Topic: Is there a good way to smoothly hard-limit/de-amplify?

[acidjack]

I've been trying to use Audacity to edit an acoustic show. Have already read the FAQs w/r/t hard limit, but I don't think this was covered (apologies if I am forgetting).  Specifically, I have the problem of not only aud noise/cheering being higher between songs (which is easier to reduce) but also points in the music where, say, the idiot college girl behind me screams loudly, and her voice peaks well above the music.

I find the limiter works fine in both instances, but in both cases, there is an audible sort of transition where you hear the limiter kick in. I tried just lowering the amount of limiter used, but it seems I always get a bit of audible transition. 

I admittedly know nothing about the two selectors on there that don't have to do with dB - I believe "wet level" and "residue." Can playing with one of these make the limiter "phase in" or something more gradually, so that you don't hear the transition so abruptly in the recording?

[Brian Skalinder]

Depending on how severely you're limiting, there may not be a way to smooth the transition.  Have you tried compression and/or volume envelope?  They offer more control, which may allow you to achieve your desired results while maintaining smooth transitions.

[acidjack]

Depending on how severely you're limiting, there may not be a way to smooth the transition.  Have you tried compression and/or volume envelope?  They offer more control, which may allow you to achieve your desired results while maintaining smooth transitions.

Thank you so much - I hadn't, but I think compression is what I needed.  It seems smoother - still hear some transition, but it's better than limiter.

Thanks again.

[Gutbucket]

I ended up typing an entire wordy essay, during which you figured it out.  The compressor sounds smoother because it works over a larger range of the music's dynamics. A limiter cuts in harder and just effects the loudest peaks. But they are really two cousins. Like mallet and a ball-peen hammer.. so on to the essay:


I find that drawing in a volume envelope like Brian suggests is easier for me to get sounding right, if more time consuming to do.  The volume envelope is easy to understand and supremely suited for adjusting long duration events like louder applause or cheering between songs. It's still straight forward, but harder to get just right for screams, claps, or short sounds in the middle of a song.  Importantly, the volume envelope doesn't change the dynamic range of the music all the time like a limiter or compressor.  It only changes things when you move the curve up or down, by moving the entire dynamic range up and down and making everything louder or quieter. As long as the volume envelope is flat, the micro dynamics moment to moment in the music are unaffected, so it won't effect the sound at all between volume changes.

The two controls you mention are maybe a wet/dry mix control, and release ?

Attack and release controls effect how fast a compressor/limiter engages itself on loud events and how fast it reverts to not doing much.  The analogy to the volume envelope is how steep you draw in the envelope change, except usually a compressor is making many more changes than you would be drawing in. The sonic effect can be subtle (or not) and tricky to set right.  It effects how well the compression/limiting effect blends into the music and often effects the tone as well.  Getting that setting right can be the difference between hearing the compressor squashing the music and not noticing it doing it's work, for the same overall reduction of range.

I think the wet/dry mix is one of the coolest tools in a compressor for what we need.  A typical compressor is all dry- you only get the effected (squashed) sound out the other side. A 100% dry setting would be no effect at all, same as the input.  So why would that control be useful? Because with a 100% wet output the result is the compressor only doing it's work on the 'loud' parts. What it considers 'loud' is controlled by the threshold setting. The wet/dry control is a way to do what's called parallel compression - effectively mixing the compressor's output with the non-compressed signal.  Doing that lets the loud parts though again unsquashed. But if the threshold of the compressor is set so it is working more or less all the time, then the quiet parts are brought up in level by the squashing effect of the compressor making them louder.  Parallel compression effectively makes a compressor a bottom up tool instead of a top down tool.  That can sound more natural, possibly because it is doing less work on the major portion of the music.

