Related Clues:

• Was friends with
• Was cognizant of
• Was versed in
• "... seen and not ___"
• Had the answer
• Had inside information
• Had no doubts about
• Was told about
• Had memorized
• Had more than just a hunch
• Was aware of the fact
• Perceived sound
• How one got the sound of many beasts
• That's not hte old sound I was accustomed to
• By the sound of it. the beasts got it, by the sound of it