As a vet you should know during anthem you stand at attention. Hand on heart is for the Pledge of Allegiance. Not being an ass, just pointing it out. :)
Are they, or I, in military uniform?
US Code
171. Conduct during playing
During rendition of the national anthem when the flag is displayed, all present except those in uniform should stand at attention facing the flag with the right hand over the heart. Men not in uniform should remove their headdress with their right hand and hold it at the left shoulder, the hand being over the heart. Persons in uniform should render the military salute at the first note of the anthem and retain this position until the last note. When the flag is not displayed, those present should face toward the music and act in the same manner they would if the flag were displayed there.
(June 22, 1942, ch. 435, §6, 56 Stat. 380; Dec. 22, 1942, ch. 806, §6, 56 Stat. 1077; July 7, 1976, Pub. L. 94–344, §1(18), 90 Stat. 812.)
Amendments
1976—Pub. L. 94–344 inserted requirement that during the rendition of the national anthem when the flag is displayed, all persons present except those in uniform should stand at attention, face the flag, and place the right hand over the heart and men with headdress should remove the headdress and hold it at the left shoulder, the hand being over the heart and when the flag is not displayed, those present should face the music and act in the same manner they would if the flag were displayed.
1942—Act Dec. 22, 1942, substituted “all present should face the flag and salute” for “the salute to the flag should be given” in last sentence.