Lambic pentameter was used for the nobles' speech while blank verse or prose was used for commoners. This could be to create a distinction between the classes and to show that the nobles were intelligent, as iambic pentameter has a natural rhythm.
To show the education and refinement of the nobles.
Explanation:
Shakespeare's noble characters speak in iambic pentameter<em> to show the education and refinement</em> of the nobles. It is usually the aristocratic members of the play who speak in verse. Iambic pentameter sounds like poetry, it has a melodious sound. On the other hand, commoners speak in prose. In Shakespeare's plays when the commoners speak the writing goes from the beginning to the end of the line.
