The commonly stated range of human hearing is 20 to 20,000 Hz. Under ideal laboratory conditions, humans can hear sound as low as 12 Hz and as high as 28 kHz, though the threshold increases sharply at 15 kHz in adults, corresponding to the last auditory channel of the cochlea. The human auditory system is most sensitive to frequencies between 2,000 and 5,000 Hz. Individual hearing range varies according to the general condition of a human's ears and nervous system. The range shrinks during life, usually beginning at around age of eight with the upper frequency limit being reduced. Women typically experience a lesser degree of hearing loss than men, with a later onset. Men have approximately 5 to 10 dB greater loss in the upper frequencies by age 40.