The baptism of believers in the Holy Spirit is accompanied by the initial physical sign of speaking in other tongues (unlearned languages) as the Spirit of God gives them audible expression (Acts 2:4).

This form of speaking in tongues is basically the same as the gift of tongues (1 Corinthians 12:4-10, 28).  The different is the purpose and use.  (The manifestation of tongues can be observed in the life of every Spirit-filled believer at the initial infilling.  The audible expression of tongues should also continue to function in the Spirit-filled believer’s personal prayer life.  However, the gift of tongues [sometimes called “messages in tongues”] operates publicly, usually in congregational worship settings.  This gift is followed by the gift of interpreting the tongues.  Both are given to individuals within the church.  Their purpose is for the spiritual benefit of the individual and the congregation.)