10 Fun Facts About Sound You Probably Didn't Know

Sound is an integral part of our daily lives. It allows us to communicate with each other, enjoy music, and perceive danger, among other things. But do you really understand everything about sound? In this article, I will introduce you to 10 fun facts about sound that will give you a whole new understanding of it.

1. The Speed of Sound Changes

Sound is produced by vibration. When an object vibrates, it causes the particles of the surrounding medium (such as air, water, or a solid) to vibrate as well, thus creating sound waves. Sound waves are longitudinal waves, which means that the particles of the medium vibrate back and forth in the direction of the wave's propagation. The speed of sound depends on the properties of the medium. In air at room temperature, the speed of sound is approximately 346 meters per second. Interestingly, the speed of sound is much faster in water (about 1500 meters per second) and even faster in solids (about 5000 meters per second in steel). The humidity and temperature of the air also affect the speed of sound propagation. In general, warm, dry air allows sound to travel faster.

2. How Astronauts Communicate in Space

Sound cannot travel in a vacuum because there is no matter in a vacuum, and therefore there are no particles that can vibrate and transmit sound waves. This also explains why space is silent - space is a vacuum with no air or other particles. Therefore, astronauts need to use radios to communicate with each other during spacewalks (or on the moon, where there is no air), converting vibrations into electrical signals for transmission.

3. Sounds from Space

Although there is no sound in space, some celestial bodies (such as stars, planets, or black holes) emit electromagnetic waves. These electromagnetic waves can be received by special instruments and converted into sounds that we can hear. The principle is similar to that of the radio mentioned in the previous section. You can imagine these electromagnetic waves as "sounds" from the depths of the universe.

4. Humans Cannot Hear All Sounds

The pitch of a sound depends on the frequency of the sound wave. The frequency of a sound wave refers to the number of times the sound wave vibrates in a unit time, which is the density of the sound wave. The higher the frequency, the higher the sound. The human hearing range is approximately 20 Hz to 20,000 Hz. Sounds below 20 Hz are called infrasound, and sounds above 20,000 Hz are called ultrasound. Some animals (such as dogs, cats, or bats) can hear ultrasound, which allows them to perceive sounds that we cannot.

5. Sound Can Be Reflected, Refracted, and Diffracted

These phenomena behave similarly to light waves, except that sound waves generally have much longer wavelengths, making them more likely to bend around obstacles. Sound reflection, known as an echo, occurs when a sound wave encounters a smooth and rigid surface, bouncing back. If there is a time delay between the reflected sound wave and the original sound wave, we perceive an echo. Sound refraction refers to the change in direction of a sound wave as it propagates through different media or temperature layers due to changes in speed. Sound diffraction occurs when a sound wave encounters an obstacle or opening, causing a change in direction due to the deformation of the wavefront.

6. Sound Interference

When two or more sound waves act simultaneously on the same point, they either reinforce or cancel each other out, resulting in changes in sound intensity. This is known as sound interference. If two sound waves have the same or similar frequencies and opposite phases, they completely cancel out, resulting in silence — the principle behind noise-canceling technology. If two sound waves have the same or similar frequencies and phases, they reinforce each other, producing a louder sound—an underlying principle of amplifiers.

7. Sound Resonance

Resonance, a phenomenon in acoustics, occurs when two objects with similar or identical natural frequencies, placed close to each other, cause one to vibrate in response to the other's vibration. Resonance can enhance the effect of sound or even damage the structure of objects. For example, when a singer produces a tone matching the natural frequency of a glass, the glass may vibrate or even shatter due to resonance.

8. Utilizing Sound for Localization

Some animals, such as bats, dolphins, and whales, use sound for localization and navigation. These animals emit ultrasonic waves, which, when they encounter obstacles, are reflected back. These reflected waves are received and analyzed by the specialized organs of these animals, allowing them to determine the position, size, shape, and distance of obstacles. This principle, known as sonar, is essential for these animals to survive and hunt in dark or murky environments. Humans also utilize sonar for detection and measurement purposes. Submarines, ships, aircraft, and other vehicles are equipped with sonar systems to detect underwater terrain, obstacles, enemy positions, and more.

9. Sound Encryption and Decryption

Sound, being a wave, can be encoded and decoded for information encryption and decryption. For instance, certain sound waves, such as ultrasonic waves, can transmit information inaudible to humans, which can only be decoded and restored by specific receivers. This method can be used for secret communication or data transmission purposes, such as identity verification or payments via mobile phones, computers, bank cards, etc., utilizing ultrasonic waves.

10. Sound Can Damage Your Hearing

The intensity of sound is measured in decibels (dB), a logarithmic unit representing the ratio of sound pressure level to reference sound pressure level. Generally, the range of sound audible to humans is from 0 dB (extremely quiet) to 140 dB (extremely loud). Prolonged exposure to high dB sounds can damage your hearing. According to the World Health Organization, human exposure to sound should not exceed 85 dB per day, as it may lead to permanent hearing loss. The higher the dB of the sound you're exposed to, the shorter the safe exposure time. For example, you can safely be exposed to 8 hours of 85 dB sound, but only 15 minutes of 100 dB sound, and only a few seconds of 120 dB sound.

These are just a few fascinating facts about sound. Have you learned something new? Sound is a remarkable phenomenon with significant importance in our lives. There are still many mysteries surrounding sound waiting for us to explore and discover. Let's use our ears to listen to the sounds of the world together!