When we hear sound, what we are really experiencing is our eardrums vibrating. That vibration comes from waves of pressure that travel to our ears from the source of the sound. To get to our ears, the waves need something to travel through, like air. Sound waves can travel through liquids and even solids, but most of what we hear comes through the air. Sound waves are longitudinal waves that travel through a medium like air or water. When we think about sound, we often think about how loud it is (amplitude, or intensity) and its pitch (frequency).
The speed of sound depends on the temperature and density of the medium it travels through. On Earth, at room temperature, sound travels at about 760 miles per hour (about 340 meters per second). In colder air, sound travels more slowly because the molecules are less energetic and do not pass vibrations along as quickly.
Why do sound waves need a medium like air, water, or solids to travel?
The word frequency appears in the chunk above. The text mentions 'pitch (frequency).' High-pitched sounds have a high frequency, and low-pitched sounds have a low frequency. If a whistle has a higher frequency than a drum, which one has a higher pitch?
Have you ever noticed that sound seems different underwater or through a wall? What does that tell you about how the medium affects sound?
Mars has an unusual atmosphere compared to Earth, with very different temperature, density, and chemistry. These differences would have three main effects on the sound you would hear. With an average surface temperature around -81 F (-63 C), Mars has a lower speed of sound, around 540 mph (about 240 meters per second), compared to about 760 mph (about 340 meters per second) on Earth. You probably would not notice up close, but over longer distances you might.
The sound level you would hear would be automatically lower on Mars. The Martian atmosphere is about 100 times less dense than on Earth-that is, there is just a lot less of it. That affects how sound waves travel from the source to the detector, resulting in a softer signal. On Mars you would have to be much closer to the source of a sound to hear it at the same volume as you would on Earth. The atmosphere of Mars, made up of 96 percent carbon dioxide, would absorb a lot of higher-pitched sounds, so only lower-pitched sounds would travel long distances. This effect is known as attenuation-a weakening of the signal at certain frequencies-and it would be more noticeable the farther you were from the source.
Why is sound quieter on Mars than on Earth?
Why would high-pitched sounds like whistles be hard to hear on Mars?
If you stood on Mars and tried to have a conversation with a friend, what would you do to make sure they could hear you?