Timeline for What does it mean to play a note for half a second?
Current License: CC BY-SA 3.0
14 events
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| Apr 26, 2015 at 9:59 | comment | added | Нет войне | Hmm, not sure that in an SE context just wanting to check that the core statements of an accepted answer are right is over-picky. But anyway as I don't know much about this either I've asked a separate question (not quite the same, but related). | |
| Apr 26, 2015 at 7:37 | comment | added | Tetsujin | @topomorto - we appear to be getting over-picky. I was trying to explain a concept, not write a dissertation on frequency analysis. | |
| Apr 25, 2015 at 20:49 | comment | added | Dave | Since the ear effectively does frequency analysis an uncertainty relation applies en.wikipedia.org/wiki/Fourier_transform#Uncertainty_principle -- thus a very short short signal does not have a well defined frequency, rather is has a spread of frequencies. | |
| Apr 25, 2015 at 20:32 | comment | added | Нет войне | But in a situation where you are listening to / recording / reading in a waveform and trying to detect frequency (which is what I think you are talking about in your answer?), How could you detect pitch accurately in only one cycle? You have no way of knowing when that first cycle is finished... | |
| Apr 25, 2015 at 20:19 | vote | accept | vin | ||
| Apr 25, 2015 at 20:19 | comment | added | vin | This answer along with your comment elsewhere has lit up a bulb. I can work it from there. | |
| Apr 25, 2015 at 20:12 | history | edited | Tetsujin | CC BY-SA 3.0 |
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| Apr 25, 2015 at 20:11 | comment | added | Tetsujin | like I said - if you're better at maths than me ;-) | |
| Apr 25, 2015 at 20:08 | comment | added | Нет войне | Yes, if you're guaranteed upfront that it's a sine wave then (ignoring things like measurement error) you can tell the frequency from an infinitesimally small section of the cycle from a simple inverse sin operation. | |
| Apr 25, 2015 at 20:05 | comment | added | Tetsujin | if the input is guaranteed pure sine [which makes it a maths question more than 'music' I admit], you only need to 'see' it pass the same point twice in the same direction for a full cycle, or pass zero twice for anything less. You'd need someone smarter than me to extrapolate from a partial sine with less info, but it can probably be done, computationally. | |
| Apr 25, 2015 at 20:02 | comment | added | Нет войне | Surely you only need one cycle to state the pitch as long as you're also given the information that what you've 'seen' is one cycle. Otherwise you have no clue whether what you've 'seen' so far is actually the whole cycle or not..? The first zero crossing doesn't necessarily represent the end of the first half of the waveform, much as the second zero crossing doesn't necessarily represent the end of the waveform. | |
| Apr 25, 2015 at 19:56 | comment | added | Tetsujin | @Dave - you made me have to think for a minute… is it 440 complete cycles, or 220 'halves'… but it is complete cycles == 440/s so 1/880s for a computer algorithm to be able to be certain [assuming pure sines all the way]. | |
| Apr 25, 2015 at 19:54 | comment | added | Dave | I guess that I learned a rule of thumb that is slightly more stringent than you. | |
| Apr 25, 2015 at 19:52 | history | answered | Tetsujin | CC BY-SA 3.0 |