When an American actor does a bad Irish accent, it's not because he's not trying enough, it may simply be he's trying too hard. The accents sound different, but are actually similar - people in both countries pronounce the "r" sound, for example. Getting the Irish lilt right that takes a bit of doing. That's why there are dialect coaches such as Deborah Hecht. Her job is to help an actor sound less "Oirish" and more "Irish." She recently guided mainly non-Irish actors, such as Oliver Platt, to sound not only believably Irish, but like Dubliners, in the Broadway production of Conor McPherson's play, "Shining City."

Martha Plimpton, who is in "Shining City," says Ms. Hecht helped fine-tune her accent, with advice on the intonations an Irish person would have when emotional. She helped lay the accent groundwork early on so that once into rehearsal, "you start not thinking about it," Ms. Plimpton says.

Ms. Hecht says that for her, dialect is a "costume for your face." This past season alone she helped with accents for a wide range of shows, including Irish ones in "Shining City," British ones for "Tarzan." and southern for "The Color Purple." This summer, she's working on English diction for "The Pirates of Penzance" at Glimmerglass Opera, in Cooperstown, N.Y. And she'll soon start nannying Edwardian accents for "Mary Poppins," which opens on Broadway this fall.

Even broad comedy demands nuance. "The Wedding Singer" is set in New Jersey, but some of the supporting cast members, such as the guitarist and his girlfriend, sound more Jersey than others, for comic effect.

A Matter of Placement

Helping actors acquire an accent can be like a Lucille Ball routine, as Ms. Hecht contorts her mouth to demonstrate how to shape the voice for certain sounds. And some accents that are supposed to be difficult, are actually easy, she says: Most Americans can get a British accent good enough for the stage.

Sometimes, however, an actor can actually acquire too much of an accent, so that it's unintelligible to the average audience. So Ms. Hecht makes sure actors' dialects are comprehensible, as well as in character.

But the sounds of language are constantly changing (the American accent is getting broader, she says), and so does a fashion for accents, depending on the political climate. Middle Eastern accents are being used in more plays, and to keep track of their various nuances, Ms. Hecht has a tape recorder at her side to capture particular phrasings and intonations when she's watching television. She also has a library of recordings, tracks dialects on Internet sites devoted to it, and even gets sound bites that she can use from films.

Ms. Hecht teaches in the graduate acting program at New York University, and credits her ear to growing up in a large musical family. She had trained as an actor and proving to be a natural coach, eventually made the leap to dialect.

She grew up in California, and though she feels she sounds uninflectedly American, it's all a matter of perspective. Her nieces and nephews in California hear something else, she says. "They tell me I have an accent."