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.
It is common to express sound intensity on a logarithmic scale, called decibel SPL (Sound Power Level). On this scale, 0 dB SPL is a sound wave power of 10-16 watts/cm2, about the weakest sound detectable by the human ear. Normal speech is at about 60 dB SPL, while painful damage to the ear occurs at about 140 dB SPL.