The title makes an expectation, the intelligent reader should be curious to discover what comes next.
The verb "to hear" is a perception verb, it means the protagonist participate to the lesson also if he doesn't want.
The lay-out of this text is not a structure that turn and return, but it's organised into a only stanza and it's composed by 11 lines.
The lines from 1 to line 5 start with "when", it makes a climax,an expectation. It's an anaphoric structure.
In the first part of the text the verbs are passive, it means the student doesn't want to hear the lesson and the intelligent reader can't know protagonist's feelings.
The expression "mystical moist night-air" suggests the conference was in the evening and there if something mystical in the air.
There is the contraposition between "perfect silence" outdoor and "much applause" in the lecture room. In the silence the protagonist can see the star with his eyes and he can admire them.
The expression "look'd up" means the protagonist doesn't see the stars until he look up.
Alliteration "d" heard, learn'd means the protagonist doesn't stand it anymore.
"I became tired" is the conclusion of weariness: the protagonist can't stand to be in the lecture room, so he goes out.
The second part is the release part; the verb are active.
The poet's message is the we can understand better something if we see them and if we enter in relation with them.