What is the meter in Herrick's Upon Julia's voice

"Upon Julia's Voice" is written in iambic pentameter, usually considered the most frequently used meter in English. The second couplet has the one slightly unusual factor of a feminine (multisyllabic) rhyme.
Herrick's most famous lyric poems generally use iambic meter (an unstressed syllable followed by a stressed one), with either five feet per line (pentameter, as here) or four feet (tetrameter) as in "Upon Julia's Clothes." What is probably his best-known poem of all, "To the Virgins, to Make Much of Time" uses iambic tetrameter but with a feminine rhyme in the second and fourth line of each stanza, thus shortening each of those lines by a single syllable. In "Upon Julia's Voice" the feminine rhyme results in an extra syllable in each line of the second couplet:

But listen to thee (walking in thy chamber)
Melting melodious words to lutes of amber.

Notice also that, as all poets do, Herrick sometimes changes the order of stresses to achieve variety, with the last line starting with an unstressed, rather than a stressed, syllable ("melting").