Hello and welcome!
For this tutorial I am using a sound file of a vocal recording. I will be using ‘adobe audition’ to edit this sound file. ‘Adobe audition’ is a popular brand of audio recording software. This software allows you to record, edit and mix sound files/recordings on independent tracks. It has loads of tools to edit/engineer your sound files exactly as you would like them to be.
This tutorial will show you how to use the noise reduction tool to remove unwanted sounds/background noise from a recording or any sound file. I am using adobe audition for this example but any decent sound editor will have this tool.
The first step is to identify an appropriate section of the sound file that contains the noise. A good area to find is that which represents a pause between the speech/vocal. Just like when you take a pause between your sentences or words when you are speaking normally. It is useful to zoom in using the software to get a nice clear view of the part your would like to work with. This is the section that will be used to clean up the entire sound file. Once you have zoomed in on your chosen section it will be apparent that where it should be a silent pause there is actually a quiet noise. This is the section that we will sample and then remove from the entire sound file.
In most cases when you record any sound there is usually a quiet hiss or humming (noise) that can be heard during playback. This can come from the recording equipment itself or from background sounds that are within the range of the recording equipment. It is generally regarded as noise because these are usually unwanted sounds.
As well as noise you will also find other quiet looking parts of the sound file that represent the sound of someone breathing in. You will usually see these breath sounds just before a vocal part begins. These breath sounds will always be recorded with voice recordings unless you use a microphone that only records outward sound. Another option is to have a very skilled vocalist! Some people choose to remove or reduce the volume of this breath sound but that should only be done after you have removed the underlying noise of the entire track first.
So now we will remove the noise!
Highlight the silent pause/noise. This is done in the exact same manner as you would highlight text in a text document. Be careful not to select any of the vocal part when making your selection. You may want to zoom in to guarantee your accuracy for this part of the process. To sample this noise in ‘adobe audition’ right-click on that highlighted section and click on “capture noise profile” from the menu that appears.
This tells the software (adobe audition) what you consider to be the noise (sound frequencies that you would like to remove or reduce). The next step is to to go ahead and remove this noise from the entire sound file. In ‘adobe audition’ this is done by using the noise reduction tool.
Whichever sound editing software you decide to use within your studio setup, the method may vary slightly, but the basic steps and terminology will be very similar.
Next, click on the “effects” menu at the top of the screen and then click on noise reduction from the menu that appears. Once you have done this a new window will appear. This window represents the noise reduction tool and displays all the options and relevant information about that tool. The noise that you captured earlier will be the default noise used by this tool. You can either completely remove the noise or you can just reduce the noise to an acceptable level using the “noise reduction level” variable shown in the image. If you click on the preview button you can listen to what the alterations will sound like before permanently applying them. This is useful to fine tune the amount of effect you want to apply.
It is important to take care and listen carefully at this stage of the process because sometimes it is possible to apply too much noise reduction. This can effect the overall sound of the file in a way that you did not intend. Once you are happy with the settings click on the OK button and the noise will be removed. Magic!
You will then see complete silence where the silent pauses between the vocal waveforms are. At this stage you will have successfully removed the unwanted noise from the entire length of sound file. This can be seen most clearly by the completely flat line (zero decibels/volume) where the pauses are. At this point you may choose to adjust the volume of the breath sounds discussed earlier if you feel it is appropriate.
It is useful to get rid of noise within all of your vocal recordings because when you have several vocal tracks playing at once it also means you have several layers of noise. This noise can easily go unnoticed but it can sometimes slightly muffle other sounds/frequencies such as your musical parts or beats. When dealing with mastering, mixing and balancing the whole mix this is a useful and important tool for a quality production and allows the beat/music to be heard crystal clear.