When I'm writing a play I hear it like music. I use the same indications that a composer does for duration. There's a difference, I tell my students, between a semi-colon and a period. A difference in duration. And we have all these wonderful things, we use commas and underlining and all the wonderful punctuation things we can use in the same way a composer uses them in music. And we can indicate, as specifically as a composer, the way we want our piece to sound.