How can a Noh performer’s movements make a mask’s expression seem to change?

In Noh theatre, the masks are renowned for their neutrality and serenity, yet they appear to change expression through the performer's subtle manipulation of light and movement.

Because the masks are carved with a neutral or ambiguous quality, a performer can alter the mask's perceived emotion by tilting their head. By angling the mask slightly upward or downward, the performer changes how light hits the carved features, which can make the expression appear to shift from joy to sorrow or from calm to intensity. This technique is part of the highly stylized performance tradition where the actor uses precise movements and mime to suggest the essence of a character rather than explicitly enacting it. The effectiveness of this illusion relies on the actor's skill in integrating these physical adjustments with the music and chanting to evoke the aesthetic of yūgen—a beauty that is only partially perceived and barely glimpsed by the viewer.12