system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How time signatures work and why songs in unusual time signatures are notable.
gpt
Consider the time signature to be like a language. Most pop music is written in the language of 4/4. This is when the emphasis is on the fourth beat, and everything is written nicely to fit into grouping of four. In this language there are many chords, scales, and note progressions that we've used to hearing. These are the words and sentences that make up the 4/4 language. Since birth, most of the music you listen to is written in 4/4, so everything seems natural and normal. Think of 1 2 3 **4**, 1 2 3 **4**, 1 2 3 **4**, 1 2 3 **4**.

There are other time signatures used in music such as 7/4 (used in a lot of Prog Rock or IDM). This time signature would sound "weird" to the average person because it features many patterns, chords, scales etc that make up the 7/4 language. It takes a little bit of practice to get into it's rhythm. Check out the song Money by Pink Floyd for an example of this: 1 2 3 4 5 6 **7**, 1 2 3 4 5 6 **7**, 1 2 3 4 5 6 **7**, 1 2 3 4 5 6 **7**. This can seem off to us because we're expecting the typical 4/4 beat and instead we get a little bit of tension hearing something different.

Finally classical music tends to be in a huge assortment of time signatures. Another language we could recognize is 3/4. This is normally reserved for waltz. This would be **1** 2 3, **1** 2 3, **1** 2 3, **1** 2 3.

Avante-garde jazz music can often change time signature requiring knowledge of multiple time signature "languages": to be able to play on the fly.