Final answer:
Longer. Long unstressed syllables slow the pace of a poem's rhythm, creating a deceleration. This is tied to the poem's meter, which is historically connected to poetry that was sung or accompanied by drums.
Step-by-step explanation:
If you change to longer unstressed syllables, the pace of a poem generally slows down, leading to deceleration. This is due to the expansion of the rhythmic pattern, contributing to a slower meter. Meter in poetry is a way to create rhythm by arranging stressed and unstressed syllables. By extending the length of unstressed syllables, there is a natural prolongation of the pulse in the verse, which can give the impression of a slowed-down pace.
Historically, meter traces back to ancient times when poetry was often sung to the accompaniment of drums, emphasizing the rhythmic and musical nature of poetic lines. Poets have used various types of meter, such as iambic pentameter, to elicit different effects in poetry. When stressed syllables are combined with longer unstressed syllables, they create a heavy and dragging rhythm, as opposed to shorter unstressed syllables that contribute to a lighter and quicker pace.