Question

Noise can be defined as-
A) Loud sound
B) Unwanted sound
C) Constant sound
D) Sound of high frequency

Answer 1

Hint: Sound that disturbs organisms and causes irritation to them can be termed as unwanted.

Complete answer:
- Noise is any unwanted sound which is unpleasant, loud or disturbing to hearing. Noise is indistinguishable from sound as both of them are vibrations through a medium, such as air or water. Noise can be produced by vehicles, engines, aircrafts, etc.
- The actual difference is noticeable when the brain receives and perceives a sound. Electric instruments too produce noise, the unwanted residual electronic noise signal can be heard as a hiss.
- Measurement of sound is based on the amplitude and frequency of a sound wave. Amplitude measures the force of the wave. The energy is measured in decibels (dB). Decibels are expressed on a logarithmic scale.
- The pitch of the sound can be described by the frequency of a sound which is measured in hertz (Hz). Noise also causes pollution, and the pollution due to noise is called noise pollution.
- Noise pollution is regarded as regular exposure to elevated sound levels that may lead to adverse effects on living organisms.
- According to the World Health Organization, sound levels less than 70 dB are safe to listen for living organisms, sound levels above 80 dB is considered as noise. Noise pollution affects both health and behaviour, itcan damage physiological health.
- Noise pollution may cause several health conditions, including cardiovascular disorders, hypertension, induce stress, hearing loss, sleep disturbances, insomnia, and other harmful effects.

Thus, the correct option is- B- Unwanted sound.

Note: Not all sounds can be termed as noise but the ones which causes noise pollution or induces a medical condition in organisms can be called noise.