Sound and Noise: Differences, Measurements and Interesting Facts
The difference between sound and noise
Sound and noise are often considered synonymous, but for experts, these concepts are significantly different:
- Sound - is vibrations perceived by the sense organs of animals and humans.
- Noise - is a disordered mixture of sounds, often perceived as unwanted or annoying.
Measuring sound and noise
Sound and noise levels are measured in decibels (dB):
- dB is a unit of sound pressure level.
- dBA is an acoustic decibel, which takes into account the peculiarities of sound perception by the human ear.
Important thresholds
- 120-130 dB: the threshold of pain for human hearing
- 200 dB: a deadly sound level
Hearing standards
Normal hearing allows a person to:
- Hear quiet speech from a distance of 5-6 meters (low tones)
- Perceive high tones from a distance of up to 20 meters
If you have difficulty distinguishing speech from a distance of 2-3 meters, it is recommended to consult an audiologist for a hearing test.
Interesting facts about sound
The illusion of sea noise
The sound of the "sea" in a seashell is actually the sound of blood flowing through your vessels. A similar effect can be achieved by placing an ordinary cup to your ear.
Sonoluminescence: when sound turns into light
This amazing phenomenon occurs under certain conditions:
- A resonator is lowered into the water, creating a spherical ultrasonic wave.
- In the rarefaction phase of the wave, a cavitation bubble is formed.
- The bubble grows and then quickly collapses in the compression phase.
- At the moment of collapse, a blue glow appears in the center of the bubble.
Sonoluminescence demonstrates a surprising connection between sound waves and light phenomena, opening up new horizons for research in the fields of physics and acoustics.
