Playing the theremin requires extreme physical control because the player never actually touches the instrument. Two metal antennas protrude from the box: a vertical one for pitch and a horizontal, looped one for volume. As the player's right hand moves closer to the pitch antenna, the frequency increases (higher notes). As the left hand moves away from the volume loop, the sound gets louder. This works through 'heterodyning,' where the hand acts as a plate in a capacitor, shifting the frequency of an internal oscillator. Because there are no keys, frets, or physical markers, thereminists must rely entirely on their ears and muscle memory. The smallest movement of the head or even a deep breath can change the pitch, making it one of the most difficult instruments in the world to play with perfect intonation.