Alaina, who is competing with Scotty McCreery for the Idol title, lost her voice during rehearsals for last night's live show but ultimately performed three songs as planned during the broadcast.
Speaking to Entertainment Weekly's Inside TV blog, Michael Orland said: "These guys have not stopped singing [all season], and they're rehearsing for the finale... She'd just had it.
"So the doctor came and saved the day. That happens to even the biggest stars in showbusiness. I think he gave her something to un-swell her vocal chords.
"Whatever he gave her, it just numbs the vocal chords a little bit so she can get through it. I only know what the doctor said [during the show]."
Orland, who is the programme's associate musical director, continued by saying that he has seen finalists battle vocal trouble on numerous occasions.
"Listen, I've done ten finales [and] I have seen this [before]," he explained. "I saw Jordin Sparks have no voice the day of the show. Katherine McPhee, David Archuleta - it just happens."
Additionally, Orland did not offer a definite answer on whether third-placed Haley Reinhart would have replaced Alaina if she had not been able to perform.
"I think that if she couldn't sing any notes, they would have had to put Haley in there... But I wasn't there, so I can't really say," he added.
Orland also paid tribute to the finalists on Twitter, saying: "I couldn't have been a prouder vocal coach to both of you if I tried."
American Idol concludes tonight on Fox.
> American Idol: The final recap
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