Does the iPhone's Voice Control keeping appearing when you hit the home button? It's annoying as it is basically useless. So how does one disable it?? Well unfortunately without a jailbreak you can't (With a jailbreak you can install the Activator app and set the 'long hold' action on the home button to no action).
However I've found that if you have the triple click Accessibility Shortcut enabled (for stuff like Invert Colours, Greyscale, Assistive Touch etc) then Voice Control seems to pop up a lot more. So if you want Voice Control to appear less often then try switching off the Accessibility shortcut - by going to Settings->General->Accessibility->Accessibility Shortcut and unticking all options. I think I've also noticed a slight overall responsiveness on the phone too (this is under iOS8.3 on ye olde iPhone 4S).