shows the part of and the height of the tongue involved in the articulation of /aʊ/
"How now brown cow" (/ˈhaʊˈnaʊˈbraʊnˈkaʊ/) is a phrase used in elocution teaching to demonstrate roundedvowel sounds. Each "ow" sound in the phrase represents the diphthong /aʊ/. Although orthographies for each of the four words in this utterance is represented by the English spelling "ow", the articulation required to create this same diphthong represented by the International Phonetic Association'sphonetic alphabet as /aʊ/ is also represented by the spelling "ou". Some examples of these homophonic /aʊ/'s are the English words "house", "blouse", "noun", and "cloud". The use of the phrase "how now brown cow" in teaching elocution can be dated back to at least 1926.
Although not in use today, the phrase "how now" is a greeting, short for "how say you now", and can be found in archaic literature, such as the plays of William Shakespeare.