In music we have lots of terms that are easily misunderstood: for instance, dissonance is usually taken to be 'ugly' and, if you want to enjoy yourself, best avoided. 'Art should be beautiful,' right? What it really means is 'something that creates anticipation,' building a sense of tension that will somehow need to be resolved.
So when you watch TV and see a character's eyebrow rise a bit, you probably think, 'Aha, she's discovered something: what?' And you'll have to wait till after the commercial break to find out. It's a way of creating anticipation requiring future resolution (otherwise, what's the point?), drawing you on so you don't tune away.
A musical dissonance might be the equivalent not only of that raised eyebrow, but of many other regularly accepted, stereotypical 'dissonances.' Imagine a horror show without a monster or a plot without a twist.
Another word we hear when talking about music is 'harmony,' which we usually think of as something 'harmonious' and therefore beautiful, though it originally meant 'living together in peace' or 'forming a pleasing whole.' But in music, it's the process by which an individual chord combines with other similar chords to create a 'pleasing whole.' Anyone who's ever taken music classes learns how these chords, building blocks of most Western music, classical and otherwise, work in certain standard ways despite tons of often confusing rules and even more exceptions.
Without getting into the particulars of how chords are built, let's just say a chord by itself is just a sound. Putting a bunch of chords together could create a string of pleasing sounds. Most of Western music is based on the idea chords together go somewhere, a journey with a beginning and a destination.
Not that I'm writing an entire Music 101 course in 987 words, but think of a piece of music as a story with a beginning and an end, and lots of stuff in between. You meet characters (themes, motives), situations evolve (the expansion of those themes, motives), things happen (contrasts), eyebrows get raised (unexpected modulation). Structurally, a longer composition, like a novel, could have several movements instead of chapters, each one subdivided into sections like scenes, and, on the micro-level, there are musical paragraphs with phrases instead of sentences.
To carry the analogy further, cadences act like punctuation – a full cadence for a period, a half cadence for a comma – shaping the music, giving it a chance to breathe both melodically and harmonically. A cadence is also a formula, a standard-operating-procedure or cliché, with specific chords which define what kind of cadence it is.
Analogies may not be the most accurate way to describe something, taken literally, but realizing there are certain generic parameters we can talk about in music might help explain the significance of each one. It's called SHMRG, an acronym standing for SONORITY, HARMONY, MELODY, RHYTHM, and GROWTH, allowing us to focus on smaller, specific details.
Basically, sonority refers to anything to do with the music's sound in general. Growth concerns structure on any level, like the overall form (like Sonata form) or the shape and expansion of a phrase.
* * ** *** ***** ******** ***** *** ** * *
Now, if you take those categories and describe them not in terms of a story but, not taking it too literally, in terms of the human body, you could think of them this way:
SONORITY is like the person's appearance in general – say, the color of the hair or eyes, recognizing somebody by their voice;
MELODY is like the skin, a surface covering everything we can't see underneath;
GROWTH (or form) is like the skeleton, giving the body support and shape: without it, we certainly wouldn't look very human;
HARMONY is like the muscles which give the body not only a sense of definition but also the power to move;
RHYTHM is like the blood that brings energy to everything, giving it life.
So, let's think about cadences which we think of primarily as HARMONY, but which also fall under MELODY, GROWTH, and RHYTHM.
A cadence is a pattern of chords which, depending on how weak or strong it is, creates some level of finality, the chords building up to it generating a sense of direction and anticipation. Increasing the harmonic rhythm – the rate the chords change – also gives the chord progression more energy and defines the phrase's structure.
A melody, supported by its underlying chords – real or implied – is not just a memorable series of pleasing pitches randomly chosen. It follows the harmony's contours, and usually takes its breath at the cadence.
We all know how important breathing is and what happens if we don't: eventually, we'll keel over from lack of oxygen. Well, what happens to the music if the performer doesn't let it breathe? That whole breathing-in, the act of, like a singer, taking a breath, allows the phrase to play out in the breathing-out.
Pay attention to the hierarchy of these breathing cadences, the open-ended ones and those that sound more – and eventually, most – final. They create a sense of direction allowing this 'tension,' these uncertainties, to increase.
How does the composer heighten tension through the use of chords, the rhythms, the high-points of phrases, the approach to cadences? Discover how any digression away from the expected can increase the listener's anticipation.
How can you, the performer, bring these different discoveries out in your interpretation? It's always more satisfying when tension is released.
– Dick Strawser