Why can't the God who spoke to young Samuel, or Saul, do it today should He choose to?
I know of examples first hand. One was a fine Christian friend, raised in an Orthodox Jewish home, planning to be a rabbi. A landmine went off in VietNam on the man in front of him, and this guy woke up three months later in Pearl Harbor, his eye hanging from the optic nerve because the socket was gone. It took 14 surgeries to put him together, he has plastic knees ( looks pretty normal, good plastic surgeons).
Anyway, when he woke up in the hospital from three months of coma, he said God spoke to him, as a devout Jew, in an audible voice, and revealed to him that Jesus was the messiah. He became the Lord's in that moment.
The other is my sister A, who lived close to another sister J, but hadn't been in her home for two years. The latter sister J was in a church against any form of doctors, medicine, having babies in hospitals, etc.
J had just had baby #5,a cute little boy a few days old. A was in her own home, and for the one and only time in her life she said God-or an angel- spoke to her with an audible voice and said "go to J's". It was so powerful a command that she dropped everything and rushed over, wondering if J would even let her in the house ( J was estranged from all of us, thanks to her cult).
A pulled up to the home and J called to her out the window that something was wrong with the baby. J's husband and pastor and elders were all unreachable, so there was nobody to help her confess the baby was healed and stand on the confession of healing and all that creative word stuff. A looked at the baby ( turning blue), grabbed it, ran to her car and said it was going to the ER.
Turned out to be a heart defect. The baby lived for 3 weeks but had too much O2 deprivation organ injury from the hour between when symptoms started and it got to the ER so they could not operate ( 7/10 chance of success had the baby made it to surgery in time).
Because of that, there was a mellowing in J and her husband for years, they reconciled to some degree with family. They also admitted that had the baby died the state might have taken away their other kids. And they have gotten medical help for two kids with broken bones ( you are not allowed to get help in this cult for a broken bone, I kid you not, you have to confess your healing since healing is in the atonement). The husband has repented and even gone to a couple Piper conferences. (Their church folded up soon after that baby died.)
I heard a PCA missionary to Afghanistan talk about what is happening in the Muslim world with dreams and visions- God is revealing himself to Muslims all over the place, in visions and even with an audible voice. Of course they seek out bibles and Christians right away to find out more, but the calling and the regeneration seems to be happening in extraordinary ways prior to their doctrinal understanding.
This is good, on how such things are not new revelation, nor for all people at all times like the canon is. Such events do not undermine the sufficiency of scripture at all.
http://www.frame-poythress.org/Poythress_books/NPoythressSpiritualGiftsFinal.pdf
Read part 12 of this essay by Vern Poythress, an OPC prof at Westminster Theological Seminary. These things are perhaps rare, but the Reformed community of the past understood them to be very valid.
Modern Spiritual Gifts as Analogous to Apostolic Gifts