I have recorded a sound file, in a factory office, and I get a lot of background nioses. All background noise weak, and under -40 decibel. Is it possible to just drop all sound wave that is not reaching -40 decibel or louder?
Audacity 1.3.x
In the “Effects” menu - “Truncate Silence”
[“Unfortunately, this effect can only be applied to Mono sounds files.
Stereo files will need to be reduced to Mono before this effect can be utilized.”]
A reading from a help web site.
I’m betting you’re not going to like the effect anyway. It’s easy to overdo noise removal and get other nasty things happening instead.
While you’re in Audacity 1.3, have you tried the noise reducer? That one has some serious adjustments available and can be made to sound way better than you think.
Koz
In Audacity 1.3.4 “Truncate Silence” works on mono or stereo files. The “Maximum Silence Duration” setting is the maximum length of “silence” (below the threshold level) that is allowed without truncating, so for example, with a threshold set at -40 dB and a Maximum Silence Duration of 500 milliseconds, any quite regions (below -40 dB) that are longer than 500 milliseconds (half a second), will be trimmed down to half a second.
<<<In Audacity 1.3.4 “Truncate Silence” works on mono or stereo files.>>>
Cool.
<<< the maximum length of “silence” (below the threshold level) that is allowed without truncating>>>
As I read the posting, the author recorded a show in a noisy room and wants the room noise to vanish when anyone loud stops talking. I maintain firmly that dipping the low parts of the performance to zero isn’t going to work. The software will do that, but parts of the room will leak through during words and give a very other-worldly effect. The other thing that will happen is the tool will cut the ends from words giving a very choppy sound. The word “rinse” will end up “rin…” because the “s” sound will fall below the threshold.
There was a commercial product called “Keypex” which did this in hardware. Everybody bought one and used it once. It’s also called “level dependent keying.”
There are no easy ways to rescue a performance in a noisy room. It’s usually a lot of work to get poor results.
Koz
Yes, I was also unsure about what exactly he was asking, but from “Delete sound under -40 db” I took it to mean “Delete” rather than “Mute”.
What effect were you thinking of using? “Noise Removal” with a fairly extreme setting, or do you know of a “noise gate” plug-in? I agree that “muting” everything under 40dB is going to sound rough.
There is a LADSPA plug-in called “Hard Gate” which would do the “muting below 40dB”, but it sounds very rough, particularly as it has a zero attack and decay time which causes a huge amount of cross-over distortion (may be useful as a distortion effect though).
Is that the same as a noise gate? i.e. downward expansion below a threshold?
<<<Is that the same as a noise gate? i.e. downward expansion below a threshold?>>>
Yes, that’s it.
“Don’t worry about the room noise, we can fix it in post.”
Maybe you can fix it in post production. I’m going home. Call me if you get anything working.
[confident of full night’s sleep]
Koz
stevethefiddle wrote:
What effect were you thinking of using? “Noise Removal” with a fairly extreme setting, or do you know of a “noise gate” plug-in? I agree that “muting” everything under 40dB is going to sound rough.
I just want to mute sounds under -40 db. But maybe that is not the right way of doing this. I have tried “Noise Removal”, but the problem is that this effect takes away to much of the sound. Even important parts of the speakers voice. Is there any other effect that I could work with, to solve this problem?
Oh, OK. In that case the effect that you need is called a “Noise Gate”, but there are 2 problems with this:
- As koz indicated, if there is enough background noise that you need to use one, then the results are likely to sound awful because of the amount of background noise present in the parts that are not gated. The sound that you want to keep will still have background noise present and it will produce a weird “chopped up” kind of sound as the background noise stops and starts.
- I don’t know of any noise gate plug-in for Audacity except for the “hard gate” which also introduces a lot of distortion.
The preferred method is to record in a quiet room.
OK, now that you’re whimpering and bleeding in the corner, why is the room noisy? The kind of noise makes an enormous difference as to appropriate tool. If you’re trying to pull one conversation out of a lot of them, you’re dead. If you’re competing with air conditioning noise, there are ways out of that.
Koz