2. Importance of root and tuber crops in Africa. In Africa, roots and tubers are generally grown in countries located in the Sub-Saharan zones, notably in Nigeria, Ghana, Cote cÃ´te'D, Ivoire, Nigeria, Benin, Cameroon Central African, Republic.D.R, C, Tanzania, Mozambique, Angola, Uganda, Malawi madagascar And. rwanda
The healthy human ear can hear frequencies ranging from 20Hz to 20,000 Hz. Over time, the hair cellâs hair-like stereocilia may get damaged or broken. If enough of them are damaged, hearing loss results. The high frequency area of the cochlea is often damaged by loud sound.
There are still plenty of sounds in the world that you canât detect. The low range of human hearing starts around 20 hertz, and tops out at about 20,000 [PDF]. By contrast, bats can hear ultrasonic sounds with frequencies up to 110,000 hertz. Other animals, like elephants, hear sounds many times lower than those a human can perceive. And as people age, their hearing gets even worse, eliminating even more sounds from the range of audible noises. Here are just a few sounds most people are missing out on: