We’ve discussed how to dampen sound and how to minimize exterior noise from your home studio. But you can only put so many fingers in the dike. There’s a lot of noises to contend with. You may have to track them down one by one in order to get that noise floor under -50dBfs. But if you can get it down to at least -47, and its not at very audible frequencies, your chances of cleaning it up more seamlessly are good.
Here are some do’s and don’ts of filtering the background noise in post:
- Don’t use the “Clean Up” or “Remove noise” settings. They usually involve taking a sample of the noise and then eliminating everything within the range of that sample. The end result of that process is mangled audio that gets under-sampled and sounds like … you used a noise reduction filter. The truth is, that filter was really designed for cleaning up, “on the spot,” outdoor video scenes, where a reporter, interviewer or narrator or whatever is talking against the sounds of the city. Not for clear audio of a home studio.
- You can edit out the noise in the silent passages, or highlight them and reduce the volume about 15 dB. That usually will cancel out any beginning of word or end of word “whoosh..” But that takes time and skill. You really have to zoom in pretty close to make it clean.
- Here’s the best strategy. A properly set “noise gate.” The name is exactly as it implies. It lets every thing above a certain volume level to pass through the gate and back into your track. Anything below that threshold volume level, gets the gate shut on it, or at least squoze down to a less audible level.
- “Threshold,” or that magic level of “yes or no,” the level that opens or closes the gate. IF your have your noise floor measured down to -50, you set that threshold around -50 dB. (There’s a readout and you can input those numbers manually, or some platforms use a slider, or both.
- The “Attack” or how fast the gate closes. The faster the close, the less noise you’ll hear at the transition. However, the faster it is, the less “Seamless” it is. If words cut off to abruptly after applying the gate or testing it, you need to set the gate a slower. (In Milliseconds) I’ve found .55 milliseconds seconds optimal. Results may vary.
- “ Release.” Essentially ,the opposite of the “Attack.” How fast the gate opens to let sound above the threshold get to your hard drive. 100 ms is the setting I usually use. Save what works the most seamlessly, as a preset. Call it into action with a single click.
- “Ratio.” A setting that allows you to set how much the gated audio is reduced from the initial signal. A standard setting is 3:1. For every dB above that level, the compressor will reduce it by 3 x each dB. It makes for a smoother transition between opening and closing the gate. Some gates have that feature and some don’t.
With a smooth transition between the gated sounds and the audible ones, background noise is reduced or eliminated seamlessly, and you save yourself tons of editing time. But you have to set it properly to achieve that seamless sound.
Any questions for the Home Studio Master? Please ask away!