Zu Xiaosun was a Chinese musician of the Sui and Tang dynasties. During the Kaihuang reign period (581–600) of Emperor Wen of Sui he was appointed as Xielülang (协律郎), joined the melodizing of ritual music, and received orders to learn the Jing Fang Temperament (京房律法) from Mao Shuang (毛爽). After the founding of Tang Dynasty, Zu served as zhuzuolang (著作郎), libulang (吏部郎) and taichang shaoqing (太常少卿).

From 626 to 628, Zu composed music for Emperor Gaozu of Tang. Zu cooperated with (张文收), solved the problem of tuning (调律) and change of keys of twelve temperament (十二律旋宫).

All Zu's works about music temperament had already been lost, only some summaries of his theory were recorded by Annals of Music (音乐志) and Annals of Rites and Nusic (礼乐志).

祖孝孙（562年 - 631年），字德懋，隋唐时期乐律学家。

曾祖祖瑗，魏东鲁二郡、锺离侯。祖祖遵，魏卫将军、右光禄大夫、淮川公。父祖崇儒，官至齐州长史。祖孝孙精历算数学。隋初开皇年间任协律郎，参定雅乐、京房律法。曾向陈山阳太守毛爽学习「京房律法」。唐初任太常少卿，教宫女音乐。教得不好，宫女没有长进，太宗责怪孝孙。王圭与温彦博替祖孝孙辩解：「孝孙雅士，今乃令教宫人，更加谴责，毋乃非宜。」太宗更加生气，王圭据理力争。《新唐书》有传。

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