Yamuna : In London, Prabhupada had a program at Conway Hall. Conway Hall was a 500-seat auditorium in Red Lion Square.
One night an extraordinary thing happened. Prabhupada led the first kirtana and then gave a lecture. I sat on the floor just to his right with the harmonium, and after the lecture, I began leading the second Hare Krishna kirtana. All of a sudden, Srila Prabhupada's voice cut through the auditorium with the potency of Lord Nrsimha right in the middle of my chanting. I had never heard Prabhupada do that, nor had I heard the words he chanted.
"Narada muni bhajay vina radhika-ramana-name," he sang. And then again he repeated it.
I looked up, and he looked down at me, signaling me to carry on. So I continued chanting Hare Krishna, and he continued singing his prayer to Narada Muni into his microphone. I closed my eyes and carried on, not knowing what was happening. Then he started leading with me. We could all understand that something inexplicable but amazing was happening. Everyone was literally jumping off the ground, leaping in the air; even little baby Saraswati was two feet off the ground, and the audience was leaping into the air. We jumped off the stage and all of us began running around the perimeter of the auditorium with the audience! The next morning I asked Prabhupada what had happened the previous night. "Didn't you see?" Srila Prabhupada said. "Narada Muni came to our kirtana." "No, I didn't see him," I answered. "Yes, Narada Muni came."
Reference: Yamuna Devi - A Life of Unalloyed Devotion