It is difficult to eliminate background noise even when recording in a treated room or quiet environment when recording audio. The best option is to minimize the unwanted sound and manage it during post-production.
You can use a gate or noise gate to enhance the quality of your recorded podcast or other audio-like music by blocking unwanted sounds or controlling them to your desired levels.
Here, we examine how noise gates work and how you can use them to clean up light background noises from your audio recordings.
How Noise Gates Work
A noise gate can be software or hardware intended to remove noise from an audio signal. Gates are of different designs, but all operate similarly.
A noise gate uses a noise threshold that you set manually to block sound signals passing through an audio channel. The gate closes when the sound is below the threshold set, blocking it. When the sound is above or louder than the threshold, the gate opens, allowing the sound to pass through the audio channel.
The basic elements of any noise gate plugin are four settings, as elaborated in the following section.
Engineer Beau Brown labels the threshold as “the key to the gate.” It is a decibel level that describes when the gate should open or close. A high threshold implies that a strong or loud sound signal is required to open the gate. A low threshold allows more sound to pass through the gate once opened.
The attack is the time taken (in milliseconds) to open the gate. Slow signals require a high attack time to open the gate slowly; otherwise, a low attack time can generate a click sound. To remove the click sound, increase the attack time until it disappears.
It is best to use slow attack times of above 10ms for vocals or speech and higher times for percussive instruments.
The release states the time taken to close the gate. It can be in milliseconds or seconds, depending on the purpose of the gate. If you use the gate to remove noise, a low value would be ideal for creating a natural decay. When used as an effect, a higher value is preferred to close the gate quickly.
The hold is the minimum time the gate remains open. You can manually set it or use the default minimum of 20 to 30ms, preventing chatter. Chatter occurs when there is a high-speed change in signal level causing continuous gate opening and closing.
Note: All noise gate software plugins will have the four parameters described above. Some noise gates will have additional settings depending on their technological advancements, specific purposes, and developers’ preferences. Noise gate hardware plugins are simple and mostly have fewer settings to adjust.
How to Use Noise Gates in Adobe Audition
Let’s explore how the four parameters in a noise gate function by using a real example.
Assuming we have the best recording possible of a podcast – the speech is impeccable, low background noises, no echoes – we may still be able to detect some slight unwanted background sounds that negatively impact the audio quality. We can use a noise gate to weaken the background noise and improve the audio quality.
Begin by analyzing a sample of the recording to find the ideal Threshold for the noise gate. You can do this like so:
- Select a sample of the audio you’d like to use as a base in the Editor window. You can select the whole recording but normally if everything stays constant, you should be able to pick a fifth or so of the whole recording.
- Go to the Window pane and select Amplitude Statistics.
- In the Amplitude Statistics window, click on Scan Selection button at the bottom.
This will analyze the selection and return a bunch of statistics from the sample. The one we are interested in is Average RMS Amplitude.
Next, is time to add the noise gate effect onto the audio channel. You can do this like so:
- Go to the Effects pane at the top and expand Amplitude and Compression submenu and click Dynamics.
- In the Dynamics window you’ll want to enable AutoGate which is what the Noise Gate is called in Adobe Audition. (Make sure you have the correct preset selected, normally Default is the way to go depending on what you want to do)
- Finally set the Threshold value to the previous Average RMS Amplitude value we found out before.
- You may have to tweak it a bit (normally rounding it down a bit) to get it to work perfectly.
If you find changing the threshold setting alone is enough, you can stop here; otherwise, you will need to adjust the other parameters (attack, release, and hold) to clean up your podcast effectively.
In such a scenario, start with setting the attack, which is a fade-in effect. If you set a high value for the attack, the gate will open slowly and may cause the gate to discard some words at the beginning of sentences. Normally, a low attack value is advised, but the audio sound will be uneven when set too low.
Next, adjust the release parameter which acts as a fade-out effect. A high release value closes the gate slowly, causing the noise gate to retain some unwanted noise. In contrast, when the value is too low, the gate may remove sections at the end of sentences and cause the audio to sound uneven. All these depend on the hold parameter settings.
Lastly, set a suitable hold time. The hold value controls the duration for the gate to close after detecting the audio being below the threshold. It operates like the release parameter and is applied before it. When you set a very low hold value, the noise gate cuts the end of the sentences, while a very high value leaves some background noise in the recording.
Note that there is no single way to adjust the noise gate. You adjust the parameters systematically until you get the desired results. Your performance will vary from recording to recording; thus, your noise gate settings will have to differ each time.
In any recording environment, whether treated or not, background noise is inevitable, so you can only work towards minimizing it. Using a noise gate plugin helps enhance your podcast recording by reducing unwanted sounds.
Applying a noise gate to a recording in adobe audition is straightforward, just add a Dynamics effect and tick the AutoGate option. You do need to understand how the four key parameters (threshold, attack, release, and hold) function effectively to block the unwanted sound, though.
The article provides you with comprehensive information to understand how noise gates work and how to use them to remove background noises from your recordings.