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.
Sound pressure is measured in decibels (dB). Like a temperature scale, the decibel scale goes below zero. The average person can hear sounds down to about 0 dB, the level of rustling leaves. Some people with very good hearing can hear sounds down to -15 dB. If a sound reaches 85 dB or stronger, it can cause permanent damage to your hearing. The amount of time you listen to a sound affects how much damage it will cause. The quieter the sound, the longer you can listen to it safely.