Vowel Change Because of Syllable Stress

In English, the vowel sound in a syllable often changes depending on if the syllable is stressed or unstressed.  A useful starting point to learn about this is with a sound that sounds like ‘uh’ and is represented by two symbols in the IPA. It is the most common sound in English. It is ubiquitous because in most cases the vowel that is the syllable core changes to this sound when the syllable is unstressed. In unstressed syllables, the sound is called a schwa and is represented by an upside-down ‘e’ [ə].  

One place this happens frequently is the “-ed” suffix following a consonant such as ‘t,’ ‘d,’ or ‘g.’  So we pronounce “waited” [weɪtəd] (WAY-tuhd), the short “uh” separates the ‘t’ sound from the ‘d’ sound. The stress is in the ; [eɪ] (ay) so the ‘e’ is unstressed and pronounced [ə] (uh).

The word “the” [ðə] (thuh) is not stressed, because it is a function word (next section).

The ‘uh’ sound can be a vowel in stressed syllables too. In that case, it is represented by the symbol [ʌ] which is called, “tuned v,” “caret,” “circumflex” and “wedge.” I am calling it ‘wedge” here. Wedge [ʌ] is the symbol for the ‘uh’ sound in words like “but,” “cut,” “shut” which are almost always stressed

This applies in sentences too. If a syllable is unstressed in a sentence, the vowel is usually reduced to a schwa. Function words are not stressed, so the vowels in function words are usually reduced to schwa, as in “I’m going to the store” [aɪm ˈɡoʊɪŋ tə ðə ˈstɔr] (IEm gOH-ing tuh thuh stOR). This is discussed in the next section.

Any English letter that represents a vowel, ‘a,’ ‘e,’ ‘i,’ ‘o,’ or ‘u’ can be reduced to schwa [ə] (or another more central vowel) in an unstressed syllable. Occasionally (more often in some dialects than others) [i] is reduced to [ɪ]. These reductions make English spelling difficult because you can’t sound out the spelling of the word.

What follows are lists of words of one, two, three, and four syllables in four formats. First is the word itself (a “gloss”), next is the word with the stressed syllable in capital letters, then the word in using phonetic spelling with the stressed vowel in capital letters, and final the IPA (International Phonetic Alphabet) spelling. In the IPA spelling, the stressed syllable is proceeded by a stress marker (ˈ).

The lists have phonetic spelling and the IPA spelling of the way that the word is said. In most cases, one of the vowels changes. There are some syllables that are never stressed and even when the word is pronounced slowly you do not make the full vowel sounds.  For instance, the ending ‘-ed’ [əd] for the past tense is never stressed, but it can be stressed in “bed” [bɛd]

Be sure and notice that not every unstressed vowel is reduced to schwa (ə), in some cases, [i] is reduced to [ɪ] which lowers the [i] and makes it more central (see the vowel chart).

Vowel Change in Two-Syllable Words

 WordStressPhonetic SpellingIPA
1.       “again”a-GAINuh-gEnəˈɡɛn
2.       “avoid”a-VOIDuh-vOIdəˈvɔɪd
3.       “behaved”be-HAVEDbi-hAYvdbɪˈheɪvd
4.       ‘billion”BILL-ionbIl-yuhnˈbɪljən
5.       “brilliant”BRILL-iantBɹIl-yuhntˈbɹɪljənt
6.       “buildings”BUILD-ingsbIl-dingzˈbɪldɪŋz
7.       “collapsed”co-LLAPSEDkuh-lApstkəˈlæpst
8.       “discuss”DI-scussdi-skUHsdɪˈskʌs
9.       “hundred”HUN-dredhUHn-druhdˈhʌndɹəd
10.   “kitten”KITT-enkIt-nˈkʰɪʔn̩
11.   “mountain”MOUNT-ainmOUnt-nˈmaʊntn̩
12.   “playful”PLAY-fulplAy-fuhlˈpleɪfəɫ
13.   “police”pol-ICEpuh-lEEspəˈlis

