Starbucks is working with Spotify on a music deal, one where Starbucks customers will be able to easily download songs from the Starbucks playlist. Here’s the hook: It’s a backdoor route to more mobile payments.

Before you dismiss this as too bizarre to have any payments impact, music has had some surprising influences on retail purchases. To be precise, it’s not the music itself as much as allowing the shopper to be in control of the music.

Note: I, too, used to scoff at the linkage between store music and purchases until I saw teen apparel chain Aeropostale turn customers who actively disliked the store’s products into repeat paying customers—solely via a music control marketing scheme.

Let’s start with Starbucks. As this FastCompany story tells well, the coffee chain’s deal with music app Spotify allows customers to use their Starbucks app to identify the song now playing. That song—and, if you want, the full Starbucks playlist—can be saved using Spotify integration.

The point? As customers see others customers doing this, they may want to try it directly—which will mean more Starbucks app downloads, which will almost certainly mean more Starbucks app mobile payments.

In effect, SBUX is using the music it’s always played as background to push its app.

Now for that apparel chain. As I wrote a few years back, that mobile trial involved iPads located in the store. The idea there, though, was perfectly tuned for teens. It wasn’t about capturing the music the store was playing. It was about choosing the song that everyone in the store would be forced to hear, sort of a mean-spirited jukebox approach.

How did this impact teen clothing sales? The idea is that the music would lure customers into the store and the tablet app would hold the promise of controlling the music, molding it to that customer’s taste. But just the jukeboxes of old, the customer needed to stay in the store and wait for their song to crop up. And while waiting, that’s when the bored customer would invariably browse and buy.

In that case study, I was stunned that an impromptu teen focus group showed the huge impact it had. The participants all agreed that they actively disliked that chain’s products. Why? The styles were seen as out-of-date and too expensive. Fair enough.

But when they heard about the tablet music program, the teens said they would go there to play their own songs. And—wait for it—they said that they probably would buy things while waiting. (Wait a second. Didn’t y’all just say that you didn’t like the clothes?)

Why go through this tale? In today’s payments world, merchants need to get creative about any ways to push payments and to get payments apps downloaded, musical manipulation included.

And if SMB merchants don’t get creative enough, their payment facilitators need to.