A.T. Robertson Commentary Acts 2:6

"And when this sound was heard, the multitude came together, and were confounded, because that every man heard them speaking in his own language." — Acts 2:6 (ASV)

When this sound was heard (γενομενης της φωνης ταυτης). Genitive absolute with aorist middle participle. Note φωνη this time, not ηχο as in verse 1. Φωνη originally meant sound as of the wind (John 3:8) or an instrument (1 Corinthians 14:7,8,10), then voice of men. The meaning seems to be that the excited "other tongues" of verse 4 were so loud that the noise drew the crowd together. The house where the 120 were may have been (Hackett) on one of the avenues leading to the temple.

Were confounded (συνεχυθη). First aorist passive indicative of συνχεω or συνχυνω, to pour together precisely like the Latin confundo, to confound. The Vulgate has it mente confusa est. It is an old verb, but in the N.T. only in Acts five times (2:6; 9:22; 19:32; 21:27,31).

In his own language (τη ιδια διαλεκτω). Locative case. Each one could understand his own language when he heard that. Every one that came heard somebody speaking in his native tongue.