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"decibels are simply a dimensionless ratio, used as a multiplier for some known value of some known quantity." Except they are not. 1 dB can sometimes mean a r
by weinzierl 1y ago
"decibels are simply a dimensionless ratio, used as a multiplier for some known value of some known quantity."
Except they are not. 1 dB can sometimes mean a ratio of ~ 1.26 and other times it can mean a ratio of ~ 1.12.
"In every context where decibels are used, either the unit they qualify is explicitly specified, or the unit is implicity known from the context."
Maybe in university, but certainly not in the real world.
- 20k 1y agoI have a feeling that a lot of people here haven't read the article. There's lots of "Its just a dimensionless ratio" comments
- hgomersall 1y agoIt's a power ratio. 1dB always means a power ratio of 1.26. That might mean a voltage or current ratio, say, of 1.12, but that is because the relationship between voltage ratios and power ratios is a simple square.
- klodolph 1y agoExactly. I’ve never seen it otherwise.
- weinzierl 1y agoI understand that and it just reinforces my point. What 1 dB essentially means is highly dependent on a most of the time silent context.
- hgomersall 1y agoNo, it always means a power ratio. That sometimes can imply something else, but that's on you to work that out.
- lxgr 1y agoYes, but that, i.e. putting the burden of disambiguating some meaning from context on the receiver instead of the sender, is just bad communication.
- hgomersall 1y agoWhat? Blaming a bad communicator for bad communication is fine. Blaming their words because they used them badly is not.
- lxgr 1y agoWhat about blaming a common but confusing usage of some words pervasive in some fields?
- twelvechairs 1y agoThe other side of the authors discussion is the use of 'decibels' to describe 'loudness'. The big difficulty there is that 'loudness' is a sense perception that varies between people and in different contexts. The article touches on this 'weighted to mimic human hearing...' but doesnt mention the systems to do this - DB(A) and others, none of which achieve scientific perfection. Our senses are all like this - for the same reason we have dozens of systems to describe color. And why perfume and wine makers can never agree descriptions.
- lxgr 1y agoThat’s maybe what it “is”, but not the only thing people use it for in many fields. Very often, it’s a ratio between a measured quantity and some (implied) base unit of the same quantity.
- hgomersall 1y agoIn which case they're misusing it, which is hardly a problem with the notation.
- lxgr 1y agoAs I read it, the criticism of TFA is directed at how people actually use the notation, not how it ought to be used in an ideal universe.
- hgomersall 1y agoBut people misuse words and notation all the time without anyone arguing they're ridiculous. I use dBs on a daily basis with plenty of other people and never have any trouble. Indeed, we'd struggle if we had to use something else.
- lxgr 1y ago> But people misuse words and notation all the time without anyone arguing they're ridiculous. That only indicates that you haven't found the many angry blog posts yet, not that they don't exist :)
- arghwhat 1y agoThe problem isn't really the ratio, but the use in arbitrary contexts that require a lot of pre-existing knowledge. The reference value is sometimes a rather arbitrary value in an arbitrary unit, neither of which is communicated by the "dB" unit suffix. The SI way to write `10 dBm` is to write `10 dB (1mW)`, clearly communicating both the power level and the reference point and unit. This ensures that you do not have to just memorize a bunch of decibell suffixes and their magical reference values.
- tpoacher 1y agoThis sounds more like a problem with the 'real' world then.
- lambdaone 1y agoIn the "real world", techically competent people understand decibels just fine. But this is not arcane knowledge only known by a priesthood. Since you are clearly confused about what a decibel is and how and why it is used, you can read https://en.wikipedia.org/wiki/Decibel https://en.wikipedia.org/wiki/Decibel and all will be revealed.