In two accounts of Paul's conversion in the book of Acts, a statement is made that critics assert is a contradiction:

Acts 9:4-7

4 And he fell to the earth, and heard a voice saying unto him, Saul, Saul, why persecutest thou me?
5 And he said, Who art thou, Lord? And the Lord said, I am Jesus whom thou persecutest: it is hard for thee to kick against the pricks.
6 And he trembling and astonished said, Lord, what wilt thou have me to do? And the Lord said unto him, Arise, and go into the city, and it shall be told thee what thou must do.
7 And the men which journeyed with him stood speechless, hearing a voice, but seeing no man.

Acts 22:7-10

7 And I fell unto the ground, and heard a voice saying unto me, Saul, Saul, why persecutest thou me?
8 And I answered, Who art thou, Lord? And he said unto me, I am Jesus of Nazareth, whom thou persecutest.
9 And they that were with me saw indeed the light, and were afraid; but they heard not the voice of him that spake to me.
10 And I said, What shall I do, Lord? And the Lord said unto me, Arise, and go into Damascus; and there it shall be told thee of all things which are appointed for thee to do.

So did the men with Paul hear a voice, or not?

Solution

From the account in Acts 22, we simply learn that either:

• The men heard another voice, i.e. an angel, but not the voice of Christ
• The men heard the voice of Christ, but didn't understand what He said to Paul, therefore they didn't "hear" Him

I find the second solution more likely, and Paul is using the word "heard" in the sense of "understood", as it's used here:

1 Corinthians 14:21

21 In the law it is written, With men of other tongues and other lips will I speak unto this people; and yet for all that will they not hear me, saith the Lord.

Did they hear God? Yes, but no. They didn't "hear" Him in the sense that they didn't hearken unto what He said, or comprehend it.

Also see Matthew 13:13, Mark 4:12, Luke 8:10, and Isaiah 6:9 for instances where people "heard" without "hearing" or "understanding". It's a pretty easy concept to comprehend.

The Scene

This is how I would imagine the scene:

• The men are travelling alongside Paul (still named "Saul" then)
• The men see a bright light, and Paul falls to the ground
• The men hear something being said to Paul, but can't fully make it out or understand it
• Meanwhile, Christ is speaking clearly to Paul

Conclusion

As in the Gospels, getting multiple accounts of the same event allows us to better understand what took place.

These verses do not have to contradict at all, which is why they don't, and neither do any of the verses in God's Word.