First of all, the term "frequencies," is a short-hand way of talking about the frequency content of the noise control problem at hand. It is a critically important consideration, because noise control treatments are generally most effective at a particular frequency, or range of frequencies. Some noise regulations even specify sound level limits on a per-frequency basis. You can think of sound frequencies like musical pitch. Low frequencies would be the low notes, and high frequencies would be the high notes. If a chorus, band, or orchestra all played random notes simultaneously, it would probably sound more like noise than music. Learn more about our company at www.ussi.com. We want to hear from you so please send us your questions at firstname.lastname@example.org.