Some notes sound like they are moving/dynamic, while other notes sound like they are still/ static. The first kind embody change: even though the pitch of the note always stays within the permissible range, it is constantly fluctuating and in motion. The second kind of note seems caught in time, suspended: motionless.
"Motionless"notes create a sense of tension, whereas "moving" notes create flow.Both in honkyoku and other types of music, all truly accomplished players use these two kinds of notes at will as they think appropriate.
At the most basic level, moving notes can be created by subtle vibrato, or by varying the volume of the note. It is much more difficult to play notes that are truly still and motionless. To be so, the note's pitch, volume, and even tone color must become perfectly constant for a period of time.
Since the sound is created with breath, andthe amount of breath remaining in your lungs is constantly decreasing, this isvery difficult. It requires subtle control over abdominal muscles, mouthmuscles, and lips, all balanced properly.
To be able to create stillness and absence of change in a note when in fact the state of your body is in constant flux is a profound challenge. If you really want to accomplish it...10 minutes of Ro daily.