Charles Boberg was was recently interviewed about current trends in American English dialects by Larry Mantle on the show Airtalk, on KPCC, an NPR-affiliate in Pasadena, CA, broadcasting to greater Los Angeles. The segment aired April 17th and can be heard here: http://www.scpr.org/programs/airtalk/2015/04/17/42443/vowels-shift-regional-accents-recede-what-american/