Question

Sound above what level (in decibels) is considered hazardous noise pollution ?
1. 30 dB
2. 40 dB
3. 60 dB
4. 80 dB

Answer 1

Correct Answer - Option 4 : 80 dB

The correct answer is 80 dB.

• Sound above 80 dB (in decibels) is considered hazardous noise pollution.
• Sound is a mechanical disturbance from a state of equilibrium that propagates through an elastic material medium. 
• The study of sound should begin with the properties of sound waves. There are two basic types of waves, transverse and longitudinal. 
• A longitudinal wave can be created in a coiled spring by squeezing several of the turns together to form a compression.
• A sound wave thus consists of alternating compressions and rarefactions, or regions of high pressure and low pressure, moving at a certain speed. 

• Noise pollution is commonly generated inside many industrial facilities and some other workplaces, but it also comes from the highway, railway, and airplane traffic and from outdoor construction activities.
• Sound waves are vibrations of air molecules carried from a noise source to the ear.
• Sound is typically described in terms of the loudness (amplitude) and the pitch (frequency) of the wave. 
• The normal human ear can detect sounds that range between 0 dB (hearing threshold) and about 140 dB, with sounds between 120dB and 140 dB causing pain.