In my April,1998, column I touched upon practicing very soft, quiet notes. This month,I'll discuss this topic more in depth.
One thing to do during the practice of blowing Ro is to blow as hard and loud as you can. Another thing to do is to practice Ro as soft as you can. Of course, gaining proficiency at either one of these two will not lead to greater musicality.
What you want is a greater "dynamic range", or the ability to play harder or softer notes at will to bring out the best of a piece. Indeed, it is the ability to use variations in volume effectively that is important in increasing musicality, not the ability to play very loudly or very softly alone.
The ability to sound as loud as thunder or as soft as a mosquito buzzing within the same breath will increase your breadth of musical expression. Similarly, the ability to make it such that one doesn't know when a prolonged note actually disappears is far preferable to having long notes cut off suddenly.
For example, try playing an Otsu Chi as softly as you can. You may find that you get lots of noise, or that no sound comes out at all, or that the sound is louder than you want it to be.
Now, try to make that sound as small as a mosquito flying about a meter in front of you. Open up the inside of your mouth as much as you can by pretending there's aping-pong ball inside your mouth.
If you find that your sound is hard to control when playing very loudly, or that it cuts off when playing very softly, it may be that playing at the volume extremes causes the direction of your air flow to change. Concentrate on making the direction of your air flow stable. It may take some experimentation.
Finally,remember that it is often true that it is not the loud notes, but the soft ones that are often the most powerful and effective during a performance.