Phthalates are another class of chemicals that are often used in deodorants and antiperspirants that you may want to avoid. Phthalates are used in cosmetics, synthetic fragrances, plastics, body care products and medical goods. They help to dissolve other ingredients and to create a better consistency.
A harmonic is a signal or wave whose frequency is an integral (whole-number) multiple of the frequency of some reference signal or wave. The term can also refer to the ratio of the frequency of such a signal or wave to the frequency of the reference signal or wave.
Frequency (wave motion) The number of times which sound pressure, electrical intensity, or other quantities specifying a wave vary from their equilibrium value through a complete cycle in unit time. The most common unit of frequency is the hertz (Hz), which is equal to 1 cycle per second. In one cycle there is a positive variation from equilibrium, a return to equilibrium, then a negative variation, and return to equilibrium.