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.
As you may already know, the SI unit for frequency is Hertz (Hz); an event that repeats once per second has a frequency of 1 Hz. According to most sources, the human hearing (frequency) range is between 20 Hz and 20,000 Hz (bats can hear up to 100,000 Hz!).