What is the name of sound waves of frequency too low to hear for human beings?

CBSE Class 9 CBSE Class 9 Science
1
  1. What is meant by wavelength of a sound wave?
  2. What is the name of sound waves of frequency too low to hear for human beings?
  3. Name the part of the ear that sends signals to the brain.
  4. Name the sound absorbent material used in concert hall.
  5. Define decibel and on what factors does it depend?
2
  1. The distance between the two consecutive compression or two consecutive rarefaction is called the wavelength. It is the minimum distance in which a sound wave repeat itself.
  2. Infrasonic sounds or infrasounds of frequencies lower than 20 Hz are too low, which cannot be heard by human beings.
  3. Auditory nerve in the ear sends signals to the brain.
  4. Compressed fibre board, rough plaster or draperies are used as sound absorbant material in concert hall.
  5. Loudness of the sound is measured in decibel (dB). It depends on the sensitivity or response of our ears.