With the recent release of the new Hobbit movie, The Desolation of Smaug, a lot of people have been talking about the pronunciation of the titular dragon's name. The inclination for English speakers is to pronounce it like smog, but Tolkien made clear in his appendixes to The Lord of the Rings that the combination au was pronounced /au/ ("ow"), as it is in German. A quick search on Twitter shows that a lot of people are perplexed or annoyed by the pronunciation, with some even declaring that they refuse to see the movie because of it. Movie critic Eric D. Snider joked, "I'm calling him 'Smeowg' now. Someone please Photoshop him to reflect the change, thanks." I happily obliged.
So what is it about the pronunciation of Smaug that makes people so crazy? Simply put, it doesn't fit modern English phonology. Phonology is the pattern of sounds in language (or the study of those patterns), including things like syllable structure, word stress, and permissible sound combinations. In my undergraduate phonology class, my professor once gave us an exercise: think of all the consonants that can follow /au/, and give an example of each. The first several came easily, but we started to run out quickly: out, house (both as a noun with /s/ and as a verb with /z/), owl, mouth (both as a noun with /θ/ and as a verb with /ð/), down, couch, hour, and gouge. What these sounds all have in common is that they're coronal consonants, or those made with the front of the tongue.
The coronal consonants in modern Standard English are /d/, /t/, /s/, /z/, /ʃ/ (as in shoe), /ʒ/ (as in measure), /tʃ/ (as in church), /dʒ/ (as in judge) /l/, /r/, and /n/. As far as I know, only two coronal consonants are missing from the list of consonants that can follow /au/--/ʃ/ and /ʒ/, the voiceless and voiced postalveolar fricatives. By contrast, /g/ is a dorsal consonant, pronounced with the back of the tongue. There are some nonstandard dialects (such as Cockney and African American English) that change /θ/ to /f/ and thus pronounce words like mouth as /mauf/, but in Standard English the pattern holds; there are no words with /aup/ or /aum/ or /auk/. (The only exception I know of, howf, is a rare Scottish word that was apparently borrowed from Dutch, and it could be argued that it appears rarely enough in Standard English that it shouldn't be considered a part of it. It appears not at all in the Corpus of Contemporary American English and only once in the Corpus of Historical American English, but it's in scare quotes. I only know it as an occasionally handy Scrabble word.)
And this isn't simply a case like orange or silver, where nothing happens to rhyme with them. Through the accidents of history, the /aug/ combination simply does not occur in modern English. Before the Great Vowel Shift, Middle English /au/ turned into /ɔ:/ (as in caught today). (Note: the : symbol here denotes that a vowel is long.) During the Great Vowel Shift, /u:/ turned into a new /au/, but apparently this /u:/ never occurred before non-coronal consonants. This means that in Middle English, either /u/ lengthened before coronals or /u:/ shortened before non-coronals; I'm not sure which. But either way, it left us with the unusual pattern we see in English today.
What all this technical gibberish means is that, in the absence of a clear pronunciation guide, readers will assume that the "au" in Smaug is pronounced as it is in other English words, which today is almost always /ɔ:/ or /ɑ:/. Thus most Americans will rhyme it with smog. (I can't speak with authority about other varieties of English, but they would probably opt for one of those vowels or something similar, but not the diphthong /au/.) It's not surprising that many readers will feel annoyed when told that their pronunciation clashes with the official pronunciation, which they find unintuitive and, frankly, rather non-English.
One final note: Michael Martinez suggests in this post that /smaug/ is not actually Tolkien's intended pronunciation. After all, he says, the appendixes are a guide to the pronunciation of Elvish, and Smaug's name is not Elvish. Martinez quotes one of Tolkien's letters regarding the origin of the name: "The dragon bears as name--a pseudonym--the past tense of the primitive Germanic verb Smugan, to squeeze through a hole: a low philological jest." He seems to take this as evidence against the pronunciation /smaug/, but this is probably because Tolkien was not as clear as he could have been. Smugan is the infinitive form; the past tense is--surprise--smaug.
Note: the definition given for the Proto-Germanic form doesn't quite match Tolkien's, though it appears to be the same verb; the Old English form, also with the infinitive smugan, is defined as "to creep, crawl, move gradually". The astute student of language will notice that the past tense of the verb in Old English had the form smēag in the first and third person. This is because the Proto-Germanic /au/ became /ēa/ in Old English and /i:/ or /ai/ in modern English; compare the German auge 'eye' and the English eye. This demonstrates once again that English lost the combination /aug/ quite some time ago while its sister languages hung on to it.
So yes, it appears that Tolkien really did intend Smaug to be pronounced /smaug/, with that very un-English (but very Germanic) /aug/ combination at the end. He was a linguist and studied several languages in depth, particularly old Germanic languages such as Old English, Old Norse, and Gothic. He was certainly well aware of the pronunciation of the word, even if he didn't make it clear to his readers. You can find the pronunciation silly if you want, you can hate it, and you can even threaten to boycott the movie, but you can't call it wrong.
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