A wearable cardiac defibrillator (“WCD”) system may include a support structure that a patient can wear, an energy storage module that can store an electrical charge, and a discharge circuit that can discharge the electrical charge through the patient so as to shock him or her, while the patient is wearing the support structure. Embodiments may actively take into account bystanders, both to protect them from an inadvertent shock, and also to enlist their help. In some embodiments the WCD system includes a microphone. The WCD system might be ready to deliver a shock, but may first wait before doing so until it hears from a bystander a preset ready word, such as: “CLEAR”.