2 And suddenly a roar came out of the sky, like the rushing of a violent wind,*Why the noise? Presumably to attract attention—God wanted to impact the whole city. Since everyone moved on foot, people would be arriving for a number of minutes, depending on where they started (the city was small in those days). and it filled the whole house where they were sitting.*They were sitting, so presumably the ‘house’ wasn’t the temple; I imagine it was the ‘upper room’. 3 Fiery tongues appeared and were distributed to them, and it [a tongue] landed*I understand from the grammar that the tongue actually touched down on the person, there was contact. on each one of them. 4 And they were all filled with Holy Spirit and began to speak different languages,*These are human languages, spoken somewhere on earth, as the following context makes clear. as the Spirit was granting to them to speak out.*"Speak out" translates a different word than the "speak" in the middle of the verse; the idea is to proclaim or project the voice. Notice that the speaking was controlled by the Spirit. The Text is emphatic that they were all filled, but they did not all start spouting languages; the languages were directed to specific hearers, as the following context makes clear. As the crowd began to gather the Spirit presumably sent the disciples (probably the same 120, at least) out to mingle with the people, and the Spirit proclaimed ‘the great works of God’ to each one in his mother tongue, using the mouths of the disciples. But there would also need to be a miracle in the ear of each hearer, to filter his own language out from the welter of sound (many languages being proclaimed at the same time). I would imagine that this activity lasted at least 10 or 15 minutes.