Why do artists use optical illusions?

Art has the ability to amaze and inspire, and few artworks do this better than those that fool the eye. These types of art—aptly referred to as illusion art—easily trick the viewer into believing what they think they see. ... The most intriguing facet of illusion art, however, is also known as optical illusions.

Explanation:

pitch- the definition of pitch is as follows:

"the quality of a sound governed by the rate of vibrations producing it; the degree of highness or lowness of a tone."