This puzzle requires the “Viral Marketing” spec record and the music player (music audio can also be listened to here \[LINK\]).
The button that makes the cool tricorder sound is not part of the puzzle. It’s just a cool tricorder sound.
Each set of lyrics has a different musical jingle that pairs with it.
Going off the sentence structure and syllable counts of the lyrics, it's possible to determine which musical jingle pairs with each set of lyrics.
Each jingle has a note, or set of notes that are more pronounced than the rest. The pronounced note(s) in each jingle will indicate one word from each set of lyrics.
Apart from the words indicated by the pronounced note(s), each set of lyrics has a word in it to help determine an order to consider each set of lyrics. The noted words from each set of lyrics, in order, will create a message.
The message will tell you to take the letters from two words and anagram them together to create one, 10-letter long word that is the answer. The answer word starts with the letters DIS
ANSWER REVEAL: The musical jingle that matches up with the first listed set of lyrics has a group of three pronounced notes that coincide with the syllables of the word REARRANGE. The first listed set of lyrics also contains the ordinal number FOURTH. So the final message will have the fourth word be “rearrange.” The jingle for the second listed set of lyrics emphasizes the word PLUS, and contains the ordinal number SECOND. The next set of lyrics has its jingle emphasize the word LETTERS and the ordinal number FIFTH. Next set has the word SEND emphasized and the ordinal number THIRD. And the last set has the word CASINO emphasized and the ordinal number FIRST. The full message, in order, says CASINO PLUS SEND REARRANGE LETTERS. Rearranging the letters in CASINO and SEND can give the answer DISSONANCE. Looking at the “music note” envelope, dissonance is synonymous with INHARMONIOUS. So INHARMONIOUS is the keyword that grants access to the envelope.