Heidi Klum says sitting on the 'America's Got Talent' judging panel with Simon Cowell has taught her to appreciate singers more.

The German supermodel was joined by fellow judges Cowell, Mel B and Howie Mandel on the most recent series of the talent show, with Nick Cannon presenting.

Klum admits Cowell has a real ear for picking out the best singers who audition and has taught her what she should be listening out for.

In an interview with Billboard, the blonde beauty - who joined the programme in 2013 - said: ''Over the years I've learned that you should always give your honest opinion, even if that means disagreeing with the other judges or getting booed by the audience! Everyone has their own thoughts on each performance and it's important to share those. Simon hasn't really changed the way I judge, but sometimes he does change my vote from a no to a yes. When there are singers on stage, Simon will have them sing a different song if he doesn't think the one they chose is the right song. He has an ear for that, so when they start singing that second song, I go, 'Oh my gosh,' he got something out of them that we didn't hear before.''

Klum stepped out from behind the table for the 'America's Got Talent Holiday Spectacular' that NBC aired on Monday night (19.12.16) to make her singing debut.

The stunning 43-year-old catwalk queen made a dazzling entrance sitting atop a giant red and white candy cane dressed in a scarlet Christian Siriano gown which was lowered onto the stage.

Klum - who was previously married to British musician Seal - then performed a duet of Eartha Kitt's 1953 festive track 'Santa Baby' with Sal Valentinetti, the 21-year-old crooner who was her golden buzzer pick from the most recent season.

Klum admitted it was great ''fun'' to get to sing with Sal and their rendition earned a standing ovation from Cowell, 57.

Ahead of their performance, she said: ''I am so proud of him! He truly is one of a kind, and he is going to do big things in the future. The producers of 'AGT' thought it would be fun for us to sing together for the holiday special, and I am always game to try! So we have (done) a fun little number. I love singing, but I'm not a singer like Sal!''

Other performances on the pre-taped special came from Grammy nominee Andra Day who sang 'Winter Wonderland' accompanied by Charles Jones, the Olate Dogs - the rescue dog winners of season seven - with their handlers Richard and Nicholas Olate, ventriloquist Terry Fator, opera singer Jackie Evancho, The Clairvoyants and season nine winner Mat Franco the Regurgitator.