The beginning of "Stairway to Heaven" by Led Zeppelin introduces a repeated set of notes played by a guitar and recorder playing along with it. The timbre of these instruments are completely different and can be distinguished from each other while they are being played together at 0:28 - 0:32 and a slight crescendo is heard. At 0:44 - 0:46, the pitch of the recorder increases and another crescendo is heard building up at 0:47 - 0:49. This crescendo prepares for the first verse and seems to set a certain mood for the audience before the lyrics are heard. One thing I found interesting was when the guitar went towards the higher notes, it slowly went into a slight crescendo, but not as intensified as the one before the first verse.
I chose to analyze "Payphone" by Maroon 5 for this section of the composition. The introduction consists of an immediate transition into the chorus. The instruments playing the background do not start playing until he finishes singing the word "payphone" at 0:05. The background music is quiet, and starts off quite slow as he runs through the chorus once. In between the chorus and the first verse, there is a point where the music distorts and is used as a transition at 0:19-0:20. The music does not start again until he finishes the second word of the first verse. At the second run through of the chorus, the music is more intense and louder, with the addition of drum beats in the background. Before the chorus is sung again, the instruments climax and suddenly it is silent again until he starts singing again at 0:55 - 0:56. The music begins to slow down and soften before the rap section of the song at 2:41-2:43. Once the rap is finishing up, the beats and piano in the background start to build up again in preparation for the last run through of the chorus at 3:12 - 3:15. At the conclusion of the song, once the singer is done singing "payphone" the instruments in the background also fade as he finishes singing the word at 3:50.