Spectrogram Analysis

One of the most important steps in animation is called sound breakdown. It is the process by which an animator will listen to sound and figure out it's timing. It an animator is going to animate a voice of a character, they need to determine the timing of the pronunciation. If they are given music, they need to be figure out the timing of the notes.


In the old days, before digital was all the rage. The audio would be on a magnetic tape and they would play that backwards and forward very slowly to time everything out. It took along time, but was a good process. With the advent of digital technology, there has actually bit a turn for the worse for most audio breakdown. Most programs to play audio aren't very accurate and don't sound great when you try to slow something down a lot and scrub through it.


You may think that the waveform of a file would be useful in figuring out the timing. Wave forms are fairly useful when some basic sounds are happening, but soon they become useless when there are too many sounds.

What I have been looking into for the last year is a different way of representing sound: spectrograms.


A spectrogram is fairly simple to understand. On the horizontal axis time is represented from left to right. The vertical axis represents the frequency of the sound. The color represents the intensity of he sound.

This is an example of a spectrogram of piano and violin music. If you can see a spectrogram in action it becomes fairly easy to distinguish notes, chords, and other sorts of sounds. You can see rhythms, scales and all sorts of other parts of the music.


While it may not be immediately apparent, there is a vast amount of extra information visible in the spectrogram which is simply hidden in the waveform.


I have two suggestion for software if you would like to try out spectrogram analysis.

The first is only for windows, and I find mostly useful when you are starting out with spectrograms because it allows for real time analysis of sound. This means that if you have a microphone on your computer, you can make noises and seem them appear on the screen. I have spent hours making noises at my computer to see what they look like.

The program is Spectrogram 16.

It is only available for Windows. There are other versions of this program, Spectrogram 5.0, and others, but for some odd reason I can't get them to work well.

If can get the program working do the following.

Press- File/Scan Input

A whole bunch of options will appear, leave them at the default. Press OK.

Now if everything is working you can start making noises and seeing the results.

I would suggest trying whistling, talking, singing, instruments and whatever other things you can think up.

The second piece of software I suggest is much more robust, is compatible with Mac and Windows and is more useful for animation audio breakdown.

Sonic Visualizer

With this software you can import prerecorded sound files and really analyze them well.

To work with this program:

File-New Session

Then press File- Import Audio.

Now to see a spectrogram:

Press Layer - Add Melodic Range Spectrogram - All channels Mixed.

Now it should generate a nice spectrogram of your audio


I will stop now with this talk about spectrograms. There are lots of settings that can be adjusted which can drastically change the appearance of a spectrogram. I will have to write an even more in depth explanation of that in the future. In general it is good to play with the settings and look at the results. If it looks more useful it probably is.

 While I have been able to really get a full grasp on this more advanced topic of spectrogram analysis, it is possible to read spectrograms, meaning if you could determine what a person said simply by looking at the spectrogram.  This ability is extremely applicable to sound break down.  For more information  see Spectrogram Reading.

If you do start using spectrogram for audio analysis, I do want to end with one word of caution: Never stop listening to what you are doing.  If you allow yourself to fall into the trap of only looking at the sounds, you could miss something very important in the sound.  Spectrogram analysis is only a tool that helps the precision and accuracy of sound break down, it is not a replacement for listening.

Kyler