His patients ran the spectrum of people living in the Palestine, and beyond, and he journeyed at times to Egypt to care for patients using his alternative techniques. As part of his practice of medicine he authored "The Way of Spiritual Healing according to the Jewish Tradition" (1939), a book published in Hebrew. While working as a medical doctor in Palestine, Sandberg’s pursued his passion for music and he was active as a composer. In 1924, Sandberg began composing music to the Book of Psalms. In 1925, Sandberg’s musical composition, "Kohelet" (Ecclesiastes) was performed in Jerusalem. In 1926, he founded the Palestine Musicians Association together with composers Jacob Weinberg and Solomon Rosowsky. In 1927, he was one of the founders of the Palestine section of the International Society for Contemporary Music. In the same year, he organized concerts for his own works and that of German composer Willi von Moellendorff in Jerusalem and Tel-Aviv; he lectured on the quarter tone system in Palestinian music in Tel-Aviv and offered courses in ear training to performers and composers. In 1928 Sandberg presented a concert in Jerusalem of his own works and those of Arnold Schoenberg. In 1929 he arranged concerts of his works in Germany and published a paper on his theory of microtonal music entitled, “Die Musik der Menschheit: Die Ton-Differenzierung und ihre Bedeutung” at the Hochschule für Musik in Berlin. He also designed a harmonium with 12th and 16th tones. In 1930, he founded the Hebrew monthly magazine, "Hallel" which included photographs of some instruments of his design. In 1938, Sandberg took part in an international conference on music and art in London. His lecture on microtonal music was later broadcast on the BBC. After the conference, he organized a number of concerts, broadcasts, and lectures of his work in England. The BBC program planner and advocate of contemporary music Edward Clark said that Sandberg was "a composer in whose path new music is following". Sandberg himself settled in the United States after the outset of World War II, later bringing his family to New York City following the end of the war. In 1939, he offered a number of lectures in music in New York including one on radio station WEVD about the “Problems of Palestinian Music”. In 1940, he taught a course at the New York College of Music on the subject of microtonal music.