This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
We heard a steam train whistle coming from outside the window.
You ready? You've gotta jump off the ship when the steam whistle blows.
In my dream last night, I was fortunate enough to witness the blowing of the Titanic’s steam whistles.