The unit that is written between parentheses alongside the dB
Clash Royale CLAN TAG#URR8PPP
$begingroup$
What is the meaning of the unit that is written between parentheses alongside the dB unit? For example 2 dB (mW) or 2 dB (uW)? What exactly does this unit refer to? Does it refers to the unit of the reference value, the measured value (P2), or both?
decibel
edited Feb 15 at 16:06
JYelton
16.3k2891192
asked Feb 15 at 14:47
John adamsJohn adams
575
$endgroup$
add a comment |
$begingroup$
What is the meaning of the unit that is written between parentheses alongside the dB unit? For example 2 dB (mW) or 2 dB (uW)? What exactly does this unit refer to? Does it refers to the unit of the reference value, the measured value (P2), or both?
decibel
edited Feb 15 at 16:06
JYelton
16.3k2891192
asked Feb 15 at 14:47
John adamsJohn adams
575
$endgroup$
1
$begingroup$
Unusual notation but I would interpret it as being 2 dB referenced to the unit in brackets.
$endgroup$
– Peter Smith
Feb 15 at 14:51
1
$begingroup$
related and might already answer the question: electronics.stackexchange.com/questions/194755/… but not exactly a duplicate
$endgroup$
– Arsenal
Feb 15 at 14:51
4
$begingroup$
I would interpret 2 dB (mW) as 2 dB over the 1 mW base unit = 1.585 mW
$endgroup$
– winny
Feb 15 at 14:52
1
$begingroup$
According to ISO 80000, such an addition of a postscript to the unit symbol dB is incorrect. This information should be carried by the quantity symbol.
$endgroup$
– Loong
Feb 15 at 18:48
1
$begingroup$
And here I expected (from the question title) that this would be about dB(A) ...
$endgroup$
– Hagen von Eitzen
Feb 15 at 20:40
add a comment |
$begingroup$
What is the meaning of the unit that is written between parentheses alongside the dB unit? For example 2 dB (mW) or 2 dB (uW)? What exactly does this unit refer to? Does it refers to the unit of the reference value, the measured value (P2), or both?
decibel
edited Feb 15 at 16:06
JYelton
16.3k2891192
asked Feb 15 at 14:47
John adamsJohn adams
575
$endgroup$
What is the meaning of the unit that is written between parentheses alongside the dB unit? For example 2 dB (mW) or 2 dB (uW)? What exactly does this unit refer to? Does it refers to the unit of the reference value, the measured value (P2), or both?
decibel
decibel
edited Feb 15 at 16:06
JYelton
16.3k2891192
asked Feb 15 at 14:47
John adamsJohn adams
575
edited Feb 15 at 16:06
JYelton
16.3k2891192
asked Feb 15 at 14:47
John adamsJohn adams
575
edited Feb 15 at 16:06
JYelton
16.3k2891192
edited Feb 15 at 16:06
JYelton
16.3k2891192
edited Feb 15 at 16:06
JYelton
16.3k2891192
16.3k2891192
asked Feb 15 at 14:47
John adamsJohn adams
575
asked Feb 15 at 14:47
John adamsJohn adams
575
asked Feb 15 at 14:47
John adamsJohn adams
575
575
1
$begingroup$
Unusual notation but I would interpret it as being 2 dB referenced to the unit in brackets.
$endgroup$
– Peter Smith
Feb 15 at 14:51
1
$begingroup$
related and might already answer the question: electronics.stackexchange.com/questions/194755/… but not exactly a duplicate
$endgroup$
– Arsenal
Feb 15 at 14:51
4
$begingroup$
I would interpret 2 dB (mW) as 2 dB over the 1 mW base unit = 1.585 mW
$endgroup$
– winny
Feb 15 at 14:52
1
$begingroup$
According to ISO 80000, such an addition of a postscript to the unit symbol dB is incorrect. This information should be carried by the quantity symbol.
$endgroup$
– Loong
Feb 15 at 18:48
1
$begingroup$
And here I expected (from the question title) that this would be about dB(A) ...
$endgroup$
– Hagen von Eitzen
Feb 15 at 20:40
add a comment |
1
$begingroup$
Unusual notation but I would interpret it as being 2 dB referenced to the unit in brackets.
