What are some effective techniques for reducing noise and background sounds in voice over audio?

The point about reviewing voice over audio in different speakers and headphones is often overlooked but so essential. Different devices can highlight different aspects of the audio, and what sounds clear on one might reveal issues on another. It's always a good practice to test audio on multiple devices to ensure consistency and quality across the board.

Determining the source of the noise is crucial, and obtaining a sample of that noise is also important, as it constitutes the next step in the noise removal process.

Important to mention is reverb as source of "noise". The amount and "quality" of the reverb can vary greatly. It depends on the location, microphone type, polar pattern and of course, mic distance and placement relative to the voice talent. Then you should consider the purpose of the recording since some productions might tolerate more reverb than others. Game VO for example should be recorded as dry as possible since no room information is wanted but rather added later. Podcasts can tolerate a bit more room information since listeners assume people are in a room and it's part of the ambience.

Keep it sounding natural. Make sure you don’t overdo it with the noise reduction. Revisit your toolset often. The quality and speed of noise reduction software is getting better at an exponential pace. Be sure to try new things to achieve the right sound for the voice you are working with.

Please exercise caution when removing noise. It could lead to sound distortion. Benefits and drawbacks must be assessed. Sometimes, leaving some noise untouched maintains the natural sound, while removing all noise can result in distortion.

Modern noise reduction tools work better as they use neural network engines behind the scenes. However, not all of them work the same. Because they are trained in different data sets or different types of noises. A few examples are Waves Clarity VX, Supertone Clear, iZotope RX, etc. There are more, but I named a few. Traditional noise reduction in Audacity or Adobe Audition does not have massive training data sets. You should try any of the modern noise reduction tools. Though they are paid plugins, each one of them offers a free trial. If a software works best for your voice, that is the software for you. However, you have to keep an eye as things are upgraded with more training datasets and more advanced technologies.

Please be careful when using those tools. Generally, noise removal won't be perfectly accurate compared to manual remove. It's often better to remove subtle noise manually.

Using a De-esser tool requires knowledge and understanding because, unfortunately, it can sometimes remove a significant portion of high frequencies, affecting sound quality and clarity. In my opinion, evaluating the need for this tool is crucial; often, manually removing disturbing sounds, especially in letters like 'S,' is more than sufficient. For issues with letters like 'P,' manual intervention works better by selectively removing the problematic frequency part. This problem can be avoided by recording properly and maintaining an appropriate distance from the microphone during recording.

These tools can be really helpful, but the first step must be to avoid plosives and sibilance at the point of recording. De-esser and de-plosive plug-ins can really affect the natural sound of a recording and have their limitations, so it's best to focus on getting the microphone placement and technique right before recording.

Always ensure your sound falls within the range of -6 to -3 decibels. These values might vary slightly at times, but the sound shouldn't be consistently loud or quiet. This is not just about noise but also about creating an acceptable listening experience for podcast, radio, and voice-over content.

This step is important even though it's not directly related to reducing noise. Exporting audio files according to the standards of the platforms where the content will be published is essential. Proper and organized naming is also highly important.

Your starting audio must still be pretty good. As others have mentioned you can overdue corrective measures and it will damage the audio further. Good clean audio from a quality mic and interface in an acoustic-treated space should need little to no post-production enhancement.

It’s important to keep an eye on the signal chain from the source. Is the microphone directional? If you’re recording and your microphone is set to fig8, you’re definitely going to get a lot more pickup from behind the microphone. Is the room properly isolated with acoustic foam? Is the shock mount correctly isolating the microphone? If you find a lot of low end interference this may be something to look at. If you’re on location use a shotgun mic backed up with a lav to be sure. What I’m trying to say is that noise reduction isn’t something that you should only start in post. You get out what you put in!