Prefixes in American English

I'm having trouble pronouncing prefixes, because I don't know when to reduce some vowels in them and when not to. My dictionaries only confuse me, since they don't seem to follow any rule of thumb... one seems to reduce every final vowel in a prefix, and Merriam Webster don't.

Some examples:
poly- /pɑli/
micro- /maɪkroʊ/
hydro- /haɪdroʊ/
pico- /pikoʊ/

Those are ok, but what happens when they are attached to something else, like in polystyrene, hydrocarbon, hydrochloride, microgram, picofarad, polygon...

Is there a rule of thumb for this? It is driving me crazy... pɑlɪ? maɪkrə? haɪdrə?
Thanks.

To be honest, I don't know of any rule either. But feel free to ask me about any prefixed words, and I'll tell you how I pronounce them (as a native English speaker from Massachusetts).

For the words in your first post, I would say:

[ˌpʰɒːliˈstaɪˌɹi:n], GA [ˌpʰa:liˈstaɪˌɹi:n]
[ˈhaɪdɹəˌkʰɑɚbn]
[ˌhaɪdɹəˈkʰlɔɚaɪd]
[ˈmɐɪkɹəˌgɹæm], GA [ˈmaɪkɹəˌgɹæm]
[ˈpʰɐɪkəˌfæɹəd], GA [ˈpʰaɪkəˌfɛɚəd]
[ˈpʰɒ:liˌgɒ:n], GA [ˈpʰɑ:liˌgɑ:n]

I think "poly" is always [pʰa:li], except in "polymer" [ˈpʰa:ləmɚ]. And I think "hydro" is always [haɪdɹə]. And in my case, at least, all of the SI prefixes end in [ə].

Thanks.
I just thought of something interesting. I think it is possible that the last vowel in prefixes is only reduced (or at least partly reduced) before consonants, unless you try to speak slowly and carefully. So it's often reduced in kilogram, hydrocarbon, polystyrene... but not in microampere, hydroelectric, polyatomic...

Does that make any sense? Of course not everyone pronounce prefixes exactly that way, but you know, as a general rule of thumb...

Oh, definitely: before vowels, I think it's universal to pronounce the last vowel of the prefix unreduced.

But before consonants it's more complex. In "poly", for example, I think it's standard to always pronounce the <y> unreduced.

I tried saying hydrocarbon both ways, as hy-dro-car-bon and as hy-dra-car-bon, and I didn't notice that one sounded more natural than the other. I guess they don't come up in conversation enough to have a preference. But on microscope, I definitely prefer "mi-cra-scope". But I would say "pol-lih-sty-rene" for polystyrene and yet also say "pol-lee-pro-pil-lene" for polypropylene -- so that's a hard question, Johnny!

Yep, it seems a difficult question! Thanks.
I'd just like to ask... how should I pronounce the Y in "polygon"? The dictionaries I checked don't agree with each other, so I'd just like to get an opinion.

<<I'd just like to ask... how should I pronounce the Y in "polygon"? The dictionaries I checked don't agree with each other, so I'd just like to get an opinion. >>

If the dictionaries don't agree, it probably doesn't matter exactly how you pronounce it.

And you can probably forget about finding any hard and fast spelling and pronunciation rules in English. Consider "micrometer" (the measuting device, not the formal synonym for micron) and "polygamy".

I'd call it more of a standard term than a formal synonym.

<<And you can probably forget about finding any hard and fast spelling and pronunciation rules in English. Consider "micrometer" (the measuting device, not the formal synonym for micron) and "polygamy".>>

Yes, but the measuring device is not a little meter (micro-meter), and polygamy is not made up of several gamy, so those are not used as prefixes... A real exception could be kilometer pronounced with the main stress on "lo", unlike kilogram, kilovolt, etc.

But I don't know if polygon is polih-gone or poly-gone. You know, the problem with such words for a learner like me is that these kinds of terms are not likely to be heard much, so practicing listening is not really of great help.

There also seem to be another exception. The stress in units of measurement is usually on the SI prefix (KI-logram, MI-crofarad, NA-nometer...), but that doesn't seem to apply to amperes. So it should be MI-croamps, but micro-AMpere. Is this true?
Thanks again.

