The sentence is active. To make it passive, you would write "Lunchtime was announced by the noon whistle."
The sentence is active because the subject "the noon whistle" is performing the action of announcing lunchtime.
The sound of the whistle signaled the start of the track race.
The referee blew his whistle to signal that there was a penalty.
Joe blew his whistle to stop the game.
He tried to whistle a tune, but he couldn't remember the notes.
He could hear the faint sound of a whistle coming from a distance.
Whistle
the whistle announced the trains's arrival at the station
the whistle announced the trains's arrival at the station
Whistle when in doubt
The sound of the whistle signaled the start of the track race.
I whistle when I'm scared.Sometimes, I whistle but only make a blowing sound.I whistle to keep a good mood.
The referee blew his whistle to signal that there was a penalty.
The nouns are whistle, start, and practice.
Joe blew his whistle to stop the game.
"when the whistle blew"
He liked to whistle as he walked.The whistle signalled the end of the match.
He could hear the faint sound of a whistle coming from a distance.