Mark Liberman pitch-tracked the president's weekly addresses:
FDR had his weekly "Fireside chats", and in 1982 Ronald Reagan began the modern tradition of weekly presidential addresses, which U.S. presidents since then have maintained. I don't think that very many people actually listen to these things — no one that I've asked has ever admitted to regular consumption. But I've been collecting them since 2004, and listening to most of them, and a few days ago I noticed something. What I noticed is that president Obama seemed a mite testy in his weekly address for 10/1/2011 ("Fighting for the American Jobs Act"). This led me to ponder the phonetics of testiness, and of emotional expression in general.
Liberman found "an average pitch of 137.3 ±0.38 Hz on October 1, vs. an average of 106.6 ±0.31 Hz on August 6, for a proportional difference of about 29%."