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Terms for Your Songwriting Toolbox

with Asaf Peres

This helpful glossary breaks down the definitions in the Song Start podcast where Top40 Theory dissects popular song structures. 


A type of hook that moves back and forth between fast (fuel) and slow (core) notes. The core is the most memorable part of the hook, while the fuel’s main role is to infuse energy into the core.

Melodic Preview

“Planting” a melodic fragment (or sometimes an entire melody) from the chorus earlier in the song, in order to make the chorus feel familiar the first time a listener hears it. It’s important to note that the purpose of this is not for the listener to consciously realize that they’ve heard this melodic fragment before, but for them to subconsciously feel that familiarity, and as a result feel more of an emotional connection to the song.

Soft/Hard Repetition

Every musical moment is made up of many musical aspects: melody, harmony, rhythm, meter, timbre, texture, lyrics, etc. When all or most of those aspects are included in a repetition, that’s a hard repetition. The one thing that slightly softens the repetition is a subtle chord change on the third “dance,” but otherwise, this repetition is very close to the hard end of the spectrum. For example, in Taio Cruz’s “Dynamite,” the verse starts with the line “I came to dance, dance, dance, dance.” All four repetitions of the word “dance” are: - on the same pitch - on the beat
 - the same length
 - identical timbre-wise (Cruz delivers each “dance” in the same way)
 By contrast, in Taylor Swift’s “Shake it Off,” even though the lyrics “shake, shake, shake, shake, shake,” as well as the rhythm, repeat in the same way that “dance, dance, dance” repeat in “Dynamite,” this repetition feels much softer because each “shake” is on a different pitch. It’s important to remember that soft/hard repetitions are not a binary, but a spectrum. Any tweak can make a repetition slightly softer or harder.

Tonal Center

The fundamental note of a key, also known as the tonic. For example, the tonal center of a song in the key of F-major is the note F and the tonal center of a song in G-minor is G. The keys C-major and A-minor contain the same notes, but C is the former’s tonal center, while A is the latter’s.

If we think of a key as a solar system, the tonic is like the sun – every other note in the key has some kind of direct or indirect gravitational pull towards it. But, depending on where the listener’s attention is directed, there can be competing centers of gravity in a song (just like the planets are the centers of gravity for their moons).

Those centers of gravity can be pitch based, like a chord or a melody that revolves around a non-tonic note, but they can also be based on lyrics, rhythm, meter, production, or any other musical aspect. Part of the songwriter and producer’s job is to create centers of gravity and help the listener experience them through tension and release.


A typical song section is made up of eight bars, divided into four two-bar units. Each of the two-bar units normally contains a single phrase, but in some types of melodic structures, some of those units are split up into shorter phrases (or fragments). This creates a feeling of acceleration and helps to intensify the energy of the section. Fragmentation usually starts in the third two-bar unit, and may or may not continue into the fourth, depending on when the songwriter chooses to hit the brakes with a melodic cadence.


  • Selena Gomez – “Good for You”

    • Unit 1: “‘Cause I just wanna look good for you, good for you, oh-oh"

    • Unit 2: “I just wanna look good for you, good for you, oh-oh”

    • Unit 3 (fragmentation)

      • “Let me show you how proud I am to be yours"

      • “Leave this dress a mess on the floor”

    • Unit 4 (hitting the brakes): “Still look good for you, good for you, oh-oh, oh-oh, oh”

  • Hailee Steinfeld, Alesso, Florida Georgia Line, Watt – “Let Me Go” 

    • Unit 1: “I've been hoping somebody loves you in the…”

    • Unit 2: “…ways I couldn't, somebody's taking care of…”

    • Unit 3 (fragmentation):

      • “…all of the mess I made”

      • “Someone you don’t have to change”

    • Unit 4: “I’ve been hoping someone will love you, let me go”


Musical phrases are often made of two or more distinct parts. These parts are called sub-phrases. For example, in the pre-chorus of Ariana Grande’s “Positions,'' there is a pause in the middle of each phrase:

“…meet your mama – (pause) – on a Sunday”

“…make a lotta love – (pause) – on a Monday”

These pauses create a tension and release relationship between the two sub-phrases that make up each phrase. They also enhance the catchiness of the chorus by distilling the connections between the “what” (meet your mama; make a lotta love) and the “when” (Sunday; Monday) parts.

Other examples of distinct sub-phrases:

Ariana Grande – “7 Rings”: “I want it – (pause) – I got it”

Camila Cabello – “Havana”: “He didn't walk up with that ‘how you doin'?’ – (pause) — When he came in the room”

Watch more episodes about songwriting, production, and collaboration, plus listen to Song Start: The Podcast, here.

For more info on Song Start click here.