I would try out 2 different advertising strategies:
1. Facebook Ads — Share a music video or post an article about your music. Set the location to those specific countries, and if you want to get even more specific, target users who are fans of similar artists. Now run another ad that targets the world in general. By comparing the two, you can see which countries are responding better to your music.
2. Feature.fm — This is a service that plays your songs as advertisements within streaming services. It works a little more naturally compared to Facebook since users are guaranteed to listen to your song. Just like Facebook, you can choose which countries you want to advertise in, so you can compare the results between South America and other countries.