Possible Clues:

• Going on and on
• Cicada activity
• Bagpipe music
• Swarm sound
• Humming monotonously
• Going on and on and ...
• Going on tiresomely, nod and grin foolishly
• Muttering medic gets on in Gateshead
• When on the gin, the doctor is being a bore
• Going on and on and...