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Spectrogram (talk | contribs) spectrograms of speech, great idea |
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{{Q&A}}
== Request soundfiles to sonogram examples ==
It would be nice if the exemplary sonograms were accompagnied by the corresponding sound files (.ogg) so that we could hear what we see :-) --[[User:Dipoar|Dipoar]] ([[User talk:Dipoar|talk]]) 01:06, 3 October 2008 (UTC)
==Aphex Twin used Coagula==
I removed the parenthetical claim that AT used Coagula because [http://www.bastwood.com/aphex.php this site that's in the links section] says he used metasynth. If anyone has a really solid reference, we can put it back up. --[[User:Hurtstotouchfire|Hurtstotouchfire]] 02:45, 15 October 2007 (UTC)
==Aphex Twin mp3==
the picture is still visible in the mp3, just not as clear. i just checked. [[User:Omegatron|Omegatron]] 06:35, Feb 1, 2004 (UTC)
:Depends on the MP3. Differently coded MP3s will lose different information. [[User:TMC1221|TMC1221]] 07:04, Feb 1, 2004 (UTC)
::true, true. [[User:Omegatron|Omegatron]]
::Not really. It's still the same acoustic signal, so the spectrogram will be the same, just with more noise in it. High MP3 compression would have a similar effect as high JPEG compression of the spectrogram. --[[Special:Contributions/129.94.166.204|129.94.166.204]] ([[User talk:129.94.166.204|talk]]) 04:32, 23 October 2012 (UTC)
==Another example==
If this image reappears, put it back in:
[[Image:Praat-spectrogram-tatata.png|Sonogram example]]
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I am suggesting that [[Waterfall plot]] be merged into the [[Spectrogram]] page. They are essentially the same thing and the terms are interchangable. A waterfall plot can be 2D with color being the third dimension. A spectrogram can also be a 3D display. The only issue is that the Waterfall Plot page has a focus on room acoustics while Spectrogram is more of DSP term. ([[User:Spectrogram|Spectrogram]] 05:51, 27 January 2007 (UTC))
While I agree that they carry the same information, I'm not sure they're the same. From my limited knowledge, a waterfall plot is merely a type of 3D plot that is often used to display freq. response vs. time. Check http://www.caspur.it/risorse/softappl/doc/matlab_help/techdoc/ref/waterfall.html for MATLAB's description which is a completely different description than what they have for spectrogram. [[User:Weston.pace|Weston.pace]] 19:29, 5 July 2007 (UTC)
I have clarified the definition of waterfall plot and believe it is now contains enough unique content to no longer require a merge. [[User:Weston.pace|Weston.pace]] 21:30, 5 July 2007 (UTC)
== Format ==
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: I think that would be a great idea but if it is heavy on details then it might be better if it was over at a place like [[Wikipedia:WikiProject_Phonetics]]. The problem with spectrogram analysis is that it is used in so many different fields, speech happens to be just one of them. Don't want to give any particular usage too much coverage. For example: there might be too much information about images being embedded in popular music (see the recent NIN entries). While I think that those edits are great, they might be a bit too much. ([[User:Spectrogram|Spectrogram]] 22:30, 22 February 2007 (UTC))
== Three-dimensional??? ==
The second line of this article is: "It is a three-dimensional plot of the energy of the frequency content of a signal as it changes over time." I don't know anything about a spectogram but I can only see two dimensions: 1) the energe of the frequency content of a signal and 2) time.
