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).
Frequency is measured in hertz (Hz). A person who has hearing within the normal range can hear sounds that have frequencies between 20 and 20,000 Hz. The most important sounds we hear every day are in the 250 to 6,000 Hz range. Speech includes a mix of low and high frequency sounds: