What is a key feature of aided AAC systems?

Aided AAC systems are characterized by their reliance on external tools or devices to facilitate communication. This includes a wide variety of supports, such as communication boards, picture exchange systems, or speech-generating devices. These external tools augment the user's ability to express thoughts and needs, making them essential for individuals who may have difficulty communicating verbally.

The other choices do not accurately represent the primary attribute of aided AAC systems. For instance, while some aided AAC systems can function independently of human assistance, many users still require support during their use. The statement that aided systems only use voice output is false since they can include non-voiced methods, such as symbol boards or printed pictures. Lastly, not all aided AAC systems are electronic, as they can also be comprised of non-electronic materials like paper or cardboard aids. Thus, the defining characteristic that clearly differentiates aided AAC systems is their necessity for external tools or devices for effective communication.