15 Replies Latest reply: Mar 26, 2015 8:45 AM by chflynt Branched to a new discussion. RSS

    Fixing Background Noise in Audio

    the_wine_snob Community Member

      Users often encounter situations, where there is much background noise also recorded along with the human speech, that they are attempting to capture. This can be heavy ambient noise from near-by traffic, and A/C unit, wind, birds in a park, or others speaking close enough to the mic to be picked up. Most of the time, these extraneous noises are unwanted in the audio portion of the AV file.

       

      Unfortunately, the best solution comes before one captures the footage. A good mic, good mic’ing technique, quieting the environment, or moving the taping to a quiet location are the best practices. Sometimes, many of these “cures” are not possible. Still, they are where one really needs to start.

       

      When the audio has been captured, there can be major issues, when trying to remove the unwanted noise. There are some programs, and techniques that might be helpful at reducing these noises, but remember, these will only be so effective. If the noises are isolated to particular frequency ranges, outside of those of human speech, the prospect increases of success. A 60Hz hum is a good candidate for removal. Other human speech is certainly not. Wind noise can be broad spectrum can be very problematic, as if you remove it, for all overlapping frequencies with the human speech, those will all be removed, leaving the desired sound removed too. This is not what you want. One’s success will depend entirely on the frequencies of the undesirable noise, and how much of it, one can live with.

       

      Now, there are some tools, that can be very useful, but only within the realm of the parameters discussed above. Regardless of which tools you use, you had better plan on spending a lot of time with a good set of headphones, and a lot of listening and testing.

       

      The first tool that I turn to is Adobe Audition. It is a pro-level audio-editing program, and is not inexpensive. It is very powerful, but with that power comes both a learning curve and a lot of manipulation. One of its Restoration Effects is Noise Reduction (Process). This is used in conjunction with the Capture Noise Reduction Profile, which, when applied to a section of the offending noise, without the human speech, will map the audio profile of that noise. This profile will then be loaded into Restoration>Noise Reduction (Process). There, one has many controls for the application of the Effect, and the ability to Preview those settings. Plan on spending some time with this Effect, as it can be very easily overdone. When this happens, the human speech will take on a strong echo. As you reduce this undesirable effect, the ambient noise level will increase. Make settings, test - repeat - repeat - repeat. When you have balanced the noise reduction vs the distortion, that is as good as it gets.

       

      From that point, one would then look to Effect>Parametric EQ (Equalizer) or Effec>Graphic EQ, to manually reduce certain frequencies (outside of the range of human speech), and also pump up certain frequencies that make up human speech -  125 - 250 Hz is about where most human speech occurs. These can be increased, but if your noise is full-spectrum, remember you will also increase any part of that noise, that resides in this range too.

       

      After all has been done here, there are three Filters, that might help too: Low-Pass, High-Pass and the Notch/Gate Filters. Again, these can be very useful if there is zero overlap from the noise to the spectrum of human speech. Again, apply, test - repeat, etc.

       

      One very useful Effect in Audition is Repair Transient. This can be used to remove pops, clicks and other transient noise. Many bird calls are Transients, and with a bit of work, can often be eliminated completely. I could not live without this Effect, as it can clean up so very much, leaving the noise floor untouched, but completely removing the Transients.

       

      Now, buying Audition is not in everyone’s budget. One good freeware program for audio-editing is Audacity. It can work with many VST’s, and there are VST versions of several different EQ’s, plus High-Pass, Low-Pass and Notch/Gate Filters. I have never seen a noise-reduction VST that really worked, nor a Transient Removal VST, but they might exist. Note: while Audacity is free, only some available VST’s will be free. Some are more expensive than Audition.

       

