intensity level in dB

Audacity 3 Help Forum Windows
1

I am using Audacity 2.0.3.
I have generated the noise with different amplify values from 0 to 1.
Is there any way to assess the generated noise level in dB

2

There are many different ways to measure dB. If you mean the “peak dB” with reference to “full scale” (so that a peak level of 1.0 on the linear scale is 0 dB) then you can measure it in the following way:

  1. Select the noise that you want to measure.
  2. Open the Amplify effect (Effect menu)
  3. The “Amplification (dB)” figure in the Amplify effect is the number of dB below zero, thus if it says “1.9 dB” then the selection has a peak amplitude of -1.9 dB.
3

We might need a better understand of what you are trying to do…

Decibels need a reference. In the “digital world”, 0dBFS (zero-decibels full-scale) is essentially the “digital maximum”. i.e. there is a limit to how high you can “count” with 16-bits or 24-bits, etc, and with digital audio 0dBFS represents that number. We don’t usually include the “FS”, but its implied.

In Acoustics (sound we hear) we measure in dB SPL (sound pressure level). In that case, 0dB SPL represents (approximately) the quietest sound humans can hear (under ideal super-quiet conditions).

In order to “calibrate” the digital DBFS level with the dBSPL level, you need a loudness meter (SPL meter). So for example, if you measure 80dB SPL with your SPL meter when you play a 0dBFS tone in Audacity, you can reduce the volume to -6dB in audacity, and you’ll have 74dB SPL in your ears. (Of course if you touch the volume control, everything changes.)

“Loudness” (human perception) gets really tricky… You can have a quiet-sounding song with 0dBFS peaks, and a loud sounding song with peaks lower than 0dB. Loudness is more-related to the average (or short-term average) than the peak.

On top of that, our hearing is not “'flat”. A mid-frequency 0dB tone will sound louder than a low-frequency or high-frequency 0dB tone. (If you have high power amp, be careful experminting with with loud high-frequency test-tones… You can fry a tweeter and you might not even hear the tone!) And, the ear’s “frequency response” is different at different loudness… It becomes more-flat at higher volumes.

4

Or you can do it the way we used to do it. Display the noise on a bouncing sound meter and optically average out the bouncing with your eyes.

“That’s about -43 or so. What do you get?”

http://kozco.com/tech/audacity/Audacity1_playback.jpg

Obviously you need to make the meters jumbo to do that. On some of the older sound meters it was the only way to do it.

Koz