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.
MOST OF THE TIME, it's in an animal's best interest to be undetectable, but sometimes it's useful to be loud-very loud. While a normal human conversation registers at about 60 decibels (dB), some animals can screech, scream and holler much louder than a subway train (100dB). The human threshold of pain is 120, and at 160 your eardrum will rupture, but many loud animal calls are not designed for human ears.