How can bellows make an ohhing sound?

Bellows can produce an "ohhing" sound when air is forced through a narrow opening, creating a vibration in the air column. This happens as the bellows expand and contract, pushing air out in a controlled manner. The specific shape and material of the bellows can influence the pitch and quality of the sound. Additionally, if the air passes over or through a resonating chamber, it can enhance the sound produced, making it more pronounced.