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.
1 Pitch is a term used to describe how high or low a note a being played by a musical instrument or sung seems to be. 2  The pitch of a note depends on the frequency of the source of the sound.  Frequency is measured in Hertz (Hz), with one vibration per second being equal to one hertz (1 Hz).