Piano improvisatory accompaniment is not only a subject including composition and performance but also a practical performing art.

钢琴即既是一门融创作与演为一体的综合学科,同时是一门实性很强的表演艺术。

Also, if the improvisatory accompany is too high or too low, the time and power is not suitable, the music will no a tune and less the beauty of strewing and harmonious.

如若左手音高不当，时间不对，力度不，能使整个音乐不够协调，缺少错落与和谐之美。