The oldest Jewish music notation? Ovadiah the Proselyte from Oppido Lucano
Born around the year 1070 in Oppido Lucano, a small hill-top town a few miles far the city of Potenza in the Molise region, to Dreux/Droco and Maria, an influential family of the Norman elite, Johannes was a Catholic priest who converted to Judaism around 1102, probably inspired by the conversion of Archbishop of Bari Andreas. As a former member of the Catholic church, Ovadiah used his music skills, more specifically the neumatic notation, to transcribe a set of melodies on Hebrew liturgical texts. It is disputed, however, whether the melodies he transcribed in neumatic notation are Jewish or Christian-Gregorian tunes combined with Hebrew texts, or contrafacta. He recorded his personal and spiritual vicissitudes in the so-called "Megillat-Ovadiah" (The Scroll of Ovadiah), transmitted by a series of fragmentary manuscripts found in the Cairo Genizah, that includes a "siddur" with a series of piyyutim (devotional compositions), namely "Mi 'al-chorev" for Shavuot and Simchat Torah, and "Barukh ha-gever" (mss. Cambridge, University Library, Taylor-Schechter, K. 5.41 and ms. New York, Jewish Theological Seminary, Adler 4096 [ex 8399]).
A comprehensive survey of the Cairo Genizah, with transcription and full translation is available at https://johannes-obadiah.org. A very detailed analysis of the music contents, together with a set of recordings of the neumatic melodies is available at the webiste of the Jewish Music Research Centre at https://www.jewish-music.huji.ac.il/content/mi-al-har-horev-manuscripts-obadiah-proselyte