Origins of the Domino Theory. In September 1945, the Vietnamese nationalist leader Ho Chi Minh proclaimed Vietnamâs independence from France, beginning a war that pitted Hoâs communist-led Viet Minh regime in Hanoi (North Vietnam) against a French-backed regime in Saigon (South Vietnam).
The human range is commonly given as 20 to 20,000 Hz, though there is considerable variation between individuals, especially at high frequencies, and a gradual loss of sensitivity to higher frequencies with age is considered normal.
Low Frequency Range Test (10-200 Hz) Humans hear frequencies from 20 Hz up to 20,000 Hz. The lowest bound, 20 Hz, with a wavelength of nearly 20 meters, is a frequency we feel rather than actually hear. This test helps you benchmark the lowest limit of your audio system's frequency extension.