Steam Whistle
noun
A steam flute is a flute that goes off using steam. The only time I can think of this happening is via a steam whistle. Choo choooo!
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.
マドの外から、汽車の汽笛が聞こえてきました。
We heard a steam train whistle coming from outside the window.
いいか？汽笛が鳴ったら、船の上で三回ジャンプするんだぞ？
You ready? When the whistle blows, you're gonna jump three times while on the ship, okay?
夜風に乗って、さびしい汽笛の音が、遠くまでひびきました。
The lonely sound of the steam whistle echoed far into the distance in the night breeze.