In this audio piece titled "Alerting Whistle", the main sound you hear is a sharp, attention-grabbing whistle. This is not just any ordinary whistle; it has a distinctive tone that immediately makes you think of a taxi whistle, the kind used to call a cab in a busy city street. The whistle's pitch varies slightly, creating a whistling melody that echoes briefly before fading. Intermingled with the whistle, you can faintly discern the ambient sounds of a bustling city. There's a clear, high-quality feel to the audio, indicative of a recording made with professional equipment, such as a Zoom H4n. The whistle repeats a few times, each call distinct and commanding, the perfect audio cue to alert a taxi driver's attention amidst the urban cacophony.