How to Reduce Background Noise in a Voice Recording

How can you improve an audio recording that contains excessive background noise? Many audio editing software programs include noise reduction tools or plug-ins. The free audio editor Audacity supplies an effect called Noise Removal. When and how should you use this tool to clean up a spoken-voice recording?

What does Noise Removal remove?

To effectively use Audacity's Noise Removal effect, you must understand what it will remove. Like any noise reduction tool, Noise Removal will not remove temporary or changing sounds such as those caused by traffic, pets, or voices in the background. These sounds are best treated as mistakes on the recording. See Amateur Voice Recording: Audio Editing by Selecting and Deleting for more information.

Noise Removal will reduce consistent, pervasive background noise. If you hear a hiss, hum, or buzz that doesn't change throughout a recording, then you can improve the sound quality with Noise Removal.

How do I use Noise Removal?

Noise Removal is somewhat different from most Audacity effects and plug-ins. It can, therefore, confuse a new user. Starting with version 1.3.3, the effect is more complicated than in earlier versions, although it provides much better noise reduction. Let's go over the controls, from top to bottom.

Get Noise Profile

Before Audacity can remove noise, it must know what the noise is. Select a part of the recording that would be pure silence if not for the background noise. The selection should not contain any mouse clicks, breaths, voices, or other sounds. The longer the selection is, the better.

Choose "Noise Removal" from the "Effect" menu. Click "Get Noise Profile." You have now taught Audacity what the background noise in your voice recording sounds like. Select the entire recording, then bring up the Noise Removal dialog again.

Noise reduction (dB)

Noise Removal in older Audacity versions used a single slider that ranged from "Less" to "More." The newer "Noise reduction (dB)" control serves the same purpose as the older slider. This determines the amount to reduce the noise by.