Does Numbers 12:6–9 Indicate God Doesn’t Always Speak Clearly?

Questions about whether Numbers 12:6–9 indicates that people don’t always hear God clearly when he is speaking and how one should approach the staff of a Christian school that’s promoting mindful meditation and teaching “how to hear from God” using mystical methods.

• Does Numbers 12:6–9 indicate that sometimes people don’t hear God clearly when he is speaking?
• How would you approach the school staff at a Christian high school that’s promoting mindful meditation and teaching “how to hear from God” using mystical methods?