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).
In the audiogram below, hearing thresholds for the right ear are represented by red circles and thresholds for the left ear are represented by the blue X. In the right ear, this person has normal hearing in the lower pitches indicated by a red circle corresponding to 15 dB at 250 Hz and 20 dB at 500 Hz. Hearing thresholds in the high pitches fall into the severe degree of hearing loss, as the threshold at 2000 Hz is 40 dB, 65 dB at 4000 Hz and 75 dB at 8000 Hz.