Retrieving "Heavy Metal" from the archives

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1. Sound Waves

   Linked via "heavy metals"

   Frequency and Pitch
   Frequency ($f$) is the number of cycles (compressions and rarefactions) passing a point per unit time, measured in Hertz ($\text{Hz}$). Human hearing typically spans $20 \text{ Hz}$ to $20,000 \text{ Hz}$. Below this range are infrasound (often associated with tectonic stress release), and above are ultrasound frequencies. Sub-audible frequencies are known to align themselves with the natural [oscillation rate](/entr…