Talk:Spectrogram

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[edit] Aphex Twin used Coagula

I removed the parenthetical claim that AT used Coagula because 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. --Hurtstotouchfire 02:45, 15 October 2007 (UTC)

[edit] Aphex Twin mp3

the picture is still visible in the mp3, just not as clear. i just checked. Omegatron 06:35, Feb 1, 2004 (UTC)

Depends on the MP3. Differently coded MP3s will lose different information. TMC1221 07:04, Feb 1, 2004 (UTC)

true, true. Omegatron

[edit] Another example

If this image reappears, put it back in:

A sonogram of a male voice saying [tatata], as displayed by Praat.

[edit] Mother tongue of the "tatata" speaker

The label for the "tatata" spectrogram should state the mother tongue of the speaker.

Possibly. But this sample is doubly artificial, since it not only is in the constructed language Lojban, but also comes from the corpus of a diphone speech synthesis system in that language, and therefore is a nonsense word.

In any case, we have since lost contact with the Belgian speaker of that corpus, so we cannot determine what his native language is. As the original uploader of that illustration I have no problem with seeing it go, since other spectrograms have now appeared. arj 20:10, 18 Apr 2005 (UTC)

That's a good example of the type of spectrogram traditionally used in voice though. I can make more cool edit spectrogram images of whatever, if you want. - Omegatron 20:30, Apr 18, 2005 (UTC)

[edit] Tubular Bells

Could we have a reference for the Tubular Bells, Rugby Transmitter spectrogram?

[edit] VLF section

I think it should read 24Hz instead of 24Khz, could someone more knowledgeable than me check this ? Zeno 04:02, 9 January 2007 (UTC)

Nevermind, i'm an audio guy, not a radio guy ! 24k is very low radio freq ! Zeno 04:08, 9 January 2007 (UTC)

[edit] Merge Waterfall_plot

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. (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. 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. Weston.pace 21:30, 5 July 2007 (UTC)

[edit] Format

I added a image of a FM spectrogram. The 'edit' link below it was moved over and I was unsure how to move it back.stemperm 20:35, 13 February 2007 (UTC)

[edit] Reading Spectrograms of Speech

How do people feel about a section regarding how to read spectrograms for speech analysis? Subsection? Separate article? I'd be willing to contribute. --Coyne025 17:17, 22 February 2007 (UTC)

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. (Spectrogram 22:30, 22 February 2007 (UTC))

[edit] History of the Spectrogram?

I'd like to know when the spectrogram was invented.

Also, I know it's been used a lot by Ethnomusicologists---it would be great to mention that somehow in the article, and I'd love to know the first (or a very) early reference to using the spectrogram in that context.

Thanks! MusicScience 23:53, 14 November 2007 (UTC)

Spectrographs were first invented by Bell Labs circa 1938 IIRC --89.127.175.78 (talk) 17:04, 12 May 2008 (UTC)

[edit] 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? Lova Falk (talk) 16:10, 17 January 2008 (UTC)

The third dimension is the intensity--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. —Preceding unsigned comment added by 128.97.68.15 (talk) 00:21, 14 May 2008 (UTC)

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 [2] --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. 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):

High quality image produced with "The_Voice" displayed using "Goldwave" from this file (converted, with some loss, from a .wav file) [[1]]

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.80.128.76.51 (talk) 14:06, 27 May 2008 (UTC)