$endgroup$
– Peter Smith
Feb 15 at 14:51
1
$begingroup$
related and might already answer the question: electronics.stackexchange.com/questions/194755/… but not exactly a duplicate
$endgroup$
– Arsenal
Feb 15 at 14:51
4
$begingroup$
I would interpret 2 dB (mW) as 2 dB over the 1 mW base unit = 1.585 mW
$endgroup$
– winny
Feb 15 at 14:52
1
$begingroup$
According to ISO 80000, such an addition of a postscript to the unit symbol dB is incorrect. This information should be carried by the quantity symbol.
$endgroup$
– Loong
Feb 15 at 18:48
1
$begingroup$
And here I expected (from the question title) that this would be about dB(A) ...
$endgroup$
– Hagen von Eitzen
Feb 15 at 20:40
1
1
$begingroup$
Unusual notation but I would interpret it as being 2 dB referenced to the unit in brackets.
$endgroup$
– Peter Smith
Feb 15 at 14:51
$begingroup$
Unusual notation but I would interpret it as being 2 dB referenced to the unit in brackets.
$endgroup$
– Peter Smith
Feb 15 at 14:51
1
1
$begingroup$
related and might already answer the question: electronics.stackexchange.com/questions/194755/… but not exactly a duplicate
$endgroup$
– Arsenal
Feb 15 at 14:51
$begingroup$
related and might already answer the question: electronics.stackexchange.com/questions/194755/… but not exactly a duplicate
$endgroup$
– Arsenal
Feb 15 at 14:51
4
4
$begingroup$
I would interpret 2 dB (mW) as 2 dB over the 1 mW base unit = 1.585 mW
$endgroup$
– winny
Feb 15 at 14:52
$begingroup$
I would interpret 2 dB (mW) as 2 dB over the 1 mW base unit = 1.585 mW
$endgroup$
– winny
Feb 15 at 14:52
1
1
$begingroup$
According to ISO 80000, such an addition of a postscript to the unit symbol dB is incorrect. This information should be carried by the quantity symbol.
$endgroup$
– Loong
Feb 15 at 18:48
$begingroup$
According to ISO 80000, such an addition of a postscript to the unit symbol dB is incorrect. This information should be carried by the quantity symbol.
$endgroup$
– Loong
Feb 15 at 18:48
1
1
$begingroup$
And here I expected (from the question title) that this would be about dB(A) ...
$endgroup$
– Hagen von Eitzen
Feb 15 at 20:40
$begingroup$
And here I expected (from the question title) that this would be about dB(A) ...
$endgroup$
– Hagen von Eitzen
Feb 15 at 20:40
add a comment |
1 Answer
1
active
oldest
votes
$begingroup$
dB is a measure of ratio, nothing more.
As such, if an absolute measurement is expressed in dB, then we need to know what the denominator of that ratio is.
For frequently used units, like dBm for instance, the string 'dBm' is a recognised standard way of expressing 'dB with respect to 1mW'.
Some writers baulk at combining dB directly with a unit, and so the practice has grown up of putting the reference level in brackets, for clarity, giving us dB(unit). Some people write dB(mW), it means exactly the same as dBm.
As a ratio, dB is dimensionless. The quantity expressed by dB(unit) will therefore have the same dimensions as the unit.
In some fields, it's not uncommon to see the unit being left off, which is very naughty, but unfortunately very common. I often read reports of sound having a level of so many dBs. You can usually guess what the default reference level is.
answered Feb 15 at 15:41
Neil_UKNeil_UK
77.2k283176
$endgroup$
1
$begingroup$
Sound is usually dB relative to the threshold of human hearing, right? Something like dBmPa or dBμPa or whatever. Edit: looked it up, I suppose that would be dB (20 μPa). dB(SPL) seems to be a more common term.
$endgroup$
– Hearth
Feb 15 at 15:53
1
$begingroup$
@Hearth I most often see "dB (SPL)". Properly, a weighting should be indicated, but I think A weighting is assumed if none is specified. In the US, laws about sound pressure levels are all with reference to A-weighted values, so at least in The States that's the default.
