SOUND BOUND is an interactive sound visualizer. It allows the user to distort and create sounds by touch interaction. The user can create virtual balls or instrument icons on the screen and can cause these objects to collide with the frequency spectrum by using a physics engine. When virtual balls collide with the spectrum bars, the amplitude of certain frequency is amplified and timbre of music is dynamically changed. When equalizer bars strikes an instruments icon, it create an instrumental sound effect. SOUND BOUND actively engages people in the activity of listening to music and enhances their experience as well.