"Whisperingly" Natural Recordings by Native Speakers
Quietly and softly, in a low and almost imperceptible tone, so as not to be overheard.
A whistle is a high-pitched sound made by forcing air through a small opening in order to produce a loud, shrill noise. It is often used to get someone's attention or to signal something. A whistle can also refer to the act of making this sound, or a device used to produce it.