Isn't two-dimensional more correct? [[User:Lova Falk|Lova Falk]] ([[User talk:Lova Falk|talk]]) 16:10, 17 January 2008 (UTC)
:The third dimension is the intensity--[[Special:Contributions/62.147.133.191|62.147.133.191]] ([[User talk:62.147.133.191|talk]]) 17:23, 26 January 2008 (UTC)
:: I would go so far as to say that this article should be generalized. While a spectrogram can often be used to plot frequency information this is not its only use. More generally a spectrogram is just a way of plotting three dimensional data on a two dimensional surface using color spectra to indicate the third dimension. For example, in the work I do we often use spectrograms of time vs particle energy vs particle flux or time vs particle angle vs particle flux. If people don't object in the next few weeks, I'm going to clean up this article so it doesn't always define spectrograms as plots of time vs frequency vs power. <small>—Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/128.97.68.15|128.97.68.15]] ([[User talk:128.97.68.15|talk]]) 00:21, 14 May 2008 (UTC)</small><!-- Template:UnsignedIP --> <!--Autosigned by SineBot-->
:::Allow me to strongly disagree. What you're talking about is not a spectrogram, just an unrelated plot. A spectrogram is time and frequency, period. And it's wrong to call it 3D, because it can only have one value in that "dimension" you call power. Also you might wanna look up the definition [http://www.google.ie/search?q=define%3Aspectrogram] --[[Special:Contributions/89.127.175.78|89.127.175.78]] ([[User talk:89.127.175.78|talk]]) 14:51, 15 May 2008 (UTC)
::::1. On the issue of the definition of a spectrogram.
::::From http://www.merriam-webster.com/dictionary/spectrogram
::::"Spectrogram - a photograph, image, or diagram of a spectrum"
::::So what is a spectrum?
::::From http://www.merriam-webster.com/dictionary/spectrum
::::"Spectrum - '''1''' a: a continuum of color formed when a beam of white light is dispersed (as by passage through a prism) so that its component wavelengths are arranged in order b: any of various continua that resemble a color spectrum in consisting of an ordered arrangement by a particular characteristic (as frequency or energy): as (1): electromagnetic spectrum (2): radio spectrum (3): the range of frequencies of sound waves (4): mass spectrum c: the representation (as a plot) of a spectrum. '''2''' a: a continuous sequence or range <a wide spectrum of interests> <opposite ends of the political spectrum> b: kinds of organisms associated with a particular situation (as an environment) c: a range of effectiveness against pathogenic organisms <an antibiotic with a broad spectrum>"
::::I don't see merriam-webster specifying any particular choice of axes. In fact a spectrum can be any "ordered arrangement by a particular characteristic." They list a large variety of potential spectra which could all be plotted as spectral diagrams. So it seems to me that, as I initially suggested, the choice of axes is commonly(canonically) those of a power spectrum but that does not mean it is exclusively a diagram of a power spectrum. Why do you think a spectrogram must always be time v. frequency v. intensity?
::::2. On the issue of the dimension of the data. It is a system of three variables; two independent, one dependent. To specify any point of data for a spectrogram, it requires three numbers. So when I say dimension I mean strictly in the technical sense, as in "dimension of a vector space" most specifically over the standard basis. You do have a point that the data is constrained. It might be more accurate to think of a spectrogram data set as a surface spanning two dimensions of a three dimensional space. We could also say that the third parameter in each data point in the space bears a functional relationship to the first and second parameters.
::::One way to verify that we are, in fact, working in three dimensions is to note that I have to specify the units and scaling on the x-axis(horizontal). the y axis(vertical), and the z axis(color) to be able to properly read the plot.
::::That said, I totally agree that the article should clearly specify the way in which spectrogram data are constrained. [[Special:Contributions/76.91.90.112|76.91.90.112]] ([[User talk:76.91.90.112|talk]]) 09:08, 17 May 2008 (UTC)
From user Spectrum1234:
I say it is 3-D. Is very thin paper 2-D or 3-D (even when viewed on your 2-D monitor) ?
