Sitting, Standing, and Channel Surfing During the National Anthem

When I’m watching a sporting event at home I sit on a couch during the national anthem. Sometimes I stand to go use the bathroom. Most of the time I watch something else until the game starts. I know the song is playing, but it’s on a different channel. Does the mere knowledge that the national anthem is playing somewhere require some sort of action?

If you camped outside the house of a pro-stander (or anti-sitter) and played the song continuously would they never sit down?

If you did the same thing at the home of a pro-sitter (or anti-stander), would they never stand up?

If the song is performed acapella using sign language in a forest, does it make a sound?