With Jan Peerce and Leonard Warren, she recorded an excellent Rigoletto for RCA Victor in 1950 - the first operatic recording to be released on microgroove, unless I am mistaken.
Definition of microgroove in US English:
microgroove
nounˈmīkrəˌɡro͞ovˈmaɪkrəˌɡruv
The very narrow groove on a long-playing phonograph record.
（唱片的）密纹
Example sentencesExamples
With Jan Peerce and Leonard Warren, she recorded an excellent Rigoletto for RCA Victor in 1950 - the first operatic recording to be released on microgroove, unless I am mistaken.