Question

change into passive voice - I heard my father's voice.

Answer 1

my father's voice was heard by me

Answer 2

When a sentence is written in passive voice, the verb used in the sentence takes precedence over the subject and acts on it. This sentence format is not as popular as its counterpart sentence that is written in active voice.

The sentence I heard my father’s voice when written in passive voice is My father’s voice was heard by me.