Help with RMS and noise floor

Hi there,

Each one of my files must have a noise floor no higher than -60dB RMS. Where exactly do I set this? Is this in the stereo/mono switch? I think I may have to re-record some stuff, darn it.

When you’re done with a file, what is the best way thru Audacity to remove any extraneous sounds ?

Thank you!

Each one of my files must have a noise floor no higher than -60dB RMS. Where exactly do I set this?

It’s best to set it by purchasing quiet equipment and then recording in a quiet, echo-free room. If you have traffic noise, record after midnight. If your noise is hiss (fffffff), it’s possible you’re going to have a bad day.

Record a 10 second mono test clip in your normal announcing style with the red sound meters peaking about -6. The first two seconds should be holding your breath and not moving at all (noise test).

Do Not apply filters or effects. We need a raw clip. Post it here.


Hi–here is my sample.

I think it might be the room. I need to find less echo then. Into the closet I go, I guess.

Thank you for listening


Into the closet I go, I guess.

That’s exactly what Ian did. He has the longest thread in the forum history. He took over a broom closet and set up shop in there to get away from traffic on La Brea Ave in Los Angeles. That’s only the isolation part. You also have to get rid of the “tight” sound by soundproofing the walls and floor.

He used actual, formal soundproofing panels. I’ve been known to do similar tricks with furniture moving pads.

I haven’t heard your clip yet.

As we go.


Open up the clip you sent and turn on View > Show Clipping. Those three or four blasts of red on the timeline are overload points. It’s too loud. The sound will be a little crunchy…and it’s permanent. Overload is one of the good ways to kill your show.

I’m very concerned with what the clip sounds like. If you didn’t do any effects or filters to it, then the computer may be trying to “help you.” The noise segment has odd ‘talking in a wine glass’ sound and your voice is changing volume. I don’t think you’re doing any of that intentionally.

So before you start throwing coats and umbrellas on the floor, let’s get basic recording down.

Some Windows machines have other effects as well. Check in the control panels. I got stuck inspecting a Win7 machine that had sound effects running and nobody told me. None of the quality sound tests worked and I couldn’t figure out why.

Here’s an Audacity setup I’m developing. Right now, it’s only a response to another poster trying to pass ACX sound compliance.


Hello again!

Ok, I went into the closet. I put up some stuff and made it quiet. Can you please check this sample now for noise floor.

However, I do not know about this overload stuff. I read the links you sent but I don’t have any effects or anything.


Ok–this one is better.

I saw your other post about making the monitor part way bigger and was able to modulate my voice. However, it does bounce slightly over -6 a couple of times. Here’s a better clip.

Is there a way to put that as a ceiling?


Oh hey–that screen in front of the mic in the picture in this thread–does that help the noise floor or just the harsh letters?


I think the Pearl Harbor clip is close enough. The -6 recording thing is a worthy goal not a law. Nobody is going to come out with a stick and hit you if you go a little over. DO NOT go all the way up to 0. We picked -6 as a good compromise between overload (too high), noise (too low) and theatrical expression (too high and too low).

I’m generating a correction list for that last clip. Remember how you shot it.

You don’t have P Popping or other voice errors to need that blast filter… like this:

As we go.


Here is the corrected clip. As near as I can tell, it’s ACX Compliant and without a whole lot of work. You need to tell us how you’re shooting this when you get done. I’m making the recipe.

A little salt, a little pepper…


Pearl Harbor Correction

Do this to the clip to make sure we get the same results. You will need to install Steve’s special voice filter into the Equalization tool. Your microphone does something really wacky down in the earthquake tones and Steve takes care of it nicely.

Select the whole clip by clicking just above the MUTE button.

Install special voice filter: (Attached)
Decompress that zip file into LF_rolloff_for_speech.xml
Effect > Equalization > Save/Manage Curves > Import… find and select LF_rolloff_for_speech.xml
Back in the equalizer: Select Curve > LF_rolloff_for_speech
It should look like the picture attachment. Don’t forget to push the Length all the way up.

Effect > Normalize > [X]Normalize to -3 [X]Remove DC

Effect > Compressor:
Threshold -20
Noise -40
Ratio 2:1
Attack 0.2
Release 1

Effect > Normalize (again) > [X]Normalize to -3 [X]Remove DC

The noise is in the -70s, the sound peaks are at -3 and the overall RMS (loudness) is -23.2 which is a teensy fraction off standard.


Screen Shot 2015-02-09 at 17.52.16.png (326 Bytes)

I’m assuming that noise at 9 seconds is you dropping something on the table. Hopefully.

Oh, I cannot thank you enough.

I’m not doing anything special with the recording. I don’t do anything with Audacity but press record.

Let me play a little with it all and then I’ll write again here.

Thanks. It will just take some getting used to actually speaking correctly into the mic.


What do you mean by “push the Length” all the way up?

Lower right. Length of Filter slider in the equalization panel.

We kind of need an answer. Can you account for those noises at 9 seconds?


Gosh, I don’t know what those sounds were at 9 seconds–it must have been something in the room. I don’t remember doing anything. Do you want me to record another cleaner one?

You don’t need to post it, but yes. Record a longer piece and make sure your system is not clicking or popping by itself. That can be a very serious problem on some machines.


Hi there–sorry about the delay–work has been crazy this week.

Ok, here is a newly recorded Pearl Harbor clip and then I did all the things you told me to do. I still don’t exactly see the LENGTH ALL THE WAY UP thing in my Audacity 2.0.6–there’s nothing in my lower right on the screen.

When I was recording, I was sure to stay under -6 on those red bars, but once I applied all this stuff, now it seems to go to -3.

Thanks again for your help!!

Hi again–

I may have to record this hour and a half book all over–I’m ok with that–but I thought I would post this link to chapter 3 and see if it is fixable.

Probably is not–this is before I went into the closet. I talked really loud and I know it is FAR above the -6.

Thanks for all the help!

Oh THAT’S where the length of filter is–I found it–it’s on that equalization where I add the noise rolloff you helped me download.