This is an introductory description of a correlogram. It was originally done for an internal Apple presentation where Leonardo Da Vinci explored various aspects of Apple technology. It explains the various features of a correlogram and shows how the correlogram changes as the pitch and formants move. The speaker/singer here is Peter Cavanaugh. It is similar to the clip labeled Duda Vowels but has fewer technical details and better singing.

Time Delay


Sight is the lord of astronomy; the prince of Mathematics. It counsels and corrects all the arts of mankind.

What fun! Here, observe! Ahhh Ahhh Ahhh (with rising pitch). See? The dark vertical lines follow what the muscles in my throat do.

Now, I will change the shape of my mouth but keep the same pitch with my throat. Ahhh, Eeee, Iyyy, Ohhh, Oooh. Yes! Yes! The horizontal lines determine what sounds come, that come out of my mouth.

Fascinating! If I had such a machine I could tell who it is that is speaking by the vertical pitch (sic, should be lines) and what was said by the horizontal lines.