Mezue nkebi ahịrịokwu a: Hertz ghọrọ onye a ma ama mgbe ọ na-eduzi egwú Wagner na Metropolitan Opera nke dị na New York. E dekọtara ụfọdụ n'ime ihe ngosi ndị ọ na-eduzi na nnwale site n'aka onye na-ede akwụkwọ na Met Lionel Mapleson na ihe a maara ugbu a dị ka Mapleson Cylinders ma mesịa wepụta na LP. O buru ụzọ bịa San Francisco dị ka onye nduzi nke Metropolitan Opera n'oge njem ya na 1906 ma nọrọ ya mgbe obodo ahụ bibiri site na
ala ọma jijiji na ọkụ.