Topic: how to remove a static sound from an interview recording?

[digitallive]

hi everyone,

i'm doing a documentary on Cleveland "rust belt rock" band The Suede Brothers.

I did the interviews twice now 'cause the 1st time the SD card took a dump, was really a bummer.

The only place we had to possibly shoot this last night has by a street lamp, and you can hear a faint buzzing, almost like tape hiss, throughout the recording.

I knew that lots of people removed tape hiss so I was wondering if this little buzzing could also be removed.

Anyone who'd like to try there hand at it I can trade bootlegs for, blanks, whatever you want

my trading my is http://digitallive.tripod.com

Thanks!

PS - if this is a double post sorry, i posted it once and it came back saying i wasnt logged in and then when i logged in to post it again it said i already posted it, etc etc

[Johnny Thunder]

You know, your best bet to get the best removal without screwing with what you want to keep in the recording is to go back to the same location with the same recorder and record several seconds of JUST THAT BUZZING. It can be a challange to get enough of JUST that sound. I know, I've been down this road before. Once you have a really clean sound byte of just the sound you want to eliminate, however, it's easy. Open the original recording in Audition, for example, then open-append the recording of just the buzzing. Highlight the portion that's just the buzzing and in the, "Noise Reduction," catagory, select "Capture Noise Reduction Profile." After capturing that sound, highlight the whole file and apply the noise reduction. I've needed this tool many times and the resaults are astonishing IF you capture a real good sample of the offending buzz/hum/hiss you're trying to get rid of. Let us know how you make out with it.

-JT

[dorrcoq]

You know, your best bet to get the best removal without screwing with what you want to keep in the recording is to go back to the same location with the same recorder and record several seconds of JUST THAT BUZZING. It can be a challange to get enough of JUST that sound. I know, I've been down this road before. Once you have a really clean sound byte of just the sound you want to eliminate, however, it's easy. Open the original recording in Audition, for example, then open-append the recording of just the buzzing. Highlight the portion that's just the buzzing and in the, "Noise Reduction," catagory, select "Capture Noise Reduction Profile." After capturing that sound, highlight the whole file and apply the noise reduction. I've needed this tool many times and the resaults are astonishing IF you capture a real good sample of the offending buzz/hum/hiss you're trying to get rid of. Let us know how you make out with it.

-JT

Great tip!

[digitallive]

thanks! actually on the recording there's about a minute of the buzzing in b/t interviewing a fan and the singer, so i took that and did the noise removal in audacity.

however it took a little "mmph" out of his voice, and he has a high voice to begin with. is there a way now to increase the low end?

[Johnny Thunder]

Hey again Digitallive. Well, I'm impressed you're back in asking this very question. Most people really hack stuff up with noise reduction and have no clue. I sure hope you kept your original copy of the interview and didn't overwrite it. We need to take a look at this the same way an MD is taught, primum non nocere. (First do no harm) We can't remove something then increase something that isn't there because we removed it. What might be best here is for you to start over again with the virgin file. Sample your noise again. But this time, use the preview feature in Audacity's noise removal filter. Your attack/decay time should generaly be 0.01 sec. Generaly, anything longer will create alot of pumping. You can play with the ammount of noise reduction applied, and hear the result real time using the preview button. There is always a tradeoff between removing alot of the noise, and loosing some of the fedelity in what you want to keep. Also play with the frequency smoothing a bit. Take your time in preview changing these settings a bit at a time until you get what you feel is the best possible result. Sometimes it helps to make dramatic changes one way and the other in preview to get a better handle on what you DON'T want. When you get as much of the best of both worlds as you can, then you can move onto the next stage, trying to get that umph back in his voice. I should also note than unlike Audition, which will allow you to preview the entire selected section, Audacity requires you to change a setting if you want to preview more than 3 seconds at a time. It's somewhere in the options. Find that and increase the preview time to something more like 20 or 30 seconds.

