Bell - Ensho

...As a result, the tunes are generally called ritsuryo. The origin of the names of the twelve tunes is explained in the Guoyu (Spring and Autumn Period) and the Hanshu (Book of Han), but it seems that in the Zhou Dynasty, the Jia Zhong was called the Enshou and the Lin Zhong was called the Kan Zhong, and that in the Spring and Autumn Period and Warring States Period, different tune names were used depending on the country. The pitch of the Yellow Zhong, which is the standard tone, is determined by the length of the tune tube. ...

*Some of the terminology explanations that mention "Enkane" are listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…これにより一般に音律を律呂（りつりよ）と呼ぶ。十二律名の語源は，《国語》(春秋時代)や《漢書》律暦志等に説かれているが，周時代には夾鐘を圜鐘（えんしよう），林鐘を函鐘と呼び，春秋戦国時代には，国により異なる律名を用いたらしい。　基準音である黄鐘の高さは律管の長さで規定する。…

※「圜鐘」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報