The invented heart activity sensory system, commonly called a heart monitor, consists of at least two skin contact sensors which can be attached to or integrated with wearable devices or accessories such as headsets, glasses, goggles, hats, helmets, necklaces, pendulums, garments, or directly to a body. Each sensor has an electrical electrode to establish a contact with skin for the purpose of measuring skin voltage potential and heart activity using the electrocardiogram (ECG or EKG) method. The sensors can communicate wirelessly with each other, calculate heart activity characteristics, record the characteristics in a memory, and inform the user visually, audibly, or with tactile means about the user's heart activity. The sensors can also transmit these characteristics wirelessly to a host device such as a smartphone.