Sound plays on iPhone, but not on iPad.

I have read that on ios7 sound only plays on trigger event. However I have created an Edge animation with auto play sound that doesn't play on an ipad with ios7 but does play on an iphone with ios7. Do you know why that would be? The animation is a loop of a car passing by.

I have this on the first frame of the timeline:

sym.$("yellow_car_fly_by2")[0].muted = false;

A little later on the timeline, I have this:

sym.$("yellow_car_fly_by2")[0].currentTime = 0;

A little more later on the timeline, I have this:

sym.$("yellow_car_fly_by2")[0].play();