Some taxes are inadvertently hidden, but others are consciously designed that way to disguise the cost of government. Itâs easy to see why: the total U.S. tax burden is equal to 56 percent of annual personal consumption spending.
Thus, the volume is proportional to the amplitude of the sound wave. The frequency of a sound wave is perceived as pitch. Humans can detect pitches within the acoustic range of 20 to 20,000 Hz, but we can't detect ultrasound or infrasound.
The hertz (symbol: Hz) is a unit derived from time which measures frequency. Frequency is how often something happens. A frequency of 1 hertz means that something happens once a second. The note Middle C (the C in the middle of the piano) is 262 Hz.