Pronunciation Pieces are short, light articles, each one usually focusing on an English word or phrase that illustrates a feature of phonetic or linguistic interest. They originally appeared in the series ‘Words of the Week’. They cover a wide range of topics include weak forms, contractions, linking R, T-epenthesis, G-dropping, T-glottaling, compound stress, rhoticity, vowel linking, aspiration, T/D-deletion, TH-fronting, tricky word stress, numerals, tricky spellings, negative transfer, pronouncing foreign words, accents of English, numerals, intonation, accentuation, word endings, prefixes and many others.

Audio

cassetteI was reminded while teaching this week how tricky the word audio is, but how instructive it can be. When non-natives pronounce this word in English, they can be misled by the spellings of the first and last vowels. The spelling au suggests a complex vowel that changes in quality (a diphthong); the spelling o suggests a simple, pure vowel that doesn’t change (a monophthong). But in English the reverse is true.

The vowel at the beginning of audio is a pure monophthong, known as the THOUGHT vowel because it’s the vowel in the word thought. This vowel is most commonly shown in dictionary transcription as /ɔː/ (British and ‘Eastern’ American) or as /ɑː/ (‘Western’ American). These symbols indicate long vowels which don’t change in quality. Here I am saying BrE audio, normally then with a prolonged first vowel to demonstrate how unchanging it is:

The vowel at the end of audio is a diphthong, the GOAT vowel (yes, it’s the vowel in the word goat). It’s most commonly shown in dictionary transcription as /əʊ/ (British) and /oʊ/ (American). These symbols indicate the different qualities at the start and end of the vowel. Here I am saying BrE /əʊ/, first at normal speed, then prolonged to reveal the change in quality from an ə-type sound to an u-type sound:

Here are some transcriptions of the word audio from online dictionaries. They’re all different, but at least they all agree that the first vowel is a monophthong, and the last vowel is a diphthong:

British: /ˈɔː.di.əʊ/ (Cambridge), /ˈɔːdɪˌəʊ/ (Collins), /ˈɔːdɪəʊ/ (Oxford Dictionaries)
American: /ˈɑː.di.oʊ/ (Cambridge), /ˈɑːdiˌoʊ/ (Merriam-Webster Learner’s), /ˈɔːdioʊ/ (Oxford Learner’s)

Further notes

The word audio is actually quite consistent with generalizations of spelling and pronunciation in English. Hundreds of words end with the final letter o pronounced as the GOAT diphthong:

hello, no, so, also, go, ago, euro, hero, photo, solo, studio, video, Romeo, Chicago, Toronto, etc

but final o is never pronounced with the THOUGHT monophthong. On the other hand, au is pronounced in hundreds of words as the THOUGHT monophthong:

August, author, auto, autumn, cause, fraud, haunt, launch, laundry, Paul, pause, etc

but au is not pronounced with the GOAT diphthong – except in French borrowings like:

aubergine, au pair, au fait, chauffeur, faux pas, Flaubert, gauche, mauve, sauté, Sauvignon, etc.