If Vox were the main issue there'd be many more than just you complaining.
My main suspect is your sound system. Not only drivers although getting them up to date is important. Aside drivers, if you have several sound "cards" they may conflict each other. In gaming computers there's usually at least two of them: The motherboard sound and the video card sound - a USB headset usually adds one more. Unless you have speakers inside your monitor and actually use them, disabling the video card audio in Device Manager and uninstalling its driver is recommendable.
Referring to the above, the issue may well hide in your AH settings: In Options>Preferences>GameSounds check that the Microphone is using the correct sound device. Also check in the Key Mappings that the Vox key doesn't have double functions. The easy way is to unmap that very key and then remap it to Voice. Similarly, if you have the Vox assigned to your joystick or any other controller, double check for double mapping.