Comparing high and low frequency decibel readings

[Fuzzie]

I tried to reopen an old thread (http://www.woodworkforums.com/f11/decibel-comparison-formula-96562/)but couldn't find the button to acknowledge the original post was old so I'm starting a new thread but not sure what forum it is really relevant to so I'm popping it here.

The old thread contains some relevant info on comparing decibel measurements.

I have been looking at an Android Sound Meter app and trying to work out how useful these are for measuring nuisance noise. When playing around for comparisons I note that deep base sounds that travel long distances don't seem to register on the android app. I assume that may be because of some issues with the tablet mic which might be optimized for voice, but it leads me on to this question:

How do you compare decibel readings across the audible range hi freq vs low freq? Sounds from sub woofers can be very annoying at distance, would they therefore be expected to read high on a decibel meter?

[BobL]

How do you compare decibel readings across the audible range hi freq vs low freq? Sounds from sub woofers can be very annoying at distance, would they therefore be expected to read high on a decibel meter?

Using specialised gear sound pressure levels can be measured at any frequency or frequency range with the result often expressed as a function. Comparison from an average human perspective is possible by applying average human ear response functions at specific frequencies ie if the ear is 50% more sensitive at frequency X than Y then one is scaled to the other. Sound pressure levels across the range of human hearing is usually handled using the dBA and dBB weighting filters

see wikipedia (Decibel - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Decibel))

dB(A), dB(B), and dB(C)<dl style="margin- 0.2em; margin-bottom: 0.5em; color: rgb(0, 0, 0); font-family: sans-serif; line- 19px; "><dd style="line- 1.5em; margin- 1.6em; margin-bottom: 0.1em; margin-right: ">These symbols are often used to denote the use of different weighting filters (http://en.wikipedia.org/wiki/Weighting_filter), used to approximate the human ear's response (http://en.wikipedia.org/wiki/Stimulus_(psychology)) to sound, although the measurement is still in dB (SPL). These measurements usually refer to noise and noisome effects on humans and animals, and are in widespread use in the industry with regard to noise control issues, regulations and environmental standards. Other variations that may be seen are dBA or dBA (http://en.wikipedia.org/wiki/A-weighting). According to ANSI standards, the preferred usage is to write LA = x dB. Nevertheless, the units dBA and dB(A) are still commonly used as a shorthand for A-weighted measurements.</dd></dl>

And here : Weighting filter - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Weighting_filter) for the specific functions

[pmcgee]

I tried to reopen an old thread (http://www.woodworkforums.com/f11/decibel-comparison-formula-96562/)but couldn't find the button to acknowledge the original post was old so I'm starting a new thread ...



"This Thread is more than 1408 days old, to reply to it you need to click in the box above the Post Reply button stating you aware this is an old thread, but want to reply anyway. You may need to go back to your reply, to do this use your back button."

I believe you are correct - I can't see it there. I've added to old threads before - I think it's a bug.

Cheers,
Paul

[RETIRED]

"This Thread is more than 1408 days old, to reply to it you need to click in the box above the Post Reply button stating you aware this is an old thread, but want to reply anyway. You may need to go back to your reply, to do this use your back button."

I believe you are correct - I can't see it there. I've added to old threads before - I think it's a bug.

Cheers,
Paul http://www.woodworkforums.com/f36/replying-old-thread-reply-167870/