      Some years ago, I was working on a particularly badly degraded piece of audio. It came from a VHS tape of an old TV show, and apparently the tape deck had major problems, and maybe the signal was poor as well. This piece of audio just did not exist beyond this VHS tape, so I had to work on it. I spent a full day in Audition, and really was not doing well. It seemed that if I reduced part of the noise, some aspect of the audio disappeared also. Months before, I had purchased one of the Magix Music Studio programs. It came bundled with a little program called Audio Cleaning Lab. I installed both programs, but never touched ACL. It just languished on my Desktop. As I was about to give up on the restoration, I opened up all of my Magix programs, hoping to find a “magic bullet.” Nothing in the usual suspects, and then I opened up ACL for the first time. It had a simple little interface and looked more like a toy, than a serious audio program. There were default presets for several parameters, but not much more. Out of curiosity, I grabbed my WAV from Audition and ran it through ACL with the default presets. I was amazed at how much it improved on my day’s work. When the shock subsided, I decided to try it on the un-altered WAV. It was amazing. I then worked on the output from ACL, back in Audition, and got a useful file. That little “toy,” had done a fabulous job within the parameters and limitations of a program that does only one thing - cleans up audio. If one does a little additional work in a full-featured audio editing-program, like Audition, things can be amazingly good. Even then, one still must be ready to adjust, test, and repeat.

       

      My audio “toolbox” runs from Audition to Audacity, and includes several of the Magix programs and many others. When trying to “clean up” existing audio, I am ready to use any/all of those, and be patient.

       

      Still, recording the cleanest audio initially, will pay dividends. Cleaning up poor audio in post-production is limited and is very labor-intensive.

       

      Another “fix” for bad audio is “dubbing.” This is the process of re-recording the audio in a quite location, with good mics, and the actors watching their performance on a monitor. This is the opposite of lip-syncing, but can be very effective, and is done in Hollywood often. Once a good clean dub has been recorded, it would be Imported into one’s NLE (Non Linear Editor) of choice and aligned with the Video portion of the Clip, that was used as a visual for the dub. The original Audio would be Deleted, or Muted. One of the nice benefits of doing things this way is that one can dub to an edited visual. If necessary, one could also do a tiny bit of Time Stretch on the dubbed Audio, to get perfect sync. This does get involved, but can be done. Many programs will allow one to alter time, but maintain pitch.

       

      If necessary, other audio, besides just the dubbed human speech, can be added, where necessary. If one needs certain SFX (Sound Effects), to match visuals, these can be added. A second similar method is to do Foley Sound, where one finds items that will sound “like” what appears on screen. These range from things like “creating” thunder by shaking a sheet of aluminum, or similar. If one’s dubbing is also missing wanted sounds, using SFX Clips (either recording these, or finding them online) or doing Foley Sound can replace those audio elements that are now Muted, or Deleted.

       

      I also highly recommend that one use a good pair of noise-canceling headphones, and apply a liberal dose of patience, when doing any audio work. Often, it can take far more time, than either setting it up correctly in the first place, or just doing a reshoot.

       

      Hope that this helps someone,

       

      Hunt

        • 1. Re: Fixing Background Noise in Audio
          mopunkie Community Member

          Thanks for the help.  I only wish to lower the volume on a part of the clip. Only when the boat starts up.  It is loud and I just want to lower its volume.  I don't need to seperate out conversation or anything.  I want to keep the volume up at the beginning of the clip and turn down the volume for the remainder of the clip.  Here is the audio clip.  I realize this isn't actually noise reduction in its true sense.

          • 2. Re: Fixing Background Noise in Audio
            the_wine_snob Community Member
            I only wish to lower the volume on a part of the clip. Only when the boat starts up.

             

            This is very easily done with the fixed Effect>Volume and Keyframes. I have done this in PrPro 2.0, as its Effects Control Panel is more similar to the one in PrE 7 & 8, and I only have PrE 4. Things will not be exactly the same in PrE 7, or 8, but this should get you started:

            Audio_Keyrames_01.jpg

             

            Below is my output file. I also added the Fill Right Effect, to get the signal into both channels.

             

            Hope that this helps. Also, I converted the AAC to PCM/WAV in QT Pro, so that it could be edited in PrE.

             

            Good luck,

             

            Hunt

            • 3. Re: Fixing Background Noise in Audio
              Sparkle Cleaning Community Member

              Thank you. Very useful information. I use this knowledge in Sparkle Cleaning project

              Your thread very help me)

              • 4. Re: Fixing Background Noise in Audio
                the_wine_snob Community Member

                You are most welcome, and welcome to the forum.

                 

                If you have any questions on either the Audio, or the Video, please feel free to post out in the main forum, where people will be most likely to see your post.

