Today I was scanning my news feed and ran across an article at Buddhistdoor entitled, Frequencies, the Brain, and Wisdom Traditions, which explores the effects of sound frequencies and music on mental states. The take-away point for me was this:

The use of sound has been historically central also in the Buddhadharma. In the Mahayana traditions (which includes Vajrayana), every practice is transmitted first and foremost through sound, irrespective of whether or not the recipient understand the meaning of the words being transmitted. It is said that only hearing the sound of a particular Buddhist teaching initializes the mindset necessary to benefit from Dharma practices.

This is exactly why Nichiren Buddhists chant the Lotus Sūtra in Shindoku. As Ryuoh Michael Faulconer explains in the introduction to Myoho Renge Kyo Romanized:

Around the world, the Lotus Sūtra is traditionally read in shindoku, a reading of the Chinese translation of the Sūtra with a Japanese pronunciation. It is a form of faith reading done as a practice which our inner Buddha nature understands.

And, of course, this is also the foundation of why we chant Namu Myōhō Renge Kyō:

QUESTION: If someone chanted Namu Myōhō Renge Kyō without understanding its meaning will the benefit of understanding still be received?

ANSWER: When a baby nurses, it does not comprehend the taste; nevertheless, it receives the benefits of the milk naturally. Did anyone know the ingredients or formula for Jīvaka’s wondrous medicines? Water is without intent but it can extinguish fire; and even though fire consumes many things, can we say it does this deliberately? This is Nāgārjuna and T’ien-t’ai’s idea! I am merely repeating it.

Shishin Gohon-shō, The Four Depths of Faith and Five Stages of Practice, Writings of Nichiren Shōnin, Faith and Practice,
Volume 4, Page 106-107