Can I prevent voiceover from announcing stickykeys?

Hi all, Am blind and have my left hand paralyszed. So in osx el el capitan I would have to use voiceover in combination with stickykeys. However, voiceover always says stickykeys whenever I press a modifier. Can I turn that annoying announcement off? I have been searching and requesting solutions for ages now, but no luck. I'd also love the capslock key act as stickykey when it is set as vo modifier in combination with stickykeys. Am using yosemite on an imac and a macbook air. Thanks in advance, Eldormilon