If a whistle is heard in a dream, it may signal the end of a certain period of time. In addition, it may also be an alarm, hoping to draw the dreamer's attention to something.
The whistles heard in dreams may be related to group sports. Whistle is an important auxiliary tool for sports training and directing game process. Therefore, the sound of the whistle is also crucial. If the voice is sharp and harsh, it may indicate that the dreamer has violated the code of conduct.
From this perspective, whistles represent a spiritual requirement.