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.
Sound is the vibration of air molecules. The higher the pitch, the faster the vibration. The stronger the vibration, the louder the sound. Pitch is measured in Hertz (Hz). 1 Hâ¦ertz means the molecule vibrates 1 time per second (back and forth), 10 Hz means 10 times per sec. etc. Humans hear sounds from 20 Hertz (very deep bass) to 20.000 Hertz (=20 kHz) (very high sizzling)