This text is from The Children's Bach by Helen Garner:
Billy drew a breath and started to scream in short, sharp cries. He flung himself back on Dexter’s lap; he clapped his left hand over his ear, and bit into the heel of his right hand, held it against his large crooked teeth and pressed, pressed. He went ‘Eeeeee!’ high up in his skull.
Does it mean: He made a sound like "Eeeeee!" that echoed in his head?
Or does it mean: the sound like "Eeeeee!" that he made was deafening?