Decibel/ volume reader

Help for Audacity 2.x.x on Windows.

ImageThis forum is for Audacity 2.x.x on Windows.
Please state which version of Windows you are using,
and the exact three-section version number of Audacity from "Help menu > About Audacity".


Audacity 1.2.x and 1.3.x are obsolete and no longer supported. If you still have those versions, please upgrade at https://www.audacityteam.org/download/.
The old forums for those versions are now closed, but you can still read the archives of the 1.2.x and 1.3.x forums.

Re: Decibel/ volume reader

Permanent link to this post Posted by steve » Sun Feb 18, 2018 2:09 pm

"dB" is not a unit of measurement.
"cm", "kilogram", "dollar", "degrees centigrade" etc are all units of measurement, but "dB" is not.

"dB" is a "ratio". It is a comparison of one magnitude to another. A measurement in "dB" says how big something is compared to something else.

When working with signal levels *as in Audacity", the reference level is "full scale", which in Audacity's case is the hight of a track.
The reference level when working with "dB" has the number 0 (zero). Thus, a waveform that touches the top or bottom of an Audacity track has a level of 0 dB.

Audio waveforms should normally be less that the track height. In other words, less than 0 dB, so normal waveforms in Audacity have negative (less than zero) dB levels.

When measuring the intensity of "sound", a "dB meter" is commonly employed. The reference level (0 dB) for audio dB meters is normally specified as "20 micropascals", which is equivalent to "0.98 pW/m2 at 1 atmosphere and 25 °C". This figure is nominally the "threshold of hearing" - for someone with excellent hearing, sound pressure levels for a frequency of 1 kHz greater than 20 micropascals will be audible, but below 20 micropascals will not be audible. Audible sounds always have a SPL (sound pressure level) greater than 0 (otherwise they would be inaudible (subjectively "silent").

There is no direct numerical relationship between signal level in Audacity and the loudness of the sound (sound pressure level), because the sound pressure level depends on how high your amplifier is turned up and the sensitivity of your headphones / speakers etc.
9/10 questions are answered in the FREQUENTLY ASKED QUESTIONS (FAQ)
steve
Site Admin
 
Posts: 47011
Joined: Sat Dec 01, 2007 11:43 am
Operating System: Linux *buntu

Re: Decibel/ volume reader

Permanent link to this post Posted by kozikowski » Sun Feb 18, 2018 2:49 pm

If you're talking about live performances, that's in Sound Pressure Levels or SPL. You can measure that with an SPL meter.

Image

And yes, those values do go positive. In that example, the knob is set for 90, so "0" on the meter is +90dBSPL. That's the one you use when you see statements like jet engine noise is some value of loudness.

A and C are "weighing." "A" responds much like human hearing with limits on really high and really low pitch. "C" is flatter and measures almost everything,

"A" is generally called out in hazard exposure measurements and regulations.

Koz
kozikowski
Forum Staff
 
Posts: 40176
Joined: Thu Aug 02, 2007 5:57 pm
Location: Los Angeles
Operating System: OS X 10.9 Mavericks

Re: Decibel/ volume reader

Permanent link to this post Posted by kozikowski » Sun Feb 18, 2018 3:00 pm

You know what A is. That's fingernails on blackboard and baby screaming on a jet. That's A weighing.

Koz
kozikowski
Forum Staff
 
Posts: 40176
Joined: Thu Aug 02, 2007 5:57 pm
Location: Los Angeles
Operating System: OS X 10.9 Mavericks

Re: Decibel/ volume reader

Permanent link to this post Posted by Toolless » Sun Feb 18, 2018 7:53 pm

Im just not getting this at all, it has no reference to any thing ells
1. my chainsaw has 113 db marked on it
2. this TV recording rates it at 105 db https://www.youtube.com/watch?v=I4jdGf3RzCs

Anyway I find the whole Audacity program far to complicated then it needs to be and It's just not a very usable friendly program

Toolless
Toolless
 
Posts: 10
Joined: Fri Feb 16, 2018 3:02 pm
Operating System: Windows 10

Re: Decibel/ volume reader

Permanent link to this post Posted by steve » Mon Feb 19, 2018 12:15 am

Toolless wrote:1. my chainsaw has 113 db marked on it
2. this TV recording rates it at 105 db https://www.youtube.com/watch?v=I4jdGf3RzCs

Those markings are probably "dB SPL" (Sound Pressure Level: reference 20 micropascals).

Let's say you recorded the chainsaw with the microphone placed 1m away from the chainsaw, and adjusted the recording level so that the sound recorded at "full scale" in Audacity.
The "signal level" in Audacity would then be "0 dB" with reference to full scale.

