All fourths

When we talk about "all fourths," we're usually talking about a type of musical tuning or tuning system. In this system, all of the intervals (or spaces between notes) are the same size, which is equal to a perfect fourth.

Think about musical notes like steps on a ladder. When we climb up the ladder, we're going up in pitch (or getting higher). And when we climb down the ladder, we're going down in pitch (or getting lower).

In the all fourths tuning system, the distance between each step is always the same size. It's like if we had a ladder where every rung was exactly the same height! That means that if we start on one note and climb up four steps (or four rungs on the ladder), we'll land on a note that's a perfect fourth higher in pitch.

So why is this important? Well, in traditional Western music, we typically use a tuning system called "equal temperament," which has some intervals that are slightly out of tune compared to the "pure" intervals we hear in nature. The all fourths tuning system can help us create music with more pure-sounding intervals that are all the same size.

This type of tuning is used in some experimental and avant-garde music, but it's not common in mainstream music. It can create a unique sound that's very different from what we're used to hearing, but it can also be a bit challenging to work with because it requires some different ways of thinking about music theory and harmony.