Important question. Thank you for asking it. Moreover, thank you for sharing the informative answer. With love for this group 💕

Chances are that it's an auditory hallucination, and hallucinations can start as early as Stage 4. If you go to the Q&A section of this website, and type "Stages of Alzheimer's" into the finder (click on the spyglass at the top of the page) I posted both the Reisberg Scale and the FAST Scale not long ago. See Stage 4 on the Reisberg Scale.