The question Ian Lang was answering:
Why do many modern pop/Top 40 songs get stuck in your head so easily, regardless of whether you like the song or not?
I don't listen to the Top 40 myself these days, but I do experience the same effect from tunes used to introduce TV/Netflix series or dramas.
Ian Lang's answer:
Having the musical talent of a ton of falling bricks, I’m not really in a position to write from a musician’s perspective. However all the musicians I know that play popular songs speak of a “hook”.
The hook is usually melody or rhythm led refrain, in western music the former is more common, and consists of a series of complementary frequencies (I believe musicians speak in terms of thirds and fifths and so on) or less commonly, patterns of rhythm, arranged in a way that is aesthetically pleasing and unique to the piece under consideration.
The uniqueness, combined with the aesthetic quality, immediately makes an association with that particular work. Because the arrangement is so novel, it sticks in the front of the mind for a time, and this is the ‘catchy’ aspect that keeps it stuck in your head for a while. In addition the refrain, whether it be melody or rhythm, is repeated, developed, and recapitulated over the course of the piece of work, reinforcing the ‘catchiness. The phenomenon has been exploited since at least the Baroque composers and probably long before that. Everybody who has ever heard it will know instantly from the first few bars Bach’s Brandenburg Concerto No.3 in G major Allegro Moderato, even if they don’t know they know it:
Similarly everybody will know Prokofiev’s Dance of the Knights, Beethoven’s Ninth (final movement) and the end of the 1812 Overture.
In the latter half of the twentieth century, because the recording companies wanted to make lots of money from single and LP sales, this sort of thing became an applied science in the service therof.
Every memorable song that stands the test of years has a strong hook. In the Rolling Stones’ Paint it Black the hook is established outright, and is melody led, and if you listen you can hear the hook in the background being developed and recapitulated and eventually rhythm, vocals and melody are subsumed into it:
An example whereby the rhythm establishes a hook which is later replaced by a melodic one is the Ting-Tings’ That’s Not My Name:
This is quite remarkable artistry; certainly I can’t think of anything else quite like it offhand. You’ll notice that the drumbeat is mirrored by the vocalist with minimal melodic variation to begin with, and then the vocalist is allowed full expression towards the middle and then both rhythmic and melodic hooks are recapitulated until the end.
Lastly but not leastly we could point to Sara Bareilles’ Brave which is nothing if not catchy (I’ll have this in my head all weekend now):
Listen for the backbeat. You think you’re listening to the vocalist. But you aren’t. What you are doing is being reeled in by the tinkly piano bit in the back. Then the vocalist puts some power in, and you’re listening to her (deservedly so, her range is huge) but subconsciously waiting for the catchy backbeat to re-appear and you’re rewarded in the second verse. By this time it’s got you ensnared.
Now as I said before, I have no musical talent. I’m just a technician that builds amplifiers and other things to do with signal processing, both analogue and digital, and I tend to think in terms of frequency and amplitude and what can be handled. If I notice these things, think how much more developed an idea in aesthetics somebody who is paid to make these musical pieces popular (and therefore lucrative) will have. And that’s why they “get stuck in your head so easily”; somebody who knows just what they’re doing has designed them to.
