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Strange Hum/Noises in Tascam recorder audio

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Cody Walters
Strange Hum/Noises in Tascam recorder audio
on Sep 28, 2013 at 1:53:10 am

Hello,

I have a very strange audio hum/noise in my recording. Link to the audio is here: http://codywaltersvideo.com/video/audioissue.wav

Screen shots of the spectral frequency:




This file is from a Tascam DR-05 recording to WAV onto a Sandisk 2GB micro SD card.
I have never heard something like this, and my first thought is the Tascam may be on its last legs. Has anyone experienced this and what is it?

Thanks,

Cody


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Eric Toline
Re: Strange Hum/Noises in Tascam recorder audio
on Sep 28, 2013 at 2:22:51 am

Cell phone HF radiation I would think.

Eric

"I push the RECORD button and hope for the best"


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Ty Ford
Re: Strange Hum/Noises in Tascam recorder audio
on Sep 28, 2013 at 10:33:25 am

Hello Cody and welcome to the Cow Audio Forum.

Thanks for posting in such great detail!

I'm with Eric on this, cell phone or other broadband devices like iPads.

Were there any of these on the set?

Regards,

Ty Ford
Cow Audio Forum Leader

Want better production audio?: Ty Ford's Audio Bootcamp Field Guide
Ty Ford Blog: Ty Ford's Blog


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Cody Walters
Re: Strange Hum/Noises in Tascam recorder audio
on Sep 28, 2013 at 12:30:38 pm

Eric and Ty, thanks for your replies. I think you are right, the shooter did have a cell phone with them.

We are not on a set. Our environment is similar to documentary shooting. I know that phones have been on the shooting location many times.

Are some audio capture devices prone to this problem more than others? I have not had this issue with our Sony Wireless Lavs. What are your suggestions on trying to remove the noise?


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Ty Ford
Re: Strange Hum/Noises in Tascam recorder audio
on Sep 28, 2013 at 12:50:45 pm

Cody,

RX noise reduction in post may be able to isolate those sounds and reduce or eliminate them. I'm still a neophyte in that particular part of the software, but have seen and heard it done. In the best of cases, the noise is just GONE!

Keep cell phones Dead Off, not just on standby or vibrate only.

Eric and I have experimented with Neutrik EMC XLR connectors and have found making cables with these connectors can help. Eric can make them for you.

Distance is pretty critical. The closer you get the noise source to the mic or to the connectors at either end, the more likely it is that your gear will pick up the radiation. Just moving the cell phone 3-4 feet away MAY (or may not) solve the problem.

Now that you have identified the source and some solutions. Play with it and figure out what works and what doesn't. As you find out more about this problem please post your results here.

Which phone is he running and on what network?

Regards,

Ty Ford
Cow Audio Forum Leader

Want better production audio?: Ty Ford's Audio Bootcamp Field Guide
Ty Ford Blog: Ty Ford's Blog


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Ty Ford
Re: Strange Hum/Noises in Tascam recorder audio
on Sep 28, 2013 at 1:20:10 pm

Cody,

It doesn't look like I can download that file from your site. If you can help me with that, I will try to see what I can do with RX3,

Regards,

Ty Ford
Cow Audio Forum Leader

Want better production audio?: Ty Ford's Audio Bootcamp Field Guide
Ty Ford Blog: Ty Ford's Blog


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Al Bergstein
Re: Strange Hum/Noises in Tascam recorder audio
on Sep 28, 2013 at 4:01:27 pm

Cody, that's almost certainly a cell phone or other wireless device, as it comes and goes. If it were steady, I'd suspect a bad fluorescent light.

I'm no cell phone engineer, but what I do know is that they *beacon* every so often, especially in areas where the signal strength is poor. These beacons are the phone reestablishing contact with their towers. This is the transmitter and receiver of the phone, and these phones, while governed by the FCC regulations on emissions of RF, are not designed to be RF neutral. To illustrate, I can easily generate RF noise by putting my cell phone next to my clock radio.

I always insist, and make it a joke, to tell the talent that we need to set our phones on 'stun" while filming. I ask them to at least turn the phone to the airplane mode, to stop the beaconing, but I ask them to actually turn it off if they can live without it for a few minutes. And I do so myself. It's especially important for those near the gear, such as the shooter, and the soundman.

