Christ was not alive then and only spoke to Paul in a voice.
Christ was dead? but still spoke???
I think we may be having a definition or terminology problem here.
This was after He had risen from the dead, and ascended to the Father in Heaven.
As far as I can tell, He has been alive ever since. No?
Yes, Christ was alive then. Remember that Acts 1 records Jesus’ ascension into Heaven. That took place before Paul’s conversion.