obvious and then turn it around. Also, make a loop of an offending section and work on that rather than wait for the bursts of it in the whole recording.
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Old January 4th, 2009, 08:07 PM   #6
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Thanks Andy. Yes I know about de-essers & I have fixed that, but this is worse than that ! It is whistle at a particular frequency!
She generates it with her "S" sound but only sometimes but the frequency is quite definite & stable, but for a fraction of a second, so hence my wanting to identify it & simply apply a sharp notch.

In my electronics business I have designed very sharp analogue filters and they are extremely effective with virtually no effect on the overall audio.

RonC.
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Old January 5th, 2009, 01:50 AM   #7
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Take a look at Spectrum Analysis in the SF help topics. Opening the spectrum analysis window and examining a sonogram of the area around the offending sound should identify the frequency you need to equalize out.
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Old January 5th, 2009, 04:05 AM   #8
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Quote:
Originally Posted by Ron Cooper View Post
Thanks Andy. Yes I know about de-essers & I have fixed that, but this is worse than that ! It is whistle at a particular frequency!
She generates it with her "S" sound but only sometimes but the frequency is quite definite & stable, but for a fraction of a second, so hence my wanting to identify it & simply apply a sharp notch.

In my electronics business I have designed very sharp analogue filters and they are extremely effective with virtually no effect on the overall audio.

RonC.
Hi Ron,

If she's the only one you have the problem with, then it's not the system, it's her.
Your efforts to apply technology to it may be valiant, but if the problem is in her mouth, there's only so much you can do. If that's the case, the kindest remedy is to find a good speech therapist for her.

Regards,

Ty Ford
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Old January 5th, 2009, 12:35 PM   #9
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May I suggest an excellent free plugin, available for both Mac and PC, that shows a running frequency graph:
RNDigital | INSPECTOR FREE

I have found this very useful in analyzing audio problems. The standard drill for your kind of problem is to find the annoying freq by emphasizing it .... sweep with a high-q positive gain, when the noise is at it's most prevelent, cut the high gain to a negative gain at that point. It is somehow easier to find the problem if it's more promenent, then whack it. Best regards / Battle Vaughan/miamiherald.com video team
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