The voice of the child crying out of the mouth of the grown woman is a misery and a disappointment.
According to our speaker, a grown woman crying like a child is a miserable and disappointing thing. Mostly it just sounds awkward to us.
Maybe, in our speaker's eyes, this is what happens when you don't move on from thoughts of the past, of a troubled childhood: you carry around that upset child. Or you remain, to some extent, an upset child on the inside… maybe like the speaker's mother?
You are miserable and disappointed with your life, or maybe you make others miserable and disappoint them. Either way, it doesn't sound very good.
The voice of the child howling out of the tall, bearded, muscular man is a misery, and a terror.
Ditto if you're a grown man doing the same thing. Only suddenly that disappointment is now a terror, which is fitting, given her description of her father as a "demon" in section 5.
We've all seen children throw tantrums. Luckily they're little and they can't (usually) do too much damage. A big, muscular grown man, though? We don't want to be around when he pitches a fit. Someone could lose an eye.