Itaru Sekiguchi first heard the Great Organ at Paris' Notre Dame cathedral when he was 10. The "infernal sound" changed his life forever.

"It was a bit of a culture shock," he said.

Today, Sekiguchi, 53 and originally from Japan, is one of a handful of specialists entrusted with tuning and voicing the fabled instrument as Notre Dame prepares to reopen on Dec. 7 after a devastating fire in 2019.