                 

                Happy editing,

                 

                Hunt

                • 5. Re: Fixing Background Noise in Audio
                  Sparkle Cleaning Community Member

                  Thank you for the warm welcome

                  • 6. Re: Fixing Background Noise in Audio
                    the_wine_snob Community Member

                    There was a recent THREAD in the PrPro CS5 forum, where a user had applied the De-Noiser Effect to some Audio Clips, that had a "fade in" via Volume Keyframes. This caused the Levels to drop noticeably, as the Effect was taking its initial measurement of the noise floor, in the Keyframed beginning.

                     

                    I reference that thread above, as it points out a potential problem, that can arise under certain circumstances. For the "spoiler" look down to the end, and especially a response from Colin. The early part of the thread is interesting reading, as folk tackled the issue, but the "climax" is at the end.

                     

                    Hope that this helps anyone experiencing an issue with Effects, like De-Noiser.

                     

                    Hunt

                    • 7. Re: Fixing Background Noise in Audio
                      John Novotny Community Member

                      This post was helpful, thanks.

                       

                      Basically I'm screwed, noise or artifacts is my current choice no matter what I do.

                      • 8. Re: Fixing Background Noise in Audio
                        the_wine_snob Community Member

                        John,

                         

                        Sorry that you were not able to clean things up enough. It can be very tough, to totally impossible, depending on the noise, and the frequencies that you wish to maintain. When it gets down to that, re-recording the Audio is often the only solution.

                         

                        The above mentioned programs and techniques only work so far.

                         

                        On CSI, they make cleaning up Audio look so easy - just a few clicks, and everything is as prefect, as if it had been done in a well-mic'ed studio. It is seldom that easy.

                         

                        Good luck,

                         

                        Hunt

                        • 9. Re: Fixing Background Noise in Audio
                          soundsdelightful Community Member

                          Dear Hunt

                          Found your post v interesting and informative and wondered if you could help with a problem?

                          I edit talks in Adobe Audition and the sound is so low I often have to amplify it x20 to be able to hear it, yet when I burn it to CD it sounds fine at the original level - amplifying is too much.

                          The speaker settings are all up full. I've tried different headsets and can improve the quality but not the volume of the sound to match what appears on the CD.

                          Do you have any suggestions?

                          Thanks from

                          Soundsdelightful

                          • 10. Re: Fixing Background Noise in Audio
                            the_wine_snob Community Member

                            I have not encountered that issue. Now, I monitor all my Audio with a pair of Bose QC-15's, and the edited Volume translates well, in my finished Projects, when tested on several of my systems from a cheap, bargain-basement DVD player and a TV with the tiny, built-in speakers and internal Audio processing, to some esoteric home theater systems.

                             

                            My first thought would be that the Volume/Gain on your testing system might be higher, than the Volume/Gain of your DAW/editing rig.

                             

                            I notice similar results with many commercially produced DVD's and BD's, in areas like the Menus' Audio - far, far too loud for me on my reference systems. That is one reason that I usually attenuate all Menu Audo by about -3 to -6 dB - I want it as "background" ONLY, and not something to really call attention to itself.

                             

                            However, I am not sure that is what you are experiencing, hence my guess.

                             

                            Good luck,

                             

                            Hunt

                             

                            PS - just like video calibration on various playback systems, how a client has their audio calibrated can really affect how things sound to them. I try to use my reference systems, and produce to them - that is the best that I can do, so the client may have to ride Volume/Gain up/down, per their systems' calibration.

                            • 11. Re: Fixing Background Noise in Audio
                              Srivas 108 Community Member

                              Hi Bill.

                               

                              Thank you for a nice post, very informative. It's hard to find something about restoration work, I mean like a live workshop, that would be really great to have. I use Audition and I have to try out some of the things you're recommending, especially those:

                               

                               

                              From that point, one would then look to Effect>Parametric EQ (Equalizer) or Effec>Graphic EQ, to manually reduce certain frequencies (outside of the range of human speech), and also pump up certain frequencies that make up human speech -  125 - 250 Hz is about where most human speech occurs. These can be increased, but if your noise is full-spectrum, remember you will also increase any part of that noise, that resides in this range too.

                               

                              After all has been done here, there are three Filters, that might help too: Low-Pass, High-Pass and the Notch/Gate Filters. Again, these can be very useful if there is zero overlap from the noise to the spectrum of human speech. Again, apply, test - repeat, etc.

                               

                              One very useful Effect in Audition is Repair Transient. This can be used to remove pops, clicks and other transient noise. Many bird calls are Transients, and with a bit of work, can often be eliminated completely. I could not live without this Effect, as it can clean up so very much, leaving the noise floor untouched, but completely removing the Transients.

