Small copper coils in most current hearing aid models and in all new cochlear implant processors called telecoils can double the functionality of the devices and allow users to connect wirelessly to various types of induction loops in a variety of settings. This is particularly useful in large venues such as churches, theaters, legislative chambers and other locations.
To learn more about telecoils and about hearing loops, here are links to leading sources of that information.
American Academy of Audiology
Hearing Loss Association of America
Let's Loop America
Loop New Mexico
NM Commission for Deaf and Hard of Hearing Persons