Topic: Recorded buzz - any way to remove?

[Spiggy Topes]

I'm new to all this, sorry, but have a whole series of problem recordings. They're voice recordings of interviews by phone, done using a voice recorder and a phone on speaker phone. Not until it came time to transcribe them was it apparent that many, but not all, included a background buzz that made the voices difficult or impossible to hear. I've dealt with that for future recordings by not using a wireless phone, but don't feel I can ask the interviewees to repeat unless there's absolutely no way that I can recover the buzzy recordings.

I don't have any experience with audio files, don't really want to spend money on software, so thought I'd try Audacity. Looking at the files at pretty much maximum zoom, the buzz is very obvious and very regular:



So I thought I'd try to find a section of silence (except for the buzz), copy to a separate track and invert it. Works beautifully. But the longest sample I have is seconds, and the whole piece is 20 - 30 minutes. I don't see an easy way in Audacity to cut and paste repeatedly without manually repositioning after each operation, and it's very, very easy to get just enough out of step that the two tracks get out of sync.

Is there any way that I can replicate the inverted section up a thousand-fold or so without repeated copying, repositioning and pasting? I know I can double up repeatedly, but it needs to be very, very precise and I keep thinking there must be an easier way. Tried the Compression and Hard Limit options, they just turn everything to mush. I don't need pristine, just intelligible.

Thanks, any help greatly appreciated!

[DigiGal]

You may want to look at a 15(?) day trial version of iZotope RX 3.  Not sure if the trial is crippled in any way though. If so there may be RX 2 copies available at a discount if you search since RX 3 is fairly new.


Another option is Sound Soap by the now defunct BIAS.

[Spiggy Topes]

Thanks, I may try that. I did think of a method to handle this, just after I'd finished posting, and it's not perfect but it works. I recorded 45 minutes of nothing but buzz, inverted that, matched the peaks from original to buzz track and played them that way. The buzz drifts enough that it's not 100%, but with millisecond tweaks to one track or the other I can keep them in sufficiently close sync that all that's left is a hint of the buzz and a far less intrusive high-pitched sound like frying eggs. I could try trimming that off based solely on frequency, I guess, but for purposes of transcription, matching up the inverted buzz seems to do the trick. 

[runonce]

Use the Audacity Noise Removal Tool....

Find a section of just the noise - use that as your sample, then select the whole track and apply the effect...

Should work well...

[DigiGal]

If you are all set great.

Just had this pop up as a suggested purchase in Amazon. Wasn't aware of it, another less expensive Izotope product ($30)...

http://www.amazon.com/eMedia-IZ11095-Izotope-Speech-Cleaner/dp/B002TXIB7U/ref=pd_rhf_ee_s_cp_1_121F?ie=UTF8&refRID=0FCDMPFK76XE3XAN3FVY

[hoppedup]

Use the Audacity Noise Removal Tool....

Find a section of just the noise - use that as your sample, then select the whole track and apply the effect...

Should work well...

x2

I just had a buzz in a PA system that I could not isolate through the spectrogram view. Or multiple attempts at notch filtering around what I thought it may be. So I selected a few seconds of it by itself between songs with the Noise Removal tool in Audacity and it did a pretty good job cleaning it up.

[Spiggy Topes]

I tried the noise removal tool in Audacity first, but I think it must have overlapped a lot of the frequencies in voice, as it either wiped everything or left a ... hard to describe, a kind of underwater gargle. Also tried the Compression, Hard Limit and Vocal Remover options, with no greater success. The inversion option seems to be the way to go. I haven't tweaked it much yet, but here's a sample result:

The original file with the inverted buzz in a second track:


and the result saved as a .wav file:


I can get a little closer by use of the Envelope tool, but there's still a degree of drift from one buzz to the other, so I still need to listen through and snip out a couple of milliseconds from one track or the other when the two files get out of sync, but the result is a file that was totally drowned out in buzz becomes understandable once more.

Thanks for the suggestions all!

Still no idea what causes it in the first place, of course...

[kirk97132]

Iztope is hands down the best noise removal tool.

