Carey's output makes use of electronic instruments such as drum machines, keyboards and synthesizers. Many of her songs contain piano-driven melodies, as she was given piano lessons when she was six years old. Carey said that she cannot read sheet music and prefers to collaborate with a pianist when composing her material, but feels that it is easier to experiment with faster and less-conventional melodies and chord progressions using this technique. While Carey learned to play the piano at a young age, and incorporates several ranges of production and instrumentation into her music, she has maintained that her voice has always been her most important asset: "My voice is my instrument; it always has been."