Assistive technology is "any item, piece of equipment, or product system, whether acquired commercially off the shelf, modified, or customized, that is used to increase, maintain, or improve functional capabilities of individuals with disabilities."
Assistive technology devices can be "high tech" or "low tech" and include:
Assistive listening devices (ALDs)
Help amplify the sounds you want to hear, especially where there’s a lot of background noise
ALDs can be used with a hearing aid or cochlear implant to help a wearer hear certain sounds better
Augmentative and Alternative Communication (AAC) Devices
Useful in places in which the above systems are unavailable or when watching TV, being outdoors, or traveling in a car. About the size of a cell phone, these devices increase sound levels and reduce background noise for a listener.