                               

                              Now, buying Audition is not in everyone’s budget. One good freeware program for audio-editing is Audacity. It can work with many VST’s, and there are VST versions of several different EQ’s, plus High-Pass, Low-Pass and Notch/Gate Filters. I have never seen a noise-reduction VST that really worked, nor a Transient Removal VST, but they might exist. Note: while Audacity is free, only some available VST’s will be free. Some are more expensive than Audition.

                               

                               

                              I would like to add that sometimes it's good to use Dynamics Processing to get rid of certain noise, I have one particularly bad audio track and this effect does a great job. Here's what I use:

                              dynamics.jpg

                              I have a point added in the middle of the expanders, straight expander line is too heavy reduction, quiet blocks between the sound, I like to fiddle with this point here and there to find the suitable reduction.

                              And another great option in Audition is Hiss Reduction. I find it smart to keep it on Light reduction level and then play around with the noise floor, usually that is enough to take away backround hiss. Sometimes Noise Reduction gives better results, sometimes Hiss reduction.

                              Another nice feature is to amplify certain frequencies with Multiband Compressor. Some person recently suggested me to use that and it's nice to add some clarity in case of low qualiy speech recordings. I choose Raise Vocals preset and then play around with gain levels on different bands.

                               

                              Actually I'm not an expert, just trying things out, but I have one audio clip and I did what I could with it, but there's not much I could do, it's an 8 bit 8kHz recording (actually 4 khz by spectral view). I used the above effects and raised volume a little more with Hard Limiting, but there's still a lot to be improved. One thing is distortion. I've read that this is practically impossible to take away, but something can be done. Do you know how to do it? I would like to learn that.

                               

                              Thanks again for a nice post.

                               

                              And have to check out this magix restoration plugin, interesting.

                               

                              Srivas

                              • 12. Re: Fixing Background Noise in Audio
                                the_wine_snob Community Member

                                Thank you for taking the time to add those suggestions and instructions.

                                 

                                As there can be so many "types" of offending noise, this thread could expand to many pages, and having good suggestions for users is wonderful. The more useful VST's, and operations, that one has at their disposal, the better. Again, thank you for posting the detailed steps. Keep the tips coming.

                                 

                                Hunt

                                • 13. Re: Fixing Background Noise in Audio
                                  the_wine_snob Community Member

                                  This AdobeTV episode might be useful for using Adobe Audition to work on Audio "noise:" http://tv.adobe.com/watch/no-stupid-questions-with-colin-smith/advanced-noise-reduction-in -audition-cs55/

                                   

                                  Hunt

                                  • 14. Re: Fixing Background Noise in Audio
                                    fredowww66 Community Member

                                    Interesting article but it focuses completly outside PE. That's a pitty, because f.e. PE 11 has already a lot of sound/noice effects/filters.

                                    I can not believe that they all don't work and if this was the case Adobe should not build them in than.

                                     

                                    So it would be nice if someone can go in on the delivered noisefilter tools in PE. In the most practical way, f.e.:

                                    problem: loud tick in sound (f.e. someone touched mic or table close to mic), how to delete this in the best way.

                                    answer: use filter X and than a detailed description of the buttons of that effect (now most users doesn't have an idea of the function of those buttons)

                                     

                                    Other problem: streetnoise while interviewing, etc.

                                    I know already that for windnoise there is no good solution, so that faq can be skipped :-)

                                    • 15. Re: Fixing Background Noise in Audio
                                      chflynt Community Member

                                      Hi wine_snob. I have an interesting problem that I hope you can help me with. I recorded sound on a video shoot a few days ago. When we got back to the studio, all tracks had this weird, chirpy background noise in them. You can hear it below.

                                      http://charlesflynt.com/chirpy_artifact.mp3

                                      Also, here is the spectral display from Audition of the same clip.

                                      chirpy_spectral.png

                                      You can see the artifact clearly. I have no idea what we did to produce this and I have not been able to reproduce it. My field recording equipment is: Azden MX 100 shotgun mic, feeding into an Azden FMX-42 field mixer, which is hooked up to a Tascam DR-40 digital recorder. I use all high quality XLR cables.

                                       

                                      Can you tell me what caused this and how to avoid it in the future?