I think the megaphone spell is the proto and to traing a young alicorn to use the royal canterlot voice, try to use the RCV wont pratise is will be stupid, is will be look like flurry and Twilight is a aduilt so will be more powerful and painful to use a out control RCV! RCV is Royal Canterlot Voice!
Sleep spell, probably.
With enough practice, it becomes second nature.
Ah, geez.
I wonder what my fuckup spell would do?
*Sonorus