A hearing aid system contains a hearing aid having with an acoustoelectric input transducer for recording a sound signal and converting the latter into an electrical input signal, a signal processing unit, connected to the input transducer, for processing the input signal, and an electro acoustic output transducer, connected to the signal processing unit, for converting the processed input signal into an acoustic output signal. A sensor is provided for capturing a measurement value of a biological measured variable and for outputting electrical information signal carrying information about the measurement value. The signal processing unit used to process the input signal is also signal-connected to the sensor and additionally configured and embodied to process the information signal. Furthermore, a method for establishing biological data of a hearing aid wearer by a corresponding hearing aid system is possible.
