Wednesday, 30 September 2015

Don’t Make These Mistakes with Noise Removal when Recording

Noise removal is a handy little tool that can be found on Audacity and other sound editing software. It will find the sound profile of your recording space, and filter out unwanted background noise, resulting in a clean recording where only your voice can be heard. But I learned to my cost, not to use it too heavily.

Noise Reduction Tips

Removing Background Noise
When I first started recording audiobooks, I became aware of traffic thundering by at the front of the house and aeroplanes gliding over every hour or so. When I began recording audiobooks, I happily used the noise reduction, filtering out cars, gliders, lawnmowers, you name it. Yes, noise removal got rid of these noises, but it also got rid of the sound frequencies that happened to overlap in the human voice, resulting in a horrible squeaky sound or underwater warble.

Firstly, pause and wait until the juggernaut has gone by, the glider has drifted past, or the lawnmower has been put in the shed. You will find you will sit and wait for sections of silence for recording. Don’t worry, these long interludes can easily be cut out of the recording. It is better to employ noise removal lightly, than to be heavy-handed.

How to use Noise Reduction Correctly

Don’t use noise removal other than to remove the sound of the room, which might be a low rumble or hush. Filtering out the sound of the quietest moments will not affect your voice and using this noise profile can be used for the entire recording.

Every now and again, an aeroplane will happen to drift by whilst I was talking. This can easily happen without my notice. Don’t perform noise remove on the sound of the aeroplane for the entire recording, only the section of recording that it affects. I will go through the WAV sound files to look for any noises that have sneaked into my recording and remove them bit by bit.

Never noise remove breaths that you take between speaking.  Your breaths will sound horrible and it will affect sections of your voice. Best leave the breaths in.

If you are unsure that a section of room noise contains other noises, amplify the section first and listen out for anything other than room noise, such as breaths or the muffled sound of the TV. You would be surprised at what the mic can pick up. Select the quietest moments and use only this noise profile for the entire recording.

Sound Compression and Equalization

Before mastering the recording, keep a copy of the original. Many audio book producers like to enhance the bass on equalizer to add presence to the voice. Beware, doing so will also bring forward distant sounds of traffic or trucks, as these have low frequencies too, not audible in the original recording. The situation is made worse when you perform compression, as this will enhance the quiet bits and quieten the loud sections. The sound of distant traffic will be 'pushed forwards' between sections of dialogue, resulting in a distant booming sound.

If you hear distant booms when you enhance bass and perform compression, you might need to perform noise removal again or go through the recording and eliminate these unwanted noises bit by bit. Be prepared (as I had) to record again and put it down to experience.

A sound proof room is not always possible and can cost thousands. I simply wait for a quiet time to record, this is essential for producing audio books. I find late evening a good time, when the traffic has died down and people are watching TV in their houses. Noise removal can then be used lightly.

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