This is what everybody feel through their experience. For example, I understood Mr. A was a relatively good speaker, but when I met him after a period of time and talked with him, I was surprised at the degressed speech of his. I asked him indirectly about his daily practice on the esophageal speech, and found out he had not practiced the speech for long. Also, many people notice that their speech degresses considerably and they themselves feel difficulty in vocalization when they catch a cold and do not speak for a several days.
It is all too natural, on the other hand, that non-advanced trainees can obtain surprisingly good results by daily practice.
A precious stone may gain its lustre by polishing it, on the contrary, the jewelly may be dulled without being taken care of. The care in the esophageal speech is practice, and you have to be really careful.
