Speech speed is measured by syllables per second, and density of information is measured by how much information is encoded per syllable. What does that mean? Let’s take an example from English. The one-syllable word “calm” is information dense because it expresses a complex state with only one-syllable. However, “easy-going” uses four syllables to express an idea easily conveyed with fewer syllables. By averaging the information density across a language, the linguists determined the density of information per language.