The treble at the back should be MIDI synthesized by the breath controller. Of course, to achieve this effect, you can also use a flute, either a Chinese flute or a foreign flute or piccolo. The main thing is that it is almost the same as long as it is tuned correctly. . In fact, Shen Si Zhe has a song called "Memory of the Forbidden City", which uses this stuff. Youku has a video of it. You can check it out. The effect is almost the same as this one.