[11][12][13][1] He has released and appeared on dozens of albums, film, theatre and dance score recordings as a soloist, accompanist and with all his ensembles.

[30] During the late 60's and early 70's, Armstrong was greatly influenced by the civil and equal rights movements and anti-Vietnam War demonstrations.

[3] In 1973, Armstrong moved to New Hampshire and in 1974,[31] met classically trained flute player Ken LaRoche and with him formed the music group Do’a (a Persian word meaning "a call to prayer and meditation").

[35][32][36] In 1986, Do’a World Music Ensemble received official recognition from the United Nations for their concert tour promoting the International Year of Peace.

[15][16] In 1992, Armstrong co-founded the Contemporary Jazz / World Fusion music group, Unu Mondo with bassist and composer Volker Nahrmann.

[45] Unu Mondo appeared on the compilation albums, World Visions – The Rhythms, Ageless Pathway and Enlightened Minds released by Global Pacific Records in 1996.

[42] In 1998 through 2000, Armstrong was commissioned to score and record the original soundtrack for the PBS television series, Dinner on the Diner, filmed in South Africa, Spain, Scotland and Southeast Asia (Thailand and Malaysia).

[62] After the signing of the Good Friday Agreement in 1998, Armstrong was selected as an artist representative to attend a Cultural Trade Mission to Ireland, Northern Ireland and England sponsored by Governor Jeanne Shaheen of New Hampshire[61] and in May 2005 attended a Curatorial Research trip on Son Jarocho music in Xalapa and Veracruz, Mexico for the Boston based New England Foundation for the Arts.

[63] Armstrong was the director of the African Drumming and World Percussion Ensemble[64] and instructor of North Indian sitar and tabla at Phillips Exeter Academy in New Hampshire from 1991 to 2020.