Spectrogram: Difference between revisions

Revision as of 23:15, 16 February 2007

Revision as of 23:50, 17 February 2007

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There are many variations of format. Sometimes the vertical and horizontal axes are switched, so time runs up and down. Sometimes the amplitude is represented as the height of a 3D surface instead of color or intensity. The frequency and amplitude axes can be either [[linear]] or [[logarithm]]ic, depending on what the graph is being used for. For instance, audio would usually be represented with a logarithmic amplitude axis (probably in [[Bel (acoustics)|dB]]), and frequency would be linear to emphasize harmonic relationships, or logarithmic to emphasize musical, tonal relationships.

{{video|filename=My_Songo_Real_Time_Analysis.ogg|title=Real Time Analysis|description=A real time analysis of a song; this spectrogram features frequency on X, magnitude on Y, and moves through time in sequence with the song.}}

== Generation ==

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* [[Fast Fourier transform]]

* [[Short-time Fourier transform]]

* [[Spectrometer]]

* [[Spectrum]]

* [[Wavelet transform]]

== External links ==

* [http://www.bastwood.com/aphex.php Several spectrogram examples, including the one by Aphex Twin]

* [http://tfd.sourceforge.net/ DiscreteTFDs - software for computing spectrograms and other time-frequency distributions]

* [http://www.fon.hum.uva.nl/praat/ Praat - doing phonetics by computer]