Being able to recognize musical intervals is one of the coolest musical skills you can possess, mainly because you can pick up on the musical distance between notes without any visual aids, like looking at sheet music, or aural aids, like using your guitar. Being able to do this gives you the ability to more deeply understand music, and having your favorite songs feel more like stories you know by heart. You can be walking around on the street and notice a car horn going by that sounds like a perfect fifth, or a bird chirping a minor third. It all starts with a simple game, where you hum your favorite song and try to recognize what intervals are taking place. Eventually, you’ll have internalized enough intervals to the point where they’ll sound more ‘correct’ to you than anything else.
The best way to learn intervals is to listen to examples in different contexts. Start with unisons and octaves, then move to more difficult ones like tritones and diminished sevenths, which are used in emotionally charged musical settings like jazz or movie themes. Try to attach specific songs to each one (major second is the interval from the first two notes of Frere Jaques; a perfect fourth is the first interval in Here Comes the Bride, etc.) After a few weeks, you can hear the difference between them when you improvise, transcribe music, or describe intervals to others. People who don’t have this ability can’t hear the relationships between the notes, but it’s easy to learn.
I know some of you might be thinking that interval recognition is something only for gifted people with perfect pitch, but I can tell you from my experience and those of many others that it is definitely a learnable skill accessible to anyone through dedicated practice. You start by listening to recordings of intervals and then rewinding them and playing them again until you commit the sounds to memory. At the same time, you practice scales and arpeggios vocally to connect the sounds you hear with the notes you sing, thus strengthening the feedback mechanism that enables you to make the fastest improvement. Once you get good enough, you should practice intervals in rhythm as well to get used to playing intervals in time, because of course you will need to do that when playing music. The net result of these efforts will be not only a sharper ear, but also increased confidence in your ability to play with others or to write your own music.
While there are many practical reasons to learn intervals, the rewards also include a greater connection to the heart and soul of music. By recognizing intervals, you can better understand a composer’s intent and create your own sound. For example, a minor 7th resolving to a major 6th can feel sad or hopeful in the same way life can. To recognize this in any song will allow you to better appreciate anything from the complex choral parts to the sparse intervals found in minimalist electronic music. To do so allows you to feel a part of every musical era and culture, and to feel like you’re having a conversation with your musical heroes. To learn intervals is not only a matter of correctness, but a way to feel the soul of music and to understand how to make it a part of your own musical identity.