In October 1986 former CBS anchorman Dan Rather was attacked in New York City while being asked, “Kenneth, what is the frequency?”
Dan didn’t know but frequency, defined as the number of occurrences in a given time period, is ubiquitous. Beats per minute is a frequency that measures heart rate, a musical time signature is a frequency that specifies beats per bar, and Hertz measures the frequency of alternating current, sound, and anything else that occurs in cycles per second.
Every frequency has a pitch. The A that orchestras tune to is 440 Hz. The common US alternating current frequency of 60 Hz is close to a B flat; in Europe it’s 50 Hz or close to a G.
Maybe if Dan Rather’s assailant had instead asked for the pitch he wouldn’t have left empty handed.