The articles you're linking are proven to be misrepresenting.
They for example look at a really small subset of music "Million song dataset" and only analysed basic metrics that could be automatically measured. To be honest I think the linked Spanish paper and the senationalist "Science proves modern music is bad" should be retracted since the methodology is flawed.
Don't take my word for it, take Tantacrul's - composer, video creator, Design Lead for MuseScore [0].
It's such a complex topic to study "music" - you have to narrow it down - genre, country of origin, purpose - it's a major simplification to say that "all music is worse now", there are a lot of types of music that didn't exist in 1961 (synths, electronic, hip-hop) - how can you compare it?