Getting rid of Dead Air!!! at DVinfo.net

Brian Doyle · January 29th, 2006, 11:45 PM

Hi,

I'm sorry about cross posting this but I was hoping someone in the premiere board might be able to help....

Here's the story....
I'm just finishing up a short film and I'm having some audio issues. There is no music in the short and in additional to the actors lines there is a strong voice over. The film has a film noir type of vibe.

My biggest problem is that I didn't shoot with great mics. I used a crapy sony wireless, the XL-1s camera mic (pointless, I know) and a Iriver lav set up.

The silence is very important and I have some dead air noise on both the VO and the lines. I took room tone and tried using that to bed it but some of the dead air still pops on. I've played with some audio filters (I'm working with adobe premiere, I have no other sound programs) but really have no idea about sound editing.

Does anyone have any tips where I should start? Where would you start noise gate or equalizer setting? Is there a filter that I would have that I'm not thinking about?

Please Help!!!!
Thanks for any help ahead of time!!!

Glenn Davidson · January 30th, 2006, 12:26 AM

If the 'pop' is more like a 'click, ' then the problem may be that when you added the room tone it was not edited at the point where the waveform crosses zero. If you can, zoom into the wave form and make sure both sides of the edits match each other. If the whole tone is popping, try reducing the gain of the room tone. I sometimes add a fast cross-fade between edits to eliminate the 'pop' . It is really difficult to solve this problem without hearing a sample.

Jean-Francois Robichaud · January 30th, 2006, 09:35 AM

It really depends what kind of noise it is. If it's very low frequency, then applying a high pass filter will make it better. If the noise is constant, you can also try to use a Noise Reduction filter, like the one in Audition, but don't push it too far, as it makes the voices sound tinny. If it's an electrical hum (60Hz), there is a filter in Premiere (can't remember the name) that can help you remove it. You can use the equaliser to boost the voices at certain frequencies to increase quality (can't remember exactly, but I think a narrow 4-6dB peak around 1Khz helps). For boosting certain frequencies and rejecting others, the parametric equalizer might be your best bet. It allows you to select a center frequency, the width of the band and the boost level (positive to boost, negative to reject).

Usually the best way to fix audio is to use a combination of subtle techniques, rather than a single fix-all solution.

Peter Ferling · February 1st, 2006, 12:05 PM

Brian, if you have adobe audition you can take a sample of the noise and use the noise reduction filter. The filter has controls to limit the effect.

A good rule of thumb when making recordings is to ensure that your floor "noise" does not peak above -42db. (Have every quiet on the set and adjust the recording level down until the ambient noise is peaks just under -42db). Then ensure the portion of audio that you want to keep (voices, music, etc) is at least above -12db, to around -6db. The will provide enough seperation between floor noise and the recorded media to allow the filter to work at low settings. If required at all.

One caveat about using noise filters is liberal use can create a canned result, where voices cut-in and fall off too quickly, sounding too abrupt. So some ambience is a good thing.

January 29th, 2006, 11:45 PM	#1
Brian Doyle Regular Crew Join Date: Sep 2005 Location: Booklyn NY Posts: 95	Getting rid of Dead Air!!! Hi, I'm sorry about cross posting this but I was hoping someone in the premiere board might be able to help.... Here's the story.... I'm just finishing up a short film and I'm having some audio issues. There is no music in the short and in additional to the actors lines there is a strong voice over. The film has a film noir type of vibe. My biggest problem is that I didn't shoot with great mics. I used a crapy sony wireless, the XL-1s camera mic (pointless, I know) and a Iriver lav set up. The silence is very important and I have some dead air noise on both the VO and the lines. I took room tone and tried using that to bed it but some of the dead air still pops on. I've played with some audio filters (I'm working with adobe premiere, I have no other sound programs) but really have no idea about sound editing. Does anyone have any tips where I should start? Where would you start noise gate or equalizer setting? Is there a filter that I would have that I'm not thinking about? Please Help!!!! Thanks for any help ahead of time!!! __________________ Brian Doyle XL1-s Bogen 503 head Sony wireless Adobe Premiere 6.0 Matrox RT2500

January 30th, 2006, 09:35 AM	#3
Jean-Francois Robichaud Regular Crew Join Date: Sep 2005 Location: Montreal, Canada Posts: 142	It really depends what kind of noise it is. If it's very low frequency, then applying a high pass filter will make it better. If the noise is constant, you can also try to use a Noise Reduction filter, like the one in Audition, but don't push it too far, as it makes the voices sound tinny. If it's an electrical hum (60Hz), there is a filter in Premiere (can't remember the name) that can help you remove it. You can use the equaliser to boost the voices at certain frequencies to increase quality (can't remember exactly, but I think a narrow 4-6dB peak around 1Khz helps). For boosting certain frequencies and rejecting others, the parametric equalizer might be your best bet. It allows you to select a center frequency, the width of the band and the boost level (positive to boost, negative to reject). Usually the best way to fix audio is to use a combination of subtle techniques, rather than a single fix-all solution. __________________ JF Robichaud

January 30th, 2006, 12:26 AM	#2
Glenn Davidson Major Player Join Date: Dec 2005 Location: Nevada City, California Posts: 499	If the 'pop' is more like a 'click, ' then the problem may be that when you added the room tone it was not edited at the point where the waveform crosses zero. If you can, zoom into the wave form and make sure both sides of the edits match each other. If the whole tone is popping, try reducing the gain of the room tone. I sometimes add a fast cross-fade between edits to eliminate the 'pop' . It is really difficult to solve this problem without hearing a sample.

February 1st, 2006, 12:05 PM	#4
Peter Ferling Trustee Join Date: May 2005 Location: Wyomissing, PA Posts: 1,141 Images: 57	Brian, if you have adobe audition you can take a sample of the noise and use the noise reduction filter. The filter has controls to limit the effect. A good rule of thumb when making recordings is to ensure that your floor "noise" does not peak above -42db. (Have every quiet on the set and adjust the recording level down until the ambient noise is peaks just under -42db). Then ensure the portion of audio that you want to keep (voices, music, etc) is at least above -12db, to around -6db. The will provide enough seperation between floor noise and the recorded media to allow the filter to work at low settings. If required at all. One caveat about using noise filters is liberal use can create a canned result, where voices cut-in and fall off too quickly, sounding too abrupt. So some ambience is a good thing.