When two dihybrid individuals are mated, this is called a dihybrid cross. Even though the parents of a dihybrid cross have the same genotype and phenotype, their offspring could show any one of 9 different genotypes and 4 different phenotypes. The phenotypic ratio of offspring produced from a dihybrid cross is 9:3:3:1. To unlock this lesson you must be a Study.com Member.
Sounds are heard by the ear as either being loud or soft. The loudness of a sound in measured in decibels. Decibels refer to the energy produced by that sound. A human can hear sounds ranging from 0.1 decibels, which is very soft, to sound which measure 120 decibels. Younger people can often hear lower volumes better than older people.
A decibel dB(A) is a unit of measurement that indicates how loud a sound is. Humans can hear sounds between 0 and 140 decibels. 0 decibel does not mean that there is no sound, merely that we cannot hear it. 0 decibel is the so-called hearing threshold for the human ear. While we can hear more than 140 decibels, it is too painful for our ears and if you expose yourself to such a loud noise you are at extremely high risk of permanent damage to your hearing. The table blow shows how loud sound is.