Define the term Bel

Bel, the unit of measurement of sound, is named after Alexander Graham Bell; Bell was the inventor of the telephone, but for some curious reason, is spelt with a single '1'. Be1 is too large a unit. Hence a unit, one - tenth as high, called 'decibel' (dB) is more commonly used. Thus the range of human hearing extends from 0-120 dB. Besides intensity, the other important characteristic of sound is frequency, which is the major determinant of pitch. Pitch is expressed in cycles per sec or Hertz (Hz), named after an eminent German physicist of nineteenth century.