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.
Pitches are labeled using: 1  Letters, as in Helmholtz pitch notation. 2  A combination of letters and numbersâas in scientific pitch notation, where notes are labelled upwards from C0, the 16 Hz C. 3  Numbers that represent the frequency in hertz (Hz), the number of cycles per second.