. >> reporter: forrest eimold is 12 years old.ys the organ, and composes. >> it's one thing to sing or play a piece by somebody, like let's say mozart, and you can definitely express emotion in that, but it's another thing entirely to be able to express your own emotions and to write exactly what you want. >> reporter: what have you written? what have you composed lately? >> i've composed many works for piano. i recently finished my second piano sonata. i'm currently working on a mass for the choir school to sing, actually. and i've done some other short pieces. >> reporter: at high mass on sunday morning, the boys sing with the men. >> when the boys sing with the men of the choir on a sunday morning, the dynamic is rather different. if they hear professional adult singers singing, they're far more likely to imitate something which is good like that and to learn from the way that the adults around them are singing, so i think it's a very positive dynamic. >> reporter: the pastor of st. paul parish is father michael drea. >> that m