主动语态中,hear只能接不带to的不定式或动名词作宾语,即：hear sb do ；hear sb doing
在被动语态中,要将不定式前加上to,即：be heard to do；be heard doing

你所提是在被动语态中,所以be heard to doing不存在.
be heard to do被听说将去做某
be heard to be doing 　是to do 的进行时：被听说正在做某事
be heard doing被听说（近期）一直在做某事

另,不定式一般时、进行时和完成时的区别
He is believed to come.(=It is believed that he will come.) 要来,还没来
He is believed to be coming.(=It is believed that he is coming.)正在来路上
He is believed to have come.(= It is believed that he has come.) 已经来了