Listening Benefits From a Hearing-aid App, a Personal Sound Amplification Product, and a Hearing Aid in Hearing-impaired Listeners

Inclusion Criteria: 1. Adults over the age of 20 who speak Korean as their mother tongue and have no mental or physical limitations in conducting test. 2. Hearing loss patients with a hearing threshold of 26 dB or higher in the four frequency (0.5, 1, 2, 4 kHz) 3. Those who do not have a history of neurological disease, cognitive disorder, learning disorder, or language disorder at the time of recruitment Exclusion Criteria: 1. In case that communication is difficult, equipment cannot be handled, or it is difficult to cooperate with the inspection 2. Acoustic nerve lesions or central nervous system disease 3. Those suspected of having false hearing loss 4. Those who have secondary benefits related to clinical trials