Noise pollution refers to the excessive and harmful levels of noise in the environment that can disrupt natural soundscape, cause health issues, and interfere with communication and daily activities.
| Noises | Noise Level (in decibels, dB) |
|---|---|
| Normal Conversation | 60 - 70 dB |
| City Traffic | 70 - 85 dB |
| Vacuum Cleaner | 70 - 80 dB |
| Loud Music (at concerts) | 100 - 120 dB |
| Chainsaw | 100 - 110 dB |
| Jet Engine (at take-off) | 120 - 140 dB |
Reflection of sound, also known as an echo, occurs when sound waves encounter a surface and bounce back towards the source. The phenomenon of an echo can be heard when the reflected sound reaches the listener’s ears after a noticeable time delay, which depends on the distance between the sound source and the reflecting surface, the speed of sound in the medium, and the time taken for the sound to travel to the surface and back.
The distance (d) between the sound source and the reflecting surface can be calculated using the formula:
\begin{equation} d = \frac{v}{2} \times t \end{equation}
Where:
v = Speed of sound in air
t = Time taken for the sound to travel to the surface and back
Similarly, the speed of sound (v) can be calculated when both the distance and time are known:
\begin{equation} v = \frac{2d}{t} \end{equation}