Plot Spectrum -
To use this feature, first select a region of audio from a single
track, then select "Plot Spectrum".
It opens up a window that
displays the Power Spectrum of the audio over that region, calculated
using the Fast Fourier Transform. The graph represents how much
energy is in each frequency. As you move the mouse over the display,
it shows you the nearest peak frequency.
This window can also display other common
functions that are calculated using the Fast Fourier Transform, including
three versions of the Autocorrelation function.
The Enhanced Autocorrelation function is very good at identifying the
pitch of a note.
Audacity does not come with any other built-in Analyze commands, so anything below the separator in this menu must be a plug-in. It is possible for a poorly written plug-in to crash Audacity, so always save your work before using a plug-in.