Matlab for Computing Spectrograms

The Matlab Signal Processing Tool Box provides the command spectrogram for computing and displaying a spectrogram (and Octave has the command stft). As a side effect, it returns the complex STFT data in a matrix.

The myspectrogram function below illustrates computation of a spectrogram in matlab for purposes of basic spectrum analysis. It is compatible with the basic functionality of Matlab's spectrogram function, but does not implement all of its features.

We also include invmyspectrogram, which inverts a spectrogram to reproduce the corresponding time-domain signal. Finally, testmyspectrogram is included to illustrate their performance on test signal.

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Subsections

• Matlab listing: myspectrogram.m
• Matlab listing: invmyspectrogram.m
• Matlab listing: testmyspectrogram.m

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About the Author: Julius Orion Smith III
Julius Smith's background is in electrical engineering (BS Rice 1975, PhD Stanford 1983). He is presently Professor of Music and Associate Professor (by courtesy) of Electrical Engineering at Stanford's Center for Computer Research in Music and Acoustics (CCRMA), teaching courses and pursuing research related to signal processing applied to music and audio systems. See http://ccrma.stanford.edu/~jos/ for details.