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.
The commonly stated range of human hearing is 20 Hz to 20 kHz. Under ideal laboratory conditions, humans can hear sound as low as 12 Hz. Humans are most sensitive to (i.e. able to discern at lowest intensity) frequencies between 2,000 and 5,000 Hz.