On Yom Kippur we read from the Talmud tractate Yoma, the section dealing with Yom Kippur in the Beit HaMikdash, the Holy Temple in Jerusalem. Chapter 3 mentions Hogros ben Levi, one of the Levites in charge of music in the Holy Temple:
"Hogros b. Levi - We have learned in a Boraitha: When he had to render his voice melodious, he placed his thumb in his mouth, and the index in his mustache. When all his fellow-priests heard his voice, they bent to the ground (from ecstasy)." Other translations state that he put his thumb under his tongue to create a most beautiful melody.
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