All of these symbols are appropriate when we apply them to the Holy Spirit. It is an extremely dangerous thing to get your idea of what was taking place at Pentecost from some modern day charismatic church services you may have attended or perhaps seen on television. Though the gift of tongues came suddenly and unexpectedly, nevertheless it was clearly understood by the disciples to have been given for the purpose of clear communication to the gathered crowds at Pentecost. This was given not as a permanent thing, but specifically to accomplish the task of communicating the gospel to those who had come from numerous foreign countries. The content was far more important than the manner in which it was given.
Crowds have a natural tendency to grow as something different and out of the ordinary is happening.
And secondly, to communicate directly. Not only were all these various nations in Jerusalem for Pentecost, they were each one represented as they stood before the disciples. There would be some from each land who recognized this unique occurrence as a manifestation of the Spirit of God. To them these were signs of divine power and symbols of abiding truth. The difference was the powerful activity in the hearts of some and not in others.