Old 12-02-2014, 07:31 AM   #1
samsome123
Human being with feelings
 
Join Date: Jan 2012
Posts: 528
Default what is noise floor?

what is noise floor?
samsome123 is offline   Reply With Quote
Old 12-02-2014, 08:06 AM   #2
paterpeter
Human being with feelings
 
paterpeter's Avatar
 
Join Date: Oct 2010
Location: Germany
Posts: 204
Default

Quote:
Originally Posted by samsome123 View Post
what is noise floor?
See e.g. http://blog.prosig.com/2008/04/14/wh...dynamic-range/
Quote:
Any practical measurement will be subject to some form of noise or unwanted signal. In acoustics this may be background noise or in electronics there are often things like thermal noise, radiated noise or any other interfering signals. In a data acquisition measurement system the system itself will actually add noise to the signals it is measuring. The general rule of thumb is: the more electronics in the system the more noise imposed by the system.
Also, Wikipedia (http://en.wikipedia.org/wiki/Noise_floor):
Quote:
the noise floor is the measure of the signal created from the sum of all the noise sources and unwanted signals within a measurement system
To put it simple (in the context of recording): whenever you record something, you'll also record noise, that's unavoidable - preamps, mics, cables, electronics, digital quantization erros, all that adds noise. And all that unwanted stuff is your noise floor.

You'll ideally want the noise floor to be as low as possible by using good equipment and a quiet recording environment. With reasonable equipment, you can record something with a noise floor that is practically inaudible. However, processing (such as increasing gain) and having multiple recordings playing at the same time (let's say 15 tracks from a whole band) and can raise the noise floor considerably, so that's something to remember.

So you'll want the "real" signal that you record (voice, instruments, what not) to be reasonably "loud" compared to the noise floor (signal/noise ratio, SNR), because a loud signal will mask the underlying quieter noise and you don't need to raise the gain afterwards (increasing the noise level, too). NB: this doesn't mean you need to record "in the red", because that brings a whole slew of other problems (distortion, clipping). It's just not a great idea to record a signal at e.g. -60dBFS if your noise floor already sits at -80dBFS.

There's also a digital noise floor in the sense that there's finite dynamic range in digital signals. E.g., a 16 bit recording has ~96dB dynamic range, so there's an inherent kind of noise floor at -96dBFS. Well, I'm not so sure if this can be called a noise floor, but it's practically the same thing I suppose.

Last edited by paterpeter; 12-02-2014 at 08:23 AM.
paterpeter is offline   Reply With Quote
Old 12-07-2014, 09:55 AM   #3
DVDdoug
Human being with feelings
 
Join Date: Jul 2010
Location: Silicon Valley, CA
Posts: 2,779
Default

Quote:
There's also a digital noise floor in the sense that there's finite dynamic range in digital signals.
The digital noise floor is real. There is something called quantization noise, and you can hear it at 8-bits.

But the difference is that quantization noise is on top of the signal and it's not there when there is no signal or data. Digital silence is absolutely silent at 8-bits, 16-bits, or 24-bits. But if you have a quiet signal at 8-bits the quantization noise becomes immediately apparent.
DVDdoug is offline   Reply With Quote
Old 12-07-2014, 11:40 AM   #4
whiteaxxxe
Banned
 
Join Date: Jul 2014
Location: United States of Europe, Germany, Mönchengladbach
Posts: 2,047
Default

Quote:
Originally Posted by paterpeter View Post
To put it simple (in the context of recording): whenever you record something, you'll also record noise, that's unavoidable - preamps, mics, cables, electronics, digital quantization erros, all that adds noise. And all that unwanted stuff is your noise floor.
nitpicking: this isnt exactly right. preamps (maybe), mics, cables and all that stuff doesnt add noise. they pick up noise. they pick up the noise that comes from the Big Bang, 13.7 trillion years ago. its the garbage, that was left over is still floating around. so to be exactly you have to blame our universe for the noise.

just saying. we are stardust as is the noise a byproduct of stardust, or we are a byproduct of the noise. dont know, ask Stephen Hawking or Brian May.
whiteaxxxe is offline   Reply With Quote
Old 12-07-2014, 11:53 AM   #5
cerendir
Human being with feelings
 
cerendir's Avatar
 
Join Date: Jun 2007
Location: Sweden
Posts: 2,003
Default

Quote:
Originally Posted by whiteaxxxe View Post
the Big Bang, 13.7 billion years ago
While we're nitpicking, I fixed that for ya
__________________
mattiaswestlund.net | facebook | soundcloud | bandcamp
cerendir is offline   Reply With Quote
Old 12-07-2014, 01:30 PM   #6
karbomusic
Human being with feelings
 
karbomusic's Avatar
 
Join Date: May 2009
Posts: 29,260
Default

Quote:
they pick up the noise that comes from the Big Bang, 13.7 trillion years ago.
Well if we are going to be picky, only about 1% of that noise is from the Big Bang. Any electrons that are moving (and they all are) create noise.

To the OP... The noise floor is everything there that isn't the main signal. It's usually the lowest sound there (hopefully at least). The distance between that noise floor and main signal is the SNR - Signal to Noise Ratio or more simply stated how far away the signal is from the noise, the farther the better and once far enough away, it becomes irrelevant.
__________________
Music is what feelings sound like.
karbomusic is offline   Reply With Quote
Old 12-08-2014, 11:08 AM   #7
Kihoalu
Human being with feelings
 
Join Date: Jan 2007
Location: Silicon Gulch
Posts: 544
Default

Quote:
Originally Posted by samsome123 View Post
what is noise floor?
It is whatever floor I am standing on when I try to play music!

(sorry, could not resist)

.
__________________
Inundated by a Perfect Storm of Gluten-Free Artisanal Bespoke Quinoa Avocado-Toast Toilet Paper.
Mahope Kakou (Later Dudes)...
Kihoalu is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -7. The time now is 10:44 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.