For the past two days, I had been hearing some scary sounds after waking up and it frightened me.I'm glad today I have not heard them.

Is it possible to use the continuous tense as it happened more than one, and despite the sounds did not last long .

But may be continuous is not require when there is "for the past two days"which already indicates that it is a repetitive event and to use a continuous tense the sounds should last a long time