This post came up after the respective question by a friend of mine.
The account at Acts 9:7 says that the men with Saul heard “a voice” (KJ) or “the sound of a voice.” (NW) Yet, as recorded at Acts 22:9, Paul (Saul) says that the men with him did not hear the voice. When what was said in the two verses is properly understood, there is no contradiction. The Greek word for “voice” (φωνή) at Acts 9:7 is in the genitive case (φωνῆς) and gives, in this verse, the sense of hearing of a voice—hearing the sound but not understanding. At Acts 22:9 φωνή is in the accusative case (φωνήν): the men “did not hear the voice”. They heard the sound of a voice but did not get the words, the meaning; they did not understand what Jesus was saying to Saul, as Saul did.
That is why the ESV Bible has the following comment on verse 9:7: “Saul’s companions heard the voice but saw no one. In his later testimony to the Jews, Paul spoke of them seeing the light but not understanding the voice (22:9). They had no vision of Jesus nor did they hear the message to Paul, but they could testify to a brilliant light and a sound, which pointed to an objective event that was not a matter of Saul’s imagination”, and renders 22:9 as: “Now those who were with me saw the light but did not understand (or hear with understanding) the voice of the one who was speaking to me”.
This knowledge of the Bible’s use of the idea of ‘hearing’ in both senses helps to clear up what would otherwise seem to be discrepancies.