The intensity of a normal conversation in decibel is between:
Show Answer & Explanation
Correct Answer: (C)
Explanation:
The intensity of sound is measured in decibels (dB). A normal, face-to-face human conversation generally falls in the range of 35 dB to 60 dB, depending on how closely the individuals are standing and their natural speaking volumes. Anything around 30 dB is considered a soft whisper, while sounds reaching 70-80 dB are comparable to loud street traffic or a vacuum cleaner.
📚 Additional Info: The Decibel (dB) Scale
The decibel scale is logarithmic, meaning a small increase in the decibel number equals a massive increase in actual sound intensity (e.g., an increase of 10 dB means the sound is 10 times more intense).
1. Common Sound Intensities for Exams
| Source of Sound | Approximate Intensity (dB) |
|---|---|
| Normal Breathing / Rustling Leaves | 10 – 20 dB |
| Soft Whisper | 30 dB |
| Normal Conversation | 35 – 60 dB |
| Busy City Traffic / Vacuum Cleaner | 70 – 80 dB |
| Heavy Machinery / Lawnmower | 90 – 100 dB |
| Jet Engine taking off | 120 – 140 dB (Threshold of Pain) |
2. Safe Noise Levels
- According to the World Health Organization (WHO), long-term exposure to noise levels above 85 dB can cause permanent hearing loss.
- The Central Pollution Control Board (CPCB) in India has set the acceptable ambient noise limit for residential areas at 55 dB during the day and 45 dB at night.