An international team published a study on Martian sounds in the journal Naturelast week. Most of the audio the researchers investigated came from a microphone on the SuperCam instrument located on Percy’s “head.” There’s another mic on the rover’s chassis.

It turns out Mars has two sound speed limits. “On Earth, sounds typically travel at 767 mph (343 meters per second),” NASA said. “But on Mars, low-pitched sounds travel at about 537 mph (240 meters per second), while higher-pitched sounds move at 559 mph (250 meters per second).”

NASA points to the planet’s thin atmosphere made up of primarily carbon dioxide as the reason sound behaves like it does on Mars. The atmosphere also muffles sounds, with high-pitched sounds hardly traveling at all.

A Sounds of Mars site lets you listen to familiar Earth sounds as they would be heard on our own planet compared with how they would sound on the red planet. Bird songs, for example, pretty much disappear.

The discoveries fall in line with what scientists expected to find about how sound travels on Mars, but there could still be some surprises in store. The researchers are curious if seasonal changes might affect how “noisy” Mars is. Perseverance will be listening.