Look at these spectrum plots (90' and 60') from the Goldwave program of an extremely quiet noise burst (thus it is about as 2-D (flat) as it could be, yet) it still 'looks' like it is 3-D (to the extent possible on a 2-D monitor):
[[Image:Britney Spears.gif|thumb|center|High quality image produced with "The_Voice" displayed using "Goldwave" from this file (converted, with some loss, from a .wav file) [[http://en.wikipedia.org/wiki/Image:Britney.ogg]] ]]
::::Every point on a spectrogram is defined by three coordinates: time (x-axis), frequency (y-axis), intensity (color or z-coordinate). three coordinates -> three dimensions -> 3D.[[Special:Contributions/80.128.76.51|80.128.76.51]] ([[User talk:80.128.76.51|talk]]) 14:06, 27 May 2008 (UTC)
:::::So it is definitely 3-dimensional. What do people think about putting a note that spectrograms don't always have to be time v frequency v power graphs? I could find an excellent example image from the physical sciences. <small>—Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/76.91.90.112|76.91.90.112]] ([[User talk:76.91.90.112|talk]]) 08:01, 12 July 2008 (UTC)</small><!-- Template:UnsignedIP --> <!--Autosigned by SineBot-->
::::::It's about as 3-dimensional as a picture. Intensity isn't a dimension, because it can only have one value. i.e. at a precise x,y coordinates, you can only have 1 intensity value. Saying that spectrograms are 3 dimensional would be like saying that the space you perceive is 6 dimensional because you have 3 space dimensions and 3 colour dimensions. A value isn't a dimension, that's the point. <span style="font-size: smaller;" class="autosigned">—Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/89.124.240.31|89.124.240.31]] ([[User talk:89.124.240.31|talk]]) 15:34, 18 December 2008 (UTC)</span><!-- Template:UnsignedIP --> <!--Autosigned by SineBot-->
:::::::I hope that the absurdity of this position is apparent to anyone who reads this. By this logic, a hemisphere placed on a table would be two-dimensional because each point of the hemisphere has only one value of height above the table. [[Special:Contributions/99.236.53.71|99.236.53.71]] ([[User talk:99.236.53.71|talk]]) 06:47, 11 December 2012 (UTC)
***
Someone should link this page to the italian corresponding article in italian, "Spettrogramma" <span style="font-size: smaller;" class="autosigned">—Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/151.67.178.125|151.67.178.125]] ([[User talk:151.67.178.125|talk]]) 11:42, 13 June 2009 (UTC)</span><!-- Template:UnsignedIP --> <!--Autosigned by SineBot-->
== sonograph vs. sonography ==
Where sonograph redirects to this page, sonography redirects to medical ultrasonography. This does not seem consistent, should we change this? --[[Special:Contributions/130.89.139.73|130.89.139.73]] ([[User talk:130.89.139.73|talk]]) 13:26, 23 July 2009 (UTC)
== Awful voice spectrograms ==
These two voice spectrograms are awful, they use such a low frequency resolution that you cannot distinguish any of their sonorants, they appear all fused together, which is misleading, and doesn't show how the pitch of voice varies (doesn't show the pitch at all actually). --[[Special:Contributions/89.124.241.234|89.124.241.234]] ([[User talk:89.124.241.234|talk]]) 14:19, 13 November 2009 (UTC)
:Please supply some better ones :) [[User:Wrapped in Grey|Wrapped in Grey]] ([[User talk:Wrapped in Grey|talk]]) 07:48, 28 June 2010 (UTC)
== spectrograms are positive? ==
[http://en.wikipedia.org/w/index.php?title=Spectrogram&diff=prev&oldid=383568209 This edit] added the following to the lead section: '''"In the field of time–frequency signal processing, it is one of the most popular quadratic Time-Frequency Distribution that represents a signal in a joint time-frequency ___domain and that has the property of being positive."''' Does that mean something to the regular contributors? Maybe there's just a simple typo throwing me off, but as a first-time visitor here, even with some experience with signal processing, I can't understand a word of it. For example, the terms "quadratic", "positive" and "distribution" are not defined, nor do they play much of a role in the article. [[User:Spiel496|Spiel496]] ([[User talk:Spiel496|talk]]) 17:44, 27 April 2011 (UTC)
: Removed. [[Special:Contributions/93.145.142.238|93.145.142.238]] ([[User talk:93.145.142.238|talk]]) 18:46, 9 August 2011 (UTC)
== Why are there a group of "Hidden Messages" links at the bottom? ==
They do not bear any apparent relation to the subject (spectrogram) or content of the article. Did some previous editor get confused between cryptograms and spectrograms? <span style="font-size: smaller;" class="autosigned">— Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/167.216.14.162|167.216.14.162]] ([[User talk:167.216.14.162|talk]]) 22:56, 15 September 2011 (UTC)</span><!-- Template:Unsigned IP --> <!--Autosigned by SineBot-->
