▁ ▁In ▁the ▁ac oust ic ▁piano , ▁har ps ich ord , ▁and ▁cla v ich ord , ▁the ▁v ibr ating ▁element ▁is ▁a ▁metal ▁wire ▁or ▁string ; ▁in ▁many ▁non - dig ital ▁electric ▁pian os , ▁it ▁is ▁a ▁t aper ed ▁metal ▁t ine ▁( R h odes ▁piano ) ▁or ▁re ed ▁( W url itzer ▁electric ▁piano ) ▁with ▁one ▁end ▁cl amp ed ▁and ▁the ▁other ▁free ▁to ▁v ibr ate . ▁Each ▁note ▁on ▁the ▁keyboard ▁has ▁its ▁own ▁separate ▁v ibr ating ▁element ▁whose ▁t ension ▁and / or ▁length ▁and ▁weight ▁determ ines ▁its ▁fundamental ▁frequency ▁or ▁pitch . ▁In ▁electric ▁pian os , ▁the ▁motion ▁of ▁the ▁v ibr ating ▁element ▁is ▁sens ed ▁by ▁an ▁elect romagnet ic ▁pick up ▁and ▁ampl ified ▁electron ically . ▁ ▁Inter val s ▁and ▁in harm onic ity ▁▁ ▁In ▁tun ing , ▁the ▁relationship ▁between ▁two ▁notes ▁( known ▁mus ically ▁as ▁an ▁interval ) ▁is ▁determined ▁by ▁evalu ating ▁their ▁common ▁harm on ics . ▁For ▁example , ▁we ▁say ▁two ▁notes ▁are ▁an ▁oct ave ▁apart ▁when ▁the ▁fundamental ▁frequency ▁of ▁the ▁upper ▁note ▁exactly ▁matches ▁the ▁second ▁harm onic ▁of ▁the ▁lower ▁note . ▁The oret ically , ▁this ▁means ▁the ▁fundamental ▁frequency ▁of ▁the ▁upper ▁note ▁is ▁exactly ▁twice ▁that ▁of ▁the ▁lower ▁note , ▁and ▁we ▁would ▁assume ▁that ▁the ▁second ▁harm onic ▁of ▁the ▁upper ▁note ▁will ▁exactly ▁match ▁the ▁fourth ▁harm onic ▁of ▁the