increment of measurement used to compare measured levels of sound energy (intensity) to the apparent level detected by the human ear; expressed as a logarithmic ratio (sound that has 10 times the energy of another sound is said to be 10 decibels louder; 100 times the energy is 20 decibels louder; 1,000 times the energy is 30 decibels louder; and so on); decibel levels are correctly expressed as the number of decibels at a measured distance from source of sound (for example,125 dB at 10 feet)