:I removed the <nowiki>{{Hidden messages}}</nowiki> navbox, as I could see no obvious relation between it and this article. –[[User:Sparkgap|Sparkgap]] ([[User_talk:Sparkgap|talk]]) 18:48, 16 September 2011 (UTC)
== Why does this article claim that spectrograms are just for sound? ==
According to [http://www.thefreedictionary.com/spectrograms] a spectrogram is a "A graphic or photographic representation of a spectrum" - which is what I always understood the general term spectrogram means. For example you could have a spectrogram of the light observed from a star. This article gives the impression that a spectrogram is always related to sound waves. You can also find scientific papers ([http://www.ncbi.nlm.nih.gov/pubmed/22097822]) citing the term spectrogram in relation to other spectra than just sound waves. [[Special:Contributions/202.180.125.97|202.180.125.97]] ([[User talk:202.180.125.97|talk]]) 18:54, 2 October 2013 (UTC)
:Well I certainly use them for vibration, and I have seen them for radio spectra as well. I'll have ago at removing the bias. The reason that many of these spectral analysis articles is stufffed is that the medical/speech boys think they are the only ones using them, and 'correct' any other usage (eg [[cepstrum]]). [[User:Greglocock|Greglocock]] ([[User talk:Greglocock|talk]]) 22:24, 2 October 2013 (UTC)
==See an online spectrogram of speech or other sounds captured by your computer's microphone.==
When you click this link under "External Links", it links to a page that doesn't exist. Can someone fix this maybe?
[[Special:Contributions/2601:8B:4400:C180:2048:CDF2:690E:727|2601:8B:4400:C180:2048:CDF2:690E:727]] ([[User talk:2601:8B:4400:C180:2048:CDF2:690E:727|talk]]) 01:33, 30 December 2015 (UTC)
== Spectrogram and spectograph ==
Some [https://en.wikipedia.org/w/index.php?title=Spectrogram&diff=735696851&oldid=735095971 recent edits] have raised the issue again about how this Spectrogram article is restricted to sound while the [[Spectograph]] article seems more restricted to EM radiation. The sentence [[User:Kvng|Kvng]] reverted is generally correct, albeit added without source. A spectogram is the output of a spectrograph, or someimtes the result of digital transformation of the input signal in a manner that is generally analogous to what a spectrograph does. Who wants to step up to resolve this? It requires an editor who can pull information from multiple disciplines. I'm happy to help, but don't think I can do the entire thing myself. [[User:jmcgnh|<b><span style="color:#248F7D"> —jmcgnh</span></b>]]<sup><small><b>[[User_talk:jmcgnh|<span style="color:#58D582">(talk)</span>]] [[Special:Contributions/jmcgnh|<span style="color:#8F7D24">(contribs)</span>]]</b></small></sup> 23:16, 22 August 2016 (UTC)
:I can do some work on this. I'm not intimately familiar with these terms but I do know how to research this. Can you provide any links to previous talk page discussion on this mess? It looks like [[Spectrometer]] and [[Optical spectrometer]] should also be put into the mix here. ~[[User:Kvng|Kvng]] ([[User talk:Kvng|talk]]) 23:45, 22 August 2016 (UTC)
::{{u|Kvng}}: Agreed. (I didn't see this until today).
::This feels like a bigger change than I'm comfortable with at my current stage of becoming an editor. Fortunately there's no deadline, right? [[User:jmcgnh|<b><span style="color:#248F7D"> —jmcgnh</span></b>]]<sup><small><b>[[User_talk:jmcgnh|<span style="color:#58D582">(talk)</span>]] [[Special:Contributions/jmcgnh|<span style="color:#8F7D24">(contribs)</span>]]</b></small></sup> 01:34, 11 September 2016 (UTC)
:::I have expanded the scope of this article to clearly include non-audio signals. I have [[Talk:Optical_spectrometer#Merge_Spectrograph|proposed a merge]] for [[Spectrograph]]. ~[[User:Kvng|Kvng]] ([[User talk:Kvng|talk]]) 16:30, 11 February 2018 (UTC)
== Resolution of a spectrogram from band-pass filters ==
How would the resolution of a spectrogram obtained with a "series of band-pass filters" compare against that created conventionally via an FFT? Particularly in the low-mid audio frequency range. An FFT or a "digital" equalizer is quite poor at resolving narrow tones without compromising the time-resolution across the spectrum. I guess there must be a catch, because this type of filter isn't used anywhere. I would like to hear an explanation with minimal maths. [[User:J7n|J7n]] ([[User talk:J7n|talk]]) 17:20, 11 February 2017 (UTC)
:OK. Minimum maths. The equation of interest is dF>=1/T. dF is the frequency resolution, T is the characteristic time of the analysis method, in the case of DSP it is the length of one frame of data or the number of samples divided by the sampling frequency
:In the case of an analogue filter the characteristic time is governed by the same equation. That is the settling time of the filter will be inversely proportional to the bandwidth of the filter.
