hear is the kind of verb which takes Catenative Complement.
1. I heard the door being unbolted.
2. I heard him play the piano.
3. I had never heard it described that way.
4. She was often heard to say: "I am a very slow learner".
In Sentence #1 hear takes a Gerund-Participle clause, in #2 a bare infinitive clause, in #3 a Past-Participle clause and in #4 a to infinitive clause. All these are Catenative Complement realised by a non-finite clause.
The problem with hear is that in most cases we can't tell for certain if the intervening Noun Phrase (NP) is the subject of the non finite clause or a part of the matrix clause, precisely the complement of the matrix verb.
Semantically in all the examples above it can be thought that the intervening NP is part of the non-finite clause. the door is the subject of being unbolted and the non finite clause is the door being unbolted. But syntactically it is not possible. In syntactic approach the NP - the door - is part of the matrix clause. And the non finite clause is subject-less. the door is the complement of the matrix verb hearm which also takes another Catenative Complement in the form of Gerund-Participle Clause - being unbolted.
I heard the door's being unbolted. [INCORRECT]
Syntactically in #2 the NP - him - is again part of the matrix clause like it was in sentence #1 because more often than not a bare infinitive clause - play the piano - doesn't take a subject except in a few rare constructions.
In #3 the NP it is part of the matrix clause, a raised object..
We heard a poem being cited. [PROGRESSIVE]
We heard the poem cited. [NON PROGRESSIVE]
English song was heard sung by a girl. [GRAMMATICALLY QUESTIONABLE USAGE]
His name was heard called. [GRAMMATICALLY QUESTIONABLE USAGE]