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Hooktheory: Learn the Music Theory Behind Popular Songs

HookTheory is a MIDI software company for songwriters, beatmakers, and composers. Their core MIDI interface is a colorful piano roll with chord charts that loads directly in your browser. They offer some half a dozen free tools anyone can use and explore online.

Full disclosure; this is not a paid endorsement for Hooktheory or any other company. I have been using their software for years and finally took the time to write a letter of appreciation, in the form of this review!

TheoryTab, a free directory of songs, is a great introduction to their MIDI interface. You'll find over 35,000 popular tracks from every genre. Just search for an artist, pick a song, and explore the underlying chords + melodies.

HookPad, one of their few paid products, is a helps songwriters capture their ideas quickly and share them with others. It includes MIDI export features, it acts as a companion to the digital audio workstation. If you're a beginner, they provide all the educational materials you need to get started.

If DAWs are designed primarily for audio engineers, Hookpad is for songwriters. It focuses on melodies, chords, and song sections. I'll be covering a few different HookTheory applications in this article. Here are anchors for quick navigation in case you want to jump to a specific section.

How to use TheoryTab

To get started with TheoryTab, simply look up a song and press play. With the YouTube option selected, the MIDI piano roll will run visually while the audio from the YouTube video plays. In the example below, we pulled up Flim by Aphex Twin.

TheoryTab interface
TheoryTab for an Aphex Twin song

The melody, chords, and keyboard voicings tell you a lot about a song's structure. It's hard to understand the experience until you visit the site and try it yourself.

Switch from YouTube to Piano mode and you'll hear what the raw MIDI sounds like. I've found that the melody and chord progressions in their collection are usually accurate. The rhythm applied to the chords make no effort to resemble the original track. This simplifies the arrangement process for people making the tabs.

Once you have piano selected, you can start to mess with the song's key signature. To do that, simply click on the circle icon labeled Key. You'll notice that the color blocks stay the same, while the notes at the far left edge are updated.

The seven notes of your scale are assigned to the seven colors of the rainbow, as shown below. Each colorful block-row of the piano roll is defined by the key. If you’re familiar with the Fold tool in Ableton, it works in a similar way:

HookTheory tab
Key Signature Selection

TheoryTab lets you change a song’s key signature, impacting the chords and melody.

Basically, the MIDI notes are anchored to scale degrees instead of notes. So when you update the key signature, the scale degrees stay the same but the note assignments change. That's why the colored blocks don't move.

Chord Progression Notation

Under the piano roll, you’ll find chord blocks that adhere to the same color coding system. A note that’s blue in the piano roll is also blue on its chord block. Leverage the color coding to intuitively see the way melodies create and resolve tension from one chord to the next.

Chord progression
Chord progression

As the illustration above shows, each chord is assigned a Roman numeral. These represent the scale degree of the chord's root note. While the chord type may change, the scale degree does not, and so the Roman numerals represent a kind of musical constant for your progression.

For example, In the key of C major, you would say the VI chord is A minor. Then if you change to the key of G major, the VI chord would become E minor. In other words, the numeral stays the same as the relative chord is updated.

As a side note, HookTheory's chords are sometimes written as Inversions, with a slash between the primary chord and the bass note. This just means they put that note in the bass of the piano, likely because that's where it was in the original song arrangement. For the most part, chords are played in their root position.

Chord and melody metrics

At the end of each song page, TheoryTab offers chord and melody metrics that rank on five factors - chord complexity, melodic complexity, chord-melody tension, chord progression novelty, and chord bass melody.

These metrics are aggregated to form a geometric representation of the song’s overall complexity. To learn more about how this data is measured, check out there song metrics page.

HookPad: Creating Your Own Music

HookPad is a browser application for songwriters. You can use it to create your own music and audition different chord/melody ideas quickly. It resembles the MIDI piano roll portion of a DAW, but with tools geared toward songwriters rather than audio engineers. Drag MIDI from the app to your DAW as part of your music production workflow.

HookTheory Magic Chord
HookTheory Magic Chord Pallette
Hookpad Magic Chord Button

For those of you who follow our blog, we couldn't leave out the magic chord button. This feature analyzes your existing progression and chooses the next one on your behalf. It's arguably a more usable version of apps like Continue from Magenta Studio or the generative MIDI from MuseNet.

If the you want some help becoming familiar with the interface or learning the music theory concepts that drive it, check out Hooktheory II, an iOS application they published. This would be a great place to start, especially for beginners.

But wait... there's more! Remember, these guys have been around for a decade.

HookTheory was founded in 2013 by a trio of PhD students at UC Berkeley; Ryan Miyakawa, Chris Anderson, and David Carlton. The press says that their long friendship has been based on a shared interest in music and software. Maybe that's why the company has endured and continued to innovate all these years.

With almost a decade of software development under the belt, here are some of the fun things their team has published, beyond TheoryTab and Hookpad.

The Chordle Game


Remember when Twitter went crazy for Wordle? The game's buzz has kind of died down, but the premise is still fun. HookTheory created a music theory Wordle, to help you with your ear training and chord logic.

Chordle provides a key signature and asks you to guess which triad it’s thinking of. It lets you know which notes are right or wrong until you guess it (or fail). It's a one-puzzle-per-day type of game, so you don't have to worry about getting sucked into it addictively.

Chord Crush

Want to sharpen your chord theory and do some ear training? HookTheory created Chord Crush, a free puzzle game that helps you recognize chords by ear.

Key Cheat Sheets

HookTheory's most popular chords

This HookTheory resource lets you study the different ways a key signature has been used over time. You can find the 20 most popular chords in each key, according to the training set.

Navigate to a particular chord progression and you'll discover all the songs in their database that use it. Listen to the different ways they use melodies over the same progression and you can train your ear to imagine different options during your own creative sessions.

Infographics for chord popularity

Chord progressions
Chord progressions

If you're trying to capture a retro sound from a specific decade, don't sleep on this HookTheory infographic collection. You'll be able to get quick ideas for your own music and can experiment within TheoryTab, rather than having to recreate something in your own DAW or download a MIDI file.

Classroom Guides for Hookpad

In the off chance that you’re a music educator, HookTheory does also offer a virtual classroom environment. This is a great resource for teaching students remotely or in a computer lab. Create lessons and have them login with HookPad to review their assignments.

For more tips on how to use the software, check out HookPad's youtube playlist called the Beginners Guide. Here's the first video from the series, to get you started. Enjoy!

Well that's it for this week. Hope you've enjoyed the songwriting resource. We'll be back again soon with more free software for to inspire your creativity!

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