The purpose of these demos is to learn both a visual and audio
connection between sounds and their waveforms.
This connection will be built by listening to
some sounds and then seeing what they look like as a function of time.
Then we'll see how their frequency content evolves over time by
looking at the spectrogram. This leads to a second connection
between the sound and its frequency content.
Many of the test signals were generated via MATLAB, but
some are recordings of "real" signals.
For the simpler cases, the time signal is plotted,
but for all cases, the spectrogram is shown.
The chirp and FM sounds were generated with MATLAB.
You could use
them to test how well you understand the spectrogram.