Recording audio, whether dialogue for a podcast, ADR, or even vocals on a song, can be a task. Noise, in general, is something that many sound engineers and sound recordists run into when recording. Here are some steps that may help reduce noise in your audio.
Before we delve into treating noisy audio in software, it would be beneficial to see what can be done on location to avoid setbacks in post. Before we look at a few steps to take to mitigate noise, let’s first understand what noise is.
What is Noise?
Audio noise refers to any unwanted or undesirable sounds in a recorded or transmitted audio signal. A variety of factors can cause these sounds, including interference from other electrical devices, background sounds in the environment, or technical limitations in the recording equipment.
Audio noise can take many forms, including hissing, crackling, humming, or buzzing sounds. It can be present at any frequency and vary in volume and intensity. In some cases, audio noise can be so loud or distracting that it makes the audio signal difficult or impossible to understand.
The most typical form of noise we run into with video is a hissing sound, and this is usually created from a poor noise-to-signal ratio. The noise-to-signal ratio (NSR) measures the relative noise level present in a signal. It is defined as the ratio of the power of the noise to the power of the signal and is typically expressed in decibels (dB).
The NSR is a useful metric for evaluating the quality of a signal, as it provides a quantitative measure of how much of the signal is made up of noise. A low NSR indicates that the noise level is relatively low and the signal is relatively free of interference. In contrast, a high NSR suggests that the signal is contaminated with a significant amount of noise. If you find that your audio has a significant amount of noise, one of the simplest ways to reduce a high NSR is with the use of signal amplification. This is typically achieved through the use of a pre-amp, as opposed to directly into your camera. Lewis runs us through this process in the video below.
With the basics of noise covered, let’s look at a few ways to lower the amount of noise entering your audio if you don’t use a pre-amp.
It’s essential to take care of the distance between the sound source and the microphone before recording. If the microphone is too far away, this can result in background noise seeping into the recording. Placing the microphone closer allows for the pickup of the sound to be more precise and reduces the chance of background noise making its way into the take.
If the subject is in a noisy environment, lavalier microphones are a great tool to pick up the dialogue only. These are commonly used by TV presenters and bloggers, and even filmmakers. Lavalier microphones are hands-free and still have a good signal-to-noise ratio due to their proximity. Sometimes the boom arm of a conventional microphone may not be long enough to reach the person when doing a wide shot.
A great way to begin recording is to ensure you are in a noise-treated room. Equipment such as foam panels absorbs any unwanted background noise. Both high-end recording studios and home studios will have foam panels allowing more control over sound reflections for a better recording.
Of course, it may not be practical to install foam panels to dampen the sound on a film set or an interview location. Therefore, look into investing in a sound absorption sheet.
The polar patterns of microphones are a significant factor when recording. Not only will choosing the correct one give you the best audio quality, but it can also reduce noise. Directional microphones can avoid making background noise due to their specific polar patterns. These include cardioid, super cardioid, and shotgun microphones. An excellent way to position the microphones is to ensure the noise sits in the null areas of the polar pattern instead of the pickup areas.
Using Good Microphones
Yes, using better microphones can significantly improve your audio recordings. While there are ways to eliminate noise in post-production, it can sometimes not be enough. While lower-budget microphones still have an excellent purpose for beginners, saving up for a higher-end microphone can avoid problems in the future. As to what microphone?
If you are looking for a budget-friendly filmmaking microphone, there are many options available in the price range of $100 to $1000. Here are a few recommendations to consider:
- Rode NTG3: This is a high-quality shotgun microphone designed for professional use. It has a directional pickup pattern and a low-noise output, making it ideal for capturing clear, focused dialogue. It is priced at around $600.
- Sennheiser MKE 600: This is another popular shotgun microphone among filmmakers. It has a supercardioid pickup pattern and a built-in shock mount, which helps to reduce handling noise. It is priced at around $450.
- Audio-Technica AT4053b: This versatile condenser microphone can be used for dialogue and ambient sound. It has a narrow pickup pattern and a low-noise output, making it ideal for capturing clear, detailed audio. It is priced at around $400.
- Rode NTG2: This is a lower-priced option suitable for those on a tighter budget. It is a shotgun microphone with a directional pickup pattern and a low-noise output, making it ideal for capturing focused dialogue. It is priced at around $200.
- Audio-Technica AT2020: This budget-friendly option is suitable for those who are just starting out. It is a cardioid condenser microphone ideal for recording dialogue and ambient sound. It is priced at around $100.
You can also find more microphone tips and recommendations in our video below with Tyler.
Post-production Tips and Tricks
It’s never too late to fix your audio. Digital Audio Workstations have audio effects and plug-ins that can help better your audio quality. One of these is reducing any noise floor heard in your recordings. The noise floor is another term for the “hiss” you might listen to in your audio recordings, especially in dialogue. Here are a few ways to reduce hiss.
On the frequency spectrum, the hissing sound falls on the high frequencies. An equalizer can help eliminate this sound and clean up the audio. In many DAW, you will find a channel EQ where you can adjust the EQ to your needs. A low-pass filter will cut away high frequencies and let the low frequencies pass through. Also, any “S” sounds can be pretty harsh in dialogue. Shaving off the high frequencies can also control this.
Using Presets and Plugins
There are plenty of sources within your DAW that can improve the audio quality. Plugins come in many forms: stock ones in the DAW and ones you can download from the internet. The plugins may have preset already set to serve the function in place. And yes, there are noise-reduction plugins and presets available! For those who use DaVinci Resolve, here’s a video explaining the noise reduction plugin.
Adobe Audition also has a preset for noise reduction. While it functions to reduce noise, it can affect the audio slightly, i.e., making it quieter or the EQ being altered somewhat. Playing around with the audio tools in your chosen DAW is good to try and get back any lost frequencies. However, this is also why taking the necessary steps before recording is essential! Here is a video explaining how to use it.
Compression is a processor that is used to reduce the dynamic range of a signal. It does this by increasing the volume of the quieter parts of the signal while leaving the louder parts unchanged. This can help to smooth out the overall volume level and make the signal more consistent. Other compression tools, such as an expander, can also help reduce the noise floor.
An expander “expands” the dynamic range of any sound and is an excellent tool for reducing hiss. Because an expander does the opposite of a compressor, the loudest parts of your recording become more vociferous, so adjusting the gain levels can fix this.
Another tool is using a noise gate. This opens and closes depending on the level you have it set at when it should close (in dB). Within the pauses in the dialogue, a noise gate will close and cut away completely any hiss. However, this can sound choppy and unnatural, so only use it when necessary!
If you are starting in the podcasting world, and need to record some ADR or sound effects, take those necessary steps before recording. Ensuring the environment you record in is quiet, or if you are in a noisy environment, using the correct microphones can save lots of time in post-production. When editing your audio, this process is to clean up any nooks and crannies here and there. Removing the noise floor in post-production can affect the overall quality of the recording. Act before you do, and you will get the results you want and more!
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