8 ms·

It's a bit like hating numbers, and saying "What do you mean by 'three'; what is it - three volts, three amps, three metres? Clearly 'three' is meaningless, and

• deleted 1y ago
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• 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 ago
    I 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 ago
    It'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 ago
      Exactly. I’ve never seen it otherwise.
    • weinzierl 1y ago
      I 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 ago
        No, it always means a power ratio. That sometimes can imply something else, but that's on you to work that out.
        • lxgr 1y ago
          Yes, 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 ago
            What? Blaming a bad communicator for bad communication is fine. Blaming their words because they used them badly is not.
            • lxgr 1y ago
              What about blaming a common but confusing usage of some words pervasive in some fields?
    • 1y ago
  • tpoacher 1y ago
    This sounds more like a problem with the 'real' world then.
  • lambdaone 1y ago
    In 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.
• sanderjd 1y ago
  > In every context where decibels are used, either the unit they qualify is explicitly specified, or the unit is implicity known from the context. The author's whole point is that this is not true. To adapt your analogy, it's not like being mad at the number three, it's like being mad about people not attaching any units to the number three, arguing that it's clear in context. It isn't!
  • klodolph 1y ago
    Sure, but the author is wrong. “How old is your son?” “He’s 3.” Clear in context. People write things like dB SPL (A-weighted) in spec sheets because spec sheets benefit from being unambiguous. Most of the time it’s really clear, like you’re talking about insertion loss or amplifier gain and there’s only one reasonable way to interpret it.
    • viraptor 1y ago
      That only works if you're already familiar with the context and system and assume other people are too and don't care about anyone new to that area. (Good luck coming to the audio equipment datasheet with no experience and figuring out what the dB means in each case) "He's 3" works because of the previous question and because everyone had experience of talking about age. dB for anyone not already knowing the answer is like going to another planet and hearing "he's 3". Of course it's on a logarithmic scale, offset to -5 as starting point, counting the skin shedding events - clear in context and you should've known that.
      • klodolph 1y ago
        Maybe I just live on the planet, but I don’t have this problem with dB and to me, it sounds like you’re the alien. Maybe you could elaborate, or give a motivating example? I just don’t remember encountering the problem you’re describing, and it’s unfamiliar to me. There’s something about your experience that I don’t understand, but I don’t know what it is.
        • 1y ago
• xeonmc 1y ago
  Interviewer: "So what's the fastest you've gone on your bike?" Kid: "Thirty." Interviewer" "Thirty what?" Kid: "Umm..." Kid: "Speed." [0] https://www.youtube.com/watch?v=OYt1kqDNlMY https://www.youtube.com/watch?v=OYt1kqDNlMY
  • dotancohen 1y ago
    KSP measures funds in some unitless value, it drives me nuts. Everything else is almost (but not quite) perfect.
    • viraptor 1y ago
      Just pretend it's a Jane Austen novel and you're earning 500. Pounds? Pieces of gold? Sheep? Who knows really ;)
    • BlueTemplar 1y ago
      https://en.wikipedia.org/wiki/Currency_sign_(generic) https://en.wikipedia.org/wiki/Currency_sign_(generic)
  • UncleMeat 1y ago
    "I was doing 70 down the highway" is absolutely the sort of thing people say. From context (this conversation takes place in the US, most highways have a speed limit somewhere around 60-70mph) people understand that you are talking about miles per hour.
    • viraptor 1y ago
      And yet, on the internet without the extra context, I can't tell if you're going slowly in km/h or the usual in mph. With dB that depends on whether you're taking to a person familiar with the context-specific conventions or not.
  • JoeDaDude 1y ago
    Maybe you can say "6 dbm/s"
• skrebbel 1y ago
  To be frank, your comment just reads to me as a "stockholm syndrome" type reaction to a needlessly complex unit that you're intimately familiar with. You see the same in HN threads where people complain that eg Git or Rust are needlessly complex, there's a swath of people who are so emotionally invested in how well they understand the ins and outs of Git resp Rust that any suggestion that maybe things could be better makes them angry. It's possible for decibels to be usable and generally fine and also for them to needlessly complex, ie for there to exist better alternatives in each place they're used. As an example, it makes no sense to me that eg in audio software, volume sliders start at 0 dB and then go down to negative $MUCHO, until complete silence at -Infinity. And then this same unit is also used to measure how loud my coffee machine is, somehow, but then it's suddenly positive and not a relative number at all? That's just weird shit, it's like expressing the luminosity of a pixel (in HSL terms) in lumen instead of a unitless percentage. In the audio software context, it would be much more intuitive for "no sound" to be 0, and "full volume" to be 100, a bit like percentages. The "but volume needs to be logarithmic because that's how we hear it!" argument doesn't disallow that at all. Just because a slider goes from 0 to 100 doesn't mean that a 10 must mean 10% of the power output. Decibels are ridiculous.
  • amluto 1y ago
    > As an example, it makes no sense to me that eg in audio software, volume sliders start at 0 dB and then go down to negative $MUCHO, until complete silence at -Infinity. This one doesn’t bother me. Those sliders, and especially the real analog sliders they’re modeled after, don’t have an absolute scale — they are attenuators that reduce voltage. So 0dB is the same as no slider at all, -20dB reduces voltage by a factor of 10, etc.
