Establishing your sound floor

Joe Whistler

There are a lot of references to getting the sound floor as quiet as possible, with target floors around the -70db to -80db mentioned as something to strive for.

Unless I've missed it in my searches, I've not found any suggestions as to just how to establish what your current floor level actually is.

Is it a simple matter of turning your mic on, recording the room noise, and reading the waveform levels?

Maybe it is just that simple, but don't want to miss the not-so-obvious.

Any specific tips or recommendations on this?

Thanks!

Joe Whistler

Sometimes I think one word, but another one comes out... I meant to ask about how to determine what your noise floor level is.

Sorry for the confusion.

Tom Greenlee · Posted: Tue Feb 06, 2007, 19:34 (GMT) Post subject:

I don't know about other programs, but Adobe Audition 2 has a db meter at the bottom of the screen. If you record total silence with your open mic and read your db meter you can see what your noise floor is. Mine fluctuates from -62 to -65 db

Todd Ellis · Posted: Tue Feb 06, 2007, 19:50 (GMT) Post subject:

A quick addendum to what Tom wrote - make sure you set your mic level at your normal "record" position. Don't be tempted to "cheat" by potting down a bit. Usually I do mic & master @ 12 O'Clock. I'm at a pretty constant -63db. AS far as I know, -70db is complete silence. Is that right? At least what we can hear?

Amy Snively · Posted: Tue Feb 06, 2007, 20:14 (GMT) Post subject:

I'm right at -63/-64 also.

George Karnes · Posted: Tue Feb 06, 2007, 20:40 (GMT) Post subject:

Dang that is a cool trick Tom!

Mine is -61db to -64db. I wonder if that is breathing?

Except when one of my kids runs across the floor directly above me then it jumps up to -57-8db or so.

Is this exceptable? Is this a "real" measurement?

Also, now that I am using headphines, I am starting to nitice more reflection from the walls. I have put some camping foam around the room, but it is only helping a little. How important is placement on that stuff?

Tom Greenlee · Posted: Tue Feb 06, 2007, 20:46 (GMT) Post subject:

George....from everything I've gathered, if you can achieve -60db or greater, you are doing really well and as far as noise floor goes you have no worries about your work not being acceptable. I have heard that depending on the job, if it is areally high end client and the vo is going to be used straight with no music bed etc. that -60 may not be good enough, but in that case you would be best off booking a studio anyway or probably would be required to go to theirs. I don't know alot about foam, but I DO know that placement is key. There are very strategic places that foam needs to be placed.

George Karnes · Posted: Tue Feb 06, 2007, 20:50 (GMT) Post subject:

Tom-
Thanks!
Do you know how to figure out that placement?

Tom Greenlee · Posted: Tue Feb 06, 2007, 20:59 (GMT) Post subject:

no....sorry George. I have seen diagrams, but off the top of my head I can't remember where.

George Karnes · Posted: Tue Feb 06, 2007, 22:10 (GMT) Post subject:

No problem...google hear I come....

Lynne Alston · Posted: Tue Feb 06, 2007, 23:41 (GMT) Post subject:

How do I figure out the noise floor using pro- tools, I thought I was doing well with the on/off and editing, now I have no clue where the db might be when recording silence. oh, and of course a visual would be helpful!

Chuck Douglas · Posted: Fri Feb 16, 2007, 04:30 (GMT) Post subject:

This is the simplest thing to measure. Record a file at your usual settings. Normalize it to 0db, then loop the sections of silence. The VU reading is your "relative" noise floor, which is really the important one. A little of this depends upon how loud of a talent you happen to be, but basically the -70db number is about the best you are going to get without some serious deadening of early reflections and isolation from the outside world.

If you ears are not ringing, it is nowhere near -70. Trust me on this. I have a booth that reads -75db or so, and when you shut the door, it feels like somebody is pulling the insides of your ears out with a q-tip covered in rubber cement. Then all you hear is yourself, your heartbeat, your tunnitus (sp?), your breathing. Untill the cans are on, you feel very uncomfortable.

The simplest treatment of a room is to take a corner, cover each wall floor to ceiling, and the ceiling too with some kind of dense sound absorption foam. Flooring can be almost anything, but carpet works well. Stick the mic as far into the corner as you can, pointing out towards the room. Then record, close miking on a hyper-cardiod setting if you can. It sounds ass backwards, but it works.

To make it much better, you can create some kind of wall that you can move. This is called a gobo. Cover it with the same foam on both sides, and prop it up to make a triangle with the corner that the mic sits in. Squeeze yourself in there, turn off the TV, muzzle the neighbors dog and unplug the fridge, and you may be able to get a good -60 out of it.