Final answer:
The sound created when air is pushed through the lips is known as a whistle, which involves the air being manipulated by the vocal cords and shaped by the mouth and tongue to create sound.
Step-by-step explanation:
The sound made when someone forces air from their lips is known as a whistle. This action involves the vocal cords located within the throat and the shaping of the mouth to create a specific type of sound. When humans produce sounds, they push air up through the lungs and across the vocal cords, which are elastic folds in the throat. These cords then vibrate, and the airflow is modulated by the changing shape of the mouth and tongue to form different sounds, including whistling. In this process, variations in pitch are achieved through changes in tension on the vocal cords, and variations in loudness are due to the airflow from the lungs influencing the amplitude of the sound pressure wave.
Whistling is a phenomenon similar to the way wind instruments function, where adjusted air columns resonate to produce specific pitches. The throat and mouth act as an air column closed at one end, playing a crucial role in determining the spectrum of overtones and the intensity of sounds produced, particularly in speech.