Hearing aid

A hearing aid, also known as a deaf aid, (PROSE: In the Blood) was a device used by humans to assist with hearing. They were worn inside the ear and were used by individuals with hearing loss and deafness.

History
After an accident in 1965, Alun Travers used a hearing aid after his hearing in one ear was badly affected. (PROSE: The Dreamer's Lament)

James Curtis, the deputy headmaster at Mildfields School, required the use of a hearing aid. When "Harold Saxon" visited the school, Curtis turned his hearing aid off during Saxon's speech. As a result, he was resistant to the Archangel Network's attempts to rewrite his memories to incorporate Saxon having attended the school. (PROSE: Speech Day)

Donna Noble believed the earpieces used by Cadmians, such as that of Fief's, resembled hearing aids. (PROSE: In the Blood)

Dot Smith-Smith, a colonist of Yemaya 4 in the 23rd century, was born deaf. Her parents refused to have her either healed medically or fitted with a hearing aid. (PROSE: SLEEPY)

Other realities
In one parallel universe, the Doctor crafted a hearing aid for Ludwig van Beethoven. (AUDIO: A Storm of Angels)