Question

Intensity of sound in normal conversation is
A) 10 - 20 dB
B) 30 - 60 dB
C) 70 - 90 dB
D) 120 - 150 dB

Answer 1

Hint: Sound is mechanical vibration which requires a medium to propagate. Intensity of sound is measured in dB- decibels. The sound intensity of a normal conversation is moderate level.

Complete answer:
Sound is mechanical vibration which requires a medium to propagate. Sound is how we perceive the world. Sound perceptible by humans has frequencies from 20 Hz - 20,000 Hz. Sound intensity is quantified on the decibel scale. High noise exposure is hazardous to hearing. It can lead permanent damage to ears and leads to loss of hearing.

Option A: 10 - 20 dB is near a low level threshold intensity. The intensity of 10 dB is that of a soundproof room. 20 dB sound intensity is that of radio, television, or recording studio. The intensity of a normal conversation is not in the range of 10 - 20 dB. Therefore, this is the incorrect option.

Option B: 30 dB - 60 dB is the sound range for normal conversation. This sound intensity is that of a normal conversation, business office, restaurants, private office and inside houses.The intensity of a normal conversation is in the range of 30 - 60 dB. Therefore, this is the correct option.

Option C: 70 - 90 dB is loud and irritating. The best examples of this range of sound intensity are street noises (honking and shouting) bus or truck interior, automobile interior and loud telephone bell. The intensity of a normal conversation is not in the range of 70 - 90 dB. Therefore, this is the incorrect option.

Option D: 120 - 150 dB is near the high end of the sound spectrum. This range of sound intensity causes irritation and damage to ear drums. Examples of this range of sound intensity are artillery fire, amplified rock music and near jet engines. More than 160 dB causes bursting of eardrums.The intensity of a normal conversation is not in the range of 120 - 150 dB. Therefore, this is the incorrect option.

Thus, the correct answer is ‘B’ 30 - 60 dB.

Note: Noise pollution is a grave concern. Old age and long time exposure to loud noises leads to permanent ear damage. Some ways to prevent noise pollution are,
i) Growing trees around the neighbourhood.
ii) Honking must be banned in public places like hospital, schools, etc
iii) Playing music and musical instruments should be allowed only to desirable limits.
iv) Soundproof systems should be installed.