  • CamperBob2 1y ago
    dB is always relative, even when it appears to be an absolute unit. The 0 dB marking at the top of the volume slider on pro audio gear (more likely +3 or +6 or something similar to leave some headroom) means "0 dB relative to the maximum rated power level." In pro gear this will be an absolute industry standard of some sort, likely one where the load impedance is also defined. 1 milliwatt into 600 ohms or something like that. The distinction between voltage and power is always going to confuse people, but that's not the dB's fault. A major reason decibels are used is to make it easy to assess the overall gain or loss of an entire chain of processing stages: you simply add the numbers. The equipment's output can only go down from 0 dB, so the rest of the scale is negative. As for sound pressure levels in dB, those are given relative to a 0-dB point that corresponded originally to the faintest sound people were generally considered capable of perceiving. These days "0 dB" refers to a specific amount of acoustic power, which I don't know off the top of my head, and that might or might not be near the threshold of perception for a given listener. But the reasoning still applies: amplification or attenuation of power levels is a simple matter of addition when expressed in dB. Arbitrarily defining a system's reference level to be 100 dB instead of 0 dB would be of no use to anyone.
• baxtr 1y ago
  > People who assume that everyone is an idiot but themselves are rarely correct. Print this, frame this, put this up on walls in schools, offices, heck even outdoor on large billboards!
  • anthomtb 1y ago
    And before doing any of that, get it tattooed onto your own forearm.
• DonHopkins 1y ago
  Some people just hate certain numbers. Many buildings don't have a 13th floor because superstitious people think it's unlucky. Some people lose their shit at 8647 because paranoid delusional people think it's out to kill them.
• lxgr 1y ago
  > It's a bit like hating numbers, and saying "What do you mean by 'three'; what is it - three volts, three amps, three metres? No, it’s a bit like saying “for chocolate M&Ms, 3 obviously means 9, to compensate for the fact that they’re much smaller than the peanut ones”.
  • timerol 1y ago
    Can I get 3 M&Ms? Obviously I mean 3 serving sizes, how else would you measure M&Ms?
• deleted 1y ago
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• DonHopkins 1y ago
  At least the Mel-frequency cepstrum is honest about being a perceptual scale anchored to human hearing, rather than posing as a universally-applicable physical unit. https://en.wikipedia.org/wiki/Mel-frequency_cepstrum https://en.wikipedia.org/wiki/Mel-frequency_cepstrum >Mel-frequency cepstral coefficients (MFCCs) are coefficients that collectively make up an MFC. They are derived from a type of cepstral representation of the audio clip (a nonlinear "spectrum-of-a-spectrum"). The difference between the cepstrum and the mel-frequency cepstrum is that in the MFC, the frequency bands are equally spaced on the mel scale, which approximates the human auditory system's response more closely than the linearly-spaced frequency bands used in the normal spectrum. This frequency warping can allow for better representation of sound, for example, in audio compression that might potentially reduce the transmission bandwidth and the storage requirements of audio signals. https://en.wikipedia.org/wiki/Psychoacoustics https://en.wikipedia.org/wiki/Psychoacoustics >Psychoacoustics is the branch of psychophysics involving the scientific study of the perception of sound by the human auditory system. It is the branch of science studying the psychological responses associated with sound including noise, speech, and music. Psychoacoustics is an interdisciplinary field including psychology, acoustics, electronic engineering, physics, biology, physiology, and computer science.
• jampekka 1y ago
  > For instance, in the case of loudness of noise to human ears in air, the unit can be taken to be dBA (in all but rare cases which will be specified) measured with an appropriate A-weighted sensor, relative to the standard reference power level. This was covered in the article. But also it was discussed why things aren't this simple. > People who assume that everyone is an idiot but themselves are rarely correct. Indeed.
• timerol 1y ago
  > multiplier for some known value of some known quantity Of course, unless it's a multiplier for an unknown value of a known quantity, like every amplifier, filter, and sensor specified in dB. > For instance, in the case of loudness of noise to human ears in air, the unit can be taken to be dBA Unless you're using dBB or dBC, but of course we all know exactly why you'd use dBC (more suitable for figuring out safety of high impulse, short events) or dBB (it's somewhere in between - you'll know it when you see it). > The apparent excessive complexity is necessary, not invented to create confusion. Wait, so writing dB instead of dBA is now necessary, not just convenient?
• WhitneyLand 1y ago
  People who assume things are not complex because they understand them are rarely correct. The complexity absolutely is not necessary. Maybe you mean to say it’s understandable or it’s coherent if you know the rules. Physics doesn’t require us to create ambiguity by assigning DB to mean multiple possible ratios. If it needs to be disambiguated, then they both didn’t need to be DB in the first place.
• mystified5016 1y ago
  Exactly, the log(x) function is stupid and useless! It's the log of what? 6? Pi? Little-g? Same for logn(x). Who the hell is n?!
• IvyMike 1y ago
  > People who assume that everyone is an idiot but themselves are rarely correct. This is an off-by-one error.
• ok_computer 1y ago
  I think college undergrad physics and engineering is an important time to gain exposure to a variety of concepts and measures. Then you learn the people who discovered or invented these concepts were writing by candlelight and not washing their hands and didn’t have modern mathematics or computers and didn’t want to piss off the church. Oftentimes working at the pleasure of a rich sponsor family or king. Like you have to describe relative intensity of waves in some way and these were experimental scientists, not commerce merchants looking for absolute interchangeability like weights and measures. Computer blog people like standards and languageisms but science isn’t determined by big tech sponsored committee. It’s the best tool put forward so far and db is a physics concept and with a reference denominator you can calculate the absolute value. It’s fine. If you dabble with physics and expect the universe to make intuitive sense then you need an education. Read books not blogs.