Defrag is a process that your computer does to sort all the information. Weird as it sounds, your computer sometimes pulls apart the pages of a file and puts them into different places on your hard drive. It leaves little notes on each sheet of paper to help it find where the next page in the file is located.
For humans, normal hearing is between â10 dB(HL) and 15 dB(HL) , although 0 dB from 250 Hz to 8 kHz is deemed to be 'average' normal hearing. Hearing thresholds of humans and other mammals can be found by using behavioural hearing tests or physiological tests.hey are not the same as equal-loudness contours, which are a set of curves representing equal loudness at different levels, as well as at the threshold of hearing, in absolute terms measured in dB SPL (sound pressure level).
Humans cannot hear sounds of every frequency. The range of hearing for a healthy young person is 20 to 20,000 hertz. The hearing range of humans gets worse with age. People lose the ability to hear sounds of high frequency as they get older.requency is measured in hertz. The hertz, Hz, is the derived SI unit of frequency. The frequency of a sound wave determines its tone and pitch. The frequency range of a young person is about 20 to 20,000 hertz. The human ear is capable of hearing many of the sounds produced in nature, but certainly not all.