AVS Forum banner
1 - 6 of 6 Posts

·
Registered
Joined
·
28 Posts
Discussion Starter · #1 ·
I often see statements such as "My system will easily reach 105 dB in my 2600 cu ft room."


I have a Radio Shack dB (or is it SPL) meter which makes it easy enough to read the relative dB difference between speakers, etc. But what exactly am I measuring in absolute terms? Would zero (if the meter went that low) mean the total absense of any sound?


With nothing turned on in the room except the HVAC, my computer (which has the cover off right now so it's a bit loud for a computer), and a lamp the meter reads about 55 dB at a distance of four feet from the computer and pointed toward the ceiling. Does that sound about right?
 

·
Registered
Joined
·
30,788 Posts

Quote:
Originally Posted by HenryPercy /forum/post/16911494


I often see statements such as "My system will easily reach 105 dB in my 2600 cu ft room."


I have a Radio Shack dB (or is it SPL) meter which makes it easy enough to read the relative dB difference between speakers, etc. But what exactly am I measuring in absolute terms? Would zero (if the meter went that low) mean the total absense of any sound?


With nothing turned on in the room except the HVAC, my computer (which has the cover off right now so it's a bit loud for a computer), and a lamp the meter reads about 55 dB at a distance of four feet from the computer and pointed toward the ceiling. Does that sound about right?

Seems pretty noisy to me but a lot depends on the frequency spectrum of the noise. Adequate low levels for home theater should be NCB 25 or less but that is a curve designation. 0dB would mean that the noise is at the threshold for human detection but under controlled conditions.
 

·
Registered
Joined
·
28 Posts
Discussion Starter · #3 ·

Quote:
Originally Posted by Kal Rubinson /forum/post/16911532


Seems pretty noisy to me but a lot depends on the frequency spectrum of the noise. Adequate low levels for home theater should be NCB 25 or less but that is a curve designation. 0dB would mean that the noise is at the threshold for human detection but under controlled conditions.

Ok, that's helpful, but what is NCB?
 

·
Registered
Joined
·
3,937 Posts
25 db is great for room noise, but very difficult for anyone without room treatments of some sort. Taking a wild guess, completely wild off the top of my head, a new construction house with adequate insulation will probably still only get 35 or 40 db on the low end. You have to remember that 55 db is still very quiet, but even that level eats into your system dynamics.
 

·
Registered
Joined
·
30,788 Posts

Quote:
Originally Posted by brandonnash /forum/post/16913462


25 db is great for room noise, but very difficult for anyone without room treatments of some sort. Taking a wild guess, completely wild off the top of my head, a new construction house with adequate insulation will probably still only get 35 or 40 db on the low end. You have to remember that 55 db is still very quiet, but even that level eats into your system dynamics.

Yes and, because the rating is frequency-variable, it is hard to assess with a regular SLM, even if it is sensitive enough.
 
1 - 6 of 6 Posts
Top