The mezzo-soprano is the middle female voice and the most common of the female singing voices, which tends to dominate in non-classical music, with vocal range that typically lies between the A below "middle C" (C4) to the A two octaves above (i.e. A3–A5). In the lower and upper extremes, some mezzo-sopranos may extend down to the F below middle C (F3) and as high as "high C" (C6). The mezzo-soprano voice (unlike the soprano voice) is strong in the middle register and weaker in the head register, resulting in a deeper tone than the soprano voice.