Decoding Time Signatures - Compound and Asymmetrical Meter

TL;DR

Compound time signatures tell you the beat divides into three, while asymmetrical meters use mixed beat groupings, making them sound uneven. Both types require you to understand how the top number indicates subdivisions and the bottom number indicates the note value of those subdivisions. Learning to group these subdivisions helps you feel the pulse correctly.

1. The Mental Model

Think of time signatures as instructions for counting music. Instead of just telling you how many simple beats are in a measure, compound and asymmetrical meters give more detailed instructions about how those beats are subdivided or how they irregularly group together. It's like having a recipe where the ingredients are measured differently than usual.

2. The Core Material

Understanding Compound Meter

Photo by Jonnathan Gonzalez on Pexels

In compound meter, each main beat naturally divides into three subdivisions. This is different from simple meters where each beat divides into two.

Here's how to spot it:
* The top number is typically 6, 9, or 12. This number tells you the total number of subdivisions in the measure.
* The bottom number indicates the note value of one of those subdivisions. Often, it's an 8 (meaning eighth notes).

To find the main beat:
1. Take the top number (total subdivisions).
2. Divide it by 3. This gives you the number of main beats in the measure.
3. The main beat will be a dotted note value.

Let's look at common examples:
* 6/8 time:
* Top number 6: There are six eighth-note subdivisions.
* Bottom number 8: An eighth note gets one count.
* To find the main beat: 6 ÷ 3 = 2. There are two main beats per measure.
* Each main beat is a dotted quarter note (because a dotted quarter note equals three eighth notes). You'd count "ONE-and-a TWO-and-a".
* 9/8 time:
* Nine eighth-note subdivisions.
* 9 ÷ 3 = 3. There are three main beats per measure.
* Each main beat is a dotted quarter note. Count "ONE-and-a TWO-and-a THREE-and-a".
* 12/8 time:
* Twelve eighth-note subdivisions.
* 12 ÷ 3 = 4. There are four main beats per measure.
* Each main beat is a dotted quarter note. Count "ONE-and-a TWO-and-a THREE-and-a FOUR-and-a".

Understanding Asymmetrical Meter

Photo by Robert So on Pexels

Asymmetrical meters are characterized by irregular groupings of beats or subdivisions within a measure. The top number can't be easily divided by 2 or 3 to get regular beats. These meters often combine groupings of 2s and 3s.

Here's how to spot it:
* The top number is usually 5, 7, 11, or 13.
* The bottom number typically indicates the subdivision (often an 8 for eighth notes, or a 4 for quarter notes).

The key here is to understand the internal grouping of the beats. Composers often indicate this with dashed lines or beams in the notation, but you can also deduce it.

Let's look at common examples:
* 5/4 time:
* Five quarter-note beats.
* This is often felt as a group of 2 beats plus a group of 3 beats, or vice-versa (2+3 or 3+2).
* You might count "ONE-two ONE-two-three" or "ONE-two-three ONE-two".
* 7/8 time:
* Seven eighth-note subdivisions.
* This can be grouped in various ways, such as 2+2+3, 2+3+2, or 3+2+2.
* The feel of the music will often tell you which grouping is intended.

Here's a diagram showing the common groupings for these meters:

graph TD
    A["Time Signature Type"] --> B["Compound Meter"]
    A --> C["Asymmetrical Meter"]

    B --> B1["Top #: 6, 9, 12 (Subdivisions)"]
    B --> B2["Bottom #: Subdiv. Note Value (e.g., 8 for 8ths)"]
    B --> B3["Main Beat = Dotted Note"]
    B1 --> B4["Example: 6/8"]
    B4 --> B4a["6 eighth notes"]
    B4 --> B4b["2 Dotted Quarter Beats"]
    B4b --> B4c["Count: ONE-and-a TWO-and-a"]

    C --> C1["Top #: 5, 7, 11, 13 (Subdivisions/Beats)"]
    C --> C2["Bottom #: Subdiv. Note Value"]
    C --> C3["Irregular Beat Groupings"]
    C1 --> C4["Example: 7/8"]
    C4 --> C4a["7 eighth notes"]
    C4 --> C4b["Common Groupings:"]
    C4b --> C4b1["2+2+3"]
    C4b --> C4b2["2+3+2"]
    C4b --> C4b3["3+2+2"]
    C4b1 --> C4c["Count: ONE-two ONE-two ONE-two-three"]

3. Worked Example

Let's break down 12/16 time.

1. Identify the type: The top number is 12, which is a multiple of 3, so it's a compound meter.
2. Count the subdivisions: The top number (12) tells us there are twelve subdivisions.
3. Identify the subdivision's note value: The bottom number (16) tells us each subdivision is a sixteenth note.
4. Find the number of main beats: Since it's compound, divide the top number by 3: 12 ÷ 3 = 4. There are four main beats in the measure.
5. Determine the main beat's note value: Each main beat consists of three sixteenth notes. Three sixteenth notes combine to make a dotted eighth note.
6. Counting: You would count "ONE-e-and-a TWO-e-and-a THREE-e-and-a FOUR-e-and-a", where the "ONE", "TWO", "THREE", "FOUR" are the main dotted eighth note beats.

4. Key Takeaways

• Compound meters have top numbers (6, 9, 12) divisible by 3, indicating each main beat divides into three subdivisions.
• The bottom number in compound meter always tells you the value of one of those subdivisions, not the main beat.
• To find the main beat in compound time, divide the top number by 3 and know that the beat is a dotted note.
• Asymmetrical meters (e.g., 5/4, 7/8) have top numbers that don't easily divide by 2 or 3, leading to irregular beat groupings.
• Understanding the internal grouping (e.g., 2+3 or 3+2) is crucial for counting asymmetrical meters correctly.
• The feel of the music often guides how asymmetrical meters are grouped.
• Common mistake: Confusing the subdivision count (top number) with the main beat count in compound time.
• Common mistake: Trying to find a single, regular main beat in asymmetrical meters; instead, look for combined smaller groupings.
• Common mistake: Assuming the bottom number represents the main beat in all time signatures, especially compound ones.

5. Now Try It

Take a piece of music (even a familiar song if you can find the sheet music, like "Take Five" for 5/4 or some Irish jigs for 6/8). Identify the time signature. For compound meters, determine the number of main beats and their note value. For asymmetrical meters, try to figure out the most likely beat grouping (e.g., 2+3, 3+2). Then, try tapping your foot to the main beats while counting the subdivisions aloud. Success looks like you consistently counting correctly and feeling the pulse of the music as intended by the time signature.