Spectrogram: Difference between revisions

Revision as of 00:21, 14 January 2006

Revision as of 20:42, 17 January 2006

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== Format ==

In the most usual format, the horizontal axis represents [[time]], the vertical axis is [[frequency]], and the [[intensity (disambiguation)|intensity]] of each point in the image represents amplitude of a particular frequency at a particular time. Often the diagram is reduced to two dimensions by indicating the intensity with thicker lines or, more intense colors or grey values.

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.