[1] Examples of this type of sound generator include the soundboard of a piano, the surfaces of drums and cymbals, the diaphragm of loudspeakers, etc.
The second kind of sound generator is the method utilized by wind instruments, such as trumpets.
In the second step of a full cycle, the valve is completely open and pressure is at a maximum.
In the third cycle, the valve is partially closed, and the pressure has decreased from the maximum value.
More examples of this type of sound instrument include sirens, organs, saxophones, and trombones.