I go to Bible hub for reference and Matthew Poole's commentary on these verses seem to be a likely explanation. i.e. Verse 9:7 the voice they hear is Saul's only and that is also in indicated in verse 22:9. i.e. "...
.heard not the voice of him that spake to me.".......................
link>>>
https://biblehub.com/commentaries/poole/acts/9.htm