Like the trumpet and all other modern brass wind instruments, the cornet makes a sound when the player vibrates ("buzzes") the lips in the mouthpiece, creating a vibrating column of air in the tubing.
The frequency of the air column's vibration can be modified by changing the lip tension and aperture or "embouchure", and by altering the tongue position to change the shape of the oral cavity, thereby increasing or decreasing the speed of the airstream.
In addition, the column of air can be lengthened by engaging one or more valves, thus lowering the pitch.
Double and triple tonguing are also possible.

Without valves, the player could produce only a harmonic series of notes like those played by the bugle and other "natural" brass instruments.
These notes are far apart for most of the instrument's range, making diatonic and chromatic playing impossible except in the extreme high register.
The valves change the length of the vibrating column and provide the cornet with the ability to play chromatically.
Like the trumpet and all other modern brass wind instruments, the cornet makes a sound when the player vibrates ("buzzes") the lips in the mouthpiece, creating a vibrating column of air in the tubing. The frequency of the air column's vibration can be modified by changing the lip tension and aperture or "embouchure", and by altering the tongue position to change the shape of the oral cavity, thereby increasing or decreasing the speed of the airstream. In addition, the column of air can be lengthened by engaging one or more valves, thus lowering the pitch. Double and triple tonguing are also possible.
Without valves, the player could produce only a harmonic series of notes like those played by the bugle and other "natural" brass instruments. These notes are far apart for most of the instrument's range, making diatonic and chromatic playing impossible except in the extreme high register. The valves change the length of the vibrating column and provide the cornet with the ability to play chromatically.
Cornet