What does dropping your voice an octave mean?

"Dropping your voice an octave" refers to lowering the pitch of your voice by one octave. One octave is the difference between one musical note and another note with exactly double its frequency. Imagine the "Do-Re-Mi-Fa-So-La-Ti-Do" scale. If you start at "Do" and move one octave lower, you will be at the "Do" one octave below. So if your normal speaking voice is at a frequency of 100 Hz (hertz), dropping your voice an octave would mean lowering it to 50 Hz.