I am not aware of any such scientific studies. However, there is a website on which a recorded recollection by a man, William V. Rathvon, who heard the Gettyburg Address at the age of nine. It is from a 1938 recording on a 78 r.p.m. record. www.npr.org/progams/lnfsound/sound/990212.sow.html Regards, David K. Barnhart