Dr. L 的第一個身份曝光，原來他是一名在大學工作的教授，是一名電腦科學和物理學專家，發明伸展物理而獲得諾貝爾獎的一位年青科學家，所以學生都對他的課堂全滿期待，來旁聽的學生擠滿大學演講廳。
Summary of Previous Chapter:
The first identity of Dr.L's revealed, he's a professor in a Hong Kong Universitty, he's an expert in computer science and physics, who's also awarded nobel prize in physics, and invented extended materials. Student are eager to attend his class, so the lecture hall is full of students.
Chapter 04: Professor's class or music concert?
Dr. L on the stage of Lecture Hall,
he is taking an electric guitar on hands and talking....
"Hello ladies and gentlemen, today, I would like to discuss a phenomenon of sound wave..."
Questions from the Students....
"What? Why need a Guitar?"
"Professor's music concert? haha..."
"What is the Black Box?!"
Dr. L is speaking again....
"OK! Now I will play one interactive fun game with you guys."
"On my right hand, which is my new invention, this Black Box is a Sound Frequency Converter"
"I will play a song with my guitar, then one unexpected situation will occur in everyone's eyes"
Surprising noise and Whispering from students....
"What is the situation of this lesson..." said girl student.
[End of Chapter Four]