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.
Frequency or pitch is measured in Hertz (Hz). Frequencies range from low-pitch to high-pitch and read from left to right on the audiogram. Each vertical line represents a different frequency. The ones used most often during testing are 250, 500, 1000, 2000, 4000 and 8000 Hz.