Quietness and a sense of space. They are, says Joni Mitchell, two of the things about the songs she writes and sings or about those of other Canadians like Gordon Lightfoot, that appeal to American audiences.

By contrast, Americans are expressing themselves in songs of bitterness and revolt and "uptightness," she says. A slim Prairie-raised girl in her mid-20s with long blonde hair and high cheekbones, Joni"s conversation is like her singing, at once gentle and intense.

After her Monday night appearance at the Capital she slowly unwound backstage and talked about her western background and growing involvement with the problems of American society. As in her hit song, "Both Sides Now", she tends to see issues from both sides, pausing often to search for a phrase that won't hurt or will express the other side.

The roots of her art are very much fixed in the Prairies, she says. As she talks of their openness, of a single grain elevator on the horizon, it's easy to imagine the young girl watching feather canyons and ice-cream castles in the clouds.

Things musical and things visual are closely linked, she says. New Yorkers must feel "wedged down" between buildings. But while her roots are here, the other side is her concern for violence and brutality in the U.S. She expresses it mainly by inference, talking of the relative simplicity and "healthiness" of Canada. Canada is "more all right" than the States.

"I have to be careful what I say. I don"t want to sound too much like an evangelist." Her songs have something of the same atmosphere, sounding more regretful than cutting when they criticize. When she talks of Canada and the U.S., it"s not a question of nationalism.

"I don't feel that I belong to a country any more," she says slowly. "It's not just me. A lot of people around my age are beginning to feel that we're of the planet Earth, rather than holding to a patriotism that seems to be dangerous."

Born in Fort McLeod, Alta., and raised in Saskatoon, Joni gave up art school in Calgary six years ago to turn to folk singing. She wrote scores of songs and played the coffee houses of Toronto, Detroit and New York, before a quick ascent to success in the last two years.

She would like to come to Canada, she says "she now has a home in the Laurel Canyon part of Los Angeles" but she would feel she was deserting the problems in the U.S. "I am involved" I don"t want to run away from it and bury my head. Yet to a certain extent, living under the tensions down there is a destructive thing."

She pauses to search for an example and adds: "All my friends have long hair. Suddenly the underground is the enemy to many people. I don't think the kids are going about it the right way, though "I mean, calling a cop a pig" they're not very diplomatic."

Joni says she can remain somewhat detached from the American situation, however. If she has to, she can make the "final cop-out" and return to Canada.