While staying at a hotel in Paris, he was in a room next to a
suite where famous opera singer
Enrico Caruso was staying. Through the
thin walls, Caruso heard Christiensen singing pieces of an opera to
himself in the bathtub. Caruso later approached Christensen and told
him he had the best voice he had ever heard and offered to give him a
lead part in his next production. Christensen, embarrassed, declined
the offer, explaining that it was impossible for him to perform before
an audience and that his singing voice only returned to him when he was
alone and thought that nobody was listening.