Phonetics of the "oo" sounds
I think there are 6 pronunciations of "oo" as a digraph. As other people have mentioned, it can also represent two vowels in hiatus, as in "cooperate" or "zoology".
1. "OO" as in "GOOSE": traditionally /uː/, phonetically [ʉw]
- With words like google, yahoo, poodle and loose, the oo has a sound similar to the German ü sound.
Although other people have said this is wrong, it actually isn't. The sound of English oo in many accents does resemble the sound of German ü. The conventional transcription of the English sound is /uː/, which happens to be different from the conventional transcription of the German "üh" sound (IPA /yː/) and the same as the conventional transcription of the German "uh" sound. However, this does not mean that English "oo" and German "uh" actually sound exactly the same. The International Phonetic Alphabet is a single "standard" in the sense that there is a single inventory of symbols and a single officially defined "cardinal" value given to each of these symbols. However, there is no single way these symbols are used in practice to transcribe words in particular languages. Unfortunately, it's necessary to make various language-specific simplifications and approximations; in addition, conservatism means that the phonetic symbols used to transcribe English often reflect older forms of the language and don't take into account recent sound changes.
You can find a general overview of the vowel sounds of contemporary British English on Geoff Lindsey's blog: The British English vowel system.
Lindsey says
I consider ɵw and ʉw equally acceptable transcriptions of SSB GOOSE.
Certainly the widespread transcriptions ʊ and uː are fossils as far as
contemporary SSB is concerned (though the ʊ of kaputt of course
survives in the north of England and in Australia). I commend those
Germans (and others) who trust their ears more than their
dictionaries, and use their ü rather than their u when speaking
English.
A small detail that Lindsey mentions in a later blog post: in one particular context, before the sound /l/ when it ends a syllable, as in words like fool, it is in fact common for speakers to use a further-back value that is closer to German "uh" than German "üh."
Lindsey covers (a variety of) British English; you can additionally see maps showing the fronting of traditional /uː/ in American English in the Atlas of North American English: the fronting of /uw/ after coronals, after non-coronals.
2. "OO" as in "FOOT": traditionally /ʊ/, phonetically [ɵ]
- With words like good and book, it is more similar to how Germans pronounce a oo sound.
I'm not sure what you mean by this. As far as I know, in German spelling, "oo" represents a long vowel /oː/. This is not very similar at all to the sound in English "good." Conventionally, the vowel in "good" is transcribed as /ʊ/, which happens to be the same symbol used to represent the short vowel in the first syllable of German "Butter." However, the actual phonetic value of the vowel in "good" is, according to Lindsey, best transcribed as [ɵ], a central vowel. He compares it to the "French schwa" in words like le; the closest equivalent in German would probably be the "short ö" sound found in e.g. Göttin.
3. "OOR" as in "DOOR": like "ore" as in "more" ([oː] or [o˞])
- For words like door we are not sure if that is the same or different.
The British English pronunciation of the word "door" is conventionally transcribed /dɔː/. Lindsey says the /ɔː/ would be better represented phonetically with [oː]. In other words, a good approximation is the German "long o" sound in a word like Mond.
In American English, there is the consonant "r" at the end, which has no good equivalent sound in German: /dɔːr/. (In fact, the "r" sound is more likely to be realized non-consonantally as "r-coloring" on the vowel: [ɔ˞] or [o˞], but this would be even harder I think for a German speaker.)
It's common for "oo" to make the sound /ɔː/ (that is, [oː], German "oh") before the letter "r."
4. "OOR" as in "POOR" can optionally have the vowel of "tour"
Some speakers use a distinct sound for "oor" in a few words, such as poor and moor. This sound is traditionally transcribed /ʊə/ in British English, and /ʊr/ in American English. It's commonly replaced with the sound of "more" in both regions, so it's really not necessary to learn it. If you do, the British pronunciation is somewhat similar to the sound in German "nur". This sound is more commonly heard after /j/, in words spelled with "ure": Lindsey transcribes it as /ʉwə/ or /ɵː/.
5. "OOD" in "BLOOD" and "FLOOD" only: like "mud"
As user46928 mentions, there is another pronunciation of oo that only occurs in two words: blood, flood. The vowel here is conventionally transcribed /ʌ/, although phonetically it's often closer to [ɐ]; there isn't a great equivalent in German, but it's probably closest to German "short a", or to the sound of unstressed -er as in Sommer (not the sound of stressed -er as in werten). It's sometimes written /ə/: it's not like German /ə/, although it may be similar to English /ə/.
