Joseph Mallord William Turner didn't so much speak as cough up phlegmatic sounds. At least, such is the early 19th-century English artist's go-to response as realized by Timothy Spall's lived-in performance in director Mike Leigh's patiently unconventional biopic "Mr. Turner." Whether barking orders at his housekeeper Hannah (Dorothy Atkinson), looking at paintings in the Royal Academy, or listening to a mellifluously foppish John Ruskin (Joshua McGuire), Spall's Turner doesn't respond with a verbal thought. He barks and doesn't care if you understand. This noise, depending on the situation, conveys disdain, curiosity, surprise, wonder, tenderness, and even humor. It's an expectorated breath equal parts grunt and scoff: a groff.