Dialect Guide - American Dialects

The IDEA (International Dialects of English Archive) has a list of twelve different sound clips from speech instructors that give a varied understanding of the "standard" or "general" american dialect.

The General American accent can be found in many works. This CD in the Dialect & Spoken Word collection can help you understand how to recognize it.

This refers to the spectrum of ‘standard’ English spoken by newscasters, TV actors, and a large percentage of middle-class Americans.

Prominent Features:

• The short-a (as in cat) is raised and diphthongized before nasal consonants. Hence man and can’t are pronounced something like IPA meən and keənt (“meh-uhn” and “keh-uhnt.”)
• Rhotic, meaning the r is pronounced at the end of words like car and mother.
• Words like lot and rod are pronounced with an unrounded vowel, as lɑt and ɹɑd (“laht” and “rahd”).
• The diphthong in words like boat and rode is pronounced relatively back: i.e. IPA boʊt and roʊd

-Dialect Blog

Topher Grace and Rashida Jones are two great examples of the General American dialect, although many actors have what can be considered a neutral accent.