There are wide range of hearing aids and types. Consumer Reports has a good guide to understanding and choosing hearing aids. https://www.consumerreports.org/cro/hearing-aids/buying-guide/index.htm
Some of the popular brands include Widex, Phonak, Starkey, Resound, Signia and Oticon.
Starkey is based in Minnesota, USA and has been innovating hearing aids since
- They are famous for their ear canal hearing aid.
Resound is a Dutch company with a long history of producing innovative and
effective hearing aids. The recently released one that integrates with the iPhone.
Oticon is based in Denmark. They have developed what they refer to as
Based in Denmark, Widex has been in the business of producing innovative hearing aids, including in-the-ear, since 1956.
Phonak is based in Switzerland and has a line of hearing aids. They are the leader in hearing devices for children.
Lyric is an extended life hearing brand that was developed by Phonak.
Formerly Siemens, and now Sivantos, this company introduced the Signia in 2016.
Solary powered hearing aid.