1. Pronunciation in American English

2. General American
General American (GA), also known as Standard American English (SAE), is a major accent of American English. The accent is not restricted to the United States. Within American English, General American and accents approximating it are contrasted with Southern American English, several Northeastern accents, and other distinct regional accents and social group accents like African American Vernacular English.

3. GA in Media
General American, like British Received Pronunciation (RP) and most standard language varieties of many other societies, has never been the accent of the entire nation. However, it has become widely spoken in many American films, TV series, national news, commercial ads, and American radio broadcasts. The General American accent is most closely related to a generalized Midwestern accent and is spoken particularly by many newscasters. The famous news anchor Walter Cronkite is a good example of a broadcaster using this accent.

4. Regional home of GA
It is commonly believed that General American English evolved as a result of an aggregation of rural and suburban Midwestern dialects, though the English of the Upper Midwest can deviate quite dramatically from what would be considered a "regular" American Accent.
The local accent often gets more distinct the farther north one goes within the Midwest, and the more rural the area, with the Northern Midwest featuring its own dialect North Central American English. The fact that a Midwestern dialect became the basis of what is General American English is often attributed to the mass migration of Midwestern farmers to California and the Pacific Northwest from where it spread.

5. Phonology A table containing the consonant phonemes
The phoneme /ʍ/ is present only in varieties that have not undergone the wine-whine merger. /ʍ/ is often analyzed as a consonant cluster of /hw/. Also, many Americans realize the phoneme /ɹ/ (often transcribed as /r/) as postalveolar, with some possible retroflexion. /t/ undergoes T-glottalization to produce a glottal stop in words like mutton and sit.
Bilabial
Labio- dental
Dental
Alveolar
Post- alveolar
Palatal
Velar
Glottal
Plosive
p  b
t  d
k  ɡ
Affricate
tʃ dʒ
Fricative
f  v
θ ð
s  z
ʃ ʒ h
Nasal m n ŋ
Lateral l
Approximant
(ʍ)  w
A table containing the consonant phonemes

6. Vowels
General American has sixteen or seventeen vowel sounds that can be used in stressed syllables as well as two that can be used only in unstressed syllables. Most of the vowel sounds are monophthongs. The monophthongs of General American are shown in the table below:
Monophthongs
Front
Central
Back
Close i u
Near-close ɪ ʊ
Close-mid e* o*
Mid ə ɚ
Open-mid ɛ
ʌ** ɝ
ɔ~ɒ
Near Open æ ɑ
^* For most speakers, what are often transcribed as /e o/ are realized as [eɪ oʊ], especially in open syllables.
^** The vowel of strut may be more central than back, depending on speaker. For example, speakers from Ohio realize this vowel as an open-mid central unrounded vowel ([ɜ]).

7. Diphtongs
Among speakers who distinguish between /ɑ/ and /ɔ/, the vowel of cot (usually transcribed /ɑ/), is sometimes more of a central vowel which may vary from [a̠] to [ɑ̟], while /ɔ/ is phonetically lower, closer to [ɒ].[10] Among cot-caught merged speakers, /ɑ/ usually remains a back vowel, [ɑ], sometimes showing lip rounding as [ɑʷ] or [ɒ], and, since these speakers do not distinguish between /ɑ/ and /ɔ/, their retracted allophones for /ɑ/ may be identical to the lowered allophones of /ɔ/ among speakers who preserve the contrast.
The diphthongs of General American are shown in the next table:
Diphthongs
Offglide is a front vowel
Offglide is a back vowel
Opener component is unrounded
aɪ eɪ* aʊ
Opener component is rounded ɔɪ
oʊ*

8. Characteristics
While there is not any single formal definition of General American, various features are considered to be part of it, including rhotic pronunciation, which maintains the coda [ɹ] in words like pearl, car, and court. Unlike RP, General American is characterized by the merger of the vowels of words like father and bother, flapping, and the reduction of vowel contrasts before [ɹ]. General American also generally has yod-dropping after alveolar consonants.

9. Recources http://www.uiowa.edu/ http://en.wikipedia.org/