Is It True That Birds Hear Daytime Words and Mice Hear Nighttime Words? [Reading Science]

Car noise is heard louder at night than during the day. What is the reason for this?
Photo by YouTube Screenshot

[Asia Economy Reporter Kim Jonghwa] The election is over. There was a lot of talk and controversy in this election as well. Many people ruined the election because of those words. In times like these, our ancestors often used the proverb, "Birds hear the words spoken during the day, and rats hear the words spoken at night."

This proverb carries the meaning of "always be careful with your words." Nowadays, it might be more accurate to say that SNS (social media) spreads the words rather than birds and rats overhearing and passing them on. However, the proverb that birds hear the words spoken during the day and rats hear the words spoken at night actually has quite a scientific basis.

"Sound" is a sensation perceived when vibrations in the air are transmitted to the ear. When you hit a drum, you feel the vibration along with the "dong~" sound, and that vibration is transmitted through the air to your ear, allowing you to perceive the sound.

The speed of sound varies depending on the medium through which it travels, such as air, water, stone, or wood. Sound travels faster in liquids like water than in air, and even faster in solids like stone or earth. Additionally, the speed of sound changes with the temperature of the air. Sound travels faster at higher temperatures and slower at lower temperatures.

To explain again, the speed of sound depends on the temperature of the medium, which is air in this case. Generally, the higher the air temperature, the faster the sound propagates. Also, sound tends to refract from regions of higher speed to regions of lower speed.

During the day, the ground warmed by sunlight heats the air near the surface, making the temperature higher near the ground and lower as you go up. Therefore, sound travels faster near the ground and slower higher up. As a result, sound bends upward and spreads out more effectively during the day.

Because the ground temperature is high due to radiant heat and the temperature decreases with altitude, sound bends upward and disperses well into the air.

Conversely, at night, the ground cools faster than the air, making the air near the ground colder. Thus, sound travels slower near the ground and faster higher up. At night, the air above the ground remains relatively warmer than the surface, causing sound to refract downward and spread farther along the ground.

Rainy days somehow feel more hectic and noisy. This is also due to the nature of sound.
[Photo by YouTube screenshot]

Therefore, sound travels better downward at night. This is also why car noises are heard more clearly at night.

Birds mainly are active during the day in trees or the sky, while rats are mainly active on the ground at night. Due to these properties of sound, birds flying in the sky during the day and rats on the ground at night can hear sounds well. The expressions of our ancestors were made with considerable scientific basis.

Sound is also affected by weather. On rainy days, raindrops in the atmosphere amplify and transmit sound more quickly, making noise louder. Conversely, on snowy days, snow crystals absorb noise, making the environment quieter.

Now you understand why car sounds from afar seem especially loud at night, why it feels noisy and bustling when it rains, and why the whole world feels quiet when it snows.

This content was produced with the assistance of AI translation services.