What would a human voice sounds like on Mars?
DB: This is Earth and Sky, with a question from Portland, Oregon. Mark Orton wonders, “What would the human voice sound like on Mars?”
JB: Mark, scientists believe that the human voice would sound quieter and lower on Mars than it does on Earth. We got this example of a woman’s speaking voice from Dr. Greg DeLory at Berkeley, who is a specialist in acoustics on Mars:
[.wav files]: This is me on Earth. This is me on Mars.
DB: Sound waves depend on the collisions of gas molecules to transmit acoustic energy. But the atmospheric pressure on Mars is less than one percent that of Earth at sea level. So there just aren’t as many molecules in a given volume of atmosphere to transmit sounds on Mars.
JB: Also, Mars is colder than Earth, which means that sound travel more slowly there. Sound waves would be weakened as they travel through the Martian atmosphere, with higher pitched sounds weakening to a greater degree than lower pitched sounds. So the pitch of the voice would be lower than on Earth. Here it is again…
[.wav files]: This is me on Earth. This is me on Mars.
DB: And it would sound lower the farther you are from it. This happens on Earth, too. It’s why thunder nearby sounds like a clap but far away sounds like a low rumble. The high frequencies get damped out more quickly and don’t travel as far. Mark, thanks for your question. And with thanks to the National Science Foundation, we’re Block and Byrd for Earth and Sky.
If you enjoyed this program, you might be interested in the following website:
Mars Microphone (University of California at Berkeley)
Author’s notes:
Dr. Greg Delory adds: Don’t try this at home – attempting to speak in a nearly pure CO2 atmosphere at the low pressures found on Mars, not to mention at about –60 C, could definitely be bad for your health!
Jean–Pierre Williams adds: The lower pressure on Mars also means that sound sources will not couple with the atmosphere as effectively. Meaning a sound source (i.e. vocal chords) will not be as efficient at converting its vibrational energy into acoustic wave energy. So the intensity (or loudness) will not be as great. There will be about a 20–dB decrease in sound intensity on Mars because of this. So I guess a human speaking with a relatively loud speaking voice on Mars would sound much like a low–pitched whisper.
The following people were interviewed for today’s program. Our thanks to:
Dr. Gregory Delory
Assistant Research Physicist
Space Sciences Laboratory
University of California
Berkeley, California
Jean–Pierre Williams
Dept. of Earth and Space Sciences
University of California, Los Angeles
