How to Reduce Noise in an Audio Recording
Posted by Mike Anonymous on September 27, 2010
The noise reduction foam and expensive microphones you find in a studio aren’t the only ways to eliminate noise in your audio recording. While these things certainly help, you can get a virtually noise free recording in your own home with almost any microphone – even the internal mic in your computer. This article will show you how to naturally reduce noise while you’re recording as well as eliminate noise in audio you’ve already recorded.
Prevent noise. Before you worry about anything else, the best thing you can do is get rid of all possible noise in your recording space. Pick the least noisy area to record. Turn off any fans, heaters, air conditions, and other non-essential applications. Even an extra laptop or idle gaming console makes noise, so if you’re not using them shut them off. Close the doors and shut the windows. Place your microphone away from any remaining noise (and power!) sources. Don’t record next to a window, even if it’s closed. Remember that your computer makes noise too! Even non-audible sounds will become noticeable once you amplify your recording. Finally, turn off any cellphones. Not vibrate, but off. You don’t want to get any GSM buzz while you’re recording.
Get as close to the mic as possible. Positioning for tonality and comfortability has to be taken into consideration, but beyond that you simply want to get as close as you can. The closer the microphone is to the audio source, the less background noise will show up in the recording. Turning up your source will accomplish a similar effect – simply speak louder, or if you’re recording an electric instrument turn up the volume. Just remember if your levels start clipping, bring the volume down on the mixer.
Tweak the EQ. Once you’ve got your audio recorded, you can often eliminate noticeable buzz or hiss using the equalizer. If your mixer has equalizer presets, try playing with those before you start recording to see what bands you can turn down to diminish noise. If you’re mixing digitally, you can record the audio straight in without any EQ and apply one during the editing process. Finding the right equalizer band to mix down is often trial and error. If it’s a hissing sound, it’s going to be in the higher spectrum. If it’s a buzzing sound, it’s probably coming from the mid to lower spectrum. A graphic equalizer is a great mechanism to form a valley in the EQ and move it around until the noise is reduced.
Use a Speech Enhancer plugin. Any good mixing program has one – even something as simple as Apple’s Garageband can do the trick. If you don’t find one, try searching the internet for a third party plugin. The Speech Enhancer will let you apply some quick tone settings to make a speaking voice sound more professional. More importantly, it will give you the option to dial back the more quiet sounds in a recording. This will help isolate the vocal and push everything out. While this type of plug-in is meant for spoken audio, it can be used (with mixed results) on any kind of audio.
Know your noise gate. The noise gate is your key to absolutely silent pauses and crystal clean audio. What the gate will do is take all noises under a certain level and turn them down however much you tell it to. If you find that your desirable audio never gets any quieter than -20dB, you can tell your noise gate to turn the recording down any time audio is not exceeding -25dB. You can even tell it how much to turn it down – all the way for a clean recording, or maybe just a little to allow some natural hiss in. The noise gate appears easy enough on the outside, but can be a little complicated to master. If your settings are too high, you will clip out parts of your recording making it obnoxiously unlistenable.
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