Vowel Changes in Three-Syllable Words

 WordStressPhonetic SpellingIPA
1.        “adequate”AD-e-quateAd-uh-kwuhtˈæɾəkwət
2.        “attention”a-TTEN-tionuh-tEn-shuhnəˈtʰɛnʃən
3.        “attractive”a-TRAC-tiveuh-trAk-tivəˈtɹæktɪv
4.        “complement”COM-ple-mentkAHm-pluh-muhntˈkʰɑmpləmənt
5.        “conference”CON-fer-encekAHn-fuhr-ruhnsˈkʰɑnfɚɹəns
6.        “connection”co-NNEC-tionkuh-nEk-shuhnkəˈnɛkʃən
7.        “customary”CUS-to-marykUHs-tuh-mair-eeˈkʰʌstəmɛri
8.        “difficult”DIF-i-cultdIf-i-kuhltˈdəfɪkəɫt
9.        “dilemma”di-LEMM-aduh-lEm-uhdəˈlɛmə
10.    “documents”DOC-u-mentsdAHk-yuh-muhntsˈdɑkjəmənts
11.    “easily”EA-si-lyEE-zuh-leeˈizəli
12.    “exhaustion”ex-HAUS-tionig-zAHs-chuhnɪɡˈzɑstʃən
13.    “horizon”ho-RIZ-onhuhr-rIEz-nhɚˈɹaɪzn̩
14.    “numerous”NU-mer-ousnOO-muhr-ruhsˈnumɚɹəs
15.    “persistent”per-SIS-tentpuhr-sIs-tuhntpɚˈsɪstənt
16.    “photograph”PHO-to-graphfOH-tuh-grafˈfoʊɾəɡɹæf
17.    “substitute”SUB-sti-tutesUHb-stuh-tootˈsʌbstəˌtut
18.    “terrible”TERR-i-bletAIR-uh-buhlˈtʰɛrəbəɫ
19.    “typical”TYP-i-kuhltIp-uh-kuhlˈtʰɪpəkəɫ

Vowel Changes in Four-Syllable Words

 WordStressPhonetic SpellingIPA
1“copulation”cop-u-LA-tionkahp-yuh-lAY-shuhnkɑpjəˈleɪʃən
2“dictionary”dic-TION-ar-ydIk-shuh-nair-eeˈdɪkʃən'ɛrɪ
3“directory”dir-EC-tor-yduhr-rEk-tuhr-reedɚˈɹɛktɚɹi
4“disestablish”dis-e-STAB-lishdis-uh-stAb-lishˌdɪsəˈstæblɪʃ
5“execution”exe-c-U-tionek-si-kyOO-shuhnˌɛksɪˈkjuʃən
6“insoluble”in-SOL-u-blein-sAHl-yuh-buhlɪnˈsɑljəbəl
7“mandatory”MAN-da-tor-ymAn-duh-tor-eeˈmændəˌtɔri
8“obligation”ob-li-GA-tionahb-luh-gAY-shuhnˌɑbləˈɡeɪʃn̩
9“persecution”per-se-CU-tionpuhr-si-kyOO-shuhnˌpɝsɪˈkjuʃən
10“population”pop-u-LA-tionpahp-yuh-lAY-shuhnˌpɑpjəˈleɪʃən
11“supposedly”su-PPO-sed-lysuh-pOH-zuhd-leesəˈpoʊzədlɪ
12“television”TEL-e-vis-iontEl-uh-vizh-uhnˈtɛləˌvɪʒən
13“termination”ter-mi-NA-tiontuhr-muh-nAY-shuhnˌtɝməˈneɪʃən
14“undoubtedly”un-DOUB-ted-lyuhn-dOU-tuhd-leeˌʌnˈdaʊtədlɪ

Words Where Stress Changes the Meaning

 Word StressPhonetic Spelling
IPAPOSMeaning
1“address”a.AD-dressA-dresæd`ɹɛs(N)A symbolic representation of a location.
b.ad-DRESSuh-drEsəˈdɹɛs(V)Write directions for delivery; direct your focus to.
2“convert”a.CON-vertkAHn-vuhrtˈkɑn,vɝt(N)a person who has been persuaded to change their religious faith or other beliefs.
b.con-VERTkuhn-vUHRtkənˈvɝt(V)Cause to change in form, character, or function.
3“decrease”a.DE-creasedEE-kreesˈdi,kɹis(N)Something that has been reduced.
b.de-CREASEdi-krEEsdɪ`kɹis(V)Cause the reduction of something.
4“invalid”a.IN-val-idin-vuh-luhdɪnvələd(N)A person made weak or disabled by illness or injury.
b.in-VAL-idin-vAL-uhdɪn`væləd(A)The action of object is not valid.
5“recall”a.RE-callrEE-kahl`ɹi,kɑl(N)An act or instance of officially recalling someone or something
b.re-CALLruh-kAHlɹə`kɑl(V)To remember something.
6“refuse”a.RE-fuserEE-fyoosˈɹɛ,fyus(N)Waste or garbage left over from an event.
b.re-FUSEri-fyOOzɹɪ`fjuz(V)To express oneself as unwilling to accept
7“subject”a.SUB-jectsUHb-jiktsʌbd͡ʒɪkt(N)A person or thing that is being discussed, described, or dealt with.
b.sub-JECTsuhb-jEktsəb`d͡ʒɛkt(V)Cause or force to undergo (a particular experience of form of treatment).
8"record"a.RE-cordREE-kordɹɛ'kɚd(N)A vinyl disk with recorded sound.
b.re-CORDruh-kOrdɹɪ'kʰɔrd(V)The act of recording sound.