Working donkeys are often associated with those living at or below subsistence levels. Small numbers of donkeys are kept for breeding or as pets in developed countries. A male donkey or ass is called a jack, a female a jenny or jennet; a young donkey is a foal.Jack donkeys are often used to mate with female horses to produce mules.he donkey has been used as a working animal for at least 5000 years. Of the more than 40 million donkeys in the world, about 96% are in underdeveloped countries, where they are used principally as pack animals or for draught work in transport or agriculture.
In simplistic language, every matter in this world vibrates, so that vibration we call frequency, and we measure it in Hz. The sound has its own frequency which is also measurable in Hz. The guy in the beginning of the video says that everything owes its existence to sound.
Example: Many ultrasonic welders have a fundamental operating frequency of 20 kHz, a sound that is at the upper frequency of audibility of the human ear. However, a good deal of noise may be present at 10 kHz, the first subharmonic frequency of the 20 â kHz operating frequency, which is audible to most people.