Catchy Tunes

The "catchy tunes" are an a cappella arrangement of a slightly odd mashup. The lyrics are flavortext:

• "There's something happening here / What it is ain't exactly clear" – Just punning on the fact that this is a puzzle.
• "I think it's time we stop, children, what's that sound" - Suggests listening to the background voices.
• "I’ve got a small query for you: What comes next?" - Suggests a transformation
• "Awesome. Wow / Do you have a clue what happens now?" - Another joke about the fact that this song is a puzzle.

The lyrics suggest listening to "What's That Sound." The syllables in the background are not the typical "dmm dmm din dah" of a cappella arrangements; in order of appearance, they are:

Zigzagoon

Bulbasaur

Chikorita

Pikachu

Ekans

Budew

Yanma

These are Pokemon. "What Comes Next" clues you to consider their evolutions:

Zigzagoon	→	Linoone
Bulbasaur	→	Ivysaur
Chikorita	→	Bayleef
Pikachu	→	Raichu
Ekans	→	Arbok
Budew	→	Roselia
Yanma	→	Yanmega

....and the first letters of the evolutions spell out LIBRARY, which is the solution to the puzzle.