firstly i see the whole hearing voices phenomena as a external intrusion using internal methods
i made the blocking hat that worked for me partially. i put it on and had no intrusive thoughts while wearing. took it off they came back within minutes.

first take a 6-12" aluminum foil sheet, fold shiny in inch by inch so its thick
take silver wire (crafts bead wire) and wind around foil strips
wind charcoal mesh screen around strips
place 4-6 in winter hat so fully covers head especially lower front and back

let me know if you have success. i know to those who think its all in the head what you would say..i always say..think again.