A whistle produces sound through the vibration of air molecules. When air is blown through the whistle, it passes through a narrow opening called the "fipple." This creates a high-velocity jet of air that causes the air molecules around it to vibrate, producing sound waves.
The science behind whistle sound is based on Bernoulli's principle, which states that as the velocity of a fluid increases, the pressure decreases. In a whistle, the fast-moving air creates a low-pressure area, causing the air molecules to vibrate and produce sound waves.
The pitch of a whistle is determined by the size, shape, and material of the whistle's fipple. A smaller fipple will produce a higher pitch, while a larger fipple will produce a lower pitch. The material of the whistle can also affect the pitch, with metal and plastic whistles producing different sounds.
The shape of a whistle can affect its sound in several ways. A longer whistle will usually produce a deeper sound, while a shorter whistle will produce a higher sound. Additionally, the shape of the fipple can also have an impact on the sound, with different fipple designs producing different tones.
No, a whistle requires air to produce sound. Without air passing through the fipple, there would be no vibration of air molecules, and therefore no sound. This is why a whistle will only produce sound when it is blown into or when air is forced through it by other means.