TTY and TDD devices facilitate communication between which two groups?

TTY (Text Telephone) and TDD (Telecommunication Device for the Deaf) devices are specifically designed to assist in communication for individuals who are deaf or hard of hearing. These devices allow users to type out messages that can be transmitted over phone lines, facilitating conversation with those who can hear. This is particularly important as it bridges the communication gap between the deaf community and individuals who are hearing, ensuring that both groups can communicate effectively.

The technology created by TTY and TDD primarily serves the needs of these two distinct groups, making it vital for inclusivity and accessibility in communication, particularly in emergencies or vital situations where immediate information exchange is necessary.