Editing Spectrogram (section)

==Format==
A common format is a graph with two geometric dimensions: one axis represents [[time]], and the other axis represents [[frequency]]; a third dimension indicating the [[amplitude]] of a particular frequency at a particular time is represented by the [[Brightness|intensity]] or color of each point in the image.

There are many variations of format: sometimes the vertical and horizontal axes are switched, so time runs up and down; sometimes as a [[waterfall plot]] where the amplitude is represented by 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. Audio would usually be represented with a logarithmic amplitude axis (probably in [[decibel]]s, or dB), and frequency would be linear to emphasize harmonic relationships, or logarithmic to emphasize musical, tonal relationships.

{{Gallery
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|File:Spectrogram of violin.png|Spectrogram of [[media:Violin for spectrogram.ogg|this recording of a violin playing]]. Note the harmonics occurring at whole-number multiples of the fundamental frequency.
|File:Spectrogram.png|3D surface spectrogram of a part from a music piece.
|File:Praat-spectrogram-tatata.png|Spectrogram of a male voice saying 'ta ta ta'.
|File:Dolphin1.jpg|alt6=|Spectrogram of dolphin vocalizations; chirps, clicks and harmonizing are visible as inverted Vs, vertical lines and horizontal striations respectively.
|File:VariableFrequency.jpg|Spectrogram of an [[Frequency modulation|FM]] signal. In this case the signal [[frequency]] is modulated with a [[sinusoidal]] frequency vs. time profile.
|File:PAL-I.png|Spectrum above and waterfall (Spectrogram) below of an 8MHz wide [[PAL]]-I Television signal.
|File:Parus major sonagram.jpg|Spectrogram of [[media:Parus major 15mars2011.ogg|great tit song]].
|File:GW170817 Gravitational Wave Chirp Spectrogram.jpg|alt8=|[[Constant-Q transform|Constant-Q]] spectrogram of a gravitational wave ([[GW170817]]).
|File:Waterfall_plot_of_a_whistle.png|alt9=|Spectrogram and waterfalls of 3 whistled notes.
|File:Mount Rainier soundscape.jpg|Spectrogram of the [[soundscape ecology]] of [[Mount Rainier National Park]], with the sounds of different creatures and aircraft highlighted
|File:SonogramVisibleSpeech.png|Spectrogram (generated with the freeware [https://github.com/Christoph-Lauer/Sonogram-Visible-Speech Sonogram visible Speech]).
|File:CQT-piano-chord.png|[[Variable-Q transform]] spectrogram of a piano chord (generated using [[FFmpeg]]'s showcqt filter).
}}[[File:Sound spectrography of infrasound recording 30301.webm|thumb|Sound spectrography of infrasound recording 30301]]