Scientists made guinea pigs listen to Adele for a week. Here’s what happened to them.

There’s always that person who puts a song on repeat forever. It’s extremely annoying. But what if you were subjected to the same Adele song for a straight week? That’s what researchers did for a group of guinea pigs. They were forced to listen to an uncompressed version of her 2015 hit, “I Miss You.”

The experiment wasn’t just about playing the same song over and over again. The key word is “uncompressed,” meaning that the recording had all the original dynamic range: the loud bits loud and the quiet bits are quiet. In most recordings today, the digital signal is compressed to reduce the difference in dynamic range. Taken to the extreme (Red Hot Chili Peppers, Metallica), the results are awful. This is known as the Loudness Wars.

The scientists’ goal with the guinea pigs was to prove that there’s a limit to the amount of compression that should be used on a recording. One group of guinea pigs listened to an uncompressed version of the song while the other listened to a compressed recording. In both cases, the volume level was 102 decibels–which, even for a human, is pushing it.

Here’s what they found:

• Extended exposure to music at this volume damaged the inner ear. At first, impairment was temporary. Then it was permanent.
• Compressed music can damage hearing in ways that uncompressed music will not. The middle ear’s stapedius muscle (a tiny 1mm thing) is stressed by compressed music. This can lead to permanent damage.
• There’s more enjoyment derived from uncompressed music because the quiet bits give the brain time to process what it just heard and to anticipate what might come next.
• Compressed music leads to a lot of listener fatigue for everyone and everything.

Note to producers, musicians, mastering technicians, and record labels: STOP with the over-compressed music!