CBS Morning News special featuring two of the preeminent soundscape recordists; acoustic ecologist Bernie Krause and "sound tracker" Gordon Hempton.
To my surprise, NASA equipped the Mars Rover with the same set of microphones that I use for my field recordings, the DPA 4006s. I've taken these to the Amazon Rainforest, the Book Cliffs, the Olympic Peninsula, but Mars (currently 140 million miles from Earth)...that is next level.
I took the above photo which is not Mars–
I have my fair share of wind recordings so, you decide– does wind on Mars sound different? (A wind recording I captured is further down).
First, check out sounds from Mars! NASA FTW
Okay, I apologize, that was a bit underwhelming...though what did you expect? A dawn of life chorus? (terrible soundscape joke, I apologize). The NASA recording has a lot of noise, noise being unwanted sound or sound artifacts in the recording. So how can you tell what to listen for and listen through to know when you are actually "hearing Mars"?
What exactly is causing the "noise" here?
First, consider the way the sound works. Sound travels via vibration, in waves of energy emanating from a source to a listener. That source– sometimes a musical instrument– vibrates and in that energy travels through a medium, such as air or water, from the source to the listener. The sound stops when the energy or vibration dissipates. Mars has a very weak atmosphere which still allows for sound transmission, but makes the sound quieter and slower moving.
Second, consider how microphones capture sound– a sound when it reaches a microphone vibrates the diaphragm (think membrane, or in a the top of a drum). This membrane vibration moves a magnet, which is how you take acoustic energy and translate it into electrical energy. The microphone translates that vibration into an electrical signal.
Listen to the same recording with the ROVER noise removed
The membrane on a microphone is designed to capture minuscule details, however, if the membrane is moved not by a sound wave but rather by wind, you get a low noise rumble and distortion. The NASA recording doesn't appear to be picking up very much wind sound, but rather it seems that the microphone membrane is being moved directly by the wind.
Most of what you hear in the NASA recording is "noise"
The NASA recording is primarily noise in the sense that it contains artifacts of the equipment.
When the ROVER sound is removed, you can hear the distortion of the microphone more than the sound of the martian environment, or at least hearing that distortion more prominently. The amplitude (or loudness/volume) from wind blowing across the membrane is creating the low rumble with volume spikes.
For comparison and to hear what I'm getting at, listen to a wind recording (with the exact same microphones) I captured in a high plains desert. The opening 30 seconds has both wind that is blowing above the microphone and some wind that comes directly in contact with the microphones.
Most of the wind noise in the "High Winds" recording is captured away from the microphone, i.e. the microphone diaphragm is not in contact with wind.
How quiet is quiet?
The High Winds recording is from one of the quietest places I've been to, the Book Cliffs, Utah. I didn't encounter another human being for the 7 or 8 days I was out there. The Sahara Desert dunes near Zagora Morocco felt quieter, but I can't say for certain; I didn't have equipment with me. The ambient noise level in the Book Cliffs was generally in the low 30 dBs (decibels). Most quiet homes are 10 times louder...! The average urban environment is 1000 times louder!! (I did not add the corresponding amount of exclamations). So ya...the Book Cliffs is quiet. It seems, so too is Mars.
Information without context is just noise
Just as the sound recording of Mars can appear misleading without an understanding of how microphones work, so too is the comparison of sound environments. Humans have an incredible range of hearing, both in frequency range and amplitude. So while it is accurate to say that the average urban environment is 1000x louder than the Book Cliffs, that fails to capture how humans perceive sound and consequently how we measure sound– which is logarithmically.
To infinity and beyond...
The accomplishment of NASA landing the rover on Mars is incredible. That the Perseverance Rover is on Mars recording sound is a feat; so far every microphone sent except the DPA 4006 has been dead on arrival. Kudos to the incredible DPA microphones that can survive the rainforest, or 7 months in space, atmospheric reentry, and the inhospitable Martian dust-scape.
The Rover may yield some interesting Martian soundscape recordings, though they will largely consist of wind, the rover, and the occasional rock fall. And while the recordings might entice people with the prospect of "hearing" Mars, the point of including the microphones is as much for NASA to listen to the Rover and to get additional insight on the object 7-months journey from Earth.
Bonus NASA consulting (this time is free, I already know what mics you like).
I deeply believe that the Mars Rover should have been equipped with Jimmy Buffet's Margaritaville playing on loop, to give a more realistic feel of an Earth tourist venturing out into the solar system. Who knows what they'll encounter, and why not lead with culture? And, if they do discover the existence of life on mars, let's hope it's a dead cat.
Bonus 2: can name the location of the photo, (hint, it's not mars, second hint, the park+state is an anagram of "cyan-swoon-haunt"
Bonus 3: Watch the Mars landing, filmed in the same studio as the Moon landing (just kidding, the studios just look similar. Okay, kidding again, the studios look nothing alike.)
And for the truly enthusiastic– listen to a wonderful PODCAST about sound on MARS below:
NASA you did well but let's be real, the planet that everyone really wants to listen to is Jupiter.