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.
Hertz is a frequency measurement unit. The SI unit of frequency is a frequency equal to one oscillation or cycle per second. The unit has a special name, the hertz (Hz), after German physisist Heinrich Rudolf Hertz who first experimentally demonstrated electromagnetic theory of light.