The contemporary music concert series, Tuesday Tanglewood Trends, brings to the summer haunts of the Boston Symphony Orchestra the sweetest folk and blues sounds on the contemporary music scene.

On the evening of July 22 in the third concert of the series, the shed will host Joni Mitchell. Tim Hardin and the Butterfield Blues Band.

A native of Saskatchewan, Canada, Joni has been spending her time south of the border. Known for her sincerity and simplicity, the Canadian folk singer charms her audience without any histrionics. Accompanying herself on acoustical guitar, Joni sings mostly her own compositions; the writing is graceful poetry, the melodies lilting and beautiful.

Tim Hardin, who wrote and sang the original "If I Were a Carpenter," will be adding his own brand of folk-rock to the performance. Known, as is Joni Mitchell, for the sensitivity of his music. Hardin has a voice that "quavers between the tugs of blues and the tender side of joy."

Paul Butterfield, the bluest white musician of his generation, will "bounce chords off the ceiling and up from the floor" in a characteristic fusion of modern sounds in an old style. With its various music and musicians, this concert should illume two contrasting colors in the spectrum of modern music that the Tanglewood series is designed to portray.