$endgroup$
– Todd Wilcox
Feb 15 at 17:03
1
$begingroup$
@ToddWilcox for A weighting (or B and C) I would write dB A while dB SPL generally means a flat frequency weighting and a 20 $mu$Pa reference. dB HL would be referenced to the norms of hearing and the corresponding dB SPL depends on the frequency and headphones/transducer. dB SL (sensation level) is referenced to the hearing of the individual.
$endgroup$
– StrongBad
Feb 15 at 18:33
$begingroup$
dB is always a measure of power ratio.
$endgroup$
– Mike Waters
Feb 15 at 20:55
add a comment |
Your Answer
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1 Answer
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1 Answer
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oldest
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$begingroup$
dB is a measure of ratio, nothing more.
As such, if an absolute measurement is expressed in dB, then we need to know what the denominator of that ratio is.
For frequently used units, like dBm for instance, the string 'dBm' is a recognised standard way of expressing 'dB with respect to 1mW'.
Some writers baulk at combining dB directly with a unit, and so the practice has grown up of putting the reference level in brackets, for clarity, giving us dB(unit). Some people write dB(mW), it means exactly the same as dBm.
As a ratio, dB is dimensionless. The quantity expressed by dB(unit) will therefore have the same dimensions as the unit.
In some fields, it's not uncommon to see the unit being left off, which is very naughty, but unfortunately very common. I often read reports of sound having a level of so many dBs. You can usually guess what the default reference level is.
answered Feb 15 at 15:41
Neil_UKNeil_UK
77.2k283176
$endgroup$
1
$begingroup$
Sound is usually dB relative to the threshold of human hearing, right? Something like dBmPa or dBμPa or whatever. Edit: looked it up, I suppose that would be dB (20 μPa). dB(SPL) seems to be a more common term.
$endgroup$
– Hearth
Feb 15 at 15:53
1
$begingroup$
@Hearth I most often see "dB (SPL)". Properly, a weighting should be indicated, but I think A weighting is assumed if none is specified. In the US, laws about sound pressure levels are all with reference to A-weighted values, so at least in The States that's the default.
$endgroup$
– Todd Wilcox
Feb 15 at 17:03
1
$begingroup$
@ToddWilcox for A weighting (or B and C) I would write dB A while dB SPL generally means a flat frequency weighting and a 20 $mu$Pa reference. dB HL would be referenced to the norms of hearing and the corresponding dB SPL depends on the frequency and headphones/transducer. dB SL (sensation level) is referenced to the hearing of the individual.
$endgroup$
– StrongBad
Feb 15 at 18:33
$begingroup$
dB is always a measure of power ratio.
$endgroup$
– Mike Waters
Feb 15 at 20:55
add a comment |
$begingroup$
dB is a measure of ratio, nothing more.
As such, if an absolute measurement is expressed in dB, then we need to know what the denominator of that ratio is.
For frequently used units, like dBm for instance, the string 'dBm' is a recognised standard way of expressing 'dB with respect to 1mW'.
Some writers baulk at combining dB directly with a unit, and so the practice has grown up of putting the reference level in brackets, for clarity, giving us dB(unit). Some people write dB(mW), it means exactly the same as dBm.
As a ratio, dB is dimensionless. The quantity expressed by dB(unit) will therefore have the same dimensions as the unit.
In some fields, it's not uncommon to see the unit being left off, which is very naughty, but unfortunately very common. I often read reports of sound having a level of so many dBs. You can usually guess what the default reference level is.
answered Feb 15 at 15:41
Neil_UKNeil_UK
77.2k283176
$endgroup$
1
$begingroup$
Sound is usually dB relative to the threshold of human hearing, right? Something like dBmPa or dBμPa or whatever. Edit: looked it up, I suppose that would be dB (20 μPa). dB(SPL) seems to be a more common term.
$endgroup$
– Hearth
Feb 15 at 15:53
1
$begingroup$
@Hearth I most often see "dB (SPL)". Properly, a weighting should be indicated, but I think A weighting is assumed if none is specified. In the US, laws about sound pressure levels are all with reference to A-weighted values, so at least in The States that's the default.
