You know how your mom or grandma or whoever is always complaining about how "kids these days" listen to louder music than when she was young? Turns out, she was scientifically correct.
Echo Nest, a Boston-based startup that builds music recommendation engines for folks like Spotify, just released a study that analyzes the top 5,000 songs since 1950. Indeed, the average volume of the songs climbs steadily until about 1990 when Kurt Cobain (probably) turned up the volume on the world. From that point on, the graph shoots upwards.
It's very important, at this point, to specify exactly what the researchers mean by "louder." This is not the actual volume of the music, the kind that you can turn up and down with a knob. Rather, this measure of loudness considers the difference between the softest part of the song and the loudest part. Over time, the softest parts of songs have been getting increasingly louder while the loudest part is getting closer and closer to the max. Try playing Rage Against the Machine and The Supremes at the same time. You'll get the point.
But that's not all. Music has actually been getting consistently more energetic—"energetic" being the mix of volume, beats, structural changes and instrument sounds. Echo Nest did a similar survey of those 5,000 songs and found that music today is about three times more energetic than it was back in the days of sock hops.