▁same ▁manner ▁as ▁a ▁silent ▁film , ▁with ▁the ▁director ▁free ▁to ▁shout ▁out ▁instructions ▁during ▁the ▁film ing ▁and ▁the ▁camera ▁un rest rict ed ▁by ▁any ▁need ▁to ▁silence ▁its ▁no ises ▁with ▁bul ky ▁sound proof ing . ▁ ▁Del bert ▁Cob ain , ▁one ▁of ▁the ▁sing ers ▁in ▁the ▁film , ▁is ▁notable ▁as ▁being ▁the ▁great - un cle ▁of ▁music ian ▁Kurt ▁Cob ain . ▁ ▁The ▁Rh ythm ▁Boys ▁The ▁Rh ythm ▁Boys ▁( B ing ▁C ros by , ▁Harry ▁Bar ris , ▁and ▁Al ▁R ink er ) ▁sang ▁Mississippi ▁M ud , ▁So ▁the ▁Blue bird s ▁and ▁the ▁Black bird s ▁Got ▁T ogether , ▁I ' m ▁a ▁Fish erman , ▁A ▁Ben ch ▁in ▁the ▁Park , ▁and ▁Happy ▁Fe et ▁in ▁the ▁film . ▁This ▁singing ▁tri o ▁also ▁recorded ▁as ▁part ▁of ▁Wh item an ' s ▁band ▁and ▁on ▁their ▁own ▁with ▁Bar ris ▁on ▁piano . ▁ ▁C ros by ▁also ▁sang ▁Music ▁H ath ▁Char ms ▁over ▁the ▁title ▁cred its ▁and ▁provided ▁the ▁singing ▁voice ▁for ▁Wh item an ▁in ▁the ▁animated ▁cart oon ▁singing ▁My ▁Lord ▁Del iver ▁Daniel . ▁ ▁B ing ▁C ros by ▁went ▁on ▁several ▁b enders ▁during ▁the ▁film ing , ▁crash ed ▁his ▁car ▁on ▁Hollywood ▁Bou lev ard , ▁sent ▁to ▁j ail ▁for ▁ 6 0 ▁days ▁for ▁talking ▁back ▁and ▁wise - c rack ing ▁to ▁a ▁judge . ▁Wh item an ▁replaced