Not necessarily. Pentecostals believe that though, which they regard as a "prayer language". They believe that the Holy Spirit intercedes for us in that way. The speaking in tongues thing is in the Book of Acts, when many people who had just received the Holy Spirit went out praising and preaching about Jesus, who He is and what He has done. The people who heard them found that many were speaking to them in their native language, from the country they had came from... a form of a miracle. The people speaking may not have even been aware that it was happening. Some people never speak in tongues, but can rest assured that they do indeed have the Holy Spirit, for He let's you know this within your own spirit. There is a void, a feeling that something is missing in our lives, that only God can fill... and He does that by having the Holy Spirit dwell within us, filling that hole in our hearts and spirit. We become temples of His Holy Spirit, living stones of His Church not built by human hands. It is the one thing that convinced the Christian Jews that the living God was indeed with the Gentiles that were being converted. This is also found in Book of Acts.