Excerpt - page 25: "... Therefore, when a dB describes a sound pressure level ratio, the "20 log" equation is used: dB sPL = 20 log (pl/po) where po and p1 are the sound pres- sures, in dynes per square centimeter or Newtons per square meter. This equation tells us ..."
Excerpt - page 81: "... other end, so you're interacting with differ- ent frequencies of sound with those different surfaces. And then, likewise, you'll see all ..."