Dialect coach Erik Singer is back, this time to take a look at tongue twisters. We've all tried tongue twisters in our lives, and know how hard they can be! But "why" are they hard? What makes one group of words more difficult to speak fluidly than others? Erik explains why our tongues get so twisted up, and breaks down how different tongue twisters affect different people with different accents.br br Ultrasound Tongue Twister footage courtesy of Professor Ian Wilson, CLR Phonetics Lab at the University of Aizu, Japanbr Sagittal Section Diagram courtesy of Professor Daniel C. Hall, Linguistics & Department of English Saint Mary’s University, Halifax, N.S.