Each day the sun rises and sets. You can count it, but you can’t set your watch to it, or your metronome. This is my analogy for meter and rhythm. The meter is the sun rising and setting like a trochee. The trochee repeats each foot, or in the case of the sun, repeats each day. The rhythm is how the sun moves through day. Each day between approximately December 21 through June 21, the sun rises earlier and sets later each day. Its height in the sky changes, too, as well as its angle. On some days, you might not even the sun, such as when it’s raining, or it might appear brighter than the previous day if there is a clear blue sky today and yesterday it was cloudy. On rarer occasions, the moon blocks the sun. The experience of the sun’s movement changes each day, but it still rises and sets each day. And if you want to consider the week as analogy to the line, then the trochaic heptameter will also have changing rhythms from line to line or week to week.
The meter is a way to measure the bounciness of a poem, and the rhythm is how we move through the poem. This might seem obvious, but The New Princeton Encyclopedia of Poetry and Poetics (1993) says, “rhythm is the vaguest term in criticism” (1068), and often I hear or read of meter and rhythm as being the same thing. As a result, I’m trying to make rhythm less vague and to distinguish it from meter.
Meter is a way to pattern stressed and unstressed syllables and to create expectations in the ear, and the poet will rely on those expectations to occasionally alter or delay them to as to create surprise and meaning. This is part of the reason why no two sonnets, for instance, are heard or experienced the same way. Even if both sonnets are in 14 lines of exact iambic pentameter, their rhythms vary. We know this. We feel the difference in the sonnets, and, in part, it’s because of rhythm.
Rhythm is affected by long vowels, short vowels, and consonants, as well as meter. It’s affected by adverbial and prepositional phrases and other grammatical items, such as punctuation. Notice how the rhythm of a sentence changes if there is a question mark at the end. The voice goes through a convoluted rising sound to indicate a question is asked and not a statement made. The pacing changes. Rhythm interacts with tone, pitch, tempo, inflections, pausing, and other auditory and bodily experiences. Rhythm is the experience of moving through metered lines or non-metered/free verse lines.
Compare these two lines:
O Romeo, Romeo! wherefore art thou Romeo? (Romeo and Juliet II, ii, 36)
Hey Reginald, Reginald! wherefore art thou Reginald?
Both lines have the same meter (or patterns of unstressed and stressed syllables), but the rhythm is different. In the beginning of Shakespeare’s line, the long vowels – o, o, e, o, o, e, o – create dramatic emotion. The reader/speaker is almost forced to emote these lines to express longing, and I feel like I have to raise my right hand above my head when I speak them. In my line that wonders where Reginald is, the emotion is different and the opening moves quicker, despite the similar meter, and instead of wanting to raise my right hand above my head, I want to move both my arms out a bit with my palms facing the audience to suggest confusion. My experience of moving through the same metered lines is different, in part, because the rhythm is different.
In short, meter can be scored and affects rhythm. Rhythm is the experience of moving through the score.
However, meter and rhythm both affect and are effected by the content.//
This might be too simplistic, but it’s a starting place. Please add to the discussion in the comments if you wish.//