In a new study, NASA scientists using equipment on the Perseverance rover have confirmed that the speed of sound on Mars and on Earth is very different. The results could have serious implications for communication between future Martians.
When we hear a sound, we actually feel the vibration of the eardrums. It appears due to pressure waves that reach the ears of a person from a sound source. To overcome this distance, some medium is needed, for example, air. Sound waves can travel through liquids and even solids, but the ideal medium is air.
What is the difference between sound on Mars and on Earth?
Mars has a very unusual atmosphere compared to Earth, with a different temperature, density and chemical composition. These differences affect some audio metrics, such as:
Sound levels on Mars will be much lower, all due to the fact that the atmosphere of the Red Planet is about 100 times more rarefied than the earth’s. Its density is about 0.020 kg/m 3, compared with 1.2 kg/m 3 on our planet, a new study has shown.
This affects how the sound waves propagate from the source to the detector, resulting in a softer signal. On Mars, a person needs to be much closer to the sound source in order to hear it at the same volume level as on Earth.
The atmosphere of Mars is 96% carbon dioxide and absorbs a lot of high-pitched sounds, so only lower-pitched sounds would travel long distances. This effect is known as attenuation – the weakening of the signal at certain frequencies. The farther a person is from the source, the more noticeable this effect.
Sounds made in the cold Martian atmosphere will take a little longer to reach the ear. With an average surface temperature of about -63°C, the speed of sound on Mars is about 240 m/s. This has already been proven by scientists in a new study. These results were announced at the 53rd Lunar and Planetary Science Conference by planetary scientist Baptiste Chide of the Los Alamos National Laboratory. For comparison, the speed of sound on Earth is approximately 340 m/s on Earth.
The scientists used the Perseverance SuperCam instrument, which fires a laser at rocks to study Martian geology. By measuring the time it took for the jerky clicks to reach the SuperCam microphone, they established the speed of sound on Mars with an accuracy of plus or minus 0.51%.
The scientists also found that the speed of sound with a frequency below 240 Hz dropped to 230 m/s. This does not happen on Earth because sounds in the audible frequency range (20 Hz to 20 kHz) travel at a constant speed. “Martian idiosyncrasy,” as scientists call it, is associated with “the unique properties of carbon dioxide molecules at low pressure.” This makes the Martian atmosphere the only one in the solar system that affects the change in the speed of sound right in the middle of the audible range, the scientists write.
This acoustic effect will cause a person to hear high sounds before bass. Below 240 Hz, there is a lot of acoustic information, including the low frequencies of music and the lowest registers of the human voice (usually male). Music on Mars would sound completely erratic (especially with increasing distance). If you add a dampening effect or muting the high frequencies, the acoustic experience becomes even stranger.
What does a voice sound like on Mars?
Together, these three factors will change the sound of the human voice in the Martian atmosphere. However, it should be borne in mind that the very atmosphere of Mars is unsuitable for human life, and they will have to wear spacesuits and use radio communications.
However, as part of the promotion of the Perseverance mission, NASA shared a special instrument that distorts the sound of a person and makes it clear how it would sound on Mars.