Suddenly, I heard a voice singing/singing voice.

[99bottles]

I was alone in the room. Suddenly, I heard a voice singing/singing voice.

Which is correct?

 

[Rollercoaster1]

I would say '...I heard someone singing'.

 

[99bottles]

I would say '...I heard someone singing'.

Yeah, I had just decided to write something like that anyway. :lol:

 

[Tarheel]

Or:

Suddenly I heard a voice. It was somebody singing.

 

[emsr2d2]

You can say "Suddenly, I heard singing".