Described is a hearing aid with a microphone (1), a signal-transmission unit (2, 3) for forming or otherwise processing the signal, an output amplifier (4) to which an earphone (10) is connected, and a battery as the power supply. The output amplifier (4) is designed essentially as a Σ-Δamplifier and is connected to a pulse generator (8) which produces a high-frequency pulsed signal in the 1 MHz region as well as a series-connected low-pass filter (15). The input signal to the signal converter is a representation, produced by signal processing, of the low-frequency input signal to the hearing aid, this signal being converted in the signal converter into a signal which can have only two possible values. The output signal (14) thus appears, after passing through the low-pass filter, essentially as an amplified copy of the low-frequency input signal.