[2manyrocks]

For some reason, some microphones pick up a buzz from telephones unless they are designed for telephone recording.  I don't know why, but it often happens.

Another possible method to try is to download the trial version of Reaper (isn't crippled), and use ReaFir to build a noise profile to subtract from the recording.  It's sort of awkward to find this feature in ReaFir, but there are three or four suboptions of which one is the noise subtraction profile.  Just capture the buzz on a quiet section and then the program extracts it from the recording.  Sometimes it works really well. 

If all that fails, then maybe someone would be willing to take a crack at it with Izotope for you. 

[ScoobieKW]

Best option is to use a purpose built interface.

The Gentner Hybrid Coupler
http://www.ebay.com/itm/like/200754591632?lpid=82

Or from JK Audio
http://www.jkaudio.com/radio-applications.htm

The Gentner unit was the industry standard for years, the JK Audio products are newer and more versatile.

[DigiGal]

Best option is to use a purpose built interface.

The Gentner Hybrid Coupler
http://www.ebay.com/itm/like/200754591632?lpid=82

Or from JK Audio
http://www.jkaudio.com/radio-applications.htm

The Gentner unit was the industry standard for years, the JK Audio products are newer and more versatile.

x2 

FWIW, for the same price I'd go for a new JK Audio Auto Hybrid over the Gentner Hybrid Coupler.  I've used both and prefer JK's Audio Hybrid.  http://www.fullcompass.com/product/243557.html

However, here's a BIN deal $50 on a used Gentner Microtel that would do the job for you, connect the Aux Out to your recorders input.  http://www.ebay.com/itm/Gentner-Microtel-Broadcast-Telephone-Handset-Line-Interface-No-AC-Adapter-/171178369826?pt=US_Other_Pro_Audio&hash=item27db06a322

[ScoobieKW]

Nice, I hadn't seen that JK unit, our shop owns these, http://www.fullcompass.com/product/260884.html along with the older Gentners. Definitely would go with the DigGal option over the Gentners. On the other hand, the only Gentners that end up in our repair shop have been from physical wear on the RJ-11 jack. Cheap fix and rare.

[rigpimp]

Iztope is hands down the best noise removal tool.

QFT.   There is a special place in heaven for the engineers that created the iZotope RX series.

[Spiggy Topes]

... and there's a special place in hell for thread hijackers! 

Okay, lots of recommendations for hardware and software, but it's too late for hardware and the Audacity software doesn't handle anything quite like this, and I don't expect it's what's usually meant by "noise", so I'm loth to buy software what won't fix the problem.

I have a workable solution, up to a point. It's still very uncomfortable to transcribe from, but my technique at least makes the conversation intelligible. There may be better and easier ways to do this, that don't involve quite so much tweaking though, and if anyone would like to take a crack at a better solution, here's a 30-second chunk to play with: http://members.shaw.ca/ccfc/Sound_Sample/ - in either .flac or .mp3 format, take your pick. It's a real oddity, the only one with a *double* buzz, but the same technique does work, just not very well.

So, my approach has been to record a piece with the same set-up but no voice, to get just the buzz. I've then inverted that to produce the anti-buzz and matched that millisecond to millisecond to the interview file.  You'll find ready-inverted buzz files in the same place. I've used Audacity's envelope tool to match peak heights from one track to the other, in order for one to cancel out the other. In this particular case, with the double buzz, I've added a second envelope-adjusted anti-buzz, and adjusted that to match the peaks of the second buzz. It works - just - , leaving a general background hiss like frying eggs. It needs constant tweaking, though, as every 15 seconds or so the alignment goes astray and has to be corrected. In a 40-minute conversation, that's a LOT of tweaking.

Anyway, if you'd like to give it a try, you're more than welcome. And if you have a better way to do this, I'm all ears!

[ScoobieKW]

As the guy accused of thread hijacking, I must defend myself.

When discussing a recording with flaws, it's perfectly reasonable to point out a way to avoid the issue in future recordings. While you may not ever need to record phone conversations, someone else searching this board may.

I'm glad you were able to make your recordings usable.