The Thai National Anthem is played everyday at 8 in the morning and 6 in the evening. By played, I mean broadcast on every local and national TV and Radio channel and from speakers in train stations, subway stations, public parks, civic and government buildings.
While the national anthem is played, every activity stops in public areas like parks and train stations. There’s an alert the national anthem is going to be played, the sound of the bells of a clock striking the hour and then a “countdown”. At the first notes of the national anthem, all people that are sitting will stand and activity stops.
You stand quietly during the anthem and resume whatever your doing once it is completed.