Recording clear dialogue isn’t always easy. Even in a relatively quiet room, microphones can pick up computer fans, air conditioning, background hum and other unwanted sounds. One tool that can help manage these distractions is a noise gate.<\/p>\n\n\n\n
Commonly found in audio editing software, digital audio workstations and podcast production tools, a noise gate automatically reduces the volume of a signal when it falls below a selected level. Used carefully, it can make the quieter moments between spoken words sound cleaner. Used incorrectly, however, it can make dialogue sound unnatural or even remove parts of the speaker’s voice.<\/p>\n\n\n\n
A noise gate is an audio processor that controls how much sound passes through based on its level. When the incoming signal rises above a chosen threshold, the gate opens and allows the audio through. When the signal falls below that threshold, the gate closes and reduces the volume.<\/p>\n\n\n\n
Imagine recording a podcast in a room with a faint computer fan running in the background. While you’re speaking, your voice is considerably louder than the fan. During pauses, however, the fan becomes more noticeable. A noise gate can reduce the sound during those pauses, helping create a quieter recording.<\/p>\n\n\n\n
It doesn’t necessarily remove the background noise while you’re speaking, because the gate will normally be open at that point.<\/p>\n\n\n\n
Most noise gates include several controls that determine how they respond to the incoming audio. The threshold sets the level at which the gate begins opening or closing. Attack controls how quickly it opens, while release determines how quickly it closes again. Some gates also include a hold control, which keeps the gate open briefly after the signal falls below the threshold.<\/p>\n\n\n\n
These settings are important because human speech contains both loud and quiet sounds. If a gate closes too quickly, it might cut off the end of a word. If the threshold is too high, quieter syllables or soft-spoken phrases may disappear entirely.<\/p>\n\n\n\n
Noise gates are particularly useful when background noise is relatively consistent and the wanted audio is clearly louder. For example, a creator recording a voiceover in a home studio might use a gentle gate to reduce the sound of a computer fan between sentences.<\/p>\n\n\n\n
Podcasters may also find gates useful when several microphones are open during a conversation. Reducing the level of microphones that aren’t currently being used can help limit unwanted background sound and microphone bleed.<\/p>\n\n\n\n
However, a noise gate is less effective when unwanted noise occurs at the same time as the dialogue. If somebody speaks while traffic passes outside, the gate cannot simply separate the voice from the traffic. Both sounds will usually pass through together.<\/p>\n\n\n\n
Although they’re sometimes confused, noise gates and noise reduction tools work differently. A noise gate reduces the volume of audio when the signal falls below a threshold. Noise reduction software attempts to identify and reduce unwanted sound within the recording itself.<\/p>\n\n\n\n
For example, a noise reduction tool might be able to reduce a steady background hum while somebody is speaking, whereas a basic noise gate will usually leave that hum audible whenever the gate is open. Neither technique is guaranteed to produce perfect results, and excessive processing can introduce unwanted artefacts.<\/p>\n\n\n\n
Start by listening to your recording and identifying the level of the background noise during pauses. Set the threshold slightly above that noise level, but below the quieter parts of the speaker’s voice.<\/p>\n\n\n\n
Use an attack time that allows the beginning of words to pass through naturally, and adjust the release so the gate doesn’t close abruptly between syllables. Listen carefully to the recording rather than relying entirely on the settings displayed by the software.<\/p>\n\n\n\n
If the dialogue sounds choppy or unnatural, try lowering the threshold, extending the release or reducing the amount of attenuation. Sometimes a gentle downward expander, which gradually reduces quieter sounds rather than closing abruptly, can produce a more natural result.<\/p>\n\n\n\n
A noise gate can be a useful finishing tool, but it isn’t a replacement for good microphone placement and a quiet recording environment. Positioning the microphone close to the speaker, controlling unwanted noise and recording at appropriate levels will generally produce better results than trying to repair everything afterwards.<\/p>\n\n\n\n