I have no musical aptitude and I can't even sing a simple tune.

我没有音乐天赋，甚至唱不出一首简单的曲子。

I heard, of course. Isn't it often said there's a correlation in musical aptitude and maths ability?

我当然听说了。不是经常说音乐天赋和数学能力有相关性吗？