The music you are listening to is "Chi Piu' Cara T'havra' Chi Tanto T'ama"
by Jacopo Peri. Peri's music was modeled by Claudio Monteverdi ("Seconda
prattica"). This music was considered to be the beginning of modern opera,
as now poetry could be set to music with a new, Humanist theory of rhetoric
tacens, and not the old, inflexible, strictly hierarchical Scholastic view of
reality.
Anti-accent marks (softer dynamic to apply to a single note):