[acidjack]

I ended up typing an entire wordy essay, during which you figured it out.  The compressor sounds smoother because it works over a larger range of the music's dynamics. A limiter cuts in harder and just effects the loudest peaks. But they are really two cousins. Like mallet and a ball-peen hammer.. so on to the essay:


I find that drawing in a volume envelope like Brian suggests is easier for me to get sounding right, if more time consuming to do.  The volume envelope is easy to understand and supremely suited for adjusting long duration events like louder applause or cheering between songs. It's still straight forward, but harder to get just right for screams, claps, or short sounds in the middle of a song.  Importantly, the volume envelope doesn't change the dynamic range of the music all the time like a limiter or compressor.  It only changes things when you move the curve up or down, by moving the entire dynamic range up and down and making everything louder or quieter. As long as the volume envelope is flat, the micro dynamics moment to moment in the music are unaffected, so it won't effect the sound at all between volume changes.

The two controls you mention are maybe a wet/dry mix control, and release ?

Attack and release controls effect how fast a compressor/limiter engages itself on loud events and how fast it reverts to not doing much.  The analogy to the volume envelope is how steep you draw in the envelope change, except usually a compressor is making many more changes than you would be drawing in. The sonic effect can be subtle (or not) and tricky to set right.  It effects how well the compression/limiting effect blends into the music and often effects the tone as well.  Getting that setting right can be the difference between hearing the compressor squashing the music and not noticing it doing it's work, for the same overall reduction of range.

I think the wet/dry mix is one of the coolest tools in a compressor for what we need.  A typical compressor is all dry- you only get the effected (squashed) sound out the other side. A 100% dry setting would be no effect at all, same as the input.  So why would that control be useful? Because with a 100% wet output the result is the compressor only doing it's work on the 'loud' parts. What it considers 'loud' is controlled by the threshold setting. The wet/dry control is a way to do what's called parallel compression - effectively mixing the compressor's output with the non-compressed signal.  Doing that lets the loud parts though again unsquashed. But if the threshold of the compressor is set so it is working more or less all the time, then the quiet parts are brought up in level by the squashing effect of the compressor making them louder.  Parallel compression effectively makes a compressor a bottom up tool instead of a top down tool.  That can sound more natural, possibly because it is doing less work on the major portion of the music.

Thanks.  That is also really helpful.  It seems that two rather basic conclusions to draw from this are:

1. Attack-release can be applied so that the compressor "fades in" a bit more by increasing the attack time - this way it will start working and ramp up in intensity. I think this would reduce some of the abruptness I heard in the limiter.

2. If I read you right, if you wanted to, say, reduce the screaming girl behind you, but not the acoustic guitar playing under her, you would make the compressor more "wet" - the compressor will push down the louder sounds above the threshold, thereby increasing the volume of the softer sounds.  Is that right?

The knowledge of folks on here is really phenomenal.  Thanks again. 

[Gutbucket]

Thanks.  That is also really helpful.  It seems that two rather basic conclusions to draw from this are:

1. Attack-release can be applied so that the compressor "fades in" a bit more by increasing the attack time - this way it will start working and ramp up in intensity. I think this would reduce some of the abruptness I heard in the limiter.

The attack setting as 'fade in' is conceptually correct, but happens so quickly that you don't really hear a fade.  Instead it effects how much of the intial transient of the sound gets through before the compression takes effect, changing the sound of things like the 'crack' of the snare, or the 'chime' of the guitar.  A limiter has the same adjustment, although it may be set differently in this case.  That could be what you are hearing or it may be that the compression ratio above the threshold is higher and takes place more abruptly with the limiter.

2. If I read you right, if you wanted to, say, reduce the screaming girl behind you, but not the acoustic guitar playing under her, you would make the compressor more "wet" - the compressor will push down the louder sounds above the threshold, thereby increasing the volume of the softer sounds.  Is that right?

Any form of compression reduces the difference between the loudest and softest sounds.  But it's a blunt tool that effects all the sound happening at that moment.  Try to squash the screaming and inevitably you squash the music too.  That's why taking the time to draw a volume envelope curve just right, listening and making small adjustments is usually most effective for me.  I try to work it so that it only effect the exact moment of the scream.

There are some new tools that seemingly do the impossible by allowing you to look at the  spectral image of the sound and draw boxes around coughs, screams and the like, if you can pick them out on the sceen, then reduce the level of just that portion of sound.  It's not fool proof but its the closet tool yet to do this sort of thing.  Like the simple volume envelope tool, it takes lots of time if she yells a lot.  Check out the demo of the Izotope RX plug-in among others.  Cool stuff.