$endgroup$
– Todd Wilcox
Feb 15 at 17:03
1
$begingroup$
@ToddWilcox for A weighting (or B and C) I would write dB A while dB SPL generally means a flat frequency weighting and a 20 $mu$Pa reference. dB HL would be referenced to the norms of hearing and the corresponding dB SPL depends on the frequency and headphones/transducer. dB SL (sensation level) is referenced to the hearing of the individual.
$endgroup$
– StrongBad
Feb 15 at 18:33
$begingroup$
dB is always a measure of power ratio.
$endgroup$
– Mike Waters
Feb 15 at 20:55
add a comment |
$begingroup$
dB is a measure of ratio, nothing more.
As such, if an absolute measurement is expressed in dB, then we need to know what the denominator of that ratio is.
For frequently used units, like dBm for instance, the string 'dBm' is a recognised standard way of expressing 'dB with respect to 1mW'.
Some writers baulk at combining dB directly with a unit, and so the practice has grown up of putting the reference level in brackets, for clarity, giving us dB(unit). Some people write dB(mW), it means exactly the same as dBm.
As a ratio, dB is dimensionless. The quantity expressed by dB(unit) will therefore have the same dimensions as the unit.
In some fields, it's not uncommon to see the unit being left off, which is very naughty, but unfortunately very common. I often read reports of sound having a level of so many dBs. You can usually guess what the default reference level is.
answered Feb 15 at 15:41
Neil_UKNeil_UK
77.2k283176
$endgroup$
dB is a measure of ratio, nothing more.
As such, if an absolute measurement is expressed in dB, then we need to know what the denominator of that ratio is.
For frequently used units, like dBm for instance, the string 'dBm' is a recognised standard way of expressing 'dB with respect to 1mW'.
Some writers baulk at combining dB directly with a unit, and so the practice has grown up of putting the reference level in brackets, for clarity, giving us dB(unit). Some people write dB(mW), it means exactly the same as dBm.
As a ratio, dB is dimensionless. The quantity expressed by dB(unit) will therefore have the same dimensions as the unit.
In some fields, it's not uncommon to see the unit being left off, which is very naughty, but unfortunately very common. I often read reports of sound having a level of so many dBs. You can usually guess what the default reference level is.
answered Feb 15 at 15:41
Neil_UKNeil_UK
77.2k283176
edited Feb 15 at 17:04
answered Feb 15 at 15:41
Neil_UKNeil_UK
77.2k283176
answered Feb 15 at 15:41
Neil_UKNeil_UK
77.2k283176
answered Feb 15 at 15:41
Neil_UKNeil_UK
77.2k283176
77.2k283176
1
$begingroup$
Sound is usually dB relative to the threshold of human hearing, right? Something like dBmPa or dBμPa or whatever. Edit: looked it up, I suppose that would be dB (20 μPa). dB(SPL) seems to be a more common term.
$endgroup$
– Hearth
Feb 15 at 15:53
1
$begingroup$
@Hearth I most often see "dB (SPL)". Properly, a weighting should be indicated, but I think A weighting is assumed if none is specified. In the US, laws about sound pressure levels are all with reference to A-weighted values, so at least in The States that's the default.
$endgroup$
– Todd Wilcox
Feb 15 at 17:03
1
$begingroup$
@ToddWilcox for A weighting (or B and C) I would write dB A while dB SPL generally means a flat frequency weighting and a 20 $mu$Pa reference. dB HL would be referenced to the norms of hearing and the corresponding dB SPL depends on the frequency and headphones/transducer. dB SL (sensation level) is referenced to the hearing of the individual.
$endgroup$
– StrongBad
Feb 15 at 18:33
$begingroup$
dB is always a measure of power ratio.
$endgroup$
– Mike Waters
Feb 15 at 20:55
add a comment |
1
$begingroup$
Sound is usually dB relative to the threshold of human hearing, right? Something like dBmPa or dBμPa or whatever. Edit: looked it up, I suppose that would be dB (20 μPa). dB(SPL) seems to be a more common term.
