"The wind bloweth where it listeth, and thou hearest the sound thereof, but canst not tell whence it cometh, and whither it goeth: so is every one that is born of the Spirit." - John 3:8 KJV

Jesus is explaining that just as the wind has a sound that accompanies it, so likewise the Spirit has a sound that accompanies it. We learn later on the Day of Pentecost, that speaking in tongues is the sound that accompanies being filled with the Spirit.

"And they were all filled with the Holy Ghost, and began to speak with other tongues, as the Spirit gave them utterance." - Acts 2:4 KJV

When Peter preached for the first time to Gentiles, they were all filled with the Holy Ghost and all spoke with tongues, as the Spirit gave them utterance.

"And they of the circumcision which believed were astonished, as many as came with Peter, because that on the Gentiles also was poured out the gift of the Holy Ghost. For they heard them speak with tongues, and magnify God." - Acts 10:45-46 KJV

Paul witnessed to disciples of John the Baptist. (Acts 19:1-4).

"When they heard this, they were baptized in the name of the Lord Jesus. And when Paul had laid his hands upon them, the Holy Ghost came on them; and they spake with tongues, and prophesied." - Acts 19:5-6 KJV