augmentative and alternative communication device
/ AAC = A-A-C /
Imagine knowing exactly what you want to say and being unable to say it — the words are there in your mind, but your voice or your hands cannot get them out. This is the daily reality for some people with severe cerebral palsy, with a disease like motor neurone disease, after a brainstem stroke, or with profound speech impairment. Augmentative and alternative communication (AAC) devices are tools and systems that give a person another route to express language when natural speech is not enough.
Augmentative means added to whatever speech a person has; alternative means used in its place. The range is wide and runs from no technology to high technology. Low-tech AAC can be as simple as a board of pictures or letters the person points to, or a partner reading down a list while the person signals yes. High-tech AAC includes speech-generating devices: a tablet or dedicated computer on which the person selects words, phrases, or symbols and the machine speaks them aloud. Crucially, the selection itself can be made in many ways — a touchscreen, a single switch pressed with any reliable movement, head-tracking, or even eye-gaze, where a camera reads where the person is looking on the screen so they can spell or pick words with their eyes alone.
AAC matters because communication is fundamental to being a person in the world — to expressing needs, decisions, relationships, and self. A well-matched AAC system can transform isolation into participation. Two honest points often misunderstood: AAC does not stop or slow the development of speech (long-standing worry, repeatedly disproven — it often supports it), and the device is only half the story. The other half is teaching the person, family, and partners to use it, and choosing a system that matches the person's physical control, vision, language, and life. A speech-language pathologist usually leads this, within the wider assistive technology assessment.
A man with motor neurone disease has lost the ability to speak and can no longer move his hands well. With an eye-gaze speech device, he looks at letters and words on a screen and the machine speaks his sentences aloud — letting him still tell his family what he thinks and feels.
Another route to language — from a picture board to an eye-gaze speech-generating device.
A persistent myth says AAC will stop a person developing speech; the evidence repeatedly shows the opposite — it tends to support communication. The device alone is half the job; teaching the person and their partners is the other half.