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  #41   Report Post  
Christian McArdle
 
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Default How loud is 43Db

Why give it a name then if it is purely abstract?

Because it is a very useful concept and deserves a name. What would you call
a decibel then? The unit formerly known as decibel? TUFKAD. Catchy. There
are other dimensionless units you would have to expunge, of course. Percent
(%) is a useful one that would have to go.

FWIW, my dictionary says it's a unit for measuring sound.


Your dictionary is wrong. It is used to measure power ratios (usually in
oscillatory systems of large dynamic range). Sound power is only one of the
measurements it is useful for. Amongst other things, it is also used to
measure vibrations and to compare electronic signals, not necessarily audio
in frequency or nature.

Christian.
BEng (Electronic and Electrical Engineering)




  #42   Report Post  
CRB
 
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Default How loud is 43Db

Dave Plowman wrote in message ...
In article ,
CRB wrote:
Well, regardless of where you start the scale, the bel must be a
'quantity' based on something as any unit is.


Not quite. A bel is a ratio, not a unit.


Why give it a name then if it is purely abstract?

FWIW, my dictionary says it's a unit for measuring sound.


Oh, it's not abstract, it's real enough. The point though, as already
made in another posting, is that it is dimensionless.

CRB
  #43   Report Post  
CRB
 
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Default How loud is 43Db

Dave Plowman wrote in message ...

Indeed. And with 'voltage' dBs, which will be the type used for quoting
the loudness of appliances etc, 6dB is a doubling of the actual voltage
measured. 3dB is a doubling of power, so applies to amplifiers, etc.


Just in case any confusion has been introduced by talking about
"types" of dBs, there is no such thing as a "voltage dB" or a "power
dB". A dB is a dB, i.e. a specific ratio, which by definition is
measured in power, but which can also be measured in voltage (or in
current come to that) as long as the two measurements share a common
impedance.

CRB
  #44   Report Post  
Christian McArdle
 
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Default How loud is 43Db

Just in case any confusion has been introduced by talking about
"types" of dBs, there is no such thing as a "voltage dB" or a "power
dB". A dB is a dB, i.e. a specific ratio, which by definition is
measured in power, but which can also be measured in voltage (or in
current come to that) as long as the two measurements share a common
impedance.


Provided that the ratio is adjusted in line with the variable's relationship
to power. Power is related to the square of voltage, so multiplication of
ten in voltage terms is not 10dB, but 20dB.

An example in numbers with a 1 ohm resistive load:

1V rms produces 1W (call this 0dB)
10V rms produces 100W

This is a 20dB amplification, as although it gives 10x the voltage it gives
100x the power, which is expressed as 20dB.

Christian.


  #45   Report Post  
Suz
 
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Default How loud is 43Db

"Christian McArdle" wrote in message
t...
Why give it a name then if it is purely abstract?


Because it is a very useful concept and deserves a name. What would you

call
a decibel then? The unit formerly known as decibel? TUFKAD. Catchy. There
are other dimensionless units you would have to expunge, of course.

Percent
(%) is a useful one that would have to go.

FWIW, my dictionary says it's a unit for measuring sound.


Your dictionary is wrong. It is used to measure power ratios (usually in
oscillatory systems of large dynamic range). Sound power is only one of

the
measurements it is useful for. Amongst other things, it is also used to
measure vibrations and to compare electronic signals, not necessarily

audio
in frequency or nature.

Christian.
BEng (Electronic and Electrical Engineering)


Everybody's right!

Main Entry: deci·bel
Pronunciation: 'de-s&-"bel, -b&l
Function: noun
Etymology: International Scientific Vocabulary deci- + bel
Date: 1928
1 a : a unit for expressing the ratio of two amounts of electric or acoustic
signal power equal to 10 times the common logarithm of this ratio b : a unit
for expressing the ratio of the magnitudes of two electric voltages or
currents or analogous acoustic quantities equal to 20 times the common
logarithm of the voltage or current ratio
2 : a unit for expressing the relative intensity of sounds on a scale from
zero for the average least perceptible sound to about 130 for the average
pain level
3 : degree of loudness; also : extremely loud sound -- usually used in
plural
www.webster.com




  #46   Report Post  
Dave Plowman
 
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Default How loud is 43Db

In article ,
Suz wrote:
Everybody's right!


When dBs are discussed, you can guarantee as many different answers as
questions. ;-)

--
*A chicken crossing the road is poultry in motion.*

Dave Plowman London SW 12
RIP Acorn
  #47   Report Post  
jacob
 
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Default How loud is 43Db

Havn't time to catch up on this thread so this may be redundant - but
43 decibles is the sound level we are asked by env health dept not to
exceed outside our boundary when we set up our joinery shop in new
premises. 43 db being a measurement of the ambient sound in the
neighbourhood and equivalent to a suburban street sound level. Its
actually 43db level equivalent measured over a sample hour. I don't
know if they actually measured it on location or merely took it from
tables.

cheers

Jacob
  #48   Report Post  
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Default How loud is 43Db

replying to Wdyw, gittyupgoosies wrote:
Yes well I see mister Nat Phil! Ah hem! So 50 Decahillbillies is "low" eh? And
40 Decahillbillies is "extremely low" Ha! Tell that to the birds and the bees
next time your trousers are down at your knees....The hills are alive with the
sound of Muzak!

--
for full context, visit https://www.homeownershub.com/uk-diy...3db-21489-.htm


  #49   Report Post  
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Default How loud is 43Db

replying to CRB, gittyupgoosies wrote:
OMG! Who is this rough rider? Quasimodo? Yikes. Can we plz finish the prostate
exam?!

--
for full context, visit https://www.homeownershub.com/uk-diy...3db-21489-.htm


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