6. "OO" in "BROOCH" only: like "coach"
This is very marginal, but as Theta30 mentioned in a comment, the word "brooch" is pronounced /broʊtʃ/ (or in British English, /brəʊtʃ/), the same as "broach" (in fact, both words have the same etymological origin according to the Oxford English Dictionary).
Etymology and distribution of the "oo" sounds
(Despite what I said in the phonetics section, I'll resort to the traditional but phonetically inaccurate symbols /uː/, /ʊ/, /ʌ/ in this section because it's easier to discuss historical development with these symbols.)
The usual pronunciation is "long", as in "goose"; the "short" vowel sound of "foot" is actually pretty rare. The short pronunciation can generally be seen as conditioned by some kind of "shortening environment". Wikipedia gives somewhat of an overview: Shortening of /uː/ to /ʊ/, although I would take it with a very large grain of salt because it seems to be edited by amateurs, like me, rather than real experts. (The article gives two contradictory accounts of the development of the vowel in "wool", for example.) And since I am a self-admitted amateur, you should also take this following section with a grain of salt (but if you find an error, I'd appreciate a comment or edit!).
I'll use "Early Modern English" here to refer to English right after the Great Vowel Shift; "Middle English" (abbreviated "MidE") is pre-Great Vowel Shift, and "Old English" (abbreviated "OE") is pre-Norman Conquest. The "OED" is the "Oxford English Dictionary".
General background information you should know:
- Both "oo" sounds generally come from the same source, Early Modern English /uː/. The /ʊ/ sound is the result of a shortening process that was only partially predictable and that seems to have been active both before and after another vowel change that un-rounded /ʊ/ to /ʌ/ in most environments. Some dialects in Northern English lack the /ʊ/ to /ʌ/ change entirely, and therefore lack the sound /ʌ/.
Early Modern English /uː/ generally developed via the Great Vowel Shift from Middle English /oː/, which in turn mostly came from Old English /oː/, which is represented in modern scholarly transcriptions as "ō". This o-sound is the origin of the spelling ⟨oo⟩.
Middle English /uː/ (usually spelled "ou" or "ow") mostly turned into the Early Modern English diphthong /aʊ/ via the Great Vowel Shift. However, before a labial consonant such as /p/ /f/ /v/ /m/, this change was inhibited, and Middle English /uː/ became Early Modern English /uː/, merging with the reflex of /oː/. This led to some un-etymological spellings such as "room" < MidE "roum(e)", "rowm(e)" < OE rūm and "droop" < MidE "droupe", "drowp(e)" Old Norse drúpa.
Another spelling quirk is that some words that were likely pronounced with /uːv/ or /uv/ in Early Modern English were spelled with "ov", with a single "o": examples are "behove" < OE bi-/behōfian (now commonly spelled "behoove" in the United States) and "love" < OE lufu (which probably usually had /uv/, but dialectally or poetically could have /uːv/), as well as the non-native verbs "move" and "prove" which have somewhat unclear phonetic development to modern /uːv/.
As fas as I can tell, short "oo" is possible before /k d t f m/, and after /w/. Here is an overview of these shortening environments.
Before the voiceless velar plosive /k/: short is regular.
-ook. Early Modern English /uːk/ seems to have quite regularly been shortened to /ʊk/, and consistently after the sound change of /ʊ/ to /ʌ/. (Speaking here of the pronunciations that contributed to modern standard English; it is well known that there is regional variability, and some regions apparently don't show shortening in "-ook" words.) So there are very few exceptions to the ⟨ook⟩-/ʊk/ correspondence in modern standard English, and they all seem to be words that originated at a time period after shortening was active.
/uːk/ occurs exceptionally in the following words:
- spook: < Dutch spook
- kook: unclear etymology; possibly from cuckoo (which has a variable first vowel)
- mook: unclear etymology. Apparently short for some speakers.
- snooker: unclear etymology. Short for some speakers.
Etymology of words with regular pronunciation:
/ʊk/ from OE -ōc /oːk/:
- book, brook (n), cook, hook, rook (the bird), shook, took, look
/ʊk/ from other sources:
- brook (v): < OE -ūk. The lack of diphthongization to /aʊ/ between Middle English and Early Modern English is apparently irregular, but it may be significant that no native English word today contains /aʊk/: the word suck < OE sūcan shows a different irregular development (early shortening of the vowel), and the word “louk” < OE lūcan is now obsolete or dialectal.
