Acts 9:7 and Acts 22:9—a Contradiction?
"And the men which journeyed with him stood speechless, hearing a voice, but seeing no man." —Acts 9:7
"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." —Acts 22:9
In the Encyclopedia of Bible Difficulties by Gleason L. Archer, the following explanation is given:
". . . In the original Greek, however, there is no real contradiction between these two statements. Greek makes a distinction between hearing a sound as a noise (in which case the verb "to hear" takes the genitive case) and hearing a voice as a thought-conveying message (in which case it takes the accusative). Therefore, as we put the two statements together, we find that Paul's companions heard the Voice as a sound (somewhat like the crowd who heard the sound of the Father talking to the Son in John 12:28, but perceived it only as thunder); but they did not (like Paul) hear the message that it articulated. Paul alone heard it intelligibly (Acts 9:4 says Paul ekousen phonen--accusative case); though he, of course, perceived it also as a startling sound at first (Acts 22:7: "I fell to the ground and heard a voice [ekousa phones] saying to me," NASB). But in neither account is it stated that his companions ever heard that Voice in the accusative case."
SOURCE: Encyclopedia of Bible Difficulties, by Gleason L. Archer, p. 382.
According to Archer, this distinction does indeed exist in the Greek language.