dr. nasseri, damage like this shuts down an a-list voice. >> the cords are meeting. no voice. >> reporter: what's that like for a singer? >> it's devastating. >> reporter: poor vocal technique and lack of rest can be culprits. because of the new realities of the music business because of touring. >> to not do any rest. not staying up tweeting about it and be famous. >> reporter: as seen in the film "never say never," justin bieber brought in voice coach jan smith to help him monitor his demanding schedule. >> voice sounded good. >> hear how your voice sounds now? he's giving it everything he's got. but doing 86 shows is a lot to ask. >> reporter: as for the damage done, dr. nasseri says doing minimally invasive surgery, like adele had done, heals the vocal chords with little risk. but it's a last resort. thanks to the cautionary tale of julie andrews. her singing voice was damaged after surgery in 1997. but it's never too late to look after your voice. as savvy superstars have learned. paul, congratulations on all that rock 'n' roll has brought you here. >> rock 'n'