:The inequality in the equation is because in practice you don't quite get as much resolution as you'd like, due to a whole bunch of real and theoretical effects.
:Apparently that equation is analogous to, or even a consequence of, Heisenberg's uncertainty principle. Cool eh?
:real time filtering systems can probably be most easily implemented by using cascades of digital filters in the time ___domain, each with a high bandwidth and with short settling times, plus feed forward. At that point I am out of my depth.[[User:Greglocock|Greglocock]] ([[User talk:Greglocock|talk]]) 03:55, 12 February 2017 (UTC)
== Some other variable ==
I am not aware of spectrograms that don't use time as one of their axis. {{u|Greglocock}} asserts that [[RPM]] can replace time and provides [https://community.plm.automation.siemens.com/t5/Testing-Knowledge-Base/What-s-an-Order/ta-p/355020 this] citation. These plots have frequency, amplitude and RPM axis but there is no indication they're called or considered spectrograms. I have marked this with {{tl|fv}}.
I think Greglocock would prefer if I just marked "or some other variable" in the lead with {{tl|cn}} but, like I said, I'm not aware of any spectrograms that don't use time and it is difficult to prove a negative. ~[[User:Kvng|Kvng]] ([[User talk:Kvng|talk]]) 15:34, 9 November 2017 (UTC)
:http://www.machinedesign.com/fea-and-simulation/noise-prediction-moving-mechanisms-using-coupled-mbd-acoustics-analysis for a free article using that terminology. What a waste of effort. [[User:Greglocock|Greglocock]] ([[User talk:Greglocock|talk]]) 03:20, 10 November 2017 (UTC)
::My interpetation is that the spectrograms mention in this article are time based. The time axis is labeled RPM in Figure 6 because, for the measurement, the machine is sped up linearly as a function of time and recorded with a microphone so there is a proportional relationship between time and RPM. Here's the description of the measurement from the article, "Once simulations are completed, the acoustic pressure at microphones surrounding the virtual prototypes is outputted. The outputs time ___domain series can be easily converted in to audio files to listen to the response of the prototype to a certain excitation. The time ___domain data can be further post-processed in the frequency ___domain by means of spectrograms which show multiple signal spectra allowing the display of noise levels evolution with respect to the working regimes."
::Whether or not you accept my interpretation of this source, the source does not provide a definition or description of ''spectrogram''; it is merely demonstrating an in-context use of the term so should not be used to override our more direct sources which clearly state that a spectrogram is a time-frequency-intensity plot. ~[[User:Kvng|Kvng]] ([[User talk:Kvng|talk]]) 15:14, 12 November 2017 (UTC)
:I think "some other variable" just feels off, and think, given the very dominant use of time, we could use - "as they vary, generally, with time." Or some similar wording.[[User:MusicPoliticsFlowers|MusicPoliticsFlowers]] ([[User talk:MusicPoliticsFlowers|talk]]) 05:29, 19 January 2018 (UTC)
::I've [https://en.wikipedia.org/w/index.php?title=Spectrogram&type=revision&diff=821612311&oldid=817324551 removed] "or some other variable" for now because there isn't a consensus to include it. We can continue discussion here and try to reach consensus. ~[[User:Kvng|Kvng]] ([[User talk:Kvng|talk]]) 15:29, 21 January 2018 (UTC)
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