Frequency modulation uses a control voltage to change the frequency (pitch) of a sound. The inaudible control voltage signal will create a vibrato effect, which is a deviation in pitch around the center carrier tone. As with amplitude modulation, when the control voltage is in the audible frequency range, the resulting signal includes carrier sidebands. The complexity and harmonics of the FM sidebands are much more complex and rich than those produced by AM. Unlike AM, the FM sidebands can actually dominate the carrier tone.