Final answer:
The acoustic coupler is the component of TTY equipment that holds the handset, enabling the conversion of audio signals into text and vice versa for communication for those with hearing or speech impairments.
Step-by-step explanation:
The component of TTY equipment that holds the handset is the acoustic coupler. A TTY device, also known as a teletypewriter or a text telephone, enables individuals who are deaf, hard of hearing, or have a speech impairment to communicate over the phone. The acoustic coupler is necessary for such devices because it helps to convert the audio signals from a telephone into text and vice versa. The handset of a phone is placed onto the acoustic coupler, which contains a microphone and speaker that translate the sound waves into electronic signals that the TTY equipment can process.
While other components like a keyboard are used to type the messages, and a printer or screen may display the received messages, and a modem can facilitate the transmission of data over a phone line, it is the acoustic coupler that specifically accommodates the telephone handset.