If your songs start sounding a bit too predictable, one way to change that is by either writing songs in different time signatures, or including within your song a few measures that have a different meter (different time signature) than your overall song.
A time signature is the meter of music, and it tells the musician how many beats per measure we are playing and what kind of note value that beat is (quarter note, half note, eighth note, etc). So for instance, 2/4 (said as “two four”) means “two quarter notes per measure”, and 6/8 means “six eighth notes per measure”. The upper number always represents quantity (how many) and the lower number represents quality (what kind). Some of the most frequently used time signatures in Western music are: 4/4, 3/4, 2/4, and 6/8.
While the listener may not think in these terms, the listener is innately aware of the time signature/meter of your song, just as the listener is aware of the key that we are in (major vs. minor), and the occurrence(s) of modulation. Consequently, adjusting the meter of our song, even slightly, will have an impact that the listener can notice and appreciate.
There are a number of time signatures one can choose to use, but the majority of music (not just rock, pop, and electro) is in 4/4 time. 4/4 time is also known as “common time” because it is the most common time we use in Western music. If you are looking at a piece of music, the time signature (along with the key signature and clef symbol) will appear on the left side of every line of the music staff. You will sometimes see the letter “C” denoting common time or just 4/4, but they both mean the same thing and are interchangeable.
Sometimes you may want to just add a few measures of a different time signature into your song for contrast, or you may want to write your entire song in an unconventional time signature. “Take Five” by The Dave Brubeck Quartet is a good example of a piece whose identifying feature is its complex time signature of 5/4. If it was in 4/4 it would lose this defining characteristic; but with it, it stands out and is embraced because of its unique meter.
There are styles of Western music that feature odd time signatures and frequent time signature modulation. Modern classical and jazz music will often experiment with time signatures, as well as certain styles of modern rock (such as modern death metal). In the case of modern death metal, and following in the footsteps of the more progressive latter works of Death (see the album “The Sound of Perseverance”), bands like Necrophagist typically step outside of the world of 4/4, where metric modulation and use of complex, compound, and mixed time signatures are a staple of the subgenre.
There is the option of just adding a few measures of a different time signature to your piece for color. The Beatle’s “Blackbird” is a good example of this, and as an example: if you are writing a piece in 4/4, if you throw in a few measures of 2/4, or even 1/4, it will give your song that little bit that it was missing, perhaps bridging the gap between sections of a piece. Often times we can use a different time signature to change sections, from verse to chorus, for instance. This metric modulation can signal to the listener a change within the composition, a transition between parts, and can be just as effective as harmonic modulation.