whistle
The sound of a whistle is typically spelled as "whooo" or "whoo-whoo".
That is the correct spelling of "whistle" (a sound or a noisemaker, or to make sound or music with the lips).
The sound a flute makes is typically spelled as "whistle" or "flutey."
There is no best frequency. If you train a dog correctly any frequency the dog can hear will control it. Your voice, whistle, 'silent' whistle. All are acceptable.
The word is spelled whistling. The root word is whistle. Rather than blowing the whistle around his neck, the man began whistling to make his dog return home.
The future tense of whistle is will whistle.
Try re-posting this question with the type of your bird and/or some detail so people have a better chance of answering correctly.
The possessive form is whistle's.
whistle whistle
You have to whisper in the library so you won't disturb people who are reading.
Associate a sound with something they like, such as food or a scratch behind their ears. i.e. Whistle right before you feed them, after awhile they will come right when you whistle.
When the referee blows the whistle the players will