$endgroup$
– Hearth
Feb 15 at 15:53
1
$begingroup$
@Hearth I most often see "dB (SPL)". Properly, a weighting should be indicated, but I think A weighting is assumed if none is specified. In the US, laws about sound pressure levels are all with reference to A-weighted values, so at least in The States that's the default.
$endgroup$
– Todd Wilcox
Feb 15 at 17:03
1
$begingroup$
@ToddWilcox for A weighting (or B and C) I would write dB A while dB SPL generally means a flat frequency weighting and a 20 $mu$Pa reference. dB HL would be referenced to the norms of hearing and the corresponding dB SPL depends on the frequency and headphones/transducer. dB SL (sensation level) is referenced to the hearing of the individual.
$endgroup$
– StrongBad
Feb 15 at 18:33
$begingroup$
dB is always a measure of power ratio.
$endgroup$
– Mike Waters
Feb 15 at 20:55
1
1
$begingroup$
Sound is usually dB relative to the threshold of human hearing, right? Something like dBmPa or dBμPa or whatever. Edit: looked it up, I suppose that would be dB (20 μPa). dB(SPL) seems to be a more common term.
$endgroup$
– Hearth
Feb 15 at 15:53
$begingroup$
Sound is usually dB relative to the threshold of human hearing, right? Something like dBmPa or dBμPa or whatever. Edit: looked it up, I suppose that would be dB (20 μPa). dB(SPL) seems to be a more common term.
$endgroup$
– Hearth
Feb 15 at 15:53
1
1
$begingroup$
@Hearth I most often see "dB (SPL)". Properly, a weighting should be indicated, but I think A weighting is assumed if none is specified. In the US, laws about sound pressure levels are all with reference to A-weighted values, so at least in The States that's the default.
$endgroup$
– Todd Wilcox
Feb 15 at 17:03
$begingroup$
@Hearth I most often see "dB (SPL)". Properly, a weighting should be indicated, but I think A weighting is assumed if none is specified. In the US, laws about sound pressure levels are all with reference to A-weighted values, so at least in The States that's the default.
$endgroup$
– Todd Wilcox
Feb 15 at 17:03
1
1
$begingroup$
@ToddWilcox for A weighting (or B and C) I would write dB A while dB SPL generally means a flat frequency weighting and a 20 $mu$Pa reference. dB HL would be referenced to the norms of hearing and the corresponding dB SPL depends on the frequency and headphones/transducer. dB SL (sensation level) is referenced to the hearing of the individual.
$endgroup$
– StrongBad
Feb 15 at 18:33
$begingroup$
@ToddWilcox for A weighting (or B and C) I would write dB A while dB SPL generally means a flat frequency weighting and a 20 $mu$Pa reference. dB HL would be referenced to the norms of hearing and the corresponding dB SPL depends on the frequency and headphones/transducer. dB SL (sensation level) is referenced to the hearing of the individual.
$endgroup$
– StrongBad
Feb 15 at 18:33
$begingroup$
dB is always a measure of power ratio.
$endgroup$
– Mike Waters
Feb 15 at 20:55
$begingroup$
dB is always a measure of power ratio.
$endgroup$
– Mike Waters
Feb 15 at 20:55
add a comment |
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1
$begingroup$
Unusual notation but I would interpret it as being 2 dB referenced to the unit in brackets.
$endgroup$
– Peter Smith
Feb 15 at 14:51
1
$begingroup$
related and might already answer the question: electronics.stackexchange.com/questions/194755/… but not exactly a duplicate
$endgroup$
– Arsenal
Feb 15 at 14:51
4
$begingroup$
I would interpret 2 dB (mW) as 2 dB over the 1 mW base unit = 1.585 mW
$endgroup$
– winny
Feb 15 at 14:52
1
$begingroup$
According to ISO 80000, such an addition of a postscript to the unit symbol dB is incorrect. This information should be carried by the quantity symbol.
$endgroup$
– Loong
Feb 15 at 18:48
1
$begingroup$
And here I expected (from the question title) that this would be about dB(A) ...
$endgroup$
– Hagen von Eitzen
Feb 15 at 20:40