From time to time Google (voice) search randomly starts on my phone (Huawei Ascend Y300, Android version 4.1.1). I'll be listening to music for example, change song, and out of nowhere Google voice search will open. I have no idea what button I'm pressing or what I'm doing to activate this. I would ideally deactivate this completely, but knowing what it is I do to open this will also be of great help.
I've gone to the settings when I get this screen. Google Now is already turned off and there doesn't seem to be anything relevant there I can do.