Now let's move on to meter, as promised.

As you might imagine, this is closely

related to poetic meter or rhythmic grouping.

Music is most often organized into groups of two, three, or four beats per bar.

We use bar lines to indicate bar boundaries and to make reading easier.

Less standard groupings, or meters, would be five, seven,

eight, ten, or in fact, any number of beats.

So any grouping is possible, but two, three

and four beats per bar are the most common.

These bars then represent the meter, so when we speak of duple

meter, typical of marches for example, we mean two beats per bar.

Triple meter, typical of waltzes, would be three beats per bar.

Quadruple meter, or four beats per bar, would be the four-four

that's most common in western classical music or electronic dance music.

In fact it's so common that it's called common time.

Generally, we're talking about crotchets or

quarter note beats here, though it's possible

to have the beat be minims or quavers, or any basic rhythmic duration.

So though four-four, four crotchets per bar, is most common, it's possible

to have quadruple meter with eighth notes or minims as the basic beat.

The way we indicate meter is with a time signature.

This consists of two numbers: a numerator on top, and

the denominator on the bottom as with fractions in arithmetic.

The numerator tells us how many beats there are

per bar, and the denominator indicates the beat type.

So four-four means four quarter notes or crotchets per bar,

whereas three-eighth means three quaver or eighth notes per bar.

Now, each of these bars has, or tends to have, weak or strong beats.

In Western classical music, we tend to favor

the down beats, or odd beats, in general.

If you have a four-four bar, that is a quadruple

meter, the accent would generally be on beats one and three.

So, for instance, if we listen to Mozart's Eine kleine

Nachtmusik, you can see quite clearly and hear these accents.

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Some pop and jazz music on the other hand, tends to favor the off or even beats.

In a four-four bar this would be beats two and four.

And this gives it the characteristic rhythmic feel we associate with this type

of music, very often with a strong snare drum stroke on those off beats.

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It doesn't stop there, I'm afraid.

In Western notation, we speak of two basic types of meter: simple and compound.

Simple meters are those that divide into beats of two, four, eight, ect.

So when we look at a simple four-four bar, we

tend to subdivide that into eighth notes, sixteenth notes, etc.

That is, groups of two, four, eight, powers of two.

Compound meters, on the other hand, use dotted rhythms as their

basic beat, so it is very easy to subdivide into three.

The most common compound meter would be a six-eight bar.

This clearly does have six quavers or eight notes per bar.

But instead of being felt as six beats per bar, it's felt as

two dotted crotchet, or dotted quarter notes per bar, each subdivided into three.

This allows us in this case to avoid having to write tuplets all the time,

or triplets, because essentially the equivalent would be

a triplet eighth note in a two-four bar.

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