Health Hygiene & Sanitation

Lesson 17 : Lighting And Noise

Measurement Of Noise

Decibel is the standard for the measurement of noise.

• The zero on a decibel scale is at the threshold of hearing, the smallest distinguishable sound.
• on the decibel scale,
• 20 dB is whisper
• 40 dB the noise in a quiet office
• 60 dB is normal conversation
• 80 dB is the level at which sound becomes physically painful.

So How Loud Is Loud?

110dB +		Close to a train(110) >130 dB Immediate hearing damage
90 dB	Very loud	Car Horn at 5 meters(100db) >90 dB regularly can cause hearing damage.
70 - 80 dB	Loud	police whistle, city street noise
45-60 dB	Moderate	Normal conversation at close up. Normal office noise
30-40 dB	Faint	Quiet conversation, private office, recording studio.
20 dB and less	Very faint	watch ticking, whispering, sound proof room

Noice Quantum of Cities

• Delhi- 80 dB
• Kolkata – 87 dB
• Bombay-85 dB
• Chennai-89 dB etc..