For the smart hearing aid without testing/self-testing, the user can input intelligent precise testing according to the listening chart of the mobile APP, which supports the listening chart of the hospital and the testing shop simultaneously. The three scenarios can be switched according to the actual situation, including normal (universal) mode, outdoor (noisy) mode, indoor (quiet) mode, APP cycle switch and big icon button, which can solve the inconvenient switching of small keys in the body of old users with inflexible fingers.
