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Under review

Rover sound seems weird

norritt 2 years ago updated by Tyler Owen (Lead Developer) 2 years ago 2

To me the rover driving sound is pretty weird. It feels too loud an becomes rather annoying after a short while.


If an electric vehicle makes a humanly audible sound at all I'd expect it to sound similar to the sound in this video.


This video gives another example (which might be useful as inspiration for the sound design). However with the rover accelerating much slower than a F1 car this sound would be too aggressive and loud.

I am aware that mars's atmosphere is thinner than earth's and has a different composition. This would probably cause sounds to become lower pitched on mars. Since we are wearing a pressurized suit I'd expect the helmet to filter high pitched noises from the electric motors rather well. However I'd expect to hear dull, muffled noises caused by driving over smal rocks or uneven terrain.


Suggestions for improvement:

  • Change the electric motor sound based on the samples above but make it rather quiet
  • Use the electric motor sound in the acceleration phase but (almost) mute it when having reached travel speed (like in the 1st video)
  • When moving with travelspeed dull muffled sounds caused by the terrain should be audible

The following video could be a good reference point for the terrain sound while driving (minus the occasional cracking underwood and humming sound on the right channel). Of course it would need to be damped because of the thinner atmosphere and sound damping caused by the EVA suit:




I actually like the rover sounds very much the way they are now. I somewhat agree with that they are a bit louder and "clearer" than what might feel right, but otherwise I think it provides a great "feel" for travelling with a vehile.


One thing that's difficult to grasp regarding the atmosphere of Mars is that it's not simply thinner, but extremely thin (about 2% of that of Earth iirc), down to hardly existing at all in terms of being able to propagate sound. So about the only sound you'd hear in any situation is what can travel as vibration from the source being in direct physical contact with the EVA suit into the pressurized interior of the suit.


In this specific case it'd be mostly the vibration of the mechanical parts of the rover, dampened by all the joints and materials it has to go through to reach the EVA suit. It could include some rolling noise from the wheels, but likely nowhere near as much as we'd expect to hear based on what we hear in this situation here on Earth.


One thing that could actually be an interesting and reasonable change is modulating the frequency / intensty of the motor noise between acceleration and coasting, but I'm not quite sure if that isn't already a thing actually as I didn't drive around in it as much yet. And with the terrain being as uneven as it is, I think there'd be hardly any coast phases to begin with most of the time. It's not like you are driving around on a perfectly flat highway where you only need to compensate drag forces once the vehicle's mass has been accelerated and its momentum carries it along.

Under review

It's a fair criticism. I may revisit the audio at some point. Thanks for the feedback.