An amplifier unit for operating a piezoelectric loudspeaker or microphone includes an audio amplifier and a detection unit, which is configured to detect whether a sound transducer coupled to the amplifier unit is a piezoelectric sound transducer or a dynamic sound transducer. The amplifier unit is configured in such a way that, after a sound transducer has been coupled, the amplifier unit sends a test signal to the coupled sound transducer. Moreover, a sound-generation unit includes a sound transducer and an amplifier unit, which amplifies an audio signal and feeds it to the sound transducer.