"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."
-- Encyclopedia of Bible Difficulties, by Gleason L. Archer,
p. 382.
According to Archer, this
distinction does indeed exist in the Greek language.