A remote-control unit (10) for controlling a hearing assistive device (20) by sending a control signal with instructions as an acoustic signal, has an input transducer (14), an output transducer (15), and a processor (11) adapted for setting the volume of the output from the output transducer (15). The processor (11) is adapted for activating the input transducer (14) for receiving environmental sound, analyzing the environmental sound, determining and setting the volume of the output from the output transducer (15) based on the environmental sound, and outputting the control signal at the set volume via the output transducer (15).