He sounds like a moose in heat!

Sounds like a cat being strangled.

A moose in heat? Do we really say that?

@Bill: do all Americans always say the same thing for everything? I think not.

That's it! I couldn't think of it for the life of me, but #6 really is a common phrase.

However, it's more about not having an ear for music than not having a good voice. In that sense you can also say that someone has a tin ear.

To me the idea of someone being a singer, able to carry a tune, but having an awful voice is a slightly different concept. You could maybe say that someone's singing voice is just a rusty croak. Or maybe raspy. I'm trying to think of singers, or more often, songwriters, who are known for really bad singing voices, so you could search for other examples. Leonard Cohen? Actors who have half-spoken their songs in musicals, like Rex Harrison, Richard Burton?

You could probably think up any number of other picturesque comparisons; a rusty hinge or a rusty door might sort of work.

But in all these cases, in English you would usually say it about the singer or the voice, not the song.