[music-dsp] spectrograph / sonogram visualization

douglas irving repetto douglas at music.columbia.edu
Wed Jul 4 02:42:51 EDT 2001

Aaron Brick wrote:
> hello all,
> i'm new to the list, and finding it fun & educational. thanks for having me.
> i have been experimenting with visualization techniques, and having gotten
> familiar with the conventional amplitude/time and fourier
> amplitude/frequency graphs, i'm trying to determine how to get a
> frequency/time graph; these are called spectrographs or sonograms?

hi aaron, 

i don't think there's much consensus on what the different graphs are
called. i've seen various names applied to various graphs. what i think
of as a sonogram is a three dimensional plot of a signal's spectra in
time. the x axis is usually time, the y axis is usually frequency and
the z axis (brightness of the image) is usually amplitude. so with a two
dimensional image you can represent all three dimensions.

here's an old application of mine that let you manipulate these
3-dimensional graphs in real time:


> there is a built-in function called "specgram" which i have not had success
> using;

in what program?

> since i want to understand the theory of such a transform i'm asking
> here. also, are there any other useful 2D visualizations?

there are lots of ways to represent sounds in n-dimensions. see matt
ingals' recent post about his stereo image visualization software for an


                        douglas irving repetto 

dupswapdrop -- the music-dsp mailing list and website: subscription info,
FAQ, source code archive, list archive, book reviews, dsp links

More information about the music-dsp mailing list