The phrase “dumbing down” has long been a catch-all term used by arts aficionados to take potshots at any organization daring to try to update their programming for modern audiences. More often than not, the changes aren’t dumbing anything down, merely acknowledging that the line between high culture and pop has blurred significantly in the last century, and that the average American’s frame of reference is defined not by symphonies and plays, but by rock albums and TV shows. At the National Performing Arts Convention in Pittsburgh, arts groups have been sharing ideas for embracing 21st-century culture without alienating their base or losing their souls.