Adobe Audition or other spectral analysis might be able to get it out, but it's not easy sometimes. I've had mixed results in removing it, without affecting the voice quality. It looks like you are using Adobe, so look at their videos on the web, they explain the way to try and remove it quite clearly.

Al


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Richard Crowley
Re: Strange Hum/Noises in Tascam recorder audio
on Sep 30, 2013 at 4:35:16 am

I concur with Messrs. Toline, Ford, and Bergstein. It is cell phone (or equivalent) type noise. Known generically as "RFI" (Radio Frequency Interference). It is quite a mild case. I have experienced situations where it was so bad you would have thought you were inches from a giant buzz saw.

This is not a function of the recorder, the media, or the file type. It is NOT any kind of indication that the recorder is dying. It IS a function of the microphone, cable, and susceptibility of the mic preamp.

As has been already mentioned, a complete prohibition on active cell phones is a very common practice in many/most types of production. AND someone should have the primary responsibility of monitoring the audio recording whenever you are rolling. It is their responsibility to yell "CUT!" when they hear that kind of interference.

Legend is that at least one famous Hollywood director carries a hammer and nails on the set. Anyone caught with an active device gets it confiscated and actually NAILED to the nearest door-frame or fence-post. Zero tolerance.


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Ty Ford
Re: Strange Hum/Noises in Tascam recorder audio
on Oct 1, 2013 at 3:59:55 pm

Cody,

Here's the response from Izotope's Matt HInes. It sounds a bit funky, but that may be due to the mp3 compression.

6589_codyphonebuzzedit.mp3.zip

Hi Ty,

I was asked to take a look at your audio file.

Here are some real quick tips that should set you on the right path, and a super rough edit via MP3 that will give you something to aim for, then improve upon (I didn't tweak too heavily, the pleasure will be all yours :-) )

• use the time/frequency selection tool and select and area of noise that is just the buzz, approximately from 1.2kHz to 24kHz. Open Spectral Denoiser, and 'learn' this limited selection. Click the chain link icon under the reduction slider to delink tonal and noisy, then leave the noisy at 0 while dragging the tonal slider up as far as 35/40. increase whitening to 10. now increase the boundaries of your selection left and right to cover the whole area the buzz occurs in. process, then repeat these same steps for the other part of the buzz.

• the first instance of buzz still has periodic elements. use the same limited bandwidth selection, and process it with declick, using the 'periodic clicks' algorithm with an emphasis on high frequencies using that slider.

• use spectral repair's replace to cover the two bursts of interference that are still present earlier in the audio file. don't process the whole bandwidth of the file, again just stick to limited selections of higher frequencies.

• now you can process the entire file with dialogue denoiser to remove surface noise and the lower, resonant noise floor.

• then, a slight touch of dereverb will bring the voice more into focus.

• then, i took the unusual step of adding uniform dither noise at a much higher than average level, to reintroduce a noise floor that's even (remember, we have chopped at this file in different areas, so it might be sounding a little filtered in certain spots). now, i learn the new noise profile, which sounds the same throughout, and masks some artifacts, and then i process to remove that entirely, leaving us with a much more even sound with a very low noise floor and no cell phone buzz. voila!

• you can apply a touch of EQ, perhaps a baxandall + lowpass filter on the high end, to enhance the sibilance that may have been slightly dulled, and also use a low mid bell to cut some of the muffled, resonant sound that still exists.

I hope those tips help. This file is definitely salvageable, I'd recommend playing around with the whitening and enhancement controls of the spectral denoiser specifically, as this will help you achieve a better result than my quick pass.

Want better production audio?: Ty Ford's Audio Bootcamp Field Guide
Ty Ford Blog: Ty Ford's Blog


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Cody Walters
Re: Strange Hum/Noises in Tascam recorder audio
on Oct 2, 2013 at 12:28:35 am

Eric, Ty, Al and Richard, thank you for your expertise. Thanks Ty for reaching out Mr. Hines. I sincerely appreciate you going out of your way. Very cool to see that this is fixable! I will try Matt's tips and see if I can pull a similar result.

To answer you previous questions, the phone was one of the Galaxy models on the Verizon 4G network.

I'll follow up this thread with my own result. Hoping it can be as good as Matt's example.

Cody Walters
Houston Video Production
Houston Wedding Videographer

Final Cut Studio 3
Adobe CS6 Master Suite
Panasonic HVX-200
Canon 7D, 60D



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