Now, this is where the EQ filter may be needed. Select the entire wav again, and go to the effects menu and select equalization. This portion should be pretty self-explanitory. If you need a little more low end in the edited recording, you're probably going to want to start punching it up around 500 Hz. Hopefully you'll get a result you're very happy with.

You may want to try giving a bit of a bump from around 500 Hz down in the edited file you've created before starting over, but like I said, it's best not to create any new problems with the audio in the noise reduction stage. Besides, the more you use the tools, the better you'll become at achiving the best possible results in the fewst number of steps. Please, do let us know how you make out. I'm more than happy to give any more assistance you might need. Remember, we're all in this thing together.

-JT

[Church-Audio]

Hey again Digitallive. Well, I'm impressed you're back in asking this very question. Most people really hack stuff up with noise reduction and have no clue. I sure hope you kept your original copy of the interview and didn't overwrite it. We need to take a look at this the same way an MD is taught, primum non nocere. (First do no harm) We can't remove something then increase something that isn't there because we removed it. What might be best here is for you to start over again with the virgin file. Sample your noise again. But this time, use the preview feature in Audacity's noise removal filter. Your attack/decay time should generaly be 0.01 sec. Generaly, anything longer will create alot of pumping. You can play with the ammount of noise reduction applied, and hear the result real time using the preview button. There is always a tradeoff between removing alot of the noise, and loosing some of the fedelity in what you want to keep. Also play with the frequency smoothing a bit. Take your time in preview changing these settings a bit at a time until you get what you feel is the best possible result. Sometimes it helps to make dramatic changes one way and the other in preview to get a better handle on what you DON'T want. When you get as much of the best of both worlds as you can, then you can move onto the next stage, trying to get that umph back in his voice. I should also note than unlike Audition, which will allow you to preview the entire selected section, Audacity requires you to change a setting if you want to preview more than 3 seconds at a time. It's somewhere in the options. Find that and increase the preview time to something more like 20 or 30 seconds.

Now, this is where the EQ filter may be needed. Select the entire wav again, and go to the effects menu and select equalization. This portion should be pretty self-explanitory. If you need a little more low end in the edited recording, you're probably going to want to start punching it up around 500 Hz. Hopefully you'll get a result you're very happy with.

You may want to try giving a bit of a bump from around 500 Hz down in the edited file you've created before starting over, but like I said, it's best not to create any new problems with the audio in the noise reduction stage. Besides, the more you use the tools, the better you'll become at achiving the best possible results in the fewst number of steps. Please, do let us know how you make out. I'm more than happy to give any more assistance you might need. Remember, we're all in this thing together.

-JT

I have done that very same thing... Works like a charm for most things, Good tip.

[Shadow_7]

If it's fixed pitch, you can notch it down in audacity.

Effect -> Nyquist Prompt

(notch2 s 60 1)

Where 60 is the Hz of the sound and 1 is the dB / volume you want to push it towards.  Analyze / Plot Spectrum to figure out what the pitch is, and it might be easier to find if you select a section of audio with just that sound.  Parenthesis are part of the command.  It doesn't remove the sound, but it can push it towards inaudible.

[admkrk]

But this time, use the preview feature in Audacity's noise removal filter.

personally, i like to preview what's being filtered out more, i assume audacity has that option also. if all you're hearing there is trash then you should be safe to run at that setting. you can take several passes also. i usually take at least 2 or 3 passes with a click filter cleaning up vinyl recordings for example.

[guysonic]

You didn't say what gear was getting the noise input.

If using external mic into recorder, keeping ALL THE CONNECTIONS clean will greatly help external sources of electrical noise from being rectified as audible input noise. 
My site's tips page has details on how to clean your connectors for best chance of eleminating all connection induced noise issues.
www.sonicstudios.com/tips.htm#maintain

Also, sometimes mic adapters are not wired correctly.  See my mic correctly wired adapters at: www.sonicstudios.com/access.htm#adapters