 Cobain chose not to <unk> a harmony vocal part during the Smart Studios sessions , possibly due to time constraints . During the Nevermind sessions , Vig had Grohl sing harmonies on the song . Grohl had difficulty hitting the proper notes , but ultimately was able to sing what Vig wanted . Vig often had to trick Cobain , who was <unk> to performing multiple takes , into recording additional takes for overdubs on the record . The producer convinced Cobain to double @-@ track his vocals on " In Bloom " by telling him , " John Lennon did it . " After doubling Cobain 's vocals , Vig decided he might as well double Grohl 's and had the drummer record an additional track of backing harmonies . 
