Acts has several accounts on the story of St Paul's conversion.There seem to be some differences between the accounts, as to whether his mates heard the voice of Jesus.
In the first account, his friends hear the voice but see no one:
"As he journeyed he came near Damascus, and suddenly a light shone around him from heaven. Then he fell to the ground, and heard a voice saying to him, “Saul, Saul, why are you persecuting Me?” And he said, “Who are You, Lord?” Then the Lord said, “I am Jesus, whom you are persecuting.It is hard for you to kick against the goads.” So he, trembling and astonished, said, “Lord, what do You want me to do?” Then the Lord said to him, “Arise and go into the city, and you will be told what you must do.” [i]And the men who journeyed with him stood speechless, hearing a voice but seeing no one.[Acts 9:3-8]" [/i]
In the second account, his friends see the light but hear no voice:
“Now it happened, as I journeyed and came near Damascus at about noon, suddenly a great light from heaven shone around me. And I fell to the ground and heard a voice saying to me, ‘Saul, Saul, why are you persecuting Me?’ So I answered, ‘Who are You, Lord?’ And He said to me, ‘I am Jesus of Nazareth, whom you are persecuting.’
“[i]And those who were with me indeed saw the light and were afraid, but they did not hear the voice of Him who spoke to me. So I said, ‘What shall I do, Lord?’ And the Lord said to me, ‘Arise and go into Damascus, and there you will be told all things which are appointed for you to do.’ And since I could not see for the glory of that light, being led by the hand of those who were with me, I came into Damascus [Acts 22:6-11 "][/i]