In saxophones, oboes and other reed instruments, the vibration is set up when the flow of air from the player’s lungs is converted into a series of air-puffs by the reed rapidly snapping open and shut over the mouthpiece opening. Another way of creating such an open-and-shut mechanism involves stretching a light membrane, such as a piece of balloon latex, over the opening in such a way that the blown air is forced to squeeze under the rim of the membrane as it enters the tube. Many variations on this idea are possible; here’s four-note bass version. It has one large tonehole to be covered by a bare hand; another with a lever and tonehole cover. You can also bend the pitch by pressing on the membrane.
A video of this instrument can be found among the demonstrations in this youtube playlist.