Some people think that stringed instruments are the loveliest-sounding part of the orchestra. Violins, violas, cellos, and double basses have rich, expressive tones created by the friction of a horsehair bow moving across a string. Players can change the sound of their instruments by adjusting their finger positions on the strings as well as by altering the speed and pressure of the bow, allowing a vast range of different musical sounds and moods. Woodwinds and brass instruments are equally appreciated. These instruments are played by blowing into specialized mouthpieces - the vibrations of the air within the instruments create sound. Like singing, playing a wind instrument involves the player's own lungs and facial muscles, creating a deep sense of connection between the player and the sound; expert players can control their instruments as precisely as master athletes perform their sports.