how can i change pitch?

Maybe what you need is here.

http://www.google.com/#hl=en&sugexp=ldymls&xhr=t&q=change+pitch&cp=12&pf=p&sclient=psy&site=&source=hp&aq=0&aqi=&aql=&oq=change+pitch&pbx=1&fp=2d73bcec2e6e3c54