| Just to be pedantic about the meaning of dB [Re: Lovebird screeching] - CLICK HERE for the Pet Manual Forum Home Page |
| Bob Blaylock |
In article <dqqt00lvcdqg9cilugr70nhnt5r3a1j381@4ax.com>,
Jerry Minasi <jminasi@loptonline.net> wrote:
> We Have a beautiful LoveBird but her screeching is driving us crazy!
> She's very tame and we let her out of her cage often. the problem is
> that she will sit on my shoulder and screech, at about 10 DB's, into
> my ears!
Of course you probably know little about acoustical measurements, but
10 dB (in the conventional use of dB as a unit of sound measure*) is
barely enough to be noticable.
Quiet human speech, at a distance of 1 meter, is around 54 dBA re 20
uPa.
The "discomfort threshhold" for humans is around 114 dBA.
The quietest level that Radio Shack's top-of-the-line sound level
meter can measure is 50 dB. This is the level of sound about 500 meters
from an average jet airliner.
* A decibel, or dB, is not in itself a unit of measure of anything,
but rather a nonlinear manner of expressing a ratio of one thing to
another. 1 dB = 10*log(X), where X is a measure of the power of
something, and log is the base-ten logarithm. Where X is an amplitude,
1 dB = 20*log(X). The reference pressure of 20 uPa was chosen because
it represents the threshhold of human hearing, or the quietest level
that most human ears can detect. Thus, the threshhold of human hearing,
in dB re 20 uPa, is 0 dB. Quieter sounds, not audible to most humans,
would be expressed in negative numbers of dB.
In air, sound is conventionally measured in dB referenced to 20
micropascals (uPa) of pressure. Furthemore, when sound is measured with
respect to human hearing, it is usually adjusted according to frequency,
in a manner that is referred to as "A Weighting"; which reflects that
the human ear is more sensitive to certain frequencies than to others.
The designation "dBA" means dB that are a-weighted.
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