Now let's say that without changing any settings, you move the chainsaw 1 km away from the microphone, and record again.
Obviously the recording level in Audacity is going to be tiny.

Now let's say that you bring the chainsaw back up to 1 m from the microphone, but turn down the recording level to 0.1. Again the signal level in the recording will be low.
In all cases, the "sound pressure level" of the chainsaw is the same, but the recording level varies depending on lots of things, including the recording settings, the sensitivity of the microphone, the distance between the microphone and the sound source ...

Toolless wrote:Anyway I find the whole Audacity program far to complicated then it needs to be and It's just not a very usable friendly program

Regardless of the simplicity or complexity of the program, physical properties remain the same - there is no direct correlation between signal level and sound pressure level.
9/10 questions are answered in the FREQUENTLY ASKED QUESTIONS (FAQ)
steve
Site Admin
 
Posts: 47011
Joined: Sat Dec 01, 2007 11:43 am
Operating System: Linux *buntu

Re: Decibel/ volume reader

Permanent link to this post Posted by kozikowski » Mon Feb 19, 2018 12:47 am

I find the whole Audacity program far to complicated then it needs to be and It's just not a very usable friendly program

You should probably find a different program.

Koz
kozikowski
Forum Staff
 
Posts: 40176
Joined: Thu Aug 02, 2007 5:57 pm
Location: Los Angeles
Operating System: OS X 10.9 Mavericks

Re: Decibel/ volume reader

Permanent link to this post Posted by Toolless » Mon Feb 19, 2018 4:24 am

You see to 9 out of say 10 people who use this program will most probably not be sound engineers (like myself)
So can you tell me if it is posible for the sound meter to messure "db spl 20 micropascals (of say) 100 db or not?


kozikowski wrote:
I find the whole Audacity program far to complicated then it needs to be and It's just not a very usable friendly program

You should probably find a different program.

Koz

When I first looked, all I wanted is something simple; that would allows me to record my voice over a backing track. I looked online and found nothing even as simple as this easy to find. Audacity was the only option. Although when I first started using the program it was a lot more complicated back then even trying to save a file (render and import mp3 stuff). But now it is a lot more easyer to use but it is still a long way off from todays standards of plug and play
Toolless
 
Posts: 10
Joined: Fri Feb 16, 2018 3:02 pm
Operating System: Windows 10

Re: Decibel/ volume reader

Permanent link to this post Posted by kozikowski » Mon Feb 19, 2018 5:37 am

it is still a long way off from todays standards of plug and play

True, but we also have many users that need good technical sound editing and services that can match other programs, and we only have enough developers to make one program.
So can you tell me if it is posible for the sound meter to messure "db spl 20 micropascals (of say) 100 db or not?

You can make a sound meter like mine do that. It's no longer available with the collapse of Radio Shack.

You can't easily cross between the sound pressure readings in the air and the digital sound readings inside the computer. That's the hard part.

Are you trying to work around legal regulations for high volume hazards? Those all require an A reading SPL meter. You can't do it in Audacity.

Koz
kozikowski
Forum Staff
 
Posts: 40176
Joined: Thu Aug 02, 2007 5:57 pm
Location: Los Angeles
Operating System: OS X 10.9 Mavericks

Re: Decibel/ volume reader

Permanent link to this post Posted by steve » Mon Feb 19, 2018 10:53 am

Toolless wrote:So can you tell me if it is posible for the sound meter to messure "db spl 20 micropascals (of say) 100 db or not?

In Audacity you can measure the level of the "signal".

How big that signal is in relation to the "sound" depends on many factors, including microphone sensitivity, microphone placement (microphones are often directional), how much the sound card amplifies the microphone signal, and your recording settings. A program running on your computer (any program, not just Audacity) has no idea what sort of microphone you are using, whether or not it is directional, how much amplification the microphone pre-amp is applying, or anything that is external to the software.

So there is no way for any software to directly measure sound pressure level.

To measure sound pressure level with software, you need to have a calibrated system, where the characteristics of the microphone, pre-amp and settings are known to the software.
9/10 questions are answered in the FREQUENTLY ASKED QUESTIONS (FAQ)
steve
Site Admin
 
Posts: 47011
Joined: Sat Dec 01, 2007 11:43 am
Operating System: Linux *buntu

Re: Decibel/ volume reader

Permanent link to this post Posted by kozikowski » Mon Feb 19, 2018 2:55 pm

kozikowski
Forum Staff
 
Posts: 40176
Joined: Thu Aug 02, 2007 5:57 pm
Location: Los Angeles
Operating System: OS X 10.9 Mavericks

PreviousNext

Return to Windows



Who is online

Users browsing this forum: Bing [Bot] and 18 guests