非常有意思，聲音是全頻的，從最低頻一直到 20khz 以上都有。所以對於這些聲音，要用能錄超聲波的麥克風才能完整捕捉（如 Sony C100）。音量非常大，至少 80dB，在旁邊耳朵都快聾了。
The piece has full frequency, from the lowest frequency up to more than 20khz. So for these sounds, you may use a microphone which can capture ultrasonic waves to record it completely (such as Sony C100). The volume is very high, at least 80dB, and my ears felt uncomfortable.
There is a sudden decrease in the sound. A man was walking by at the moment. I didn’t expect bodies to block the sound so effectively.