The torture group has several modes of communication available to them. They choose speech as the main. They could easily do visual based communication with objects and animated sequences representing concepts. What they have in their catalogue of non-verbal communication is all designed to be run in support of the audio torture of computerized speech.
The sensation technology could be used the exact same way it runs to signal the victim of say “This sweater is itchy.” but the torture group adds in those actual words. They’re insecure about non-verbal communication. With a collection of multi-sensory technologies the torture group could do many things with them. When the torture group does speech it’s simple sentences and emotional tone.
The torture group displays the psychological and scientific theories they’ve based their torture design on in the actions they do. Someone convinced or ordered the torture group to depend 100% on verbal communication. The torture group doesn’t believe in anything but speech being a reliable communicator. That’s interesting to note when they do use non-verbal communication as a support. They’re not very confident in their torture using non-verbal communication