 This serves to prevent air from escaping while simultaneously supporting the reed, allowing it to vibrate, and constrict the reed preventing it from vibrating too much.With woodwinds, it is important to ensure that the mouthpiece is not placed too far into the mouth, which would result in too much vibration (no control), often creating a sound an octave (or harmonic twelfth for the clarinet) above the intended note.If the mouthpiece is not placed far enough into the mouth, no sound will be generated, as the reed will not vibrate.