She was often heard singing vs to sing in her room.

She was often heard singing vs to sing in her room.

My friends and I were having a discussion about this and we held different opinions. I used the service of Fraze.it. There were no results for 'was heard to'. There were several results for 'was heard singing'.

I have a gut feeling that 'was heard singing' is the better of the two. I find it difficult to imagine the other option is wrong though. One reason I think 'was heard to sing' is not appropriate here is that the 'to do' structure often carries with it a future meaning, as in 'want to read the book'. Another reason is that this structure is in the passive voice, and I have to constantly remind myself of that fact that nobody was forcing her to be heard singing.

Both "She was often heard singing" and "She was often heard to sing" are correct. I would say the latter is more formal.

Yes, I agree that She was often heard singing in her room is much better.

The structure 'heard to-infinitive' does exist, but as emsr2d2 suggests, it usually carries a more formal or literary register. I'm reminded of one of the lyrics to the song Grantchester Meadows by Pink Floyd:

Icy wind of night be gone! This is not your domain
In the sky a bird was heard to cry