>>Those are ok, but what happens when they are attached to something else, like in polystyrene, hydrocarbon, hydrochloride, microgram, picofarad, polygon...<<

I just had to provide my own pronunciations, which are similar to Lazar's and GA's pronunciations, but have some notable differences which are of note here (such as the pronunciation of "pico", and whether reduction of final vowels in prefixes is mandatory):

polystyrene: [pʰa̠ːɰiˈsʲtʲəːe̯ʁĩːn]
hydrocarbon: [həːe̯dʒɹ̠oˈkʰɑːʁbɨ̃ːn], [həːe̯dʒɹ̠oˈkʰɑːʁbn̩ː], [həːe̯dʒɹ̠əˈkʰɑːʁbɨ̃ːn], [həːe̯dʒɹ̠əˈkʰɑːʁbn̩ː]
hydrochloride: [həːe̯dʒɹ̠oˈkʰx̆ɰɔːʁaːe̯d̥], [həːe̯dʒɹ̠əˈkʰx̆ɰɔːʁaːe̯d̥]
microgram: [məe̯kʁoːˈgʁɛ̯̃æ̃ːm], [məe̯kʁəːˈgʁɛ̯̃æ̃ːm]
picofarad: [pʰɨkoˈfɛ̝ːʁɨːd̥], [pʰɨkəˈfɛ̝ːʁɨːd̥]
polygon: [ˈpʰa̠ːɰiːgãːn]

Here are some other words mentioned above that I provided pronunciations for for the sake of comparison:

microampere: [məe̯kʁoːˈɛ̯̃æ̃mpɪːʁ], [məe̯kʁoːˈɛ̯̃æ̃mpiːʁ̩ː], [məe̯kʁəːˈɛ̯̃æ̃mpɪːʁ], [məe̯kʁəːˈɛ̯̃æ̃mpiːʁ̩ː]
hydroelectric: [həːe̯dʒɹ̠oːəˈɰɜ̟ktʃɹ̠ɨk], [həːe̯dʒɹ̠əːːˈɰɜ̟ktʃɹ̠ɨk]
polyatomic: [pʰa̠ːɰiːəˈtʰãːmɨk]
microscope: [ˈməe̯kʁəskop]
polypropylene: [pʰa̠ːɰiˈpʰʁopʊːwĩːn]
micrometer (device): [məe̯ˈkʰʁɑ̃ːmɨɾ̥ʁ̩ː]
micron: [ˈməe̯kʁãːn]
polygamy: [pʰəːˈɰɪːgə̃ːmiː]

Ok, thanks. I see everyone pronounce words their own way. :-)

I also have to say I am not able to understand much about "advanced" IPA, like the one in Travis's transcriptions. For example, I noticed a lot of interesting (or strange) features in the way you speak, but I don't know if it's just me that don't understand, lol. But that's another matter... I'll probably open more specific threads.

***...just me that don't understand... ---> ...just me that doesn't understand...***

Sorry, sometimes I feel I am too influenced by African American English... sometimes I catch myself writing "she don't..." :-)

>>Ok, thanks. I see everyone pronounce words their own way. :-)

I also have to say I am not able to understand much about "advanced" IPA, like the one in Travis's transcriptions. For example, I noticed a lot of interesting (or strange) features in the way you speak, but I don't know if it's just me that don't understand, lol. But that's another matter... I'll probably open more specific threads.<<

Part of my transcriptions above is that they are very narrow transcriptions, and I am including both vowel length and vowel nasalization. Some differences between my transcription and Lazar's of his own dialect and GA are trivial and are just as much differences in transcription practices as in actual pronunciation, such as the difference between [aɪ̯] and [ae̯] and between [ɪ] and [ɨ]. Also, others reflect common differences between English dialects, such as the difference between [tɹ] and [tʃɹ̠], variation in the exact distribution of [ə] versus [ɨ], and variation in the specific nature of vowel reduction. These are things that are actually of little significance within English dialects overall, and free variation of such really is unlikely to affect intelligiblity as a whole, at least amongst native speakers.

On the other hand, there are some aspects of my dialect which are markedly different from GA and Lazar's dialect, such as my realization of historical /r/ and /l/, the my marked NCVS, my use of a monophthongal /o/, and my very broad Canadian Raising (Lazar has Canadian Raising, but his is narrower in scope than my own). Similarly, my explicit marking of vowel length and nasalization is due to such actually being potentially distinctive in my dialect. Very many individuals do not mark such in their transcriptions because in many English dialects such are of little consequence, but in my dialect they are actually necessary for proper comprehension in cases, and very much make things "sound wrong" when they are incorrect even when intelligibility is not affected.

>>***...just me that don't understand... ---> ...just me that doesn't understand...***

Sorry, sometimes I feel I am too influenced by African American English... sometimes I catch myself writing "she don't..." :-)<<

That's not specifically an AAVE feature. While such is the norm in AAVE, one will frequently hear it in non-AAVE dialects as well. For instance, in the dialect around here (other than AAVE), you can often hear individuals use "don't" rather than "doesn't" if their speech is not influenced much by GA. Mind you that such is still linked to social class here even amongst white people; "don't" in the place of "doesn't" tends to be associated with lower social class combined with basilectal speech here, and is not even present in the lowest registers in the speech of most middle class people here (which can otherwise be quite non-standard amongst younger people).