This hearing aid comprises a microphone (101) and an external input terminal (102), a hearing aid processor (150) to which audio signals from the microphone (101) and the external input terminal (102) are inputted, and a receiver (113) to which audio signals that have undergone hearing aid processing by this hearing aid processor (150) are outputted. The hearing aid processor (150) has a mixer (112) that mixes audio signals from the microphone (101) with audio signals from the external input terminal (102) and outputs these audio signals to the receiver (113), a mix ratio determination unit (111) for determining the mix ratio between audio signals from the microphone (101) and audio signals from the external input terminal (102) in this mixer (112), and a facial movement detector (110) that is connected to this mix ratio determination unit (111).