Recitation of Buddha's name，
Diamond recitation with clear thoughts
~teaching by Venerable Master Miao Lian
To practice nianfo (recitation of Buddha's name), no matter to recite aloud, in middle voice, low voice, with diamond recitation or silent recitation, what matters most is to concentrate on the pure mind continuously without interruption.
In Diamond recitation you just move your lips but no sound is heard; in silent recitation you don't move your lips nor utter a sound but merely concentrate your mind and thoughts on recitation.
In the latter although you don't utter a sound, you hear every single Buddha's name in your mind clearly and distinct, and visualize every single Buddha's name obviously in your mind.
With such way of practice, you will gain a pure mind and hear every sound clearly with dharma joy.