- crook: The OED says < "Middle English crōk, crōc, apparently < Old Norse krókr"
- rook (chess piece): The OED says "< Anglo-Norman and Middle French roc",
ultimately "< Arabic ruḵḵ"
- rookie: uncertain etymology
- cookie: The OED says “probably < Dutch koekje /ˈkuːkjə/ diminutive of koek 'cake',"
I think its pronunciation has possibly been influenced by English "cook"
Before the coronal plosives (t d): several possibilities.
-ood. Early Modern English /uːd/ seems to have only sometimes been shortened to /ʊd/; this is perhaps comparable to the inconsistent shortening of -ead from Middle English /ɛːd/ (as in bead, thread). This shortening seems to have occured before the /ʊ/ > /ʌ/ change in a couple of words. “Wood” is a special case that actually maybe never had a long vowel (I don’t actually know); see section on “woo-” below.
/uːd/ < OE -ōd /oːd/: brood, food, mood (emotional), rood, snood
/ʊd/ < OE -ōd /oːd/: good, stood, hood
< OE -ād /ɑːd/: -hood (irregular vowel development between OE and MidE)
< OE -ud /ud/: wood; see section on “woo-” below.
/ʌd/ < OE -ōd: flood, blood (apparently shortened before /ʊ/ > /ʌ/ change)
-oot. Shortening is variable and apparently fairly recent in at least some cases. (There's some dialectal variation today for root.) Perhaps comparable to the inconsistent shortening of -eat from Middle English /ɛːt/ (as in meat, sweat).
- /ʊt/: soot, foot only
- /uːt/: shoot, boot, many others
- variable /uːt/ or /ʊt/: root
Before the labial non-plosive consonants (f m): sometimes variable.
-oof. Early Modern English /uːf/ seems to have only shortened to /ʊf/ variably and fairly recently. This is perhaps comparable to the inconsistent shortening of -eaf from Middle English /ɛːf/ (as in leaf, deaf). It’s also interesting to compare this to the early shortening of Early Modern English /uːv/ > /uv/ > /ʊv/ > /ʌv/ that apparently occured in the words glove (< OE glóf), dove (n) (< Germanic *dūƀōn or Old Norse dūfa), and shove (< OE sc(e)úfan).
- variable /uːf/ or /ʊf/ < OE -ōf: roof, hoof
< OE ōwef: woof (weaving) (unusual phonetic development)
- /ʊf/: woof (dog bark) (onomatopoeia; no OE etymon)
-oom. There also seems to be some current variability in the reflex of Early Modern English /uːm/, from Old English /oːm/ or /uːm/:
- /uːm/: gloom, doom
- variable /uːm/ or /ʊm/: room, groom, broom
After the labial semivowel /w/: sometimes short, kind of.
woo-. This isn’t a useful class of words to memorize, but they’re interesting in terms of etymology. The sequence ⟨wu⟩ is uncommon in English spelling (the letter w, as its name implies, used to be written as two u’s, which makes “wu” the awkward sequence ⟨uuu⟩). Consider the spelling of the word “wolf” /wʊlf/ < OE wulf. This tendency to avoid “wu” seems to have led to the predominance of the spellings “wool” (< Old English wull) and “wood” (< Old English widu, wiodu, later wudu) over “wull” and “wud”. Phonetically, the preceding semivowel /w/ seems to have preserved the rounding on the vowel, inhibiting the general Early Modern English change of /ʊ/ to /ʌ/. As far as I can tell, "woof" is unrelated.
I would guess that all speakers use /ʊ/ in these two words; if there are any speakers that use /uː/, that would require some more explanation. It is known that at least some dialects had lengthening of Old English /u/ to Middle English /oː/ in open syllables: this is supposed to be the origin of the Early Modern English pronunciations of above < OE abufan and love < OE lufu with long /uː/ that show up from time to time in poetry. (See "Rhyme in Elizabethan sonnets".) This could at least explain */wu:d/, if that pronunciation exists. I have no idea how */wu:l/ could be explained, if it exists.
Other words containing “woo” (aside from "woof") have long “oo”, such as “woo”, “swoon” and “swoop”. These words tend to have unusual etymologies, often with irregular development from Old English (if they even go back that far).
Before the liquid /r/
Discussed above in the phonetics section.
In all other environments
As said earlier, "oo" is generally long in all other environments.
Sources
Example words taken from Jakub Marian’s useful article on the pronunciation of “oo”, which Josh linked to in a comment on a related question, as well as OneLook Dictionary Seach. OneLook and its indexed dictionaries were used along with the Oxford English Dictionary to find etymological information.
Information on the Great Vowel shift taken in part from this great "Great Vowel Shift" handout from Anthony Kroch's website, which I also learned about from Josh's answer to the following question: Why do "bomb" and "tomb" have different pronunciations?
