This audio file, titled "070121_16 - Whistle.wav", features a sound effect or foley of a whistle being blown. The audio starts off quiet, quickly escalates as the whistle is blown, creating a sharp, piercing sound that dominates the audio clip. The whistle sound is clear, distinct, and high-pitched, typical of what you'd hear in a sports match or a training session. It then gradually fades away, creating a sound effect that is both realistic and attention-grabbing.