首楞嚴義疏注經 6.274

6.274

娑婆世界耳根最利，故用音聲以為佛事。由從耳根發識聞聲，引生第六識中聞慧，緣名句文，熏成解心種子，納為教體，故云教體在音聞也。教體既成，然後思惟修習，入三摩提，成大解脫。

In the Sahā world the ear faculty is the sharpest; hence sound is used to perform the Buddha's work. Arising from the ear faculty, consciousness hears sound, inducing the wisdom born of hearing within the sixth consciousness, which takes names, phrases, and syllables as conditions, perfuming them into seeds of an understanding mind and receiving them as the teaching-substance; therefore it is said that the teaching-substance is in hearing sounds. Once the teaching-substance is established, one then reflects and cultivates, enters samādhi, and accomplishes great liberation.