Supermodel Heidi Klum was scared of going into the studio with her husband Seal - because the singer's work ethic is "intimidating". The couple has recorded a duet on Seal's forthcoming album System, but Klum admits she only agreed to the musical challenge because the song was written on the day the pair were married. She says, "Of course I was intimidated. He's such a professional that he was very different towards me in the studio. I was a bit stiff and nervous and he was going, 'Sing low and strong', even through my natural singing voice is quite high. "But he wrote the song on our wedding day (10May05) and asked me to sing it with him so I did."