The model behind every 1980s talking toy. LPC fits an all-pole filter to each short frame of a sound — the filter that best predicts each sample from the last dozen — and treats what's left as the excitation. Separate the two and you can keep the filter (the moving vocal-tract shape, the words) but replace the excitation with a fresh buzz at whatever pitch you play: a talkbox. Swap the buzz for noise and the same words come out as a whisper — the source–filter split laid bare. The built-in source sweeps through vowels; drop your own voice to make it sing that. Analysis is offline; play it with the keyboard.
Speed slides the words faster or slower without changing the pitch you play — time and pitch are independent in LPC.
Higher order = more poles = sharper formants (and more of the pitch leaks into the filter).
hold a note (a s d f …) to voice the words at that pitch — it's monophonic, like a real talkbox