For the March episode, Paul discusses the phonetic phenomena known as the glottal stop and the schwa. The glottal stop is that little explosion you feel in your throat when you say phrases such as  "uh-huh," "huh-uh," and "uh-oh," while the schwa is the most common vowel in the English language that is not formally a vowel. Instead, it's a vowel substitute that sounds like "uh."