my ipod is being funky. i need help.?

for some reason when i'm listening to my ipod all the background parts of every song r really loud but i can't hear the lyrics :/ idk what's the problem &idk really how to explain th problem but am hoping someone understands. say if i was listening to seasons of love from rent the piano is loud, and the chorous is kinda loud and the echoing parts where they go "seasons of. loooooooooooooove." are really loud, but the rest lot of the lyrics r like a freaking